Insects’ hibernation

During the walk in a winter forest, it seems to us that the life around is almost still. However, the snow cover keeps many secrets under it! The researcher and intern at the Research Department, Galina Veniaminovna Sokolova, tells us how insects hibernate and when we should expect them in the spring.

With cold snaps coming people take care of warm clothes, beasts change their summer fur to a warmer winter one. And what do insects do? They have to find secret places, where they could peacefully hibernate and not freeze to death, long in advance before the snow. Since the third week in October, mosquitoes hide into basements and tree hollows, corn bugs, bumblebees, ground beetles, some butterflies’ caterpillars and some other insects find shelter for the winter period under the leaf-litter, an opulent layer of old grass and fallen and slump leaves and fir needles.

In winter, the insects neither crawl nor do they fly, they stay in the state of a suspended animation, which is a temporal slowing of life processes in the body, both externally and internally influenced. One of the terms for suspended animation is anabiosis, which can be translated as life for «bios» and «ana» either meaning a negation, a «no», or conversely meaning «again» or «back» as in «back to life». In this period, the life processes of the body slow down to the extent that they can only be detected with a special equipment. Thus, in this period insects, invertebrates, amphibians and reptiles do not need food or water, they do not feel cold, but their respiration, heartbeat and certain biochemical reactions in the body do not stop. Only some poikilotherm species demonstrate a true anabiosis. For instance, a frog’s heart stops, its kidneys do not work and it absolutely does not breathe, however when it gets warm, its heart starts beating again and all other functions recover as well.

So how do insects survive the winter? Thanks to their condition factor and the salts accumulated in summer, they can endure low temperatures for a long time without being frozen and keep the ability to come back to life with the arrival of warm weather. However many of them do not manage to survive until spring. The reasons for it may include a bad choice of the shelter, a lack of summer supplies, frosts too strong or a sharp temperature difference like this year.

But no matter what, in spring nature comes back to life. According to many years of observation, insects in the Moscow region wake up in the middle of the calendar spring. In the first weeks of April, bees make their first play flight, water striders appear on the surface of water and red wood ants start fussing around the paths. And starting from mid-May wasps begin to buzz in the air and Aedes mosquitoes start their human hunt.