Subject: First insect of spring
Location: Riverbend Park, Virginia
March 9, 2015 4:23 pm
Hello, while walking along the Potomac River today, we saw this insect in fair abundance. It appears the American Coots and other waterfowl were eating them from the surface of the river. They were also landing on people, trees, and the still snowy ground. As far as I know, the first sighting of them was yesterday. Average length was 0.75 inches. Do you know what this insect is? Thank you!
This is a Winter Stonefly in the family Taeniopterygidae. According to BugGuide: “The defining need of winter stonefly nymphs is for very high levels of oxygen in the water. Warm temperatures, excessive organic matter, and many pollutants all reduce oxygen levels. The result: they’re only active in the coldest part of the year and are very sensitive to pollution. Their main interest to humans is as an indicator species: you can tell that water is unpolluted if stoneflies live there. They also provide food for trout – though not as much as species active when trout are themselves more active in warmer parts of the year.” Here is an image of a member of the genus Taeniopteryx from BugGuide that looks very similar.