A few weeks ago I wrote a basic overview of caddisflies and included photos of an individual I found in late May. In mid June I came across a different caddisfly, shown above. It was in the same location as the first, in a wooded area just above the River Raisin downstream from Blissfield, Michigan.
As these photos suggest, adult caddisflies are usually found resting on vegetation during the day. Most species are nocturnal and become active around dusk. Lately there have been vast numbers of various caddisflies swarming around my porch light in Palmyra, about ten miles upstream from Blissfield. They seem unusually common around here this year.
As I mentioned in my last caddisfly post, these insects have aquatic larvae that are relatively sensitive to poor water conditions. This stretch of river is typically considered to be of poor quality, and yet the caddisfly numbers seem to suggest that many different species are doing uncommonly well in the area.
As I pointed out before, the heavy rain and flooding we had in April and May could have lead to a temporary improvement in the river’s quality. Excessive rain may have helped flush away contaminants, and the turbulent flow may have served to oxygenate the water.