A process of acclimatization in which certain organisms produce specific proteins that protect them from freezing to death during the winter. Among other organisms, the common housefly, the fruit fly, and “no-see-em’s” (i.e., Culicoides variipennis) can produce these proteins (e.g., during the gradually decreasing temperatures of a typical fall season in North America). The amount of such proteins produced within their bodies is proportional to the severity and duration of the cold experienced.
For example, prior to cold hardening, Culicoides variipennis insects usually die after exposure for two hours to a temperature of 14°F (-1 0°C). Ifthose insects are first exposed for one hour to a temperature of 41°F (5°C), approximately 98 percent of these insects can then survive exposure for three days to a temperature of 14°F (-10°C).