Composition: Where have all the bugs gone in winter?

In the cold winter, trees fall down and crops and insects that were once active disappear. Did they all die because they could not stand the cold? No, it's not that simple. In fact, whenever winter comes, most insects will enter the wintering period and stop their activities. No matter how many generations insects can produce in a year, when the environmental conditions are unfavorable to them, there will be a period of growth and development stagnation, that is, the "dormant period", which is often in hot summer or cold winter, so it is also called overwintering or wintering.

Remember the overwintering nymph under the fallen leaves in the nearby overwintering area? (Photograph by Li Hu) The overwintering larva of pupa (the larva of scarab) was observed and studied for a long time, and finally some mysteries of insect overwintering were discovered. The first is to accumulate nutrients. Insects are busy eating a lot before winter, which gradually increases the body fat content, thus compensating the metabolic consumption when there is no food supplement in winter; The second is to reduce the water content in the body. Once the living tissue is frozen, the expanding ice crystals will inevitably destroy the cell membrane and cause fatal trauma. Most importantly, insects can produce a lot of "antifreeze" to lower the freezing point of liquid in the body, thus improving the cold resistance.

Insects can escape the long winter in one or more insect States, such as eggs, larvae, pupae or adults, under litter, rocks, bark, soil cracks and even human houses. When the bad conditions in spring are eliminated, they can recover and continue their life journey.