Caterpillars pass through five stages of growth, called instars, before they make chrysalises or cocoons. They enter each new stage by shedding their old skins. This Polyphemus cat is nearing the end of its last stage.

Caterpillars often stop eating a day or so before shedding. They use silk to attach their rear ends to leaves or twigs. They puff themselves up to loosen their old skins. Then, like these Gulf Fritillary and Eastern Black Swallowtail caterpillars, they crawl away and leave the skin behind.

As well as shedding their skins, caterpillars shed the faceplates that cover their faces.  These usually show up at the bottom of the cage, amid balls of poop and scraps of leaves.

Some caterpillars look pretty much the same from instar to instar – they just get bigger. But others change dramatically.

The early instars of Spicebush Swallowtails resemble dollops of bird poop.

Later instars look like cartoon characters.

Other insects shed skins and pass through instars as well. Ladybugs go through several instars that don’t look anything like their final form.

These Polyphemus cats have several instars to go Happy munching!