Thursday, January 17, 2013

Bad hair day

Even though a caterpillar's skin appears soft and stretchy, it is an exoskeleton that cannot grow. Therefore, a caterpillar must periodically take breaks from eating in order to molt; it develops a new, larger skin underneath its old skin, which is then be shed.

A queen butterfly (Danaus gilippus) caterpillar just after molting.
The queen butterfly caterpillar pictured above had recently molted.  Its old skin can be seen clasped higher up on the leaf vein and its old head capsule can be seen to the left of the caterpillar.  However, the queen butterfly caterpillar itself does not look much different than usual.  In contrast, a freshly molted spotted oleander caterpillar can be recognized easily by its clumped and curly hair!

A spotted oleander caterpillar (Empyreuma affinis) just after molting.

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