Posted by allison anonymous on October 15, 2008

Q: Hello,

I recently discovered a wooly bear on a trip to Fire Island and have decided to keep it for my students to observe. I understand that the molt about 6 times in their life cycle, but this was a strange sight indeed!

The caterpillar had been sluggish for a few days, hanging out on its twig and eating little. I laid out a fresh layer of leaf litter on the bottom of its jar (with many holes punched in the top!) and placed it on the exterior window sill pending the identification of a good spot outside for winter. We figured it would move to the bottom soon, but instead, it remained clinging to the twig and finally seemed to split in half this morning! What it left behind was a near identical version of itself, about 1/3 of its size... furry and all. Then its face turned bright pink, like a rose. Then it tried desperately to grab onto the molt and tear it off the twig (unsuccessfully it seems). IT gave up after awhile, then later that evening (several hours after) it ATE the molt, despite the availability of ample fresh grass and leaves, which it has been eating up to now, at the bottom of the jar. Is this normal wooly bear behavior? It has been both alarming and entertaining to say the least.

Also, at what point will it be appropriate to plant the jar outside for winter? Should we wait until it curls up at the bottom? Right now the temperature on the sill matches the outdoor temperature, but it unfortunately can't be used as a permanent location throughout the season.

Thanks!

State: New York

Habitat: forest/open woods

A: It's great that you were able to observe the Woolly Bear behavior. From your description, it's clear that your animal was not finished growing and still had one more molt to make. I was interested in the fact that your animal ate its own skin though - I have never heard that they would do this. I really can't say if this is normal behavior or not but would assume that it is. One of the benefits of having animals like this in captivity is the fact that people get to see behaviors that are usually overlooked in the wild. I'm sure zookeepers see all kinds of interesting behaviors that would be missed otherwise.

Although the weather still hasn't been all that cold this fall (mid Oct now) in New York, to be on the safe side, I'd release your Woolly Bear now. It may take some time for it to "decide" where it wants to overwinter so giving it plenty of time to do this is probably the best for it. Be sure to release it well away from roads so it doesn't get run over. If you release it once the temp gets down to freezing, it will be less able to find that perfect spot. Thanks for writing and good luck with your little guy.

John Wiessinger ( October 16, 2008)