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13 14 15 Chapter 3 Life cycle studies Destruction, degradation and fragmentation of habitat, excessive grazing, indiscriminate application of pesticides etc. are the major threats to butterfly diversity.Effective conservation strategies demand a complete thorough understanding of the various stages of their life cycle, the challenges and the adaptive as well as defensive mechanisms they have developed. In view of this,study of various stages of butterfly life cycle was taken up. Though major portion of this study relied on field observation and photographic documentation, life cycle studies to some extent involved in vitro observations under controlled conditions.Eggs and the caterpillars with their specific host plants were maintained in a confined area to fecilitate easier observation.Various stages of life cycle were documented like this. After the emergence of the adult butterfly from the pupa, it was released back into it's habitat. Butterflies are “holometabolous” insects with four distinct phases in their life cycle.They are egg, larva or caterpillar, pupa or chrysalis and adult . Each stage has distinctly varied morphology,life needs, challenges and defences. Egg The female butterfly produces fertilized eggs after mating, which are laid either in large clusters or single in a species specific manner. The eggs are laid on appropriate larval host plant; on the apt part of it, which is carefully chosen by the female. This ensures the adequate supply of most appropriate food for the larvae as soon as they hatch out. The eggs may be laid either on the upper side or the underside of the leaves or any other tender parts of the plant. The eggs are stuck to the leaf surface by a sticky material covering them. Eggs in most of the species are provided with species specific, complex ornamental patterns as pits, ridges or polygonal cells. Egg laying pattern in butterflies Single (White Orange Tip) Cluster (Pioneer) Eggs of butterflies Papilionidae Blue Mormon Pieridae Common Wanderer Nymphalidae Blue Tiger 16 Lycaenidae Pea Blue Hesperidae African Marbled Skipper Larva After a few days (variable with species, temperature etc.), the larva eats through the tip of the egg shell and emerges out of it. Usually the first meal of the larva comprises the shell itself, supplying nutrients and also destroying the evidence for a protective reason (Kunte). Larva is the only active feeding and growing stage, during which enormous amount of nutrients/resources is stored for future stages of the life cycle. The caterpillars of various species have specific larval food plants or soft parts therein (fresh leaves or soft inside of fleshy fruits etc.). As a result of continuous, voracious feeding, the caterpillar shows rapid increase in its body size and weight. During larval growth period, it casts off its outer skin layers five times which is known as “moulting”. The period of time between two consecutive moultings is an instar. Around a day before each moulting the larva stops feeding and moving. Often after throwing away its old “hide”, it feeds on it, possibly as a nutrition supplement. After complete growth the lava enters into the pupal stage; short and compact form with no distinct head nor jaws nor legs. Body of a caterpillar is soft, flexible except the head, a hard chitinous capsule. The head bears biting and chewing mouthparts used in voracious feeding, spinneret, the silk spinning organ and a pair of simple eyes. The thoracic region is made up of three segments, each with a pair of true legs, used to grip the leaves while feeding. The abdominal region has 7-10 segments, each with a pair of fleshy prolegs used for holding the silk threads on which the caterpillar rests. The last segment has a pair of claspers, used for suspending the larva during pupation Larval Forms of butterflies . Papilionidae Crimson Rose Pieridae Common Jezebel Hatching Nymphalidae Striped Tiger Eating the egg shell Lycaenidae Pale Grass Blue Moulting Hesperidae Common Banded Awl Devouring its 'hide' Pupa / Chrysalis This is the dormant stage in the life cycle during which larval tissues / organs are dismantled and organs/structures of an active adult butterfly are produced. The complete appearance of the insect changes. The blade like mouth parts are replaced by long, coiled proboscis and the prolegs disappear with the development of wings. Simple eyes are replaced by the compound eyes. The body becomes more distinctly regionalized into head, thorax and abdomen. In total during pupal stage, the adult is formed, however, with small and soft wings. 17 Pupae Papilionidae Common Rose Pieridae Great OrangeTip Nymphalidae Blue Tiger Lycaenidae Pea Blue Hesperidae Grass Demon The adult butterfly emerges out from the pupa after a few days. Roughly a day before emergence the pupal skin becomes transparent and the wings, legs as well as other parts of the body become visible. The butterfly pushes the pupal case from inside with it's legs so that it breaks open like a door. Now the butterfly slips out and holds onto the surface, where it pupated or any other place to suspend itself. With the wings smaller and crumpled, the butterfly looks wet and unrecognizably different. When the butterfly suspends itself, blood is pumped into the veins of the wings causing slow unfolding of the latter. After the wings are extended and dry the adult flies off. Finding a mate to continue the species is the major assignment of the adult butterfly. The female has to find the appropriate larval host plants before laying eggs. Adult stage is short living and still it is the one which gets maximum attention and recognition. Maximum information about butterflies is of this stage. The body is typically divisible into head, thorax and abdomen. The head has a pair of compound eyes, a long tube like proboscis and a pair of antennae. The compound eyes can perceive UV light (Kunte). The proboscis is kept coiled (composed of two parts) when not in use. When the butterfly feeds, the two halves join to form a tube and nectar is sucked in. The thorax has three pairs of legs and two pairs of wings. The scaly wings have speciesx color patterns which form the major index of taxonomic identification. Males of some of the species have “scent scales” used for chemical communication between the opposite sexes. Each thoracic segment bears a pair of segmented legs. The segmented abdomen does not have any appendages. It bears the sex specific genitalia at the posterior end which facilitate the process of mating. Blue Tiger Striped Tiger 18 19 20 21