I need help with an old mystery. About 30 years ago, when we were living near Chicago, Il. a Monarch butterfly showed up in our 6-year old daughter's bedroom. It was December or January, clearly too cold and snowy a time of year for a Monarch to be out. Our daughter had apparently brought in a pupa from the yard, and then forgotten about it. It was far to cold to release the butterfly, so we fed and kept it as best we could for about a month, before it died. We were enchanted by this beautiful unexpected visitor, but distressed that its life cycle was disrupted.
I am a storyteller and would like to include this event in a story I am writing for a program to use at libraries this summer during their reading program titled Catch the Reading Bug. My question is, how could the pupa have lasted long enough to have the adult emerge in December or January? After 30 years, my memory of the actual month the butterfly showed up may be fuzzy. However, we all remember that it was below freezing and it was way too cold for a butterfly.
Does temperature affect the development of the egg, caterpillar, and pupa? Can a pupa overwinter? I would appreciate any information or suggestions you can give that would explain our mystery.