Butterflies Freeze To Death

This year the winter is very cold with us. Because of cold and dry weather we are getting more frost as compare to previous year. This forced the insects to go behind the screen, probably they have died or hibernated. Some days ago I was searching sickle senna plants to find out live pupae of common emigrant. I certainly found a few pupae, but unfortunately the butterflies inside the cocoons were all dead. In the first picture you see a half emerged butterfly, which is frozen to death. The second butterfly was found dead inside the cocoon.

Butterflies Freeze To Death