Winter activities

Field work on my insect of choice, grasshoppers, is at a standstill here on the Colorado Front Range. I’m spending my time trolling the Web, building up this blog, writing my honor’s thesis on ant anosmia, and enjoying the beautiful snowfall we have today.

In case you’re curious about what happens with insects during the winter, here’s some general information. Some insects are “freeze-tolerant,” meaning that they have evolved strategies to survive colder temperatures than those that are “freeze-resistant” or those that die from cold. Generally speaking, non-feeding stages such as eggs and pupae can survive colder temperatures than other stages. Some insects, particularly larvae, burrow into the ground to escape the cold or hide beneath leaf-litter (e.g. a woolly bear caterpillar). Some replace the water in their body with glycerol (glycerin; part of triglycerides in humans) and use it as an antifreeze.

The nymphs (juveniles) of dragonflies, mayflies, and stoneflies can live beneath ice and feed actively all winter so they’re ready to emerge in spring. Preying mantises (Mantodea) lay eggs that overwinter. And the pupae of some moths in the family Saturniidae may be found attached to branches in the winter.

Photo by Kathie Hodge

And, of course, the the old standby, migration, is an excellent strategy for escaping killing cold. The Monarch Butterfly is the likely the best-known migrator (see http://www.monarchwatch.org for more information). But other insects, especially crop insects, migrate into northern areas from the southern states in the Spring.

The list wouldn’t be complete without mentioning the tiny Collembola, a close relative of insects, that can be found on the surface of snow!

This link from Colorado State University’s extension office explains more about evolutionary strategies for insect overwintering: Insects in Winter. So when you’re tromping about in the snow, don’t forget to look around you!

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