Somehow, I forgot to offer a “What Is It!” post for March. To make up for that oversight, April will be “What Is It!” month. Here’s one to get us started. A reader submitted this image from her yard in late March. Email your identification and any comments to Irubinacci@amesfreelibrary.org and check back next week for the answer.
Remember how last week’s post described non-biting midges? I intended to return to the brook to photograph some adults. I didn’t. I visited a vernal pool instead and, by accident, found a very active midge larva.
This specimen came from the bottom of the pool, which was carpeted in dead leaves. It is an immature insect despite the common name “bloodworm.” Here is a single frame from the video clip. Notice the insect’s segments, head, posterior prolegs, and digestive tract.
This greatly-enlarged diagram shows anatomical details that are unclear when a larva is actively swimming.
Midge larvae (family: Chironomidae)
Drawing by Philip Kurzeja from "Benthic Invertebrate Fauna, Wetland Ecosystems
Matthew J. Cooper, Donald Uzarski, T.M. Burton via Research Gate
The larvae of some species of non-biting midge, like this one, are red because they “have hemoglobin in their circulatory fluid.” According to the Animal Diversity Web, this iron-rich substance “helps them survive in low-oxygen habitats.” Midges, however, live in a wide range of aquatic and moist environments. Our insect is just one of many, many species in the Chironomid family. The University of Minnesota’s Chironomidae Research Group asserts that “There are more than 1050 species of Chironomidae in North America.” Worldwide estimates range from 5000 to over 20,000 species. That’s a lot of flies! Unfortunately for us amateur naturalists, midges can be very difficult to identify.
If midge diversity is impressive, so are midge populations. You may have gotten this impression if you watched last week’s linked Youtube video, “Midges – What Are They?” filmed near Lake Erie. According to the University of Minnesota, non-biting midges “usually make up over 50% of the insects that live at the bottom of streams and lakes as larvae.” Although I have often seen midges in swarms and pond water, I never realized how important they were to aquatic food chains. By consuming aquatic plants, detritus, and sometimes small prey, midge larvae make energy available to larger animals – by getting eaten! And, boy, are they eaten . . . by fish, larger aquatic insects, amphibians, birds, dragonflies, bats, and more. Next time you see an annoying swarm of bugs, think of all the mouths it will feed.