Lepidoptera is an insect order containing large number of species showing complete metamorphosis of larva to be transformed into adult.

1. Metamorphosis in
Lepidoptera
Md Ekramuddin
Asst. Professor

2. What is metamorphosis
• Transformation of immature post embryonic
stage into adult stage in life cycle of animals
through metabolic process.
• Physiological,biochemical and behavioural
changes in tissue of immature stage- the
nymph or larva in case of insects.
• Controlled by hormones.
• Different food habit in larva and adult lowers
competition.

3. Lepidopteran metamorphosis
• Lepidoptera is an insect order under Subclass
Pterygota
• Four stages in life cycle-egg,larva,pupa and
adult. Larva is named caterpillar
• Complete or holometamorphosis that means
every tissue of larval body undergoes change
• Larva transforms into strikingly different adult
form distinct from morphology, anatomy and
behaviour

4. Lepidopterans
Butterfly Moth

5. Life cycle of a lepidopteran insect

6. Caterpillar
• Larval stage of lepidopterans
• Usually lasts from about two weeks to a month
• can grow in size more than 30,000 times.
• segmented body consisting of a head, a thorax (with
three pairs of jointed legs with hooks), and an abdomen
(usually with five pairs of stumpy prolegs). Its primary
function is to eat and grow in preparation for pupating.

8. Metamorphic changes
• Primarily transforms into non-feeding pupa
• First, the caterpillar digests itself, releasing
enzymes to dissolve all of its tissues
• Certain highly organized groups of cells known
as imaginal discs survive the digestive process
• Imaginal discs-discs for its eyes, for its wings,
its legs and so on.
• certain caterpillar muscles and sections of the
nervous system are largely preserved in the
adult lepidopteran

9. Changes cont….
• Once a caterpillar has disintegrated all of its
tissues except for the imaginal discs, those discs
use the protein-rich soup all around them to fuel
the rapid cell division required to form the wings,
antennae, legs, eyes, genitals and all the other
features of an adult butterfly or moth
• New cuticle is formed by molting through
synthesis of molting fluid(MF)
• Ecdysone is the molting hormone of insects. It
causes an insect to molt.

10. Molting
• The caterpillar releases an enzyme that dissolves
the inner layer of its cuticle (skin).
• Then it expands its body and splits the cuticle to
enable it crawl out of it. The critical part is
dissolving the inner layer to separate themselves
from it.
• The head capsule is the first part of the old skin
to come off during the molting process.
• Then the old skin peels back from the front of the
caterpillar
• Several molting events take place and each
intermediate larval stage is called an instar

13. Endocrine regulation of Lepidopteran
metamorphosis

16. Thank you