Where Do Insects Go in Winter?
In parts of the world where winters are cold, most insects die at summers end. But they leave many eggs to hatch in the spring. Some insects sleep all winter long. They hide in the ground and under the bark of trees. Crickets and ants do this. But ants come out on sunny winter days.
Honeybees huddle together in their beehive and eat the honey they collected during the summer. They also are able to raise the temperature by vibrating wing muscles. Heat energy is produced by the oxidation of the honey, and circulated throughout the hive by the wing-fanning of worker bees.
Some insects spend the winter wrapped snuggly in their cocoons. Many insects successfully pass the winter as immature larvae. The protection of heavy covers of leaf litter or similar shelters protect the woolly bear caterpillar, while other insects replace the water in their bodies with glycerol, a type of antifreeze! Some grubs simply burrow deeper into the soil to escape the cold.
Migration is one strategy for escaping the killing temperatures. Monarch butterflies and ladybugs are like birds. They fly south to warmer places for the winter. Not many insects are active in the winter, but the nymphs of dragonflies, mayflies and stoneflies live in waters of ponds and streams, often beneath ice. They feed actively and grow all winter to emerge as adults in early spring.
Many insects hibernate as adults. Lady bird beetles are a well-known example, and are sometimes seen in great numbers in the fall as they congregate at high elevations. Many large wasps seek shelter in the attics of houses or barns. Tree holes, leaf litter, and under logs and rocks are common shelters for overwintering adult insects.
In general, insects are able to survive cold temperatures easiest when the temperatures are stable, not fluctuating through alternate thaws and freezes. Many insects can gain shelter and nourishment through the winter in a variety of micro-habitats. Among these niches are under the soil, inside the wood of logs and trees, and even in plant galls.
One kind of fly is known by fishermen to be present in certain galls in winter, and the fly larvae are consequently used as fish-bait. Blankets of snow benefit insects by insulating the ground and keeping the temperature surprisingly constant.
Insects that are inactive during the winter months undergo a state in which their growth, development, and activities are suspended temporarily, with a metabolic rate that is high enough to keep them alive. This dormant condition is termed diapause. In comparison, vertebrates undergo hibernation, during which they have minor activity and add tissues to their bodies.