Nature Notebook – Promethea Moth Caterpillars

Many insects spend most of their life cycle as “children.” The proportion of their time as a larva and/or a pupa is much longer than their time as an adult.

These Promethea moth caterpillars are a prime example. Their eggs were laid in June. Tiny hairy, black caterpillars hatched a few weeks later. The larvae grow slowly, changing their appearance with each successive molt (shedding of their exoskeleton). By fall, they will be about 2 inches long and ready to pupate.

Each larva crawls away from its food source into a tree. It “sews” a leaf shelter around itself before forming its cocoon. It will remain in this stage (the pupa)  until spring.

The adults that emerge do not eat; they rely on fat stored during the larval stage.  Their one- to two-week stint as an adult is spent creating the next generation.