LEPIDOPTERA

 

There are about 140 000 species that belong to the order of Lepidoptera, one of the most numerous orders of the insect class. Their size (wing span) ranges from 0,5 mm to 250 mm. Adult insects (imagoes) have two pairs of well-developed wings. The whole body and a wing membrane are covered with thick layers of tile resembling thin scales (lepidos – shell, scale), which they were named after as scale wing insects (often hairy or naked). The body of a butterfly is elongated and divided into main regions: head (cephalon or caput), chest (thorax) and stomach (abdomen). The head (caput) of a butterfly is of orthognatic type, of round or semi-round shape, free and connected to the chest with a small «neck». The sensory organs are located on the upper side of the head – one pair of segmented well-developed antennas of different structure: spiny, head-shaped, and simply or double pinnated. Principally, the male and female antennas are different. The mouth apparatus is adapted to liquid food sucking, it rarely shows the remains of upper jaws, tentacles (lower jaw and lower mouth) with only one developed pair, either maxilar or labial. The proboscis is folded into spiral (spiritromp) resembling to a small trunk while the butterfly rests. The proboscis consists of snuggled highly elongated gutter like upper jaw pieces that are grown together along the edges. A pair of protruding compound eyes (facetted eyes) is located on the head. They are composed of a number of simple cuneiform eyes and most often two simple eyes.

Thorax is made of segments that are grown together and it carries the locomotion organs: two pairs of wings at the back and three pairs of legs on the abdominal side. Many species have a «tympanum», i.e. a hearing membrane at the back thorax or in the abdomen basis. Imagoes of some butterflies have highly rudimentary wings while some imago species do not have wings. The fore wings are usually bigger than the hind wings. The wing joint is created by overlapping of opposite wing edges or by jugum, fraenulum. Day butterflies keep their wings upright and other species keep them mainly horizontal or laid above the body in a curved line. The butterflies with wings that are not reduced preserve the flying ability although there are butterfly species without flying ability despite the wings (the example is a female Lymantria dispar L - Lymantriidae). The legs are well developed although the front legs are either stunted with some species (Nymphalidae) or completely missing (Psychidae). The legs are covered with hair, scales and some even with strong bristles. Some species also have the apparatus for antenna cleaning at front leg tibias. Some males have a range of fragrant scales on their hind legs. The foot (tarsus) is composed of five segments– the first segment is the longest, claws are in pairs, simple or branched. There are no extremities on the abdomen. It is cylindrical or spindle shaped with genital additions that can be seen on its last modified segment. Male and in some cases female copulation organs as well, are of specific structure and they make a highly significant taxonomic property.

Caterpillars are butterfly larvae and they consume plant material – leaves or other plant organs – or they feed by carving corridors in wood (shipworms – Cossidae), branches or fruit. Some species are zoophagous – meat eaters and some species of caterpillars eat caterpillars of their own species (cannibalism). They are elongated and cylindrical but they can also be short and thickset. The body can be either naked or hairy with possible different warts, excrescences and heaps. The head is firm, supplied with short and strong nibbling mouth apparatus and with six (stemmata) simple spotted eyes of special simplified structure. Caterpillars have three pairs of straight, segmented thoracic legs and five pairs of false, abdominal legs the flattened foot piece of which is surrounded with tiny hooks. The hair (haetotaxia) distribution is used as a significant taxonomic property in recognising larvae of certain butterfly groups and species. The abdominal legs of Geometer moths – caterpillars are reduced to only one pair. Geometer moths – move by consecutive pulling and stretching of the front and back part of the body. The butterfly caterpillar head is big, round with the settling in the centre – vertical triangle – of varying depth that is used as a significant taxonomic property in recognising larvae of certain butterfly groups and species. A head can be naked or with primary and secondary bristles and different excrescences. It is highly sclerotised and mobile. Caterpillars spin cocoons in which they reach the dormant stage that is better known as pupa.

Pupa is covered, it is close to the larvae feeding area, individually or in groups. It can be covered with cobweb or it can be in a cocoon spinned by caterpillar. Pupas are spindle-shaped and they resemble to mummies while future butterfly can partially be seen through a thin scale. Antennas, legs and wings can also be seen but they are immobile glued with pupa epidermis. Butterflies lay eggs on different plants, most often in the form of heaps of glued eggs. Imago – the adult butterflies feed by sucking flower nectar and sweet liquids. Some primitive groups also use pollen while certain species do not feed at all in this stage. Imagoes that do not feed (gypsy moth) maintain their life functions thanks to the fatty tissue that the insect collected in the dynamic larvae stage when it deposited food reserves. In insects with this property, the intestine channel is filled with air and it is underdeveloped. The intestine channel in butterflies having the intestine channel in imago stage the same can differ according to development stages; in caterpillars that feed with solid food the intestine channel is adapted to such food; if butterfly imago feeds on nectar its intestine channel is adapted to liquid food.

Out of all development stages only imago – an adult butterfly has the flying ability. In comparison to structure and size relation between fore and hind wings, the butterflies belong to the group of insects with, principally speaking, smaller hind wings. Butterfly wing morphology and structure is specific, wings are intertwined with wing nerves or veins. The nerves act as wing stabilisers. The nerves system consists of a certain number of branching side (vertical) veins and cross (horizontal) veins that connect those vertical ones. When we look at a butterfly starting from the front edge of one wing, the main vertical veins are: costal, subcostal, medial, cubital and anal. Wing disks – a significant system property – are located within the nerves network. Blood liquid runs through the nerves and body cavity. 

LEPIDOPTERA

Red Lepidoptera sadrži oko 140 000 vrsta, jedan je od najobimnijih redova klase insekata. Veličine su (raspon krila) od 0,5 mm pa do 250 mm.Odrasli insekti (imago) imaju dva para dobro razvijenih krila. Celokupno telo i krilna membrana pokriveni su gustim slojevima crepasto poređanih sitnih ljuspica (lepidos – ljuspa, krljušt), a po ovoj karakteristici su i dobili ime ljuspokrilci, često su i dlakavi ali i ogoljeni. Telo leptira je izduženo, podeljeno na glavne regione: glavu (cephalon ili caput), grudi (thorax) i trbuh (abdomen). Glava (caput) leptira je ortognatskog tipa, loptasta ili poluloptasta, slobodna i malim ”vratom”spojena sa grudima. Glava ima sa gornje strane čulne organe – jedan par člankovitih dobro razvijenih pipaka, različite građe: čekinjasti, glavičasti, prosto ili dvostruko perasti. U principu se razlikuju pipci mužjaka i ženki, usni aparat za sisanje prilagođen je za sisanje tečne hrane, retko sa ostacima gornjih vilica, sežnjaci (donjovilični i donjousneni), od kojih je razvijen samo jedan par, ili maksilarni ili labijalni, sisaljka je, dok leptir miruje, savijena u spiralu (spiritromp) – duga surlica. Sisaljka je sastavljena od priljubljenih, jako izduženih delova donje vilice koji su olučasti i po obodima srasli. Na bokovima glave je par ispupčenih složenih očiju (facetovane oči) sastavljenih od mnoštva ugrađenih prostih klinastih očiju i najčešće dva prosta oka.

Grudi leptira su srasle i nose lokomotorne organe: dva para krila sa leđne strane a tri para nogu sa trbušne strane. Na zadnjim grudima ili u osnovi trbuha kod mnogih vrsta postoji ''timpanum'' – slušna membrana. Imaga nekih leptira imaju veoma rudimentirana krila, a neke vrste imaga nemaju krila. Prednja krila obično su veća od zadnjih. Spoj krila nastao je preklapanjem naspramnih ivica krila ili pomoću juguma, frenuluma. Dnevni leptiri u miru drže krila uspravno, druge vrste uglavnom horizontalno ili krivoliko položene preko tela. Leptiri kojima krila nisu redukovana zadržavaju sposobnost da lete, međutim, postoje vrste leptira koje i pored prisustva krila nemaju sposobnost leta (takav primer je i ženka gubara Lymantria dispar L-Lymantriidae). Noge su razvijene ali kod nekih vrsta prednje noge su zakržljale (Nymphalidae) dok su kod nekih potpuno izostale (Psychidae). Noge su pokrivene dlačicama, ljuspicama, neke imaju snažne čekinje. Kod nekih vrsta postoji aparat za čišćenje pipaka na golenima prednjih nogu. Kod pojedinih mužjaka su na zadnjim nogama nalaze se nizovi mirisnih ljuspica. Stopalo (tarsus) petočlano je, prvi članak stopala je najduži, kandže su parne, proste ili račvaste. Trbuh je bez ekstremiteta, cilindričan je ili vretenast, a na njegovom poslednjem modifikovanom segmentu nalaze se spoljni genitalni dodaci. Legalica je teleskopska. Muški a u nekim slučajevima i ženski kopulacioni organi specifične su građe i predstavljaju veoma značajno taksonomsko obeležje.

Gusenice su larve leptira i hrane se biljnom hranom, lišćem ili drugim biljnim organima, ili se hrane dubeći hodnike u drvetu (drvotočci – Cossidae), granama ili plodovima. Neke vrste su zoofage – mesojedne, a neke vrste gusenica proždiru gusenice svoje vrste (kanibalizam). Izdužene su i cilindrične, ali mogu biti kratke i zdepaste. Telo može biti golo ili dlakavo, a na površini može biti raznih bradavica, izraslina i kupa. Glava je čvrsta, snabdevena kratkim snažnim usnim priborom za grickanje i sa po šest (stemmata) prostih tačkastih očiju posebne uprošćene građe. Gusenice imaju tri para pravih, člankovitih grudnih nogu i pet pari lažnih, trbušnih nogu, čiji je zaravljeni stopalni deo opkoljen sitnim kukicama. Raspored čekinja (haetotaxia) koristi se kao značajno taksonomsko obeležje za raspoznavanje larvi pojedinih grupa i vrsta leptira. Kod gusenica Geometridae – zemljomerki redukovane su trbušne noge na samo jedan par nogu. Geometridae – zemljomerke kreću se naizmeničnim povlačenjem i opružanjem prednjeg i zadnjeg dela tela. Glava gusenica leptira je krupna, loptasta, ulegnuće na sredini glave – vertikalni trougao – različite je dubine, koristi se kao značajno taksonomsko obeležje za raspoznavanje larvi pojedinih grupa i vrsta leptira. Glava može biti gola  ili sa primarnim i sekundarnim čekinjama ali i raznim izraštajima. Glava je veoma sklerotizirana i pokretna. Gusenice opredaju čauraste tvorevine – kokone, u kojima dostižu stadijum mirovanja poznatiji kao lutka.

Lutka je pokrivena, nalazi se u blizini ishrane larve, pojedinačno ili u grupama. Lutka može biti obavijena paučinom ili u kokonu koji ispreda gusenica. Lutke su vretenastog oblika i podsećaju na mumije, a budući leptir se delimično providi kroz tanku ljusku, pipci, noge i krila se vide ali su nepokretni, slepljeni pokožicom lutke.  Jaja leptiri polažu na razne biljke, najčešće u vidu gomilica zalepljenih jaja. Imago – odrasli leptiri hrane se sišući nektar cveća i slatke tečnosti, a primitivne grupe koriste i polen, dok se pojedine vrste ne hrane u ovom stadijumu. Imaga koja se ne hrane (gubar, borov prelac, nona) održavaju životne funkcije zahvaljujući masnom tkivu koje je sakupio insekt u dinamičnom stadijumu larve kada je deponovao rezerve hrane. Kod insekata sa ovom karakteristikom crevni kanal je ispunjen vazduhom i zakržljao. Crevni kanal kod leptira koji kao imago imaju crevni kanal razlikuje se po fazama razvoja; kod gusenice koja se hrani čvrstom hranom crevni je kanal prilagođen ovoj hrani, imago leptira se hrani nektarom, njegov crevni kanal je prilagođen tečnoj hrani.

Od svih razvojnih stadijuma jedino imago – odrasli leptir ima sposobnost leta. U odnosu na strukturu i odnos veličine prednjih i zadnjih krila, leptiri spadaju u grupu insekata koji imaju u principu zadnja krila manja od prednjih. Specifična je morfologija i struktura krila leptira, krila su isprepletana krilnim nervima ili žilama. Nervi su stabilizatori krila. Sistem nerava sadrži određeni broj uzdužnih žilica koje se granaju i poprečnih žila koje povezuju uzdužne. Kada posmatramo leptira polazeći od prednje ivice jednog krila, glavne uzdužne žile su: kostalna, supkostalna, medijalna, kubitalna i analna. U okvirima mreže nerava nalaze se krilna polja – važna sistematska odrednica. U nervima se kao i u telesnoj šupljini nalazi krvna tečnost.