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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
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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.
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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
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