The analyses are best performed during the caterpillar phase.
This is where the main food intake takes place and the main detoxification mechanisms are active.
For that the caterpillar's body must be able to grow very fast.
caterpillar of map butterfly with black fore-shoved head capsule
The chitin integument needs to be changed several times in a caterpillar's life.
The first hint for an imminent skinning is the fore-shoving of the animals head-capsule.
freshley moulted map butterfly caterpillar with the old skin on the left
After the old skin is stripped off, the freshly moulted caterpillar is still very sensitive.
The chitin skin needs a few hours to cure completely. The picture above shows a caterpillar, which has moulted a few minutes ago. You still can see its old skin beside.

In some species, the caterpillars change their appearance after every moulting.
moulted head capsule of the map butterfly caterpillar
The map butterfly caterpillar for example gets a pair of forehead cones in its third instar.
The end of the larval stage is followed by pupation.

caterpillar of a small tortoiseshell caterpillar, Nymphalis urticae, preparing for pupating To succeed, the caterpillar needs to find an appropriate place. It trenches into the soil

or attaches itself on a leaf stalk with its hind legs
by way of a spinned silk pad.
There it holds out until its final moult.
freshley pupated caterpillar of small tortoiseshell

During this stage the pupae's body completes under the final skin.


© Ltd, Microscopy-UK, and all contributors 1995 onwards. All rights reserved. Main site is at with full mirror at