Nature Bulletin No. 142   Febraury 14, 1948
Forest Preserve District of Cook County 
William N. Erickson, President
Roberts Mann, Supt. of Conservation

****:HIBERNATING INSECTS

Insects pass through the winter in every stage of their lives: some kinds 
as eggs, some as larvae, some as pupae, some as nymphs, some as 
adults. Only a few, notably the Monarch butterfly, migrate southward. 
Of those that hibernate as adults, there are a few butterflies.

The Mourning Cloak butterfly spends the winter in barns or sheds or 
hollow trees, and on unusually warm winter days they may emerge and 
fly about -- good-sized butterflies with rusty black wings spotted with 
blue and bordered with pale yellow.

Ladybird beetles, or "Lady bugs", hibernate in big colonies under the 
loose bark of trees, in tree cavities, and in buildings. On warm winter 
days they may come out and crawl around. House flies, and the blow 
flies known as Bluebottles and Greenbottles, winter in cellars, attics and 
the crevices of buildings.  If the temperature rises above 50 degrees, 
they will crawl or fly aimlessly about.

Many adult insects spend the winter underground. The May beetle, or 
"June bug", burrows down below the frost line. So do most kinds of 
ants. The young queen bumblebees lie dormant in burrows well below 
the ground surface. Many insects spend the winter as adults in or under 
rotting logs; some beneath the leaf mold or in the topsoil of woodlands; 
some among grass roots or in bunches of grass. Some beetles, for 
instance, get ready for hibernation by storing up fat, like bears. Other 
insects seem to be able to eliminate water from their bodies and can 
endure freezing temperatures for weeks at a time.

In general, uniformly cold winters with plenty of snow are easiest on 
insect life. Next best, are very mild winters with little or no freezing. 
Cold winters with occasional warm thawing days, and warm winters 
interrupted by severe cold spells, are both disastrous to many kinds of 
hibernating insects.

The snuggest bug is in a rug.