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Bugs in Winter


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I got down to the river about 2:30 p.m. but my little dragonflies were nowhere to be seen. I saw one fly and a tiny spider and a baby centipede under a rock. That was it.

All this raises the question, "Where do the bugs go in winter?" They are ectothermic (cold blooded) and in danger of freezing in even a light frost. Ice forming ruptures cell walls and is usually deadly.

To be blunt, most adult insects, having lived out their lives and reproduced, have fulfilled their destiny and just die. Others, like the Monarch butterfly, migrate to overwinter in warmer climes. But unlike birds, their navigation is all instinctive. The ones that migrate to Mexico were not born there so the navigation is all inherited.

Some insects nearly mummify themselves, getting rid of as much water from their cells as possible. Less water means less crystallization. I suspect that is how my variegated meadowhawk dragonflies manage surviving frosty nights. Looking through my photos, most late winter specimens' abdomens are translucent and nearly empty.

Some insects actually produce an antifreeze in their blood as the temperatures drop. I've read that is how fungus gnats manage in the cold.

A different strategy is to lay eggs somewhere they will not freeze, like running water. It's the strategy of mayflies (order Ephemeroptera), which live for only a couple of days as adults merely to mate and lay eggs before they fall exhausted onto the water to drown and feed the fish. Caddisflies (order Trichoptera) lay eggs in water as well, their larvae building tiny structures from stream debris they carry around. Still others live out the cold months in the soil or underneath rocks, below the reach of frost.

Regardless of their strategy, the chemical processes of life are slowed down in the cold and bugs are much less active. Many will sit out the winter as eggs or pupae (cocoons). Others, like adult mourning cloak butterflies, stay dormant for months but warm up on sunny winter days and briefly brighten our days with an appearance.  

It's a Bug's Life

I am using the word "bug" in the generic sense ... any small creepy crawly critter born with more than four legs. Technically, a bug is a member of the insect order Hemiptera. The "true bugs" are generally shield shaped, with front wings about half the size of the rear wings and piercing/sucking mouth parts.

If you stop to think about it, the world of arthropods is a fearsome place. I can't think of a single major human crime that is not perpetrated daily in my yard by one or another critter. As the apocryphal poem goes, "Great fleas have little fleas, upon their backs to bite 'em, and little fleas have lesser fleas, and so ad infinitum."

One thing I noticed from my first digital photos of insects was the difficulty of shooting a perfect insect. Many entomological photographers actually raise specimens to get photos of undamaged butterflies and moths. At first I was disappointed finding a butterfly's wing torn or a spider missing a leg, but I soon realized these were the marks of the animal's history, like the scars on my own hands. They tell the story of a hard life. In their world, there are no police to run to, no judicial system to appeal to; it is truly dog eat dog.

Insects have six legs and spiders eight, so they can afford to sacrifice one if it allows them to escape with their lives. Butterfly wings are much larger in proportion to their bodies compared to many other fliers. The loss of some surface area is less of a problem for them than it might be for a fly or even a bird. They are, in a sense, over designed.

I cannot conceive of a single one of the nearly million identified species of insects, not to mention spiders, centipedes, millipedes, sow bugs, or scorpions that is so fierce as to be immune from predators. Some of the fiercest, like the black widow and the praying mantis, resort to cannibalism on occasion. The insects we see today are the products of millions and millions of generations of daily, deadly struggle. It is little wonder they are so tough. 



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