What Do Woolly Bear Caterpillars Eat?

Woolly Bear.JPGDid you ever wonder?

The Woolly Bear Caterpillar, the larval stage of the Isabella Tiger Moth, can be spotted all over the place on the East Coast this time of year. Like most insects except the Monarch, they will spend the winter here in a hibernation-like state called diapause. Many species of butterfly and moth actually spend the winter tucked into their chrysalis. The Woolly Bear is spotted out a bit later in the season perhaps in part because it actually spends the winter in caterpillar form, with a special anti-freeze inside of it that will keep it from forming ice crystals inside its body.

Like actual bears, preparing for all of this winter stuff (and the metamorphosis that follows in the spring) requires a lot of eating!!!

Woolly Bear Eating.JPG

In fact, all caterpillars are eating machines. The Woolly Bears we see this time of year are most often walking in our path, making them very visible. Most caterpillars, when they have completed their eating and growing phase (the very definition of a caterpillar might as well be walking digestive tract), go through a period of wandering. The Woolly Bears that we see, fully grown, are seeking out a good spot to wait out the cold. It is less common to witness them eating, so I was delighted to witness this act in my own neighborhood just the other day. I recently moved, and although I have lived in Maryland suburbs for a good portion of my life I’ve never seen as many caterpillars as I have in my new ‘hood. These photos were taken at night, because being a walking GI tract is a 24/7 enterprise.


This guy is eating some dandelion! In fact, the answer to your question is that Woolly Bears are not picky, and this is likely a huge contributor to their seeming ubiquity. Also helpful in making Woolly Bears one of the most frequently spotted species is that they eat foods that are likely to grow near where humans live! Especially the low growing weedy types, which botanists and nature nerds like me call herbaceous. In addition to Dandelion, they are willing to munch on various grasses, Nettles, Meadowsweet, and lettuce. OMG OMG OMG but what kind of winter are they predicting this year? I remain as dubious of this association as I do of astrology, but it is a good way to get kids paying these little critters a bit of special attention. Meanwhile I’ll beΒ hoping for a mild cold season.


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