The Suitcase Lady

Cocoon

June 24, 2014, 9:59 pm

Summertime has officially arrived and with it comes the world’s most charismatic insects, the butterflies and moths, a.k.a. the Lepidoptera family.

Thanks to a wonderful exhibit at a Chicago natural history museum, I can finally and clearly understand the difference between a cocoon and a chrysalis. Unfortunately, these words are often used interchangeably in our American speech, books and schools despite the scientific fact that a cocoon is not a chrysalis.

Both butterflies and moths, like all insects, metamorphose, or change, at different times in their lives. They cycle through four stages; egg, larva (caterpillar), pupa and adult. The pupa stage is where our confusion sets in.

Both butterfly and moth caterpillars truly are hungry; they eat voraciously. They outgrow their skins and molt numerous times.

When butterfly caterpillars molt for the last time, their new skins harden into protective chrysalises. They morph right beneath their own skins. “The chrysalis is not a container, IT IS AN ACTUAL INSECT.” Some chrysalises are stunningly beautiful. The brilliant green and gold rimmed Monarch chrysalis could easily be mistaken for a pendant crafted by a master jeweler.

Most moth caterpillars do things a bit differently. They create a cocoon from silk they spin, leaves or other materials before they enter the pupa stage. Think of the cocoon as a sleeping bag around the pupating moths. The moths cut their way out of the cocoons or secrete a fluid that softens the structures. Both the butterfly and moth need to hang from their resting places until their wings stretch out and dry and their bodies harden.

I love Eric Carle and his Very Hungry Caterpillar, but his famous caterpillar made a cocoon and then emerged as a butterfly. It should have made a chrysalis.


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