The short-lived adult Burrowing Mayfly can be a useful bioindicator for the cleanliness and health of the Great Lakes and connected waterways.
Due to their sensitivity to pollution in the early stages of life, the presence of Burrowing Mayflies has long been used as a means of judging the purity of the Great Lakes ecosystem. Before pollution and sewage were allowed to pour into the Great Lakes, swarms of Burrowing Mayflies would inhabit the area creating a nuisance for residents. After pollution was allowed into the waterways and lakes, the Burrowing Mayflies all but disappeared. Their return to the region would be a sign of improved cleanliness in the waters their juveniles call home.
Burrowing Mayflies are have large yellow wings with a net-like vein pattern on them. Their bodies are yellow with brown diagonal stripes on each segment of the abdomen. A long neck separates the head from the tubular abdomen. Two large eyes flank the sides of the head. The front pair of legs may be lifted like antennae. Female Burrowing Mayflies lay fertilized eggs in water (lakes, streams, creeks, ponds). The offspring lives underwater for a few years and is called a nymph. Even small traces of contaminants in the water they live in can kill them. Gills along the sides of their bodies allow them to 'breathe' under water. They feed on aquatic plant matter and hide in the sediment to avoid being eaten by fish or larger naiads. They will molt several times over the course of a year or more before finally leaving the water to finish metamorphosis.
Once the larva crawls out of the water, it molts and its first wings appear. This first rendition of maturity is called the subimago stage and is eventually followed by another molting. A second molt will generate a brighter body color. The full adult is called an imago and they are fertile, but short-lived. In fact, the lifespan at the imago level may be one day at best. They live only long enough to mate and deposit eggs for a future generation.
Burrowing Mayfly larvae are a major food source for fish and are used as live bait by fisherman. Artificial lures mimicking their body shape and color are also used by anglers to catch fish. Adults are also a major food source for birds, insects and spiders. Because both life stages are eaten by a variety of other creatures, survival of the species depends on mass reproduction which can lead to those annoying swarms seen decades ago. Nowadays, such a sight around the Great Lakes region might be greeted with delight and curiosity.
Scientific Name: Hexagenia spp.
Other Name(s): Common Burrowing Mayfly, Golden Mayfly, Michigan Mayfly, Great Leadwing Drake, Green Bay Mayfly
Size (Adult; Length): 10mm to 30mm (0.39in to 1.17in)
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