Hibernaculum: Winter Home to Red-spotted Purple

Partially grown Red-spotted Purple caterpillar preparing its hibernaculum (winter home)

On September 23, 2012, I watched one of the very last Red-spotted Purples in the garden. It danced around the Beach Plums and I thought it must be laying eggs. I looked closely at leaf after leaf, zeroing in on the very tip where Red-spotted Purples carefully lay their jewel-like egg, but could find none.

As I scrutinized the leaves I spotted a different treasure than expected – a teeny-tiny caterpillar silking a bit of leaf to the branch and silking the leaf curled shut.

I stepped back from the Beach Plum, looked at the bush as a whole, and noticed other similar leaves .   I knew just what I was looking at, though I’d never seen one before – a nearly completed HIBERNACULUM, where a partially grown Red-spotted Purple caterpillar would winter, hopefully safely.

Learn about the complete life cycle of the Red-spotted Purple and how they survive the winter in my latest column at Native Plants and Wildlife Gardens, where fellow long-time wildlife gardeners share what we’ve learned over years of sometimes painful trial and error.