In different regions of the World mosquitoes can employ different overwintering strategies that mostly depend on environmental conditions there.
Mosquitoes as well as many other insects survive temperatures below freezing. This freezing tolerance is fulfilled by two distinct biochemical processes. In the first process, the insect's body water is replaced by glycerol, which acts as antifreeze and keeps the body cells from tearing open when temperatures reach the freezing point. During the second process, "supercooling," the mosquito’s body temperature is lowered below the freezing point without its fluids becoming solid. The insect's body temperature is decreasing as the environmental temperature lovers to a point at which fatality occurs; the insect dies at this supercooling point. During mild winters or in proper hiding places the supercooling point is never reached.
All life stages of mosquitoes except adults are aquatic and can occur in a variety of wet or moist places such as ponds, artificial containers, moist areas of fields or forests, salt water marshes and so on.
The majority of mosquitoes in Alaska spend the winter as eggs within the specific habitat. These eggs lie dormant throughout the winter until water temperatures are warm enough for hatching to occur the following spring.
Adult overwitering mosquitoes select hidings where the temperatures would not drop down markedly during typical winter. Such places include abandoned houses, basements or other similar structures (3 picture), as well as different irrigation pipes (2 picture). Some of mosquitoes hide under the tree bark or in piles of leaves and branches that are covered by snow during the winter (1 picture).
Individuals that overwinter in situ in a dormant state usually do not constitute the main part of the next season's mosquito populations.
In warmer climatic zones several types of overwintering strategies are recognized by scientists: continued reproduction without diapause; diapausing female adults; diapausing eggs; diapausing larvae and diapausing eggs and larvae.