Winter Insects in the North Cascades

February 17th, 2017 | Posted by in Naturalist Notes

For weeks here in the North Cascades, the ground has been blanketed in a thick layer of snow and ice, two or three feet deep in places. It is not the kind of weather in which you’d expect to see many insects out and about—and indeed, most insects go into a dormant phase in the winter, surviving the season in a state of suspended torpor as eggs, larvae, or adults. Yet it turns out that some insects will brave the snow and venture out in near-freezing temperatures.

After some of our recent snowfalls, I’ve gone snowshoeing and found winter insects alive and well, crawling about on the recently fallen snow crystals. Below are a few of the insect species you might encounter in the North Cascades even in the depths of winter:

Illustration of a midge or ‘no-see-ums’ courtesy of Wikipedia

Midges – In late January, fellow graduate M.Ed student Dan Dubie and myself went out hunting for midges after we noticed several of the tiny insects flying outside the window of the North Cascades Institute Environmental Learning Center dining hall. Midges are a type of true fly, meaning they belong to the same family as house flies, bluebottles, mosquitoes, and hundreds of other insects with a single pair of wings. Midges are among the smallest and most delicate members of the fly order, making it all the more impressive that they can survive in winter.

First we set out to find where the midges were coming from. Most midges spend the first part of their life cycle underwater, so I went down to the shore of Lake Diablo to look for signs of them. There, I found what appeared to be the shed pupal casings of a small insect floating in the water. I hypothesized that the midges we’d seen were recently-emerged adults that came out of these cases, just as a butterfly emerges from a chrysalis.

We next caught several in small jars, and I later examined them under a microscope to try to identify them. While I can’t be 100% positive (tiny insects are extremely difficult to identify, and in many cases only experts can make the call with certainty), I’m fairly confident the midges we found belong to the family Ceratopogonidae, the “no-see-ums.” They are also known as biting midges—but they never bit me, leading me to think this particular species must feed on animals other than humans.

In fact most midges, even those belonging to Ceratopogonidae, are completely harmless to people. Midges and other flies are among the most under-appreciated of insects, but they are an important part of the ecosystem and their ability to be active in winter testifies to their tenacity.

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