Abstract 1. 1. A variety of adult and immature insects, most of which occupy highly exposed habitats. successfully overwinter in interior Alaska. 2. 2. A number of adult beetles are freezing-tolerant. All exhibit relatively high supercooling points and synthesize large quantities of polyhydric alcohols in response to cold. 3. 3. At least four other orders are represented by adult insects that tolerate freezing, but in contrast to adult beetles, all exhibit relatively low supercooling points associated with the build-up of glycerol. 4. 4. At least three species of larvae that overwinter in galls undergo a remarkable increase in supercooling capability (to ca. −60°C) associated with synthesis of large quantities of glycerol in winter. 5. 5. None of the larvae tested could survive freezing in spite of their high glycerol levels.