In the warm, summer months insects seem to bug our everyday existence. From ants scurrying en-mass from a disturbed nest to bothersome wasps at a picnic or moths chewing holes in our favourite sweater they can affect every moment of our lives. Then when the weather cools, they mysteriously vanish. So where do insects go in winter? The answer is as mysterious as their sudden disappearance.
Most insects are cold-blooded and have devised some clever methods of survival when the temperature dips. Many remain tucked up inside a water tight egg which provides a barrier against the cold. Some eggs are even insulated with hair to make conditions really cosy.
Other insects enter into a state of hibernation. This I found to my surprise when I left a few wasps outdoors in a container to check with our experts if they were queens or workers. When I came to collect them a week later, the wasps had stopped crawling around the container. I shook the container. Nope. They weren’t moving at all. Presuming that the cold had killed them I tucked the container into my bag and headed into the office. But when I produced them a few hours later – to my astonishment they had seemingly arisen from the dead and were buzzing around the container. So what happened?
The wasps (all queens by the way) went into a form of hibernation known as diapause. During diapause insects fall into a deep sleep which reduces the demand for the body to burn energy. The duration of the diapause can be controlled by the length of the daylight hours, drought, lack of food or cold weather. Queen wasps look for somewhere to overwinter like a shed or folds of curtains and enter diapause before they start nest building in the spring; other insects look for shelter which is safe from predators such as under stones, amongst leaf litter or logs.
As mentioned before, adolescents as well as adults hibernate. Sometimes the adult dies and leaves its legacy behind in egg, larvae or pupae form. Some dig into the soil or bore into wood in order to escape harsh weather.
Many insects hibernate in our homes for the winter and although our homes are warm, most of these insects will still go through diapause. Fleas however will remain active year round as long as they have a host.
Very few insects migrate south but one of the most famous is the monarch butterfly which migrates from North America to Central America or Southern California, and then returns back home to the north in the spring.
A few insects remain active all year round. Many aquatic insects, in their immature stages are able to survive all year. Some insects such as snow fleas and the winter gnat are at their most active during the winter. The freeze resistant winter stone fly is active only during the winter and into the early spring months.
Such tiny creatures are incredible – insects should not be underestimated.