Adapting in the Cold

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Are you beginning to find and use coats, gloves, hats and heavy socks to stay warm in the cold temperatures? Insects have several unique ways of surviving cold temperatures.

Insects spend winter in various life stages including eggs, adults, nymph, larvae, pupae. The overwintering stage is generally the one best adapted to cold temperatures. Structures like cocoons can protect and improve the chances of surviving the cold.

Some insects spend the winter in an inactive state called ‘diapause’ that is like going dormant. There are two major classes of these insects:  freeze-susceptible and freeze-tolerant. Both types of insects are affected by their species, size, moisture, nutrition, temperature, and stage of growth. A freeze-susceptible insect avoids freezing by using antifreeze compounds to supercool body fluids and tissues. To continue life, these insects use the same compound (ethylene glycol) used in antifreeze for vehicles.

Freeze-tolerant insects do not totally freeze. The fluid bathing the living cells freezes, forcing water out of the living cells and lowering the freezing point. The bodies of the insects can reach below-freezing temperatures without forming ice crystals that would damage cells.

Other insects remain active and survive by migration to a warmer area or by finding a suitable protected habitat. Microclimates and hiding places like light fluffy snow can provide good insulation from winter cold. Some insects overwinter in fallen leaves, others behind loose bark and others deep in the soil. The fluctuations in temperature can indeed affect insect survival depending on how low the temperature drops and how long the temperature remains low.

Diapause is stopped in the spring after a long period of cold precedes the rise in temperatures. Insect growth and development return to normal.

Insects survive cold temperature easiest when the temperatures are stable with limited fluctuations but most will survive.