Nature Notebook – Freeze Tolerant Insects

Late fall and early winter are great times for insect-averse people to take walks in the woods. By then insects have hunkered down to wait out the winter temperatures that are not conducive to insect activity.

Most insects move into a state of “suspended animation” called diapause. In this state, they can experience lower temperatures without dire consequences. Some are freeze-avoidant. They burrow into cover or build shelters then, flood their system with glycerol, which allows them to become supercooled but not frozen.

Other insects are freeze-tolerant. They produce ice-nucleating proteins in the fluid that surrounds its cells. These become the preferred “sites of freezing.” Ice slowly (very important) forms and uses up water in the fluid. This controlled dehydration means no water is available for freezing inside the cell where ice formation would be disastrous.

The dehydration process even worked for naturally dried fly larvae from the African desert. They survived immersion in liquid helium to -269°C!!