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External morphology of Lepidoptera

The external morphology of Lepidoptera is the physiological structure of the bodies of insects belonging to the order Lepidoptera, also known as butterflies and moths. Lepidoptera are distinguished from other orders by the presence of scales on the external parts of the body and appendages, especially the wings. Butterflies and moths vary in size from microlepidoptera only a few millimetres long, to a wingspan of many inches such as the Atlas moth. Comprising over 160,000 described species, the Lepidoptera possess variations of the basic body structure which has evolved to gain advantages in adaptation and distribution.[1]

The head of a small white butterfly (Pieris rapae). Note the upward pointing labial palpi on both sides of the coiled proboscis.
Comparison of moth and butterfly dorsal anatomy.
Adult Essex skipper (Thymelicus lineola)
Pupa of a sphingid moth
Caterpillar of the subfamily Arctiinae
Eggs of the buff-tip (Phalera bucephala), a notodontid moth

Lepidopterans undergo complete metamorphosis, going through a four-stage life cycle: egg, larva or caterpillar, pupa or chrysalis, and imago (plural: imagines) / adult. The larvae – caterpillars – have a toughened (sclerotised) head capsule, chewing mouthparts, and a soft body, that may have hair-like or other projections, three pairs of true legs, and up to five pairs of prolegs. Most caterpillars are herbivores, but a few are carnivores (some eat ants, aphids, or other caterpillars) or detritivores.[2] Larvae are the feeding and growing stages and periodically undergo hormone-induced ecdysis, developing further with each instar, until they undergo the final larval–pupal moult. The larvae of many lepidopteran species will either make a spun casing of silk called a cocoon and pupate inside it, or will pupate in a cell under the ground. In many butterflies, the pupa is suspended from a cremaster and is called a chrysalis.

The adult body has a hardened exoskeleton, except for the abdomen which is less sclerotised. The head is shaped like a capsule with appendages arising from it. Adult mouthparts include a prominent proboscis formed from maxillary galeae, and are adapted for sucking nectar. Some species do not feed as adults, and may have reduced mouthparts, while others have them modified for piercing and suck blood or fruit juices.[3] Mandibles are absent in all except the Micropterigidae which have chewing mouthparts.[4] Adult Lepidoptera have two immobile, multi-faceted compound eyes, and only two simple eyes or ocelli, which may be reduced.[5] The three segments of the thorax are fused together. Antennae are prominent and besides the faculty of smell, also aid navigation, orientation, and balance during flight.[6] In moths, males frequently have more feathery antennae than females, for detecting the female pheromones at a distance. There are two pairs of membranous wings which arise from the mesothoracic (middle) and metathoracic (third) segments; they are usually completely covered by minute scales. The two wings on each side act as one by virtue of wing-locking mechanisms. In some groups, the females are flightless and have reduced wings. The abdomen has ten segments connected with movable inter-segmental membranes. The last segments of the abdomen form the external genitalia. The genitalia are complex and provide the basis for family identification and species discrimination.[7]

The wings, head parts of thorax, and abdomen of Lepidoptera are covered with minute scales, from which feature the order Lepidoptera derives its names, the word lepidos in Ancient Greek meaning "scale". Most scales are lamellar (blade like) and attached with a pedicel, while other forms may be hair like or specialised as secondary sexual characteristics. The lumen, or surface of the lamella, has a complex structure. It gives colour either due to the pigments contained within it or through its three-dimensional structure.[8] Scales provide a number of functions, which include insulation, thermoregulation, and aiding flight, amongst others, the most important of which is the large diversity of vivid or indistinct patterns they provide which help the organism protect itself by camouflage, mimicry, and to seek mates.

External morphology edit

 
Parts of an adult butterfly: A: Forewing; B: Antenna; C: Compound eye; D: Proboscis; E: Thorax; F: Leg; G: Abdomen; H: Hindwing; I: Tail

In common with other members of the superorder Holometabola, Lepidoptera undergo complete metamorphosis, going through a four-stage life cycle: egg, larva / caterpillar, pupa / chrysalis, and imago (plural: imagines) / adult.[9]

Lepidopterans range in size from a few millimetres in length, such as in the case of microlepidoptera, to a wingspan of many inches, such as the Atlas moth and the world's largest butterfly Queen Alexandra's birdwing.[10]: 246 

General body plan edit

The body of an adult butterfly or moth (the imago) has three distinct divisions, called tagmata, connected at constrictions; these tagmata are the head, thorax, and abdomen. Adult lepidopterans have four wings – a forewing and a hindwing on both the left and the right side of the thorax – and, like all insects, three pairs of legs.[11]

The morphological characteristics which distinguish the order Lepidoptera from other insect orders are:[10]: 246 

  • Head: The head has large compound eyes and, if mouthparts are present, they are almost always a drinking straw-like proboscis.
  • Scales: Scales cover the external surface of the body and appendages.
  • Thorax: The prothorax is usually reduced.
  • Wings: Two pairs of wings are present in almost all taxa. The wings have very few cross veins.
  • Abdomen: The posterior abdominal segments are extensively modified for reproduction. Cerci are absent.
  • Larva: Lepidoptera larvae are known as caterpillars, and have a well-developed head and mandibles. They can have from zero to five pairs of prolegs, usually four.
  • Pupa: The pupae in most species are adecticous (with no functional mandibles in the pupal state) and obtect (with appendages fused or glued to the body), while others are decticous (with functional mandibles present in the pupal state) and exarate (having the antennae, legs, and wings free).

Distinguishing taxonomic features edit

The chief characteristics used to classify lepidopteran species, genera, and families are:[12]

  • the mouthparts
  • the shape and venation of the wings
    • whether the wings are homoneurous (the venation of the forewings and hindwings alike) or heteroneurous (forewings and hindwings different)
    • whether the wings are aculeate (more or less covered with specialized bristles called microsetae) or nonaculeate
    • the type of wing coupling (jugate or frenate)
  • the anatomy of the reproductive organs
  • the structure of larva and position of primary setae
  • whether the pupa is exarate or obtect

The morphological characteristics of caterpillars and pupae used for classification are completely different from that of adults;[13]: 637 [14] different classification schemes are sometimes provided separately for classifying adults, larvae, and pupae.[14][15]: 28–40  The characteristics of immature stages are increasingly used for taxonomic purposes as they provide insights into systematics and phylogenies of Lepidoptera that are not apparent from examination of adults.[15]: 28 

Head edit

 
Lepidoptera head illustration from G. F. Hampson's Moths of British India Vol. 1 (1892)

Like all animal heads, the head of a butterfly or moth contains the feeding organs and the major sense organs. The head typically consists of two antennae, two compound eyes, two palpi, and a proboscis.[11] Lepidoptera have ocelli which may or may not be visible. They also have sensory structures called chaetosemata, the functions of which are largely unknown. The head is filled largely by the brain, the sucking pump, and its associated muscle bundles.[16] Unlike the adults, the larvae have one-segmented mandibles.[16]

The head capsule is well sclerotised and has a number of sclerites or plates, separated by sutures. The sclerites are difficult to distinguish from sulci (singular – sulcus) which are secondary thickenings. The regions of the head have been divided into a number of areas which act as a topographical guide for description by lepidopterists but cannot be discriminated in terms of their development.[16] The head is covered by hair-like or lamellar scales and found either as tufts on the frons or vertex (referred to as rough-scaled) or pressed close to the head (referred to as smooth-scaled).

The sensory organs and structures on the head show great variety, and the shape and form of these structures, as also their presence or absence, are important taxonomic indicators for classifying taxa into families.[13]

Antennae edit

 
 
Sexual dimorphism in antennae in Caligula japonica family Saturniidae: feathery antennae of male (left) and linear form in female (right)

Antennae are prominent paired appendages that project forwards between the animal's eyes and consist of a number of segments. In the case of butterflies, their length varies from half the length of the forewing to three-quarters of the length of the forewing. The antennae of butterflies are either slender and knobbed at the tip and, in the case of the Hesperiidae, are hooked at the tip. In some butterfly genera such as Libythea and Taractrothera the knob is hollowed underneath.[11] Moth antennae are either filiform (thread like), unipectinate (comb like), bipectinate (feather like), hooked, clubbed, or thickened.[13]: 636  Bombyx mandarina is an example with bipectinate antennae.[17] Some moths have knobbed antennae akin to those of butterflies, such as the family Castniidae.[18]

Antennae are the primary organs of olfaction (smell) in Lepidoptera. The antenna surface is covered with large numbers of olfactory scales, hairs, or pits; as many as 1,370,000 are found on the antennae of a monarch. Antennae are extremely sensitive; the feathered antennae of male moths from the Saturniidae, Lasiocampidae, and many other families are so sensitive that they can detect the pheromones of female moths from distances of up to 2 km (1.2 mi) away. Lepidoptera antennae can be angled in many positions. They help the insect in locating the scent and can be considered to act as a kind of "olfactory radar".[6] In moths, males frequently have antennae which are more feathery than those of the females, for detecting the female pheromones at a distance.[7] Since females do not need to detect the males, they have simpler antennae.[6] Antennae have also been found to play a role in the time-compensated sun compass orientation in migratory monarch butterflies.[19]

Eyes edit

 
Front view of the compound eyes of Aglais io.
 
Ocellus of Mythimna unipuncta seen to the right of base of antenna, in close contact with the compound eye.

Lepidoptera have two large, immovable compound eyes which consist of a large number of facets or lenses, each connected to a lens-like cylinder which is attached to a nerve leading to the brain.[11] Each eye may have up to 17,000 individual light receptors (ommatidia) which in combination provide a broad mosaic view of the surrounding area.[6] One tropical Asian family, the Amphitheridae, has compound eyes divided into two distinct segments.[13][20] The eyes are usually smooth but may be covered by minute hairs. The eyes of butterflies are usually brown, golden brown, or even red as in the case of some species of skippers.[11]

While most insects have three simple eyes, or ocelli, only two ocelli are present in all species of Lepidoptera, except a few moths, one on each side of the head near the edge of the compound eye. On some species, sense organs called chaetosemata are found near the ocelli.[11][21] The ocelli are not homologous to the simple eyes of caterpillars which are differently named as stemmata.[5] The ocelli of Lepidoptera are reduced externally in some families; where present, they are unfocussed, unlike stemmata of larvae which are fully focussed. The utility of ocelli is not understood at present.[5]

Butterflies and moths are able to see ultraviolet (UV) light, and wing colours and patterns are principally observed by Lepidoptera in these wavelengths of light.[13] The patterns seen on their wing under UV light differ considerably from those seen in normal light. The UV patterns act as visual cues which help differentiate between species for the purpose of mating. Studies have been carried out on Lepidoptera (mostly butterflies) wing patterns illuminated by UV light.[13]

Palpi edit

 
Gastropacha populifolia (family Lasiocampidae) with modified mouthparts

Typically, the labial palpi are prominent, three-segmented, springing from under the head and curving up in front of the face.[7] There is great variation in morphology of labial palpi in different families of Lepidoptera; sometimes the palpi are separate and sometimes they are connivent and form a beak, but they are always independently movable. In other cases, the labial palpi may not be erect but porrect (projecting forward horizontally).[11][13] Palpi consist of a short basal segment, a comparatively long central segment, and a narrow terminal portion. The first two segments are densely scaled and may be hirsute; the terminal segment is bare. The terminal segment may be blunt or pointed; it may project straight or at an angle from the second segment inside which it may be concealed.[11]

Mouthparts edit

 
Butterfly proboscis, showing the structure of the two galeae that comprise it.
 
Legend: Section of mouthparts of Lepidoptera. a: pilifer (labrum); b: epipharynx (labrum); c: galea (maxilla); d: trachea; e: nerve; f: muscles; g: food canal; h: labium; i: labial palp

While mandibles or jaws (chewing mouthparts) are only present in the caterpillar stage, the mouthparts of most adult Lepidoptera mainly consist of the sucking kind; this part is known as the proboscis or haustellum. A few Lepidoptera species have reduced mouthparts and do not feed in the adult state. Others, such as the basal family Micropterigidae, have chewing mouthparts.[21]

The proboscis (plural – proboscises) is formed from maxillary galeae and is adapted for sucking nectar.[3] It consists of two tubes held together by hooks and separable for cleaning. Each tube is inwardly concave, thus forming a central tube up which moisture is sucked. Suction is effected through the contraction and expansion of a sac in the head.[11] The proboscis is coiled under the head when the insect is at rest and extended only when feeding.[16] The maxillary palpi are reduced and even vestigial. They are conspicuous and five segmented in some of the more basal families and are often folded.[7]

The shape and dimensions of the proboscis have evolved to give different species a wider and therefore more advantageous diet.[3] There is an allometric scaling relationship between body mass of Lepidoptera and length of proboscis[22] from which an interesting adaptive departure is the unusually long-tongued sphinx moth Xanthopan morganii praedicta. Charles Darwin predicted the existence and proboscis length of this moth before its discovery based on his knowledge of the long-spurred Madagascan star orchid Angraecum sesquipedale.[23]

There are primarily two feeding guilds in Lepidoptera – the nectarivorous who obtain the majority of their nutritional requirements from floral nectar and those of the frugivorous guild who feed primarily on juices of rotting fruit or fermenting tree sap. There are substantial differences between the morphology of the proboscises of both feeding guilds. Hawkmoths (family Sphingidae) have elongated proboscises which enable them to feed on and pollinate flowers with long tubular corollas. Besides this, a number of taxa (especially noctuid moths) have evolved different proboscis morphologies. Certain noctuid species have developed piercing mouthparts; the proboscis has sclerotised scales on the tip with which to pierce and suck blood or fruit juices. Proboscises in some Heliconius species have evolved to consume solids such as pollen.[24] Some other moths, mostly noctuids, have modified proboscises to suit their mode of nutrition – lachrymophagy (feeding on tears of sleeping birds). The proboscises often have sharp apices as well as a host of barbs and spurs on the stem.[25][26]

Thorax edit

 
The forelegs are reduced in the Nymphalidae
 
Diagram of an insect leg

The thorax, which develops from segments 2, 3, and 4 of the larva, consists of three invisibly divided segments, namely prothorax, metathorax, and mesothorax.[11] The organs of insect locomotion – the legs and wings – are borne on the thorax. The forelegs spring from the prothorax, the forewings and middle pair of legs are borne on the mesothorax, and the hindwings and hindlegs arise from the metathorax. In some cases, the wings are vestigial.[11][27]

The upper and lower parts of the thorax (terga and sterna respectively) are composed of segmental and intrasegmental sclerites which display secondary sclerotisation and considerable modification in the Lepidoptera. The prothorax is the simplest and smallest of the three segments while the mesothorax is the most developed.[27]

Between the head and thorax is the membranous neck or cervix. It comprises a pair of lateral cervical sclerites and is composed of both cephalic and thoracic elements.[10]: 71 [27] Between the head and the thorax is a tufted scale called the pronotum. On either side is a shield-like scale called a scapula.[11] In the Noctuoidea, the metathorax is modified with a pair of tympanal organs.[7]

Leg edit

Forelegs in the Papilionoidea exhibit reduction of various forms: the butterfly family Nymphalidae, or brush-footed butterflies as they are commonly known, have only the rear two pairs of legs fully functional with the forward pair strongly reduced and not capable of walking or perching. In the Lycaenidae, the tarsus is unsegmented, as the tarsomeres are fused, and, tarsal claws are absent. The aroliar pad (a pad projecting between the tarsal claws of some insects) and pulvilli (singular: pulvillus, a pad or lobe beneath each tarsal claw) are reduced or absent in the Papilionidae. The tarsal claws are also absent in the Riodinidae.[28]

In Lepidoptera, the three pairs of legs are covered with scales.[13] Lepidoptera also have olfactory organs on their feet which aid in "tasting" or "smelling" food plants.[6]

Wings edit

Adult Lepidoptera have two pairs of membranous wings covered, usually completely, by minute scales. A wing consists of an upper and lower membrane which are connected by minute fibres and strengthened by a system of thickened hollow ribs, popularly but incorrectly referred to as "veins", as they may also contain tracheae, nerve fibres, and blood vessels.[11][29] The membranes are covered with minute scales which have jagged ends or hairs and are attached by hooks. The wings are moved by the rapid muscular contraction and expansion of the thorax.[11]

The wings arise from the meso- and meta-thoracic segments and are similar in size in the basal groups. In more derived groups, the meso-thoracic wings are larger with more powerful musculature at their bases and more rigid vein structures on the costal edge.[7]

Besides providing the primary function of flight, wings also have secondary functions of self-defence, camouflage and thermoregulation.[3][30] In some Lepidoptera families such as the Psychidae and Lymantriidae, the wings are reduced or even absent (often in the female but not the male).[7]

Shape edit

The shape of wings exhibits great variety in Lepidoptera. In the case of the Papilionoidea, the costa may be straight or highly arched. It is sometimes concave on the hindwing. It is occasionally serrate or minutely saw toothed on the forewing. The apex may be rounded, pointed, or falcate (produced and concave below). The termen tends to be straight or concave on the forewing while it is usually more or less convex on the hindwing. The termen is often crenulate or dentate, i.e. produced at each vein and concave in between them. The dorsum is normally straight but may be concave.[11]

The hindwing is frequently caudate, i.e. the veins near the end of the tornus have one or more tails. The tornus itself being often produced and frequently lobed.[11] Along the hindwing termen there are tightly packed scales in a double row. The underside of the scales project and form a regular narrow fringe referred to as cilia.[11]

Venation edit

 
Terms associated with the wings. For detailed explanation, refer Glossary of entomology terms.
 
An adult male pine processionary moth (Thaumetopoea pityocampa). Notice the bristle springing from the underside of the hindwing (frenulum) and running forward to be held in a small catch of the forewing, the function of which is to link the wings together.

Tubular veins run through the two-layered membranous wing. Veins are connected to the haemocoel and in theory allow haemolymph to flow through them. In addition, a nerve and trachea may pass through the veins.[29]

Lepidopteran venation is simple in that there are few crossbars.[15]: 88  The wing venation in Lepidoptera is a diagnostic for distinguishing between the taxa as also the genera and families.[13] The terminology is based on the Comstock-Needham system which gives the morphological description of insect wing venation.[32] In the basal Lepidoptera, the venation of the forewing is similar to that of the hindwing; a condition referred to as "homoneurous". The Micropterigidae (Zeugloptera) have venation that resembles the most primitive caddisflies (Trichoptera). All other Lepidoptera, the vast majority (around 98%), are "heteroneurous", the venation of the hindwing differing from that from the forewing and being sometimes reduced. Moths of the families Nepticulidae, Opostegidae, Gracillariidae, Tischeriidae, and Bucculatricidae, amongst others, often have greatly reduced venation in both wings.[13]: 635 [32]: 56  Homoneurous moths tend to have the "jugum" form of wing coupling as opposed to the "frenulum–retinaculum" arrangement in the case of more advanced families.

Wing coupling edit

 
Oiketicus spp. (family Psychidae). The frenulum can be seen at the top of the rear wing, which hooks onto the retinaculum so that the wings travel together during flight. Magnification: 10x

The Lepidoptera have developed a wide variety of morphological wing-coupling mechanisms in the imago which render these taxa "functionally dipterous" (two winged).[33] All but the most basal forms exhibit this wing coupling.[34] There are three different types of mechanisms – jugal, frenulo–retinacular, and amplexiform.[35]

The more primitive groups have an enlarged lobe-like area near the basal posterior margin (i.e. at the base of the forewing) called a jugum, that folds under the hindwing during flight.[7][34] Other groups have a frenulum on the hindwing that hooks under a retinaculum on the forewing.[7]

In all butterflies (with the exception of male Euschemoninae) and in Bombycoidea moths (with the exception of the Sphingidae), there is no arrangement of frenulum and retinaculum to couple the wings. Instead, an enlarged humeral area of the hindwing is broadly overlapped by the forewing. Despite the absence of a specific mechanical connection, the wings overlap and operate in phase. The power stroke of the forewing pushes down the hindwing in unison. This type of coupling is a variation of frenate type but where the frenulum and retinaculum are completely lost.[33][36]

Scales edit

 
Wing scales form the colour and pattern on wings. The scales shown here are lamellar. The pedicel can be seen attached to a few loose scales.

The wings of Lepidoptera are minutely scaled, which gives the name to this order; the name Lepidoptera was coined in 1735 by Carl Linnaeus for the group of "insects with four scaly wings". It is derived from Ancient Greek lepis (λεπίς) meaning "(fish) scale" (and related to lepein "to peel") and pteron (πτερόν) meaning "wing".[37]

Scales also cover the head, parts of the thorax and abdomen as well as parts of the genitalia. The morphology of scales has been studied by J. C. Downey and A. C. Allyn (1975)[38] and scales have been classified into three groups, namely hair-like, or piliform, blade-like, or lamellar and other variable forms.[8]

Primitive moths (non-Glossata and Eriocranidae) have "solid" scales which are imperforate, i.e., they lack a lumen.[8]

A few taxa of the Trichoptera (caddisflies), which are the sister group to the Lepidoptera, have hair-like scales, but always on the wings and never on the body or other parts of the insect.[13] Caddisflies also possess caudal cerci on the abdomen, a feature absent in the Lepidoptera.[7] According to Scoble (2005),[8] "morphologically, scales are macrotrichia, and thus homologous with the large hairs (and scales) that cover the wings of Trichoptera (caddisflies)".

Structure edit

Although there is great diversity in scale form, they all share a similar structure. Scales, like other macrochaetes, arise from special trichogenic (hair-producing) cells and have a socket which is enclosed in a special "tormogen" cell;[15]: 9  this arrangement provides a stalk or pedicel by which scales are attached to the substrate. Scales may be piliform (hairlike) or flattened. The body or "blade" of a typical flattened scale consists of an upper and lower lamella with an air space in between. The surface towards the body is smooth and known as the inferior lamella. The upper surface, or superior lamella, has transverse and longitudinal ridges and ribs. The lamellae are held apart by struts called trabaculae and contain pigments which give colour. The scales cling somewhat loosely to the wing and come off easily without harming the butterfly.[8][13][39]

Colour edit

The scales on butterfly wings are pigmented with melanins that can produce the colours black and brown. The white colour in the butterfly family Pieridae is a derivative of uric acid, an excretory product.[13][40]: 84  Bright blues, greens, reds, and iridescence are usually created not by pigments but through the microstructure of the scales. This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales.[41][42][43] The specialised scales that provide structural colours to reflected light mostly produce ultraviolet patterns which are discernible in that part of the ultraviolet spectrum that lepidopteran eyes can see.[13] The structural colour seen is often dependent upon the angle of view. For example, in Morpho cypris, the colour from the front is a bright blue but when seen from an angle changes very quickly to black.[44]

The iridescent structural coloration on the wings of many lycaenid and papilionid species, such as Parides sesostris and Teinopalpus imperialis, and lycaenids such as Callophrys rubi, Cyanophrys remus, and Mitoura gryneus, has been studied.[45] They manifest the most complex photonic scale architectures known – regular three-dimensional periodic lattices, that occur within the lumen of some scales.[46] In the case of the Kaiser-i-Hind (Teinopalpus imperialis), the three-dimensional photonic structure has been examined by transmission electron tomography and computer modelling to reveal naturally occurring "chiral tetrahedral repeating units packed in a triclinic lattice",[47][48] the cause of the iridescence.

Function edit

 
Closeup of male Luna moth eyespot
 
Androconial patch on hindwing of Bicyclus anynana, a nymphalid

Scales play an important part in the natural history of Lepidoptera. Scales enable the development of vivid or indistinct patterns which help the organism protect itself by camouflage, mimicry, and warning. Besides providing insulation, dark patterns on wings allow sunlight to be absorbed and are probably involved in thermoregulation. Bright and distinctive colour patterns in butterflies which are distasteful to predators help communicate their toxicity or inedibility, thus preventing predation. In Batesian mimicry, wing colour patterns help edible lepidopterans mimic inedible models, while in Müllerian mimicry, inedible butterflies resemble each other to reduce the numbers of individuals sampled by inexperienced predators.[8]

Scales may have evolved initially for providing insulation. Scales on the thorax and other parts of the body may contribute to maintaining the high body temperatures required during flight. The "solid" scales of basal moths are however not as efficient as those of their more advanced relatives as the presence of a lumen adds air layers and increases the insulation value.[8] Scales also help increase the lift to drag ratio in flight.[8]

For newly emerged adults of most myrmecophilous Lycaenidae, deciduous waxy scales provide some protection from predators as they emerge from the nest.[8] In the case of the moth butterfly (Liphyra brassolis), the caterpillars are unwelcome guests in nests of tree ants, feeding on ant larvae. The adults emerging from pupae are covered with soft, loose adhesive scales which rub off and stick on the ants as they make their way out of the nest after hatching.[49]

 
Male Danaus chrysippus showing the pheromone pouch and brush-like organ in Kerala, India

Androconia edit

Male Lepidoptera possess special scales, called androconia (singular – androconium), which have evolved as a result of sexual selection for the purposes of disseminating pheromones for attracting suitable mates. Androconia may be dispersed on the wings, body, or legs or occur in patches, referred to as "brands", "sex brands" or "stigmata" on the wings, usually in invaginations of the upper surface of the forewings, sometimes concealed by other scales. Androconia are also known to occur in the folds of wings. These brands sometimes consist of hairlike tufts which facilitate the diffusion of the pheromone. The role of androconia in the courtship of pierid and nymphalid butterflies, such as Pyronia tithonus and Dryas iulia, has been proven experimentally.[15]: 16–17 [50][51][52][53]

Successive close-ups of the scales of a peacock wing

Photographic and light microscopic images      
Zoomed-out view of an Aglais io. Closeup of the scales of the same specimen. High magnification of the coloured scales (probably a different species).
Electron microscopic images        
A patch of wing Scales close up A single scale Microstructure of a scale
Magnification Approx. ×50 Approx. ×200 ×1000 ×5000


Abdomen edit

The abdomen or body is composed of nine segments. In the larva it ranges from segments 5 to 13. The eleventh segment of the larva holds a pair of anal claspers, which protrude in some taxa and represent the genitalia.[11]

Many families of moths have special organs to help detect bat echolocation. These organs are known as tympana (singular – typanum). The Pyraloidea and almost all Geometroidea have tympana located on the anterior sternite of the abdomen. The Noctuoidea also have tympana, but in their case, the tympana are located on the underside of the metathorax, the structure and position of which are unique and a taxonomic distinguishing feature of the superfamily.[21][54]

The females of some moths have a scent-emitting organ located at the tip of the abdomen.[6]

Genitalia edit

 
Male genitalia of Lepidoptera
 
Female genitalia of Lepidoptera

The genitalia are complex and provide the basis for species discrimination in most families and also in family identification.[7] The genitalia arise from the tenth or most distal segment of the abdomen. Lepidoptera have some of the most complex genital structures of all insects, with a wide variety of complex spines, setae, scales and tufts in males, claspers of different shapes and modifications of the ductus bursae in females, through which stored sperm is transferred within the female directly, or indirectly, to the vagina for fertilisation.[13][55][56]

The arrangement of genitalia is important in courtship and mating as they prevent cross-specific mating and hybridisation. The uniqueness of a species' genitalia led to the use of the morphological study of genitalia as one of the most important keys in taxonomic identification of taxa below family level. With the advent of DNA analysis, the study of genitalia has now become just one of the techniques used in taxonomy.[6]

There are three basic configurations of genitalia in the majority of the Lepidoptera based on how the arrangement in females of openings for copulation, fertilisation and egg laying has evolved:

  • Exoporian: Hepialidae and related families have an external groove that carries sperm from the copulatory opening (gonopore) to the (ovipore) and are termed Exoporian.[7]
  • Monotrysian: Primitive groups have a single genital aperture near the end of the abdomen through which both copulation and egg laying occur. This character is used to designate the Monotrysia.[7]
  • Ditrysian: The remaining groups have an internal duct that carry sperm and form the Ditrysia, with separate openings for copulation and egg laying.[7]

The genitalia of the male and female in any particular species are adapted to fit each other like a lock (male) and key (female).[6] In males, the ninth abdominal segment is divided into a dorsal "tegumen" and ventral "viniculum".[56] They form a ring-like structure for the attachment of genital parts and a pair of lateral clasping organs (claspers or "harpe"). The male has a median tubular organ (called the aedeagus) which is extended through an eversible sheath (or "vesica") to inseminate the female.[55] The males have paired sperm ducts in all lepidopterans; the paired testes are separate in basal taxa and fused in advanced forms.[55]

While the layout of internal genital ducts and openings of the female genitalia depends upon the taxonomic group that insect belongs to, the internal female reproductive system of all lepidopterans consists of paired ovaries and accessory glands which produce the yolks and shells of the eggs. Female insects have a system of receptacles and ducts in which sperm is received, transported, and stored. The oviducts of the female join to form a common duct (called the "oviductus communis") which leads to the vagina.[55][56]

When copulation takes place, the male butterfly or moth places a capsule of sperm (spermatophore) in a receptacle of the female (called the corpus bursae). The sperm, when released from the capsule, swims directly into or via a small tube into a special seminal receptacle (spermatheca), where the sperm is stored until it is released into the vagina for fertilisation during egg laying, which may occur hours, days, or months after mating. The eggs pass through the ovipore. The ovipore may be at the end of a modified ovipositor or surrounded by a pair of broad setose anal papillae.[55][56]

Butterflies of the Parnassinae (family Papilionidae) and some Acraeini (family Nymphalidae) add a post-copulatory plug, called the sphragis, to the abdomen of the female after copulation preventing her from mating again.[13]

The males of many species of Papilionoidea are furnished with secondary sexual characteristics. These consist of scent-producing organs, brushes, and brands or pouches of specialised scales. These presumably meet the function of convincing the female that she is mating with a male of the correct species.[11]

Three species of hawkmoth have been recorded to emit ultrasound clicks by rubbing their genitalia; males produce by rubbing rigid scales on the exterior of the claspers while females produce sound by contracting their genitalia which causes rubbing of scales against the abdomen. The function of this noise making is not clear and suggestions put forward include the jamming of bat echolocation, and, advertising that the bat's prey are prickly and excellent fliers.[57]

Cloaca edit

Lepidopteran insects feature a cloaca at the end of the abdomen. This may be complete, incorporating the anus, the ovipore and the copulatory pore, as in the case of the Dacnonypha, Zeugloptera and the majority of the Monotrysia; or incomplete, incorporating the anus and ovipore only, as found in some of the Monotrysia, the Psychidae, and in some Choreutidae and Cossidae.[58]

Development edit

 
Three stages of a sphingid moth – larva (or caterpillar), chrysalis (or pupa), and adult (or imago)

The fertilised egg matures and hatches to give a caterpillar. The caterpillar is the feeding stage of the lepidopteran life cycle. The caterpillar needs to be able to feed and to avoid being eaten and much of its morphology has evolved to facilitate these two functions.[59]: 108  After growth and ecdysis, the caterpillar enters into a sessile developmental stage called a pupa (or chrysalis) around which it may form a casing. The insect develops into the adult in the pupa stage; when ready the pupa hatches and the adult stage or imago of a butterfly or moth arises.

Egg edit

 
The butterfly can be seen laying eggs underneath the leaf.

Like most insects, the Lepidoptera are oviparous or "egg layers".[40] Lepidopteran eggs, like those of other insects, are centrolecithal in that the eggs have a central yolk surrounded by cytoplasm. The yolk provides the liquid nourishment for the embryo caterpillar until it escapes from the shell.[60] The cytoplasm is enclosed by the vitteline envelope and a proteinaceous membrane called the chorion protects the egg externally.[60][61] The zygote nucleus is located posteriorly.[61]

In some species of Lepidoptera, a waxy layer is present inside the chorion adjacent to the vitelline layer which is thought to have evolved to prevent desiccation. In insects, the chorion has a layer of air pores in the otherwise solid material which provides very limited capability for respiratory function. In Lepidoptera, the chorion layer above this air pore layer is lamellar with successive sheets of protein arranged in a particular direction and stepped so as to form a helical arrangement.[61]

The top of the egg is depressed and forms a small central cavity called micropyle through which the egg is fertilised.[11] The micropyle is situated on top in eggs which are globular, conical, or cylindrical; in those eggs which are flattened or lenticular, the micropyle is located on the outer margin or rim.[18][62]

The eggs of Lepidoptera are usually rounded and small (1 mm) though they may be as large as 4 mm in the case of Sphingidae and Saturniidae.[13]: 640  They are generally quite plain in colour, white, pale green, bluish green, or brown. Butterfly and moth eggs come in various shapes; some are spherical, others hemispherical, conical, cylindrical, or lenticular (lens shaped). Some are barrel shaped or pancake shaped, while others are turban or cheese shaped. They may be angled or depressed at both ends, ridged or ornamented, spotted or blemished.[18][62]

The eggs are deposited singly, in small clusters, or in a mass, and invariably on or near the food source. Captive moths have been known to lay eggs in the cages they have been sequestered in.[18][62] Egg size in the Lepidoptera is affected by a number of factors. Lepidoptera species which overwinter in the egg stage usually have larger eggs than the species that do not. Similarly, species feeding on woody plants in the larval stage have larger eggs than those species feeding on herbaceous plants. Eggs laid by older females of a few butterfly species have been noted to be smaller in size than their younger counterparts. In the absence of adequate nutrition, the females of the corn-borer moth ( Ostrinia spp.) have been recorded to lay clutches with egg sizes below normal.[61]

While escaping, the newly hatched larvae of many species sometimes eat the chorion to emerge. Alternatively, the egg shell may have a line of weakness around the cap which gives way allowing the larva to emerge.[61] The egg shell and a small amount of yolk trapped in the amniotic membranes forms the first food for most lepidopteran larvae.

Caterpillar edit

 
A – head, B – thorax, C – abdomen, 1 – prothoracic shield, 2 – spiracle, 3 – true legs, 4 – midabdominal prolegs, 5 – anal proleg, 6 – anal plate, 7 – tentacle, a – eye, b – stemmata (ocelli), c – antenna, d – mandible, e – labrum, f – frontal triangle.

Caterpillars, are "characteristic polypod larvae with cylindrical bodies, short thoracic legs and abdominal prolegs (pseudopods)".[63] They have a toughened (sclerotised) head capsule, mandibles (mouthparts) for chewing, and a soft tubular, segmented body, that may have hair-like or other projections, three pairs of true legs, and additional prolegs (up to five pairs).[2] The body consists of thirteen segments, of which three are thoracic (T1, T2, and T3) and ten are abdominal (A1 to A10).[21]

 
Caterpillar head morphology (click to enlarge)
 
Spiracles on caterpillar of Actias selene
 
Old World swallowtail caterpillar everting its osmeterium in defence
 
Crochets on a caterpillar's prolegs

All true caterpillars have an upside-down Y-shaped line that runs from the top of the head downward. In between the Y-shaped line lies the frontal triangle or frons. The clypeus, located below the frons, lies between the two antennae. The labrum is found below the clypeus. There is a small notch in the centre of the labrum with which the leaf edge engages when the caterpillar eats.[64]

The larvae have silk glands which are located on the labium. These glands are modified salivary glands. They use these silk glands to make silk for cocoons and shelters.[21] Located below the labrum are the mandibles.[64] On each side of the head there are usually six stemmata just above the mandibles. These stemmata are arranged in a semicircle. Below the stemmata there is a small pair of antennae, one on each side.[21][64]

The thorax bears three pairs of legs, one pair on each segment. The prothorax (T1) has a functional spiracle which is actually derived from the mesothorax (T2) while the metathorax has a reduced spiracle which is not externally open and lies beneath the cuticle.[59]: 114  The thoracic legs consist of coxa, trochanter, femur, tarsus, and claw and are constant in form throughout the order. However they are reduced in the case of certain leaf-miners and elongated in certain Notodontidae. In Micropterigidae, the legs are three-segmented, as the coxa, trochanter, and femur are fused.[59]: 114 

Abdominal segments three through six and ten may each bear a pair of legs that are more fleshy.[21] The thoracic legs are known as true legs and the abdominal legs are called prolegs.[64] The true legs vary little in the Lepidoptera except for reduction in certain leaf-miners and elongation in the family Notodontidae.[59]: 114  The prolegs contain a number of small hooks on the tip, which are known as crochets. The families of Lepidoptera differ in the number and positioning of their prolegs. Some larvae such as inchworms (Geometridae) and loopers (Plusiinae) have five pairs of prolegs or less, while others like Lycaenidae and slug caterpillars (Limacodidae) lack prolegs altogether.[21][64] In some leaf-mining caterpillars there are crochets present on the abdominal wall which are reduced prolegs, while other leaf-mining species lack the crochets entirely.[65] The abdominal spiracles are located on each side of the body on the first eight abdominal segments.[64]

Caterpillars have different types of projections; setae (hairs), spines, warts, tubercles, and horns. The hairs come in an assortment of colours and may be long or short; single, in clusters, or in tufts; thinner at the point or clubbed at the end. A spine may either be a chalaza (having a single point) or a scolus (having multiple points). The warts may either be small bumps or short projections on the body. The tubercles are fleshy body projections that are either short and bump like or long and filament like. They usually occur in pairs or in a cluster on one or more segments. The horns are short, fleshy, and are drawn to a point. They are usually found on the eighth abdominal segment.[65]

A large number of species of families Saturniidae, Limacodidae, and Megalopygidae have stinging caterpillars which have poisonous setae, called urticating hairs, and in the case of Lonomia – a Brazilian saturniid genus – can kill a human due to its potent anticoagulant poison.[13]: 644  Caterpillars of many taxa that have sequestered toxic chemicals from host plants or have sharp urticating hair or spines, display aposematic colouration and markings.[66]

Caterpillars undergo ecdysis and have a number of larval instars, usually five but varying between species. The new cuticle is soft and allows the increase in size and development of the caterpillar before becoming hard and inelastic. In the last ecdysis, the old cuticle splits and curls up into a small ball at the posterior end of the pupa and is known as the larval exuvia.[67]: 31 

Chrysalis or pupa edit

 
Chrysalis suspended from its cremaster
 
The obtect pupa of Cecropia moth showing parts
 
The exarate pupa of a micropterygid moth, Mnemonica auricyanea

A cocoon is a casing spun of silk by many moth caterpillars, and numerous other holometabolous insect larvae as a protective covering for the pupa. Most Lepidoptera larvae will either make a cocoon and pupate inside them or will pupate in a cell under the ground,[21] with the exception of butterflies and advanced moths such as noctuids, whose pupae are exposed.[13] The pupae of moths are usually brown and smooth whereas butterfly pupae are often colourful and their shape varies greatly.[21] In butterflies, the exposed pupa is often referred to as a chrysalis, derived from the Greek term "chrysalis": χρυσός (chrysós) for gold, referring to the golden colour of some pupae.[68]

The caterpillars of many butterflies attach themselves by a button of silk to the underside of a branch, stone, or other projecting surface. They remain attached to the silk pad by a hook-like process called a cremaster. Most chrysalids hang head downward, but in the families Papilionidae, Pieridae, and Lycaenidae, the chrysalis is held in a more upright position by a silk girdle around the middle of the chrysalis.[21]

The pupae of most Lepidoptera are obtect, with appendages fused or glued to the body, while the rest have exarate pupae, having the antennae, legs, and wings free and not glued to the body.[69]

During the pupal stage, the morphology of the adult is developed through elaboration from larval structures.[40]: 151  The general aspect of the adult is visible before the outer surface hardens – the head, resting on the thorax, the eyes, antennae (brought forward over the head), the wings brought over the thorax, and the six legs between the wings and the abdomen.[70] Among the features discernible in the head region of a pupa are sclerites, sutures, pilifers, mandibles, eye-pieces, antennae, palpi, and the maxillae. The pupal thorax displays the three thoracic segments, legs, wings, tegulae, alar furrows, and axillary tubercles. The pupal abdomen exhibits the ten segments, spines, setae, scars of larval prolegs and tubercles, anal, and genital openings, as well as spiracles. The pupa of borers display the flange-plates while those of specialised Lepidoptera exhibit the cremaster.[14]: 23–29 

While the pupa is generally stationary and immobile, those of the primitive moth families Micropterigidae, Agathiphagidae, and Heterobathmiidae have fully functional mandibles.[59]: 131  These serve principally to allow the adult to escape from the cocoon.[14]: 34  Besides this, all appendages and the body are separate from the pupal skin and enjoy a degree of independent motion. All other superfamilies of the Lepidoptera are more specialised, have non-functional mandibles, appendages and body attached to the pupal skin, and lose a degree of independent movement.[14]: 20 

The pupae of some moths are able to wriggle their abdomen. The three caudal segments of the pupal abdomen (segments 8–10) are fixed; the other segments are movable to some degree. While the more evolved Lepidoptera can wriggle only the last two or three segments at the end of the abdomen, more basal taxa such as the Micropterigidae can wriggle the remaining seven segments of the abdomen; this presumably helps them to protrude the anterior end from the pupal case before eclosion.[14]: 28 [67] The pupae of Hepialidae are able to move back and forth in the larval tunnel by wriggling, aided by projections on the back in addition to spines.[67] Abdominal wriggling is considered to be of startle value and discouraging to predators. In the case of a few hawk moths, such as Theretra latreillii, the wriggling of the abdomens is accompanied by a rattling or clicking sound which adds to the startle effect.[67]

In some species, such as Heliconius charithonia, mating can occur inside the pupa of females by males.[71]

Defense and predation edit

 
The orange oakleaf (Kallima inachus) resembles a dried leaf perfectly.
 
Filamentous tails of a lycaenid butterfly, the common cerulean (Jamides celeno). These tails are thought to confuse a predator as to the location of the head thereby increasing the butterfly's chances of survival.
 
Queen Alexandra's birdwing (Ornithoptera alexandrae family Papilionidae), the largest butterfly in the world, has bright colours and distinctive markings which advertise its inedibility.

Lepidopterans are soft bodied, fragile, and almost defenseless while the immature stages move slowly or are immobile, hence all stages are exposed to predation by birds, small mammals, lizards, amphibians, invertebrate predators (notably parasitoid and parasitic wasps and flies) as well as fungi and bacteria. To combat this, Lepidoptera have developed a number of strategies for defense and protection which include camouflage, aposematism, mimicry, and the development of threat patterns and displays.[72]

Camouflage is an important defense strategy enabled by changes in body shape, colour, and markings. Some lepidopterans blend with the surroundings, making them difficult to be seen by predators. Caterpillars can be shades of green that match their host plant. Others resemble inedible objects, such as twigs or leaves. The larvae of some species, such as the common Mormon and the western tiger swallowtail look like bird droppings.[72][73]

Some species of Lepidoptera sequester or manufacture toxins which are stored in their body tissue, rendering them poisonous to predators; examples include the monarch butterfly in the Americas and Atrophaneura species in Asia. Predators that eat poisonous lepidopterans may become sick and vomit violently, and so learn to avoid those species. A predator who has previously eaten a poisonous lepidopteran may avoid other species with similar markings in the future, thus saving many other species as well.[72][74] Toxic butterflies and larvae tend to develop bright colours and striking patterns as an indicator to predators about their toxicity. This phenomenon is known as aposematism.[75]

Aposematism has also led to the development of mimicry complexes of Batesian mimicry, where edible species mimic aposematic taxa, and Müllerian mimicry, where inedible species, often of related taxa, have evolved to resemble each other, so as to benefit from reduced sampling rates by predators during learning. Similarly, adult Sesiidae species (also known as clearwing moths) have a general appearance that is sufficiently similar to a wasp or hornet to make it likely that the moths gain a reduction in predation by Batesian mimicry.[76]

Eyespots are a type of automimicry used by some lepidopterans. In butterflies, the spots are composed of concentric rings of scales of different colours. The proposed role of the eyespots is to deflect predators' attention. Their resemblance to eyes provokes the predator's instinct to attack these wing patterns.[77] The role of filamentous tails in Lycaenidae has been suggested as confusing predators as to the real location of the head, giving them a better chance of escaping alive and relatively unscathed.[78]

Some caterpillars, especially members of Papilionidae, contain an osmeterium, a Y-shaped protrusible gland found in the prothoracic segment of the larvae. When threatened, the caterpillar emits unpleasant smells from the organ to ward off the predators.[79][80]

See also edit

Footnotes edit

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External links edit

  • SEM image of butterfly scale and its pedicel (third from top).
  • – photo-feature on lepidopteran eggs by National Geographic.
  • – photo-feature on moths by National Geographic.

external, morphology, lepidoptera, external, morphology, lepidoptera, physiological, structure, bodies, insects, belonging, order, lepidoptera, also, known, butterflies, moths, lepidoptera, distinguished, from, other, orders, presence, scales, external, parts,. The external morphology of Lepidoptera is the physiological structure of the bodies of insects belonging to the order Lepidoptera also known as butterflies and moths Lepidoptera are distinguished from other orders by the presence of scales on the external parts of the body and appendages especially the wings Butterflies and moths vary in size from microlepidoptera only a few millimetres long to a wingspan of many inches such as the Atlas moth Comprising over 160 000 described species the Lepidoptera possess variations of the basic body structure which has evolved to gain advantages in adaptation and distribution 1 The head of a small white butterfly Pieris rapae Note the upward pointing labial palpi on both sides of the coiled proboscis Comparison of moth and butterfly dorsal anatomy Adult Essex skipper Thymelicus lineola Pupa of a sphingid mothCaterpillar of the subfamily ArctiinaeEggs of the buff tip Phalera bucephala a notodontid mothLepidopterans undergo complete metamorphosis going through a four stage life cycle egg larva or caterpillar pupa or chrysalis and imago plural imagines adult The larvae caterpillars have a toughened sclerotised head capsule chewing mouthparts and a soft body that may have hair like or other projections three pairs of true legs and up to five pairs of prolegs Most caterpillars are herbivores but a few are carnivores some eat ants aphids or other caterpillars or detritivores 2 Larvae are the feeding and growing stages and periodically undergo hormone induced ecdysis developing further with each instar until they undergo the final larval pupal moult The larvae of many lepidopteran species will either make a spun casing of silk called a cocoon and pupate inside it or will pupate in a cell under the ground In many butterflies the pupa is suspended from a cremaster and is called a chrysalis The adult body has a hardened exoskeleton except for the abdomen which is less sclerotised The head is shaped like a capsule with appendages arising from it Adult mouthparts include a prominent proboscis formed from maxillary galeae and are adapted for sucking nectar Some species do not feed as adults and may have reduced mouthparts while others have them modified for piercing and suck blood or fruit juices 3 Mandibles are absent in all except the Micropterigidae which have chewing mouthparts 4 Adult Lepidoptera have two immobile multi faceted compound eyes and only two simple eyes or ocelli which may be reduced 5 The three segments of the thorax are fused together Antennae are prominent and besides the faculty of smell also aid navigation orientation and balance during flight 6 In moths males frequently have more feathery antennae than females for detecting the female pheromones at a distance There are two pairs of membranous wings which arise from the mesothoracic middle and metathoracic third segments they are usually completely covered by minute scales The two wings on each side act as one by virtue of wing locking mechanisms In some groups the females are flightless and have reduced wings The abdomen has ten segments connected with movable inter segmental membranes The last segments of the abdomen form the external genitalia The genitalia are complex and provide the basis for family identification and species discrimination 7 The wings head parts of thorax and abdomen of Lepidoptera are covered with minute scales from which feature the order Lepidoptera derives its names the word lepidos in Ancient Greek meaning scale Most scales are lamellar blade like and attached with a pedicel while other forms may be hair like or specialised as secondary sexual characteristics The lumen or surface of the lamella has a complex structure It gives colour either due to the pigments contained within it or through its three dimensional structure 8 Scales provide a number of functions which include insulation thermoregulation and aiding flight amongst others the most important of which is the large diversity of vivid or indistinct patterns they provide which help the organism protect itself by camouflage mimicry and to seek mates Contents 1 External morphology 1 1 General body plan 1 2 Distinguishing taxonomic features 2 Head 2 1 Antennae 2 2 Eyes 2 3 Palpi 2 4 Mouthparts 3 Thorax 3 1 Leg 3 2 Wings 3 2 1 Shape 3 2 2 Venation 3 2 3 Wing coupling 4 Scales 4 1 Structure 4 2 Colour 4 3 Function 4 3 1 Androconia 5 Abdomen 5 1 Genitalia 5 2 Cloaca 6 Development 6 1 Egg 6 2 Caterpillar 6 3 Chrysalis or pupa 7 Defense and predation 8 See also 9 Footnotes 10 External linksExternal morphology edit nbsp Parts of an adult butterfly A Forewing B Antenna C Compound eye D Proboscis E Thorax F Leg G Abdomen H Hindwing I TailIn common with other members of the superorder Holometabola Lepidoptera undergo complete metamorphosis going through a four stage life cycle egg larva caterpillar pupa chrysalis and imago plural imagines adult 9 Lepidopterans range in size from a few millimetres in length such as in the case of microlepidoptera to a wingspan of many inches such as the Atlas moth and the world s largest butterfly Queen Alexandra s birdwing 10 246 General body plan edit The body of an adult butterfly or moth the imago has three distinct divisions called tagmata connected at constrictions these tagmata are the head thorax and abdomen Adult lepidopterans have four wings a forewing and a hindwing on both the left and the right side of the thorax and like all insects three pairs of legs 11 The morphological characteristics which distinguish the order Lepidoptera from other insect orders are 10 246 Head The head has large compound eyes and if mouthparts are present they are almost always a drinking straw like proboscis Scales Scales cover the external surface of the body and appendages Thorax The prothorax is usually reduced Wings Two pairs of wings are present in almost all taxa The wings have very few cross veins Abdomen The posterior abdominal segments are extensively modified for reproduction Cerci are absent Larva Lepidoptera larvae are known as caterpillars and have a well developed head and mandibles They can have from zero to five pairs of prolegs usually four Pupa The pupae in most species are adecticous with no functional mandibles in the pupal state and obtect with appendages fused or glued to the body while others are decticous with functional mandibles present in the pupal state and exarate having the antennae legs and wings free Distinguishing taxonomic features edit The chief characteristics used to classify lepidopteran species genera and families are 12 the mouthparts the shape and venation of the wings whether the wings are homoneurous the venation of the forewings and hindwings alike or heteroneurous forewings and hindwings different whether the wings are aculeate more or less covered with specialized bristles called microsetae or nonaculeate the type of wing coupling jugate or frenate the anatomy of the reproductive organs the structure of larva and position of primary setae whether the pupa is exarate or obtectThe morphological characteristics of caterpillars and pupae used for classification are completely different from that of adults 13 637 14 different classification schemes are sometimes provided separately for classifying adults larvae and pupae 14 15 28 40 The characteristics of immature stages are increasingly used for taxonomic purposes as they provide insights into systematics and phylogenies of Lepidoptera that are not apparent from examination of adults 15 28 Head edit nbsp Lepidoptera head illustration from G F Hampson s Moths of British India Vol 1 1892 Like all animal heads the head of a butterfly or moth contains the feeding organs and the major sense organs The head typically consists of two antennae two compound eyes two palpi and a proboscis 11 Lepidoptera have ocelli which may or may not be visible They also have sensory structures called chaetosemata the functions of which are largely unknown The head is filled largely by the brain the sucking pump and its associated muscle bundles 16 Unlike the adults the larvae have one segmented mandibles 16 The head capsule is well sclerotised and has a number of sclerites or plates separated by sutures The sclerites are difficult to distinguish from sulci singular sulcus which are secondary thickenings The regions of the head have been divided into a number of areas which act as a topographical guide for description by lepidopterists but cannot be discriminated in terms of their development 16 The head is covered by hair like or lamellar scales and found either as tufts on the frons or vertex referred to as rough scaled or pressed close to the head referred to as smooth scaled The sensory organs and structures on the head show great variety and the shape and form of these structures as also their presence or absence are important taxonomic indicators for classifying taxa into families 13 nbsp Head of a moth of family Gracillariidae showing extent of scales on the head nbsp Rough scaled head of moth Monopis icterogastra family Tineidae nbsp Smooth scaled head of moth Glyphipterix simpliciella family Glyphipterigidae nbsp Smooth scaled head of moth Stegasta variana family Gelechiidae Antennae edit Main article Antenna biology nbsp nbsp Sexual dimorphism in antennae in Caligula japonica family Saturniidae feathery antennae of male left and linear form in female right Antennae are prominent paired appendages that project forwards between the animal s eyes and consist of a number of segments In the case of butterflies their length varies from half the length of the forewing to three quarters of the length of the forewing The antennae of butterflies are either slender and knobbed at the tip and in the case of the Hesperiidae are hooked at the tip In some butterfly genera such as Libythea and Taractrothera the knob is hollowed underneath 11 Moth antennae are either filiform thread like unipectinate comb like bipectinate feather like hooked clubbed or thickened 13 636 Bombyx mandarina is an example with bipectinate antennae 17 Some moths have knobbed antennae akin to those of butterflies such as the family Castniidae 18 Antennae are the primary organs of olfaction smell in Lepidoptera The antenna surface is covered with large numbers of olfactory scales hairs or pits as many as 1 370 000 are found on the antennae of a monarch Antennae are extremely sensitive the feathered antennae of male moths from the Saturniidae Lasiocampidae and many other families are so sensitive that they can detect the pheromones of female moths from distances of up to 2 km 1 2 mi away Lepidoptera antennae can be angled in many positions They help the insect in locating the scent and can be considered to act as a kind of olfactory radar 6 In moths males frequently have antennae which are more feathery than those of the females for detecting the female pheromones at a distance 7 Since females do not need to detect the males they have simpler antennae 6 Antennae have also been found to play a role in the time compensated sun compass orientation in migratory monarch butterflies 19 nbsp Filiform antennae Eriocrania cicatricella Eriocraniidae nbsp Unipectinate antennae Abantiades barcas Hepialidae nbsp Bipectinate antennae Actias artemis Saturniidae nbsp Hooked antennae Epargyreus clarus Hesperiidae nbsp Clubbed antennae Vanessa atalanta Nymphalidae nbsp Thickened antennae Deleiphila elpenor Sphingidae nbsp Clubbed moth antennae Athis inca Castniidae nbsp Longhorn moth Nemophora degeerella Adelidae has antennae up to five times the length of its wings Eyes edit nbsp Front view of the compound eyes of Aglais io nbsp Ocellus of Mythimna unipuncta seen to the right of base of antenna in close contact with the compound eye Lepidoptera have two large immovable compound eyes which consist of a large number of facets or lenses each connected to a lens like cylinder which is attached to a nerve leading to the brain 11 Each eye may have up to 17 000 individual light receptors ommatidia which in combination provide a broad mosaic view of the surrounding area 6 One tropical Asian family the Amphitheridae has compound eyes divided into two distinct segments 13 20 The eyes are usually smooth but may be covered by minute hairs The eyes of butterflies are usually brown golden brown or even red as in the case of some species of skippers 11 While most insects have three simple eyes or ocelli only two ocelli are present in all species of Lepidoptera except a few moths one on each side of the head near the edge of the compound eye On some species sense organs called chaetosemata are found near the ocelli 11 21 The ocelli are not homologous to the simple eyes of caterpillars which are differently named as stemmata 5 The ocelli of Lepidoptera are reduced externally in some families where present they are unfocussed unlike stemmata of larvae which are fully focussed The utility of ocelli is not understood at present 5 Butterflies and moths are able to see ultraviolet UV light and wing colours and patterns are principally observed by Lepidoptera in these wavelengths of light 13 The patterns seen on their wing under UV light differ considerably from those seen in normal light The UV patterns act as visual cues which help differentiate between species for the purpose of mating Studies have been carried out on Lepidoptera mostly butterflies wing patterns illuminated by UV light 13 Palpi edit nbsp Gastropacha populifolia family Lasiocampidae with modified mouthpartsTypically the labial palpi are prominent three segmented springing from under the head and curving up in front of the face 7 There is great variation in morphology of labial palpi in different families of Lepidoptera sometimes the palpi are separate and sometimes they are connivent and form a beak but they are always independently movable In other cases the labial palpi may not be erect but porrect projecting forward horizontally 11 13 Palpi consist of a short basal segment a comparatively long central segment and a narrow terminal portion The first two segments are densely scaled and may be hirsute the terminal segment is bare The terminal segment may be blunt or pointed it may project straight or at an angle from the second segment inside which it may be concealed 11 Mouthparts edit nbsp Butterfly proboscis showing the structure of the two galeae that comprise it nbsp Legend Section of mouthparts of Lepidoptera a pilifer labrum b epipharynx labrum c galea maxilla d trachea e nerve f muscles g food canal h labium i labial palpWhile mandibles or jaws chewing mouthparts are only present in the caterpillar stage the mouthparts of most adult Lepidoptera mainly consist of the sucking kind this part is known as the proboscis or haustellum A few Lepidoptera species have reduced mouthparts and do not feed in the adult state Others such as the basal family Micropterigidae have chewing mouthparts 21 The proboscis plural proboscises is formed from maxillary galeae and is adapted for sucking nectar 3 It consists of two tubes held together by hooks and separable for cleaning Each tube is inwardly concave thus forming a central tube up which moisture is sucked Suction is effected through the contraction and expansion of a sac in the head 11 The proboscis is coiled under the head when the insect is at rest and extended only when feeding 16 The maxillary palpi are reduced and even vestigial They are conspicuous and five segmented in some of the more basal families and are often folded 7 The shape and dimensions of the proboscis have evolved to give different species a wider and therefore more advantageous diet 3 There is an allometric scaling relationship between body mass of Lepidoptera and length of proboscis 22 from which an interesting adaptive departure is the unusually long tongued sphinx moth Xanthopan morganii praedicta Charles Darwin predicted the existence and proboscis length of this moth before its discovery based on his knowledge of the long spurred Madagascan star orchid Angraecum sesquipedale 23 There are primarily two feeding guilds in Lepidoptera the nectarivorous who obtain the majority of their nutritional requirements from floral nectar and those of the frugivorous guild who feed primarily on juices of rotting fruit or fermenting tree sap There are substantial differences between the morphology of the proboscises of both feeding guilds Hawkmoths family Sphingidae have elongated proboscises which enable them to feed on and pollinate flowers with long tubular corollas Besides this a number of taxa especially noctuid moths have evolved different proboscis morphologies Certain noctuid species have developed piercing mouthparts the proboscis has sclerotised scales on the tip with which to pierce and suck blood or fruit juices Proboscises in some Heliconius species have evolved to consume solids such as pollen 24 Some other moths mostly noctuids have modified proboscises to suit their mode of nutrition lachrymophagy feeding on tears of sleeping birds The proboscises often have sharp apices as well as a host of barbs and spurs on the stem 25 26 nbsp Scanning electron micrograph of the proboscis of a moth from family Pyralidae nbsp A nymphalid butterfly sucking on a banana nbsp Sara longwing Heliconius sara one of many Heliconius species known to feed on pollen with pollen on its proboscis nbsp Xanthopan morganii an African sphingid has a foot long proboscis adapted for feeding from the orchid Angraecum sesquipedale nbsp Lachryphagous Lepidoptera such as the two Julia butterflies Dryas iulia drinking the tears of turtles in Ecuador have hooks and barbs at the tip of the proboscisThorax edit nbsp The forelegs are reduced in the Nymphalidae nbsp Diagram of an insect legThe thorax which develops from segments 2 3 and 4 of the larva consists of three invisibly divided segments namely prothorax metathorax and mesothorax 11 The organs of insect locomotion the legs and wings are borne on the thorax The forelegs spring from the prothorax the forewings and middle pair of legs are borne on the mesothorax and the hindwings and hindlegs arise from the metathorax In some cases the wings are vestigial 11 27 The upper and lower parts of the thorax terga and sterna respectively are composed of segmental and intrasegmental sclerites which display secondary sclerotisation and considerable modification in the Lepidoptera The prothorax is the simplest and smallest of the three segments while the mesothorax is the most developed 27 Between the head and thorax is the membranous neck or cervix It comprises a pair of lateral cervical sclerites and is composed of both cephalic and thoracic elements 10 71 27 Between the head and the thorax is a tufted scale called the pronotum On either side is a shield like scale called a scapula 11 In the Noctuoidea the metathorax is modified with a pair of tympanal organs 7 Leg edit Forelegs in the Papilionoidea exhibit reduction of various forms the butterfly family Nymphalidae or brush footed butterflies as they are commonly known have only the rear two pairs of legs fully functional with the forward pair strongly reduced and not capable of walking or perching In the Lycaenidae the tarsus is unsegmented as the tarsomeres are fused and tarsal claws are absent The aroliar pad a pad projecting between the tarsal claws of some insects and pulvilli singular pulvillus a pad or lobe beneath each tarsal claw are reduced or absent in the Papilionidae The tarsal claws are also absent in the Riodinidae 28 In Lepidoptera the three pairs of legs are covered with scales 13 Lepidoptera also have olfactory organs on their feet which aid in tasting or smelling food plants 6 Wings edit Main article Insect wing For a key to the terms used see Glossary of entomology terms Adult Lepidoptera have two pairs of membranous wings covered usually completely by minute scales A wing consists of an upper and lower membrane which are connected by minute fibres and strengthened by a system of thickened hollow ribs popularly but incorrectly referred to as veins as they may also contain tracheae nerve fibres and blood vessels 11 29 The membranes are covered with minute scales which have jagged ends or hairs and are attached by hooks The wings are moved by the rapid muscular contraction and expansion of the thorax 11 The wings arise from the meso and meta thoracic segments and are similar in size in the basal groups In more derived groups the meso thoracic wings are larger with more powerful musculature at their bases and more rigid vein structures on the costal edge 7 Besides providing the primary function of flight wings also have secondary functions of self defence camouflage and thermoregulation 3 30 In some Lepidoptera families such as the Psychidae and Lymantriidae the wings are reduced or even absent often in the female but not the male 7 Shape edit The shape of wings exhibits great variety in Lepidoptera In the case of the Papilionoidea the costa may be straight or highly arched It is sometimes concave on the hindwing It is occasionally serrate or minutely saw toothed on the forewing The apex may be rounded pointed or falcate produced and concave below The termen tends to be straight or concave on the forewing while it is usually more or less convex on the hindwing The termen is often crenulate or dentate i e produced at each vein and concave in between them The dorsum is normally straight but may be concave 11 The hindwing is frequently caudate i e the veins near the end of the tornus have one or more tails The tornus itself being often produced and frequently lobed 11 Along the hindwing termen there are tightly packed scales in a double row The underside of the scales project and form a regular narrow fringe referred to as cilia 11 nbsp The plume moths family Pterophoridae have split wings nbsp In the many plumed moths family Alucitidae wings are split along each vein nbsp Microlepidoptera of the Gelechioidea such as Palumbina guerinii have hair like fringes along the hindwings nbsp Tailed hindwings of Madagascan sunset moth Chrysiridia rhipheus family Uraniidae nbsp Lycaenids such as the monkey puzzle Rathinda amor have filamentous tails which are attempted to be explained by the false head hypothesis 31 nbsp Hyaline patches on the wings of a hummingbird hawk moth the snowberry clearwing Hemaris diffinis nbsp Pachyerannis obliquaria mating pair winged male above small wingless female belowVenation edit nbsp Terms associated with the wings For detailed explanation refer Glossary of entomology terms nbsp An adult male pine processionary moth Thaumetopoea pityocampa Notice the bristle springing from the underside of the hindwing frenulum and running forward to be held in a small catch of the forewing the function of which is to link the wings together Tubular veins run through the two layered membranous wing Veins are connected to the haemocoel and in theory allow haemolymph to flow through them In addition a nerve and trachea may pass through the veins 29 Lepidopteran venation is simple in that there are few crossbars 15 88 The wing venation in Lepidoptera is a diagnostic for distinguishing between the taxa as also the genera and families 13 The terminology is based on the Comstock Needham system which gives the morphological description of insect wing venation 32 In the basal Lepidoptera the venation of the forewing is similar to that of the hindwing a condition referred to as homoneurous The Micropterigidae Zeugloptera have venation that resembles the most primitive caddisflies Trichoptera All other Lepidoptera the vast majority around 98 are heteroneurous the venation of the hindwing differing from that from the forewing and being sometimes reduced Moths of the families Nepticulidae Opostegidae Gracillariidae Tischeriidae and Bucculatricidae amongst others often have greatly reduced venation in both wings 13 635 32 56 Homoneurous moths tend to have the jugum form of wing coupling as opposed to the frenulum retinaculum arrangement in the case of more advanced families nbsp Insect wing venation showing the names after the Comstock Needham system nbsp Homoneurous venation in Sabatinca lucilia Micropterigidae nbsp Heteroneurous venation in Gonepteryx rhamni Pieridae nbsp Reduced venation in Synanthedon tipuliformis Sesiidae Wing coupling edit nbsp Oiketicus spp family Psychidae The frenulum can be seen at the top of the rear wing which hooks onto the retinaculum so that the wings travel together during flight Magnification 10xMain article Wing coupling The Lepidoptera have developed a wide variety of morphological wing coupling mechanisms in the imago which render these taxa functionally dipterous two winged 33 All but the most basal forms exhibit this wing coupling 34 There are three different types of mechanisms jugal frenulo retinacular and amplexiform 35 The more primitive groups have an enlarged lobe like area near the basal posterior margin i e at the base of the forewing called a jugum that folds under the hindwing during flight 7 34 Other groups have a frenulum on the hindwing that hooks under a retinaculum on the forewing 7 In all butterflies with the exception of male Euschemoninae and in Bombycoidea moths with the exception of the Sphingidae there is no arrangement of frenulum and retinaculum to couple the wings Instead an enlarged humeral area of the hindwing is broadly overlapped by the forewing Despite the absence of a specific mechanical connection the wings overlap and operate in phase The power stroke of the forewing pushes down the hindwing in unison This type of coupling is a variation of frenate type but where the frenulum and retinaculum are completely lost 33 36 Scales edit nbsp Wing scales form the colour and pattern on wings The scales shown here are lamellar The pedicel can be seen attached to a few loose scales The wings of Lepidoptera are minutely scaled which gives the name to this order the name Lepidoptera was coined in 1735 by Carl Linnaeus for the group of insects with four scaly wings It is derived from Ancient Greek lepis lepis meaning fish scale and related to lepein to peel and pteron pteron meaning wing 37 Scales also cover the head parts of the thorax and abdomen as well as parts of the genitalia The morphology of scales has been studied by J C Downey and A C Allyn 1975 38 and scales have been classified into three groups namely hair like or piliform blade like or lamellar and other variable forms 8 Primitive moths non Glossata and Eriocranidae have solid scales which are imperforate i e they lack a lumen 8 A few taxa of the Trichoptera caddisflies which are the sister group to the Lepidoptera have hair like scales but always on the wings and never on the body or other parts of the insect 13 Caddisflies also possess caudal cerci on the abdomen a feature absent in the Lepidoptera 7 According to Scoble 2005 8 morphologically scales are macrotrichia and thus homologous with the large hairs and scales that cover the wings of Trichoptera caddisflies Structure edit Although there is great diversity in scale form they all share a similar structure Scales like other macrochaetes arise from special trichogenic hair producing cells and have a socket which is enclosed in a special tormogen cell 15 9 this arrangement provides a stalk or pedicel by which scales are attached to the substrate Scales may be piliform hairlike or flattened The body or blade of a typical flattened scale consists of an upper and lower lamella with an air space in between The surface towards the body is smooth and known as the inferior lamella The upper surface or superior lamella has transverse and longitudinal ridges and ribs The lamellae are held apart by struts called trabaculae and contain pigments which give colour The scales cling somewhat loosely to the wing and come off easily without harming the butterfly 8 13 39 Colour edit The scales on butterfly wings are pigmented with melanins that can produce the colours black and brown The white colour in the butterfly family Pieridae is a derivative of uric acid an excretory product 13 40 84 Bright blues greens reds and iridescence are usually created not by pigments but through the microstructure of the scales This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales 41 42 43 The specialised scales that provide structural colours to reflected light mostly produce ultraviolet patterns which are discernible in that part of the ultraviolet spectrum that lepidopteran eyes can see 13 The structural colour seen is often dependent upon the angle of view For example in Morpho cypris the colour from the front is a bright blue but when seen from an angle changes very quickly to black 44 The iridescent structural coloration on the wings of many lycaenid and papilionid species such as Parides sesostris and Teinopalpus imperialis and lycaenids such as Callophrys rubi Cyanophrys remus and Mitoura gryneus has been studied 45 They manifest the most complex photonic scale architectures known regular three dimensional periodic lattices that occur within the lumen of some scales 46 In the case of the Kaiser i Hind Teinopalpus imperialis the three dimensional photonic structure has been examined by transmission electron tomography and computer modelling to reveal naturally occurring chiral tetrahedral repeating units packed in a triclinic lattice 47 48 the cause of the iridescence nbsp Structural blue colour in morpho cypris a nymphalid nbsp When the same Morpho cypris specimen is seen end on the blue colour turns black nbsp The white colour in pierids such as Delias eucharis is a derivative of uric acid an excretory product nbsp The green iridescence of the swallowtail Kaiser i Hind Teinopalpus imperialis led to the discovery of three dimensional photonic crystal structure nbsp Wing coloration in certain Lepidoptera permits camouflage as can be seen in the case of the geometrid moth Colostygia aqueata Function edit nbsp Closeup of male Luna moth eyespot nbsp Androconial patch on hindwing of Bicyclus anynana a nymphalidScales play an important part in the natural history of Lepidoptera Scales enable the development of vivid or indistinct patterns which help the organism protect itself by camouflage mimicry and warning Besides providing insulation dark patterns on wings allow sunlight to be absorbed and are probably involved in thermoregulation Bright and distinctive colour patterns in butterflies which are distasteful to predators help communicate their toxicity or inedibility thus preventing predation In Batesian mimicry wing colour patterns help edible lepidopterans mimic inedible models while in Mullerian mimicry inedible butterflies resemble each other to reduce the numbers of individuals sampled by inexperienced predators 8 Scales may have evolved initially for providing insulation Scales on the thorax and other parts of the body may contribute to maintaining the high body temperatures required during flight The solid scales of basal moths are however not as efficient as those of their more advanced relatives as the presence of a lumen adds air layers and increases the insulation value 8 Scales also help increase the lift to drag ratio in flight 8 For newly emerged adults of most myrmecophilous Lycaenidae deciduous waxy scales provide some protection from predators as they emerge from the nest 8 In the case of the moth butterfly Liphyra brassolis the caterpillars are unwelcome guests in nests of tree ants feeding on ant larvae The adults emerging from pupae are covered with soft loose adhesive scales which rub off and stick on the ants as they make their way out of the nest after hatching 49 nbsp Male Danaus chrysippus showing the pheromone pouch and brush like organ in Kerala IndiaAndroconia edit Male Lepidoptera possess special scales called androconia singular androconium which have evolved as a result of sexual selection for the purposes of disseminating pheromones for attracting suitable mates Androconia may be dispersed on the wings body or legs or occur in patches referred to as brands sex brands or stigmata on the wings usually in invaginations of the upper surface of the forewings sometimes concealed by other scales Androconia are also known to occur in the folds of wings These brands sometimes consist of hairlike tufts which facilitate the diffusion of the pheromone The role of androconia in the courtship of pierid and nymphalid butterflies such as Pyronia tithonus and Dryas iulia has been proven experimentally 15 16 17 50 51 52 53 Successive close ups of the scales of a peacock wing Photographic and light microscopic images nbsp nbsp nbsp Zoomed out view of an Aglais io Closeup of the scales of the same specimen High magnification of the coloured scales probably a different species Electron microscopic images nbsp nbsp nbsp nbsp A patch of wing Scales close up A single scale Microstructure of a scaleMagnification Approx 50 Approx 200 1000 5000Abdomen editThe abdomen or body is composed of nine segments In the larva it ranges from segments 5 to 13 The eleventh segment of the larva holds a pair of anal claspers which protrude in some taxa and represent the genitalia 11 Many families of moths have special organs to help detect bat echolocation These organs are known as tympana singular typanum The Pyraloidea and almost all Geometroidea have tympana located on the anterior sternite of the abdomen The Noctuoidea also have tympana but in their case the tympana are located on the underside of the metathorax the structure and position of which are unique and a taxonomic distinguishing feature of the superfamily 21 54 The females of some moths have a scent emitting organ located at the tip of the abdomen 6 Genitalia edit Main article Lepidoptera genitalia nbsp Male genitalia of Lepidoptera nbsp Female genitalia of LepidopteraThe genitalia are complex and provide the basis for species discrimination in most families and also in family identification 7 The genitalia arise from the tenth or most distal segment of the abdomen Lepidoptera have some of the most complex genital structures of all insects with a wide variety of complex spines setae scales and tufts in males claspers of different shapes and modifications of the ductus bursae in females through which stored sperm is transferred within the female directly or indirectly to the vagina for fertilisation 13 55 56 The arrangement of genitalia is important in courtship and mating as they prevent cross specific mating and hybridisation The uniqueness of a species genitalia led to the use of the morphological study of genitalia as one of the most important keys in taxonomic identification of taxa below family level With the advent of DNA analysis the study of genitalia has now become just one of the techniques used in taxonomy 6 There are three basic configurations of genitalia in the majority of the Lepidoptera based on how the arrangement in females of openings for copulation fertilisation and egg laying has evolved Exoporian Hepialidae and related families have an external groove that carries sperm from the copulatory opening gonopore to the ovipore and are termed Exoporian 7 Monotrysian Primitive groups have a single genital aperture near the end of the abdomen through which both copulation and egg laying occur This character is used to designate the Monotrysia 7 Ditrysian The remaining groups have an internal duct that carry sperm and form the Ditrysia with separate openings for copulation and egg laying 7 The genitalia of the male and female in any particular species are adapted to fit each other like a lock male and key female 6 In males the ninth abdominal segment is divided into a dorsal tegumen and ventral viniculum 56 They form a ring like structure for the attachment of genital parts and a pair of lateral clasping organs claspers or harpe The male has a median tubular organ called the aedeagus which is extended through an eversible sheath or vesica to inseminate the female 55 The males have paired sperm ducts in all lepidopterans the paired testes are separate in basal taxa and fused in advanced forms 55 While the layout of internal genital ducts and openings of the female genitalia depends upon the taxonomic group that insect belongs to the internal female reproductive system of all lepidopterans consists of paired ovaries and accessory glands which produce the yolks and shells of the eggs Female insects have a system of receptacles and ducts in which sperm is received transported and stored The oviducts of the female join to form a common duct called the oviductus communis which leads to the vagina 55 56 When copulation takes place the male butterfly or moth places a capsule of sperm spermatophore in a receptacle of the female called the corpus bursae The sperm when released from the capsule swims directly into or via a small tube into a special seminal receptacle spermatheca where the sperm is stored until it is released into the vagina for fertilisation during egg laying which may occur hours days or months after mating The eggs pass through the ovipore The ovipore may be at the end of a modified ovipositor or surrounded by a pair of broad setose anal papillae 55 56 Butterflies of the Parnassinae family Papilionidae and some Acraeini family Nymphalidae add a post copulatory plug called the sphragis to the abdomen of the female after copulation preventing her from mating again 13 The males of many species of Papilionoidea are furnished with secondary sexual characteristics These consist of scent producing organs brushes and brands or pouches of specialised scales These presumably meet the function of convincing the female that she is mating with a male of the correct species 11 Three species of hawkmoth have been recorded to emit ultrasound clicks by rubbing their genitalia males produce by rubbing rigid scales on the exterior of the claspers while females produce sound by contracting their genitalia which causes rubbing of scales against the abdomen The function of this noise making is not clear and suggestions put forward include the jamming of bat echolocation and advertising that the bat s prey are prickly and excellent fliers 57 nbsp Citheronia regalis with claspers closed nbsp Citheronia regalis with claspers open nbsp Female Apollo with sphragis or mating plug nbsp Close up of the hardened sphragis extruding 2 to 3 mm behind the abdomen of ParnassiusCloaca edit Lepidopteran insects feature a cloaca at the end of the abdomen This may be complete incorporating the anus the ovipore and the copulatory pore as in the case of the Dacnonypha Zeugloptera and the majority of the Monotrysia or incomplete incorporating the anus and ovipore only as found in some of the Monotrysia the Psychidae and in some Choreutidae and Cossidae 58 Development edit nbsp Three stages of a sphingid moth larva or caterpillar chrysalis or pupa and adult or imago The fertilised egg matures and hatches to give a caterpillar The caterpillar is the feeding stage of the lepidopteran life cycle The caterpillar needs to be able to feed and to avoid being eaten and much of its morphology has evolved to facilitate these two functions 59 108 After growth and ecdysis the caterpillar enters into a sessile developmental stage called a pupa or chrysalis around which it may form a casing The insect develops into the adult in the pupa stage when ready the pupa hatches and the adult stage or imago of a butterfly or moth arises Egg edit See also Egg biology nbsp The butterfly can be seen laying eggs underneath the leaf Like most insects the Lepidoptera are oviparous or egg layers 40 Lepidopteran eggs like those of other insects are centrolecithal in that the eggs have a central yolk surrounded by cytoplasm The yolk provides the liquid nourishment for the embryo caterpillar until it escapes from the shell 60 The cytoplasm is enclosed by the vitteline envelope and a proteinaceous membrane called the chorion protects the egg externally 60 61 The zygote nucleus is located posteriorly 61 In some species of Lepidoptera a waxy layer is present inside the chorion adjacent to the vitelline layer which is thought to have evolved to prevent desiccation In insects the chorion has a layer of air pores in the otherwise solid material which provides very limited capability for respiratory function In Lepidoptera the chorion layer above this air pore layer is lamellar with successive sheets of protein arranged in a particular direction and stepped so as to form a helical arrangement 61 The top of the egg is depressed and forms a small central cavity called micropyle through which the egg is fertilised 11 The micropyle is situated on top in eggs which are globular conical or cylindrical in those eggs which are flattened or lenticular the micropyle is located on the outer margin or rim 18 62 The eggs of Lepidoptera are usually rounded and small 1 mm though they may be as large as 4 mm in the case of Sphingidae and Saturniidae 13 640 They are generally quite plain in colour white pale green bluish green or brown Butterfly and moth eggs come in various shapes some are spherical others hemispherical conical cylindrical or lenticular lens shaped Some are barrel shaped or pancake shaped while others are turban or cheese shaped They may be angled or depressed at both ends ridged or ornamented spotted or blemished 18 62 The eggs are deposited singly in small clusters or in a mass and invariably on or near the food source Captive moths have been known to lay eggs in the cages they have been sequestered in 18 62 Egg size in the Lepidoptera is affected by a number of factors Lepidoptera species which overwinter in the egg stage usually have larger eggs than the species that do not Similarly species feeding on woody plants in the larval stage have larger eggs than those species feeding on herbaceous plants Eggs laid by older females of a few butterfly species have been noted to be smaller in size than their younger counterparts In the absence of adequate nutrition the females of the corn borer moth Ostrinia spp have been recorded to lay clutches with egg sizes below normal 61 While escaping the newly hatched larvae of many species sometimes eat the chorion to emerge Alternatively the egg shell may have a line of weakness around the cap which gives way allowing the larva to emerge 61 The egg shell and a small amount of yolk trapped in the amniotic membranes forms the first food for most lepidopteran larvae nbsp Eggs of pioneer Anaphaeis aurota family Pieridae nbsp Eggs of crimson rose Atrophaneura hector family Papilionidae nbsp Egg of mallow skipper Carcharodus alceae family Hesperiidae nbsp Egg of large copper Lycaena dispar family Lycaenidae nbsp Side by side eggs of ditrysian lepidopteran baldcypress leafroller Archips goyerena family Tortricidae nbsp Upright eggs of ditrysian lepidopteran moon moth Actias luna family Saturniidae laid in captivity on paper nbsp Eggs of pine looper moth Bupalus piniaria family Geometridae nbsp Eggs of lackey moth Malacosoma neustria family Lasiocampidae Caterpillar edit Main article Caterpillar nbsp A head B thorax C abdomen 1 prothoracic shield 2 spiracle 3 true legs 4 midabdominal prolegs 5 anal proleg 6 anal plate 7 tentacle a eye b stemmata ocelli c antenna d mandible e labrum f frontal triangle Caterpillars are characteristic polypod larvae with cylindrical bodies short thoracic legs and abdominal prolegs pseudopods 63 They have a toughened sclerotised head capsule mandibles mouthparts for chewing and a soft tubular segmented body that may have hair like or other projections three pairs of true legs and additional prolegs up to five pairs 2 The body consists of thirteen segments of which three are thoracic T1 T2 and T3 and ten are abdominal A1 to A10 21 nbsp Caterpillar head morphology click to enlarge nbsp Spiracles on caterpillar of Actias selene nbsp Old World swallowtail caterpillar everting its osmeterium in defence nbsp Crochets on a caterpillar s prolegsAll true caterpillars have an upside down Y shaped line that runs from the top of the head downward In between the Y shaped line lies the frontal triangle or frons The clypeus located below the frons lies between the two antennae The labrum is found below the clypeus There is a small notch in the centre of the labrum with which the leaf edge engages when the caterpillar eats 64 The larvae have silk glands which are located on the labium These glands are modified salivary glands They use these silk glands to make silk for cocoons and shelters 21 Located below the labrum are the mandibles 64 On each side of the head there are usually six stemmata just above the mandibles These stemmata are arranged in a semicircle Below the stemmata there is a small pair of antennae one on each side 21 64 The thorax bears three pairs of legs one pair on each segment The prothorax T1 has a functional spiracle which is actually derived from the mesothorax T2 while the metathorax has a reduced spiracle which is not externally open and lies beneath the cuticle 59 114 The thoracic legs consist of coxa trochanter femur tarsus and claw and are constant in form throughout the order However they are reduced in the case of certain leaf miners and elongated in certain Notodontidae In Micropterigidae the legs are three segmented as the coxa trochanter and femur are fused 59 114 Abdominal segments three through six and ten may each bear a pair of legs that are more fleshy 21 The thoracic legs are known as true legs and the abdominal legs are called prolegs 64 The true legs vary little in the Lepidoptera except for reduction in certain leaf miners and elongation in the family Notodontidae 59 114 The prolegs contain a number of small hooks on the tip which are known as crochets The families of Lepidoptera differ in the number and positioning of their prolegs Some larvae such as inchworms Geometridae and loopers Plusiinae have five pairs of prolegs or less while others like Lycaenidae and slug caterpillars Limacodidae lack prolegs altogether 21 64 In some leaf mining caterpillars there are crochets present on the abdominal wall which are reduced prolegs while other leaf mining species lack the crochets entirely 65 The abdominal spiracles are located on each side of the body on the first eight abdominal segments 64 Caterpillars have different types of projections setae hairs spines warts tubercles and horns The hairs come in an assortment of colours and may be long or short single in clusters or in tufts thinner at the point or clubbed at the end A spine may either be a chalaza having a single point or a scolus having multiple points The warts may either be small bumps or short projections on the body The tubercles are fleshy body projections that are either short and bump like or long and filament like They usually occur in pairs or in a cluster on one or more segments The horns are short fleshy and are drawn to a point They are usually found on the eighth abdominal segment 65 A large number of species of families Saturniidae Limacodidae and Megalopygidae have stinging caterpillars which have poisonous setae called urticating hairs and in the case of Lonomia a Brazilian saturniid genus can kill a human due to its potent anticoagulant poison 13 644 Caterpillars of many taxa that have sequestered toxic chemicals from host plants or have sharp urticating hair or spines display aposematic colouration and markings 66 Caterpillars undergo ecdysis and have a number of larval instars usually five but varying between species The new cuticle is soft and allows the increase in size and development of the caterpillar before becoming hard and inelastic In the last ecdysis the old cuticle splits and curls up into a small ball at the posterior end of the pupa and is known as the larval exuvia 67 31 nbsp Two instars of the papilionid common Mormon with different camouflage schemes resembling bird droppings and vegetation nbsp The larvae of notodontid moths such as that of Stauropus fagi have elongated thoracic legs nbsp The larva of Lonomia obliqua a saturniid moth from Brazil has urticating hairs with a lethal anticoagulant poison nbsp Saddleback moth Acharia stimulea larvae display aposematic colouring in the shape of a saddle nbsp Underside of slug caterpillars of Phobetron pithecium family Limacododiae showing the absence of prolegs nbsp Caterpillar of common aspen leafminer Phyllocnistis populiella nbsp The mahogany shoot borer Hypsipyla grandella damages mahogany in Brazil nbsp Bagworm caterpillar possibly Hyalarcta huebneri family Psychidae emerging from its case nbsp Last instar of blue Mormon larva resembling vegetation Chrysalis or pupa edit Main article Pupa nbsp Chrysalis suspended from its cremaster nbsp The obtect pupa of Cecropia moth showing parts nbsp The exarate pupa of a micropterygid moth Mnemonica auricyaneaA cocoon is a casing spun of silk by many moth caterpillars and numerous other holometabolous insect larvae as a protective covering for the pupa Most Lepidoptera larvae will either make a cocoon and pupate inside them or will pupate in a cell under the ground 21 with the exception of butterflies and advanced moths such as noctuids whose pupae are exposed 13 The pupae of moths are usually brown and smooth whereas butterfly pupae are often colourful and their shape varies greatly 21 In butterflies the exposed pupa is often referred to as a chrysalis derived from the Greek term chrysalis xrysos chrysos for gold referring to the golden colour of some pupae 68 The caterpillars of many butterflies attach themselves by a button of silk to the underside of a branch stone or other projecting surface They remain attached to the silk pad by a hook like process called a cremaster Most chrysalids hang head downward but in the families Papilionidae Pieridae and Lycaenidae the chrysalis is held in a more upright position by a silk girdle around the middle of the chrysalis 21 The pupae of most Lepidoptera are obtect with appendages fused or glued to the body while the rest have exarate pupae having the antennae legs and wings free and not glued to the body 69 During the pupal stage the morphology of the adult is developed through elaboration from larval structures 40 151 The general aspect of the adult is visible before the outer surface hardens the head resting on the thorax the eyes antennae brought forward over the head the wings brought over the thorax and the six legs between the wings and the abdomen 70 Among the features discernible in the head region of a pupa are sclerites sutures pilifers mandibles eye pieces antennae palpi and the maxillae The pupal thorax displays the three thoracic segments legs wings tegulae alar furrows and axillary tubercles The pupal abdomen exhibits the ten segments spines setae scars of larval prolegs and tubercles anal and genital openings as well as spiracles The pupa of borers display the flange plates while those of specialised Lepidoptera exhibit the cremaster 14 23 29 While the pupa is generally stationary and immobile those of the primitive moth families Micropterigidae Agathiphagidae and Heterobathmiidae have fully functional mandibles 59 131 These serve principally to allow the adult to escape from the cocoon 14 34 Besides this all appendages and the body are separate from the pupal skin and enjoy a degree of independent motion All other superfamilies of the Lepidoptera are more specialised have non functional mandibles appendages and body attached to the pupal skin and lose a degree of independent movement 14 20 The pupae of some moths are able to wriggle their abdomen The three caudal segments of the pupal abdomen segments 8 10 are fixed the other segments are movable to some degree While the more evolved Lepidoptera can wriggle only the last two or three segments at the end of the abdomen more basal taxa such as the Micropterigidae can wriggle the remaining seven segments of the abdomen this presumably helps them to protrude the anterior end from the pupal case before eclosion 14 28 67 The pupae of Hepialidae are able to move back and forth in the larval tunnel by wriggling aided by projections on the back in addition to spines 67 Abdominal wriggling is considered to be of startle value and discouraging to predators In the case of a few hawk moths such as Theretra latreillii the wriggling of the abdomens is accompanied by a rattling or clicking sound which adds to the startle effect 67 In some species such as Heliconius charithonia mating can occur inside the pupa of females by males 71 nbsp Papilionid chrysalids are typically attached to a substrate by the cremaster and with the head up held by a silk girdle nbsp Suspended golden coloured nymphalid chrysalis of Euploea core nbsp Actias luna family Saturniidae emerging from cocoon nbsp The specialised pupa of a sphingid moth Agrius convolvuli can wriggle its abdomen making a clicking sound which can have a startle effect Defense and predation edit nbsp The orange oakleaf Kallima inachus resembles a dried leaf perfectly nbsp Filamentous tails of a lycaenid butterfly the common cerulean Jamides celeno These tails are thought to confuse a predator as to the location of the head thereby increasing the butterfly s chances of survival nbsp Queen Alexandra s birdwing Ornithoptera alexandrae family Papilionidae the largest butterfly in the world has bright colours and distinctive markings which advertise its inedibility Lepidopterans are soft bodied fragile and almost defenseless while the immature stages move slowly or are immobile hence all stages are exposed to predation by birds small mammals lizards amphibians invertebrate predators notably parasitoid and parasitic wasps and flies as well as fungi and bacteria To combat this Lepidoptera have developed a number of strategies for defense and protection which include camouflage aposematism mimicry and the development of threat patterns and displays 72 Camouflage is an important defense strategy enabled by changes in body shape colour and markings Some lepidopterans blend with the surroundings making them difficult to be seen by predators Caterpillars can be shades of green that match their host plant Others resemble inedible objects such as twigs or leaves The larvae of some species such as the common Mormon and the western tiger swallowtail look like bird droppings 72 73 Some species of Lepidoptera sequester or manufacture toxins which are stored in their body tissue rendering them poisonous to predators examples include the monarch butterfly in the Americas and Atrophaneura species in Asia Predators that eat poisonous lepidopterans may become sick and vomit violently and so learn to avoid those species A predator who has previously eaten a poisonous lepidopteran may avoid other species with similar markings in the future thus saving many other species as well 72 74 Toxic butterflies and larvae tend to develop bright colours and striking patterns as an indicator to predators about their toxicity This phenomenon is known as aposematism 75 Aposematism has also led to the development of mimicry complexes of Batesian mimicry where edible species mimic aposematic taxa and Mullerian mimicry where inedible species often of related taxa have evolved to resemble each other so as to benefit from reduced sampling rates by predators during learning Similarly adult Sesiidae species also known as clearwing moths have a general appearance that is sufficiently similar to a wasp or hornet to make it likely that the moths gain a reduction in predation by Batesian mimicry 76 Eyespots are a type of automimicry used by some lepidopterans In butterflies the spots are composed of concentric rings of scales of different colours The proposed role of the eyespots is to deflect predators attention Their resemblance to eyes provokes the predator s instinct to attack these wing patterns 77 The role of filamentous tails in Lycaenidae has been suggested as confusing predators as to the real location of the head giving them a better chance of escaping alive and relatively unscathed 78 Some caterpillars especially members of Papilionidae contain an osmeterium a Y shaped protrusible gland found in the prothoracic segment of the larvae When threatened the caterpillar emits unpleasant smells from the organ to ward off the predators 79 80 See also edit nbsp Insects portal nbsp Arthropods portalDifferences between butterflies and moths Glossary of entomology terms Insect morphology Lepidoptera Morphology biology Footnotes edit Kristensen Niels P Scoble M J Karsholt Ole 2007 Z Q Zhang W A Shear eds Linnaeus Tercentenary Progress in Invertebrate Taxonomy PDF Vol 1668 pp 699 747 doi 10 11646 zootaxa 1668 1 30 ISBN 978 0 12 690647 9 S2CID 4996165 Archived from the original PDF on 15 May 2013 Retrieved 19 February 2011 Chapter Lepidoptera phylogeny and systematics the state of inventorying moth and butterfly diversity a href Template Cite book html title Template Cite book cite book a journal ignored help a b Dugdale J S 1996 Natural history and identification of litter feeding Lepidoptera larvae Insecta in beech forests Orongorongo Valley New Zealand with especial reference to the diet of mice Mus musculus PDF Journal of the Royal Society of New Zealand 26 4 251 274 doi 10 1080 03014223 1996 9517513 permanent dead link a b c d Scoble M J 1995 Mouthparts The Lepidoptera Form Function and Diversity Oxford University Press pp 6 19 ISBN 978 0 19 854952 9 Borror Donald J Triplehorn Charles A Johnson Norman F 1989 Introduction to the Study of Insects 6 illustrated ed Saunders College Publications ISBN 978 0 03 025397 3 Retrieved 16 November 2010 No preview a b c Scoble 1995 Section Sensation pp 26 38 a b c d e f g h Hoskins Adrian Butterfly Anatomy Head amp other pages Learn about butterflies Retrieved 15 November 2010 a b c d e f g h i j k l m n Powell Jerry A 2009 Lepidoptera In Resh Vincent H Carde Ring T eds Encyclopedia of Insects 2nd ed Academic Press pp 661 663 ISBN 978 0 12 374144 8 a b c d e f g h i Scoble 1995 Section Scales pp 63 66 Mallet Jim 12 June 2007 Details about the Lepidoptera and Butterfly Taxome Projects The Lepidoptera Taxome Project University College London Retrieved 14 November 2010 a b c Gillot Cedric 1995 Butterflies and moths Entomology 2nd ed Springer ISBN 978 0 306 44967 3 a b c d e f g h i j k l m n o p q r s t Evans W H 1932 Introduction Identification of Indian Butterflies 2nd ed Mumbai Bombay Natural History Society pp 1 35 Lepidopteran Encyclopaedia Britannica 2011 Retrieved 12 February 2011 a b c d e f g h i j k l m n o p q r s Heppner J B 2008 Butterflies and moths In Capinera John L ed Encyclopedia of Entomology Gale virtual reference library Vol 4 2nd ed Springer Reference p 4345 ISBN 978 1 4020 6242 1 a b c d e f Mosher Edna 2009 1918 A Classification of the Lepidoptera Based on Characters of the Pupa reprint ed BiblioBazaar LLC ISBN 978 1 110 02244 1 a b c d e Kristensen Niels P 2003 Lepidoptera Moths and Butterflies Morphology Physiology and Development Volume 2 Volume 4 Part 36 of Handbuch der Zoologie Walter de Gruyter ISBN 978 3 11 016210 3 a b c d Scoble 1995 Section The Adult Head Feeding and Sensation pp 4 22 Heppner John B 2008 Silkworm Moths Lepidoptera Bombycidae In Capinera John L ed Encyclopedia of Entomology Springer Netherlands pp 3375 3376 doi 10 1007 978 1 4020 6359 6 4198 ISBN 9781402062421 a b c d Holland W J 1903 Introduction PDF The Moth Book London Hutchinson and Co ISBN 978 0 665 75744 0 Merlin Christine Gegear Robert J Reppert Steven M 2009 Antennal circadian clocks coordinate sun compass orientation in migratory Monarch butterflies Science 325 5948 1700 1704 Bibcode 2009Sci 325 1700M doi 10 1126 science 1176221 PMC 2754321 PMID 19779201 Robinson G S 1988 A phylogeny for the Tineoidea Lepidoptera Insect Systematics amp Evolution Brill 19 2 117 129 doi 10 1163 187631289x00113 in many Amphitheridae s l the compound eye of males is partially or completely divided horizontally a b c d e f g h i j k Triplehorn Charles A Johnson Norman F 2005 Borror and Delong s Introduction to the Study of Insects Belmont California Thomson Brooks Cole ISBN 978 0 03 096835 8 Agosta Salvatore J Janzen Daniel H 2004 Body size distributions of large Costa Rican dry forest moths and the underlying relationship between plant and pollinator morphology Oikos 108 1 183 193 doi 10 1111 j 0030 1299 2005 13504 x Kunte Krushnamegh 2007 Allometry and functional constraints on proboscis lengths in butterflies Functional Ecology 21 5 982 987 doi 10 1111 j 1365 2435 2007 01299 x Krenn H W Penz C M 1 October 1998 Mouthparts of Heliconius butterflies Lepidoptera Nymphalidae a search for anatomical adaptations to pollen feeding behavior International Journal of Insect Morphology and Embryology 27 4 301 309 doi 10 1016 S0020 7322 98 00022 1 Mackenzie Debora 20 December 2006 Moths drink the tears of sleeping birds New Scientist Reed Business Information Retrieved 10 February 2012 Hilgartner Roland Raoilison Mamisolo Buttiker Willhelm Lees David C Krenn Harald W 22 April 2007 Malagasy birds as hosts for eye frequenting moths Biology Letters 3 2 117 120 doi 10 1098 rsbl 2006 0581 PMC 2375961 PMID 17251126 a b c Scoble 1995 Chapter 3 The adult thorax a study in function amp effect pp 39 40 Scoble M J Aiello Annette 1990 Moth like butterflies Hedylidae Lepidoptera a summary with comments on the egg PDF Journal of Natural History 24 1 159 164 doi 10 1080 00222939000770101 permanent dead link a b Chapman R F 1998 Thorax The Insects Structure and Function 4th ed Cambridge University Press p 45 ISBN 978 0 521 57890 5 Krishna Anirudh Nie Xiao Warren Andrew D Llorente Bousquets Jorge E Briscoe Adriana D Lee Jaeho 2020 Infrared optical and thermal properties of microstructures in butterfly wings Proceedings of the National Academy of Sciences of the United States of America 117 3 1566 1572 Bibcode 2020PNAS 117 1566K doi 10 1073 pnas 1906356117 ISSN 0027 8424 PMC 6983360 PMID 31919285 Robbins Robert K 1981 The False Head Hypothesis Predation and Wing Pattern Variation of Lycaenid Butterflies American Naturalist 118 5 770 775 doi 10 1086 283868 S2CID 34146954 a b Scoble 1995 Section Wings Pg 55 a b Dudley Robert 2002 The Biomechanics of Insect Flight Form Function Evolution Princeton University Press ISBN 978 0 691 09491 5 a b Stocks Ian 2008 Wing coupling In Capinera John L ed Encyclopedia of Entomology Gale virtual reference library Vol 4 2nd ed Springer Reference p 4266 ISBN 978 1 4020 6242 1 Scoble 1995 Section Wing coupling pp 56 60 Gorb Stanislav 2001 Inter locking of body parts Attachment Devices of Insect Cuticle Springer p 305 ISBN 978 0 7923 7153 3 Harper Douglas Lepidoptera The Online Etymology Dictionary 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reference library Vol 4 2nd ed Springer Reference ISBN 978 1 4020 6242 1 a b c d Common I F B 1990 Moths of Australia Brill Publishers ISBN 978 90 04 09227 3 Harper Douglas Chrysalis Online Etymology Dictionary Dictionary com Retrieved 16 November 2010 Stehr Frederick W 2009 Pupa and puparium In Resh Vincent H Carde Ring T eds Encyclopedia of Insects 2nd ed Academic Press pp 970 973 ISBN 978 0 12 374144 8 Figuier Louis 1868 The Insect World Being a Popular Account of the Orders of Insects Together With a Description of the Habits and Economy of Some of the Most Interesting Species New York D Appleton amp Co Sourakov Andrei 2008 Pupal Mating in Zebra Longwing Heliconius charithonia Photographic Evidence News of the Lepidopterists Society 50 1 26 32 a b c Caterpillar and Butterfly Defense Mechanisms EnchantedLearning com Retrieved 7 December 2009 Latimer Jonathan P Karen Stray Nolting 2000 Butterflies Houghton Mifflin Harcourt p 12 ISBN 978 0 395 97944 0 Tiger swallowtail Kricher John 1999 6 A Neotropical Companion Princeton University Press pp 157 158 ISBN 978 0 691 00974 2 Santos J C Cannatella D C 2003 Multiple recurring origins of aposematism and diet specialization in poison frogs Proceedings of the National Academy of Sciences of the United States of America 100 22 12792 12797 Bibcode 2003PNAS 10012792S doi 10 1073 pnas 2133521100 PMC 240697 PMID 14555763 Insects and Spiders of the World Vol 10 Marshall Cavendish Corporation Marshall Cavendish January 2003 pp 292 293 ISBN 978 0 7614 7344 2 a href Template Cite book html title Template Cite book cite book a CS1 maint others link Carroll Sean 2005 Endless Forms Most Beautiful The New Science of Evo Devo and the Making of the Animal Kingdom W W Norton amp Co pp 205 210 ISBN 978 0 393 06016 4 Butterfly eyespots defense Heffernan Emily 2004 Symbiotic Relationship BetweenAnthene emolus Lycaenidae andOecophylla smaragdina Formicidae An Obligate Mutualism in the Malaysian Rainforest PDF MSc thesis University of Florida Osmeterium Merriam Webster Retrieved 9 December 2009 Hadley Debbie Osmeterium About com Guide Retrieved 9 December 2009 External links editSEM image of butterfly scale and its pedicel third from top Exquisite castaways photo feature on lepidopteran eggs by National Geographic Uncommon vision photo feature on moths by National Geographic Retrieved from https en wikipedia org w index php title External morphology of Lepidoptera amp oldid 1186125653 Androconia, wikipedia, wiki, book, books, library,

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