Kyla, I'm still waiting for my 5 BST chrysalises to eclose. They formed their chrysalises around the same time as the Monarchs. The Monarchs have all eclosed now, but not the BSTs. Hopefully they will emerge soon while all the fall flowers are still in bloom and the days are still pleasant.
Last year, I had a late BST caterpillar who formed a chrysalis and then overwintered that way. I didn't keep him inside because of the warmth in the house--I didn't want him to come out and find no nectar, no mate, etc. He stayed outside all winter, and then in the spring I took his stick out of the mason jar and under the Joe Pye weed. Then I seemed to lose track of his stick. Don't know what ever happened to him.
