Well, you never can tell with them Liz. The one thing I have learned about Swallowtail chrysalides is that they are very unpredictable. I have had them pupate in July and not eclose until the next April, and I have had them pupate in September and eclose in October. You just never know. I just keep mine outside on my porch until it gets cold and it's clear that they are not coming out, and then I move them into the garage for the winter. Were your chrysalides outside?
Angie

So I am curious, in the mainland U.S., your swallowtail pupates and ecloses depending on season temp?? I felt so releive knewing my citrus swallowtails takes 3 to 4 weeks before eclosing!

Dr. Liz, I have a BST chrysalis darkening as we type! It is even colder up here, I am amazed that it will emerge this late. And there are 2 other green chrysalises in the tank, although I have had a couple green ones over-winter in prior years.

I imagine that he/she will play it by ear, and head towards the coast, or maybe south of here, where the temps are milder.

It's exciting anyway! I'm not complaining, butterfly season is so short around here.

Hello, Hawaiiponder-
I am clearly anything but an expert, since this is my first year. However, some, but not all, of our summer species here in the temperate zone will overwinter. Some, like monarchs, migrate. I am not sure about all the species of swallowtails, but BST spend the winter in the chrysalis. They will then emerge next spring to start the cycle over again. What triggers any given butterfly to eclose immediately or overwinter is certainly beyond my level of knowledge. Maybe only the butterfly knows for sure!

Perhaps some other members can chime in about the habits of other swallowtail species. I am guessing that the tiger swallowtail also overwinters here as a chrysalis, but I am not sure even about that. I don't know anything about giant swallowtails, zebra swallowtails, etc.
Liz

Tigers overwinter here in Dane Co. WI as do BSTs.
I have seen Giants "overwinter" in SoFla (Sleeping Giants hehehe). All temperate swallowtails overwinter as pupae unless improperly handled or wacky weather occurs. Swallowtails in subtropical regions, such as South Texas, South Florida and Hawaii can be seen all year, but may spend a little longer in the pupa during cooler, drier months.