Most insects hibernate in the larval or pupal stage. The larvae of many caterpillars hatch in Summer and sleep all Winter. A few insects, as certain moths, butterflies and beetles, hibernate in the adult stage. Caterpillars hide under moss, the bark of trees, etc., but they freeze solid and may be broken into pieces like an icicle; they gradually thaw out in the Spring, but when the changes are sudden, great numbers die. In Europe insects pass the winter, not as adults, but in the pupa stage, well wrapped up in a cocoon.

The queen bumble bee makes for herself a hole in the ground, the sides of which she polishes very thoroughly. She goes into this winter home in early October and does not come out for five months or more. She shifts her position and has moments of restlessness but does not take food. She sleeps through all or most of her period of hibernation.

Queen wasps, though preferring a hole behind a piece of loose bark or in the wood of a decaying tree, employ a greater variety of hiding places than does the bumble bee, and retire in September. They are wide awake and active if the weather becomes warm.