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The '''external morphology of Lepidoptera''' is the [[morphology (biology)|physiological structure]] of the bodies of [[insect]]s belonging to the order [[Lepidoptera]], also known as [[butterfly|butterflies]] and [[moth]]s. Lepidoptera are distinguished from other orders by the presence of [[Scale (Lepidoptera)|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.<ref name="Inventory">{{cite book |editor1=Z.-Q. Zhang |editor2=W. A. Shear |year=2007 |title=Linnaeus Tercentenary: Progress in Invertebrate Taxonomy |journal=[[Zootaxa]] |volume=1668 |isbn=978-0-12-690647-9 |url=http://www.lepidoptera.ee/images/lingid/Zootaxa1668p699.pdf |author1=Kristensen, Niels P. |author2=Scoble, M. J. |author3=Karsholt, Ole |pages=699–747 |quote=Chapter: "Lepidoptera phylogeny and systematics: the state of inventorying moth and butterfly diversity" |doi=10.11646/zootaxa.1668.1.30 |s2cid=4996165 |access-date=19 February 2011 |archive-date=15 May 2013 |archive-url=https://web.archive.org/web/20130515015416/http://www.lepidoptera.ee/images/lingid/Zootaxa1668p699.pdf |url-status=dead }}</ref>
Lepidopterans undergo [[metamorphosis|complete metamorphosis]], going through a four-stage [[Biological life cycle|life cycle]]: [[egg (biology)|egg]], [[larva]] or [[caterpillar]], [[pupa]] or [[Pupa#Chrysalis|chrysalis]], and [[imago|imago (plural: ''imagines'')]] / adult. The larvae – caterpillars – have a toughened ([[sclerite|sclerotised]]) head capsule, chewing [[Insect mouthparts|mouthparts]], and a soft body, that may have hair-like or other projections, three pairs of [[arthropod leg|true legs]], and up to five pairs of [[proleg]]s. Most caterpillars are [[herbivore]]s, but a few are [[carnivore]]s (some eat ants, aphids, or other caterpillars) or [[detritivore]]s.<ref name="Dugdale">{{cite journal|last1=Dugdale |first1=J. S. |year=1996 |title=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'') |journal=[[Journal of the Royal Society of New Zealand]] |volume=26 |issue=4 |pages=251–274 |url=http://www.royalsociety.org.nz/media/publications-journals-nzjr-1996-058.pdf |doi=10.1080/03014223.1996.9517513 |bibcode=1996JRSNZ..26..251D }}{{dead link|date=December 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> 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 [[pupa#Cocoon|cocoon]] and [[Metamorphosis|pupate]] inside it, or will pupate in a cell under the ground. In many butterflies, the pupa is suspended from a [[Pupa#cremaster|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 [[Galea (insects)|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.<ref name="Scoble – mouthparts">{{cite book |title=The Lepidoptera: Form, Function and Diversity |last=Scoble |first=M. J. |year=1995|publisher=[[Oxford University Press]] |isbn=978-0-19-854952-9|chapter=Mouthparts|pages=6–19|chapter-url=https://books.google.com/books?id=gnpd_5iNTiwC}}</ref> [[Mandible (insect mouthpart)|Mandibles]] are absent in all except the [[Micropterigidae]] which have [[Insect mouthparts#Chewing insects|chewing mouthparts]].<ref name="Borror, Triplehorn & Johnson (1989)">{{cite book |title=Introduction to the Study of Insects|last=Borror |first=Donald J. |edition=6, illustrated |author2=Triplehorn, Charles A. |author3=Johnson, Norman F. |year=1989|publisher=Saunders College Publications |isbn=978-0-03-025397-3 |url=https://books.google.com/books?id=lfPXAAAAMAAJ |access-date=16 November 2010}} (No preview.)</ref> Adult Lepidoptera have two immobile, multi-faceted [[compound eye]]s, and only two [[simple eye in invertebrates|simple eyes]] or ocelli, which may be reduced.<ref name="Scoble-Sensation">Scoble (1995). Section "Sensation", (pp. 26–38).</ref> The three segments of the [[Thorax (insect anatomy)|thorax]] are fused together. [[Antenna (biology)|Antennae]] are prominent and besides the faculty of smell, also aid navigation, orientation, and balance during flight.<ref name="Hoskins web site">{{cite web| url = http://www.learnaboutbutterflies.com/Anatomy.htm| work = Learn about butterflies| access-date = 15 November 2010| author = Hoskins, Adrian| title= Butterfly Anatomy Head (& other pages)}}</ref> In moths, males frequently have more feathery antennae than females, for detecting the female [[pheromone]]s at a distance. There are two pairs of [[Biological membrane|membranous]] [[insect wing|wings]] which arise from the mesothoracic (middle) and metathoracic (third) segments; they are usually completely covered by minute [[Scale (insect anatomy)|scales]]. The two wings on each side act as one by virtue of [[Wing coupling|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 [[Lepidoptera genitalia|genitalia]]. The genitalia are complex and provide the basis for family identification and species discrimination.<ref name="Resh & Carde">{{cite book |last1=Powell |first1=Jerry A.|editor2-last=Cardé |editor2-first=Ring T.|editor1-first=Vincent H. |editor1-last=Resh |title=Encyclopedia of Insects |chapter-url=https://books.google.com/books?id=Ip57QSMCRk4C&pg=PA631 |edition=2nd |year=2009 |publisher=[[Academic Press]] |isbn=978-0-12-374144-8 |pages=661–663|chapter=Lepidoptera}}</ref>
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{{ nowrap |'''H''': [[Hindwing]];}}
{{ nowrap |'''I''': [[Tail]]}}]]
In common with other members of the [[order (biology)|superorder]] [[
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]].<ref name="Gillot">{{cite book |title=Entomology |last=Gillot |first=Cedric |edition=2nd|year=1995 |isbn=978-0-306-44967-3 |chapter-url=https://books.google.com/books?id=DrTKxvZq_IcC |chapter=Butterflies and moths|publisher=Springer }}</ref>{{rp|246}}
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[[File:SEM image of a Peacock Head, front view.JPG|thumb|alt=Scanning electron micrograph in black and white of the compound eyes of a butterfly seen from front.|Front view of the compound eyes of ''[[Aglais io]]''.]]
[[File:Mythimna_unipuncta_male_head.jpg|thumb|alt=colour image of butterfly head|[[Ocellus]] of ''[[Mythimna unipuncta]]'' seen to the right of the base of the antenna, in close contact with the compound eye.]]
Lepidoptera
"</ref> 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 [[skipper (butterfly)|skippers]].<ref name="Evans"/>
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.<ref name="Evans"/><ref name="Triplehorn & Johnson (2005)">{{cite book |title=Borror and Delong's Introduction to the Study of Insects |last=Triplehorn |first=Charles A. |author2=Johnson, Norman F. |year=2005 |publisher=Thomson Brooks/Cole |location=Belmont, California |isbn=978-0-03-096835-8 }}</ref> The ocelli are not [[homology (biology)|homologous]] to the simple eyes of caterpillars which are differently named as [[Stemmata#Stemmata|stemmata]].<ref name="Scoble-Sensation"/> 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.<ref name="Scoble-Sensation"/>
Butterflies and moths
=== Palpi ===
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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 (phylogenetics)|basal]] family Micropterigidae, have chewing mouthparts.<ref name="Triplehorn & Johnson (2005)"/>
The proboscis (plural – [[proboscis]]es) is formed from [[Galea (insects)|maxillary galeae]] and is adapted for sucking [[nectar]].<ref name="Scoble – mouthparts"/> 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.<ref name="Evans"/> The proboscis is coiled under the head when the insect
The shape and dimensions of the proboscis have evolved to give different species a wider and, therefore, more advantageous diet.<ref name="Scoble – mouthparts"/> There is an [[allometry|allometric]] scaling relationship between body mass of Lepidoptera and length of proboscis<ref name="Agosta & Janzen (2004)">{{cite journal |last1=Agosta |first1=Salvatore J. |last2=Janzen |first2=Daniel H. |year=2004 |title=Body size distributions of large Costa Rican dry forest moths and the underlying relationship between plant and pollinator morphology |journal=[[Oikos (journal)|Oikos]] |volume=108 |issue=1 |pages=183–193 |doi=10.1111/j.0030-1299.2005.13504.x}}</ref> from which an interesting adaptive departure is the unusually long-tongued sphinx moth ''[[Xanthopan morganii|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]]''.<ref>{{cite journal |last1=Kunte |first1=Krushnamegh |year=2007 |title=Allometry and functional constraints on
There are primarily two [[guild (ecology)|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,
<gallery>
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File:Heliconius sara-01 (xndr).jpg|Sara longwing (''[[Heliconius sara]]''), one of many ''Heliconius'' species known to feed on pollen, with pollen on its proboscis
File:NHM_Xanthopan_morgani.jpg|''[[Xanthopan morganii]]'', an African [[sphingid]], has a foot-long proboscis adapted for feeding from the orchid ''[[Angraecum sesquipedale]]''
File:A_butterfly_feeding_on_the_tears_of_a_turtle_in_Ecuador.jpg|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 proboscis
</gallery>
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=== Leg ===
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 [[Arthropod leg#tarsus|tarsus]] is unsegmented, as the [[Arthropod leg#tarsomere|tarsomere]]s are fused, and, [[Glossary of spider terms#tarsal claw|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]].<ref name="Scoble & Aiello (1990)">{{cite journal |last1=Scoble |first1=M. J. |last2=Aiello |first2=Annette |year=1990 |title=Moth-like butterflies (Hedylidae: Lepidoptera): a summary, with comments on the egg |journal=[[Journal of Natural History]] |volume=24 |issue=1 |pages=159–164 |doi=10.1080/00222939000770101 |bibcode=1990JNatH..24..159S |url=http://stri.si.edu/publications/PDFs/Aiello_Scoble%20&%20Aiello%20.pdf }}{{Dead link|date=December 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
In Lepidoptera, the three pairs of legs are covered with scales.<ref name="Heppner"/> Lepidoptera also have olfactory organs on their feet which aid in "tasting" or "smelling" food plants.<ref name="Hoskins web site"/>
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=== Colour ===
The scales on butterfly wings are pigmented with [[melanin]]s 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.<ref name="Heppner"/><ref name="Gullan & Cranston (2005)">{{cite book |title=The Insects: an Outline of Entomology |last=Gullan |first=P. J. |edition=3rd |author2=Cranston, P. S.|year=2005 |publisher=[[Wiley-Blackwell]] |isbn=978-1-4051-1113-3 |url=https://books.google.com/books?id=ZZaVjVWUaXIC}}</ref>{{rp|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.<ref name="Mason (1927)">{{cite journal |last=Mason|first=C. W. |year=1927 |title=Structural colours in Insects – II| journal=[[Journal of Physical Chemistry]] |volume=31 |issue=3 |pages=321–354 | doi=10.1021/j150273a001 }}</ref><ref name="Vukusic (2006)">{{cite journal |last1=Vukusic |first1=P. |year=2006 |title=Structural colour in Lepidoptera |journal=[[Current Biology]] |pmid=16920604 |volume=16 |issue=16 |pages=R621–R623 |url=http://newton.ex.ac.uk/research/emag/pubs/pdf/Vukusic_CB_2006.pdf |doi=10.1016/j.cub.2006.07.040 |s2cid=52828850 |doi-access=free |bibcode=2006CBio...16.R621V }}</ref><ref name="Prum (2006)">{{cite journal |last=Prum| first=R. O. |author2=Quinn, T. |author3=Torres, R. H.| year = 2006|title = Anatomically diverse butterfly scales all produce structural colours by coherent scattering| journal = [[Journal of Experimental Biology]] |volume=209 | issue=4 | pages=748–765 |pmid=16449568 |doi=10.1242/jeb.02051 |doi-access=free |hdl=1808/1600 |hdl-access=free }}</ref> 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.<ref name="Heppner"/> 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.<ref name="Kinoshita (2008)">{{cite book |title=Structural Colors in the Realm of Nature |url=https://archive.org/details/structuralcolors00kino |url-access=limited |last=Kinoshita |first=Shu-ichi |year=2008 |publisher=World Scientific |isbn=978-981-270-783-3 |pages=[https://archive.org/details/structuralcolors00kino/page/n66 52]–53}}</ref>
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.<ref>{{cite journal |last1=Michielsen |first1=K. |last2=Stavenga |first2=D. G. |year=2008 |title=Gyroid cuticular structures in butterfly wing scales: biological photonic crystals |journal=[[Journal of the Royal Society Interface]] |volume=5 |issue=18 |pages=85–94 |doi=10.1098/rsif.2007.1065 |pmid=17567555 |pmc=2709202 }}</ref> They manifest the most complex photonic scale architectures known – regular three-dimensional periodic lattices, that occur within the lumen of some scales.<ref>{{cite journal |last1=Poladian |first1=Leon |last2=Wickham |first2=Shelley |last3=Lee |first3=Kwan |last4=Large |first4=Maryanne C. J. |year=2009 |title=Iridescence from photonic crystals and its suppression in butterfly scales |journal=[[Journal of the Royal Society Interface]] |volume=6 |issue=Suppl. 2 |pages=S233–S242 |pmid=18980932 |pmc=2706480 |doi=10.1098/rsif.2008.0353.focus}}</ref> 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",<ref name="Argyros et al">{{cite journal |last1=Argyros |first1=A. |author2=Manos, S. |author3=Large, M. C. J. |author4=McKenzie, D. R. |author5=Cox, G. C. |author6=Dwarte, D. M. |year=2002 |title=Electron tomography and computer visualisation of a three-dimensional 'photonic' crystal in a butterfly wing-scale |journal=[[Micron (journal)|Micron]] |pmid=11976036 |volume=33 |issue=5 |pages=483–487 |doi=10.1016/S0968-4328(01)00044-0}}</ref><ref>{{cite journal |last1=Ghiradella |first1=Helen |year=1991 |title=Light and color on the wing: structural colors in butterflies and moths |journal=[[Applied Optics]] |volume=30 |pmid=20706416 |issue=24 |pages=3492–3500 |doi=10.1364/AO.30.003492|bibcode=1991ApOpt..30.3492G }}</ref> the cause of the iridescence.
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[[Eyespot (mimicry)|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.<ref name="Caroll">{{Cite book |last=Carroll |first=Sean |title=Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom |pages=[https://archive.org/details/endlessformsmost00carr_0/page/205 205]–210|isbn=978-0-393-06016-4 |url=https://archive.org/details/endlessformsmost00carr_0 |url-access=registration |quote=Butterfly eyespots defense. |publisher=W. W. Norton & Co. |year=2005}}</ref> 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.<ref>{{cite thesis |last=Heffernan |first=Emily |year=2004 |url=http://etd.fcla.edu/UF/UFE0004770/heffernan_e.pdf |title=Symbiotic Relationship Between ''Anthene emolus'' (Lycaenidae) and ''Oecophylla smaragdina'' (Formicidae): An Obligate Mutualism in the Malaysian Rainforest |publisher=[[University of Florida]] |degree=[[Master of Science|MSc]]}}</ref>
Some caterpillars, especially members of Papilionidae, contain an [[osmeterium]], a Y-shaped protrusible [[gland]] found in the [[Prothorax|prothoracic]] segment of the larvae. When threatened, the caterpillar emits unpleasant smells from the organ to ward off the predators.<ref>{{Cite web |url=http://www.merriam-webster.com/dictionary/osmeterium |title=Osmeterium |publisher=Merriam-Webster |access-date=9 December 2009}}</ref><ref name="About">{{Cite web |url=http://insects.about.com/od/entomologyglossary/g/def_osmeterium.htm |title=Osmeterium |last=Hadley |first=Debbie |publisher=About.com Guide |access-date=9 December 2009 |archive-date=23 July 2008 |archive-url=https://web.archive.org/web/20080723145419/http://insects.about.com/od/entomologyglossary/g/def_osmeterium.htm |url-status=dead }}</ref>
== See also ==
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{{DEFAULTSORT:External Morphology of Lepidoptera}}
[[Category:Lepidopterology]]▼
[[Category:Insect morphology]]
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