All cold blooded animals have their body temperature roughly similar to the surrounding temperature. Insects are cold blooded. They become sluggish in temperatures below 50 F. Freezing temperatures kill insects.
During winter, some insects migrate to warmer places. Others hibernate or diapauses.
Every fall, the Monarch butterfly moves south in large numbers and spend winter in tropical areas. In spring they begin return journey back home. Migration with seasons is a method of escaping unfavorable weather.
The second method, hibernation or diapauses is seen in non-migrant species of butterfly. During this phase, the butterfly suspends temporarily its activities. No growth and development occur in egg, caterpillar or pupa. The adult hides itself in a suitable place and remains motionless.
Diapauses are nature’s safeguard to butterflies during adverse conditions.
The eggs of Banded Hairstreak survive the winter with no development taking place. Larvae do not hatch until the exit of winter.
The caterpillars of Red spotted Purple and Viceroy Butterflies burrow underground or roll into leaf tubes and crawl inside. They stop feeding and sustain on the body reserves.
Gray Hairstreak, Cabbage white and Swallow tails spend winter in their pupal stage. The pupal cover acts as an insulation chamber. The pupa uses the energy stored from the larval stage and remains dormant. Metamorphosis into adult butterfly gets temporarily suspended.
Adults of Mourning cloaks, Question marks, Commas recede into spaces in-between log piles, bark and even attics inside houses.
When the butterfly is in diapauses, it keeps itself alive by a process of ant freezing. Scientists have found Sorbitol and Glycerol in the blood of some butterflies. These chemical substances are believed to function as ant freezing agents.
After all what good is winter for the butterfly, when there are no flowers around to smell or feed upon?