Hawk moth caterpillars don’t hibernate, but if they’re lucky and live long enough, they pupate. This means during their last molt their exoskeleton splits to reveal something like a brown seed pod. The pod doesn’t move very much and does not eat, but within it, the caterpillar’s old body is destroyed, and the new body of the moth is built. If the pupa is to overwinter, it may go into dormancy or diapause where the transformation is halted for a while until the weather warms up.