These eggs then lie dormant throughout the winter until water temperatures are warm enough for hatching to occur the following spring. Mosquito eggs can sometimes lie dormant for several years, particularly when the eggs are deposited in depressions that are not flooded with water each year. A few species of mosquitoes overwinter in either the larval or pupal stages. The largest of Alaskan mosquitoes, Culiseta Alaskaensis or the snow mosquito, overwinters as an adult under the snow, usually in leaf litter, beneath loose tree bark, or in dead tree stumps. This is the first species to emerge each spring, usually from mid- to late April.
Many insects including mosquitoes survive temperatures below freezing in Alaska.
This freezing tolerance is accomplished by two different biochemical processes. In the first process, the insect's body water is replaced by glycerol, a type of carbohydrate, which acts as an antifreeze and keeps the body cells from rupturing when temperatures reach the freezing point. The supercooling point varies for different species and life stages of insects. The larval stage, however, has a slightly lower supercooling point of -24 degrees F since it overwinters in tree trunks above the snow line where it is subjected to lower temperatures. Below average winter temperatures, light snow cover, and cold soil and leaf litter temperatures during fall and spring months as well as cold water temperatures in May and June are some of the environmental factors that reduce overwintering mosquito populations.