Female Burrowing Mayflies lay fertilized eggs in water (lakes, streams, creeks, ponds). The larvae live underwater and are called naiads, or nymphs. Even small traces of contaminants in the water they live in will 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.
Burrowing Mayfly larvae are a major food source for fish and are used at live bait by fisherman. Artificial lures mimicking their body shape and color are also used by anglers to catch fish. Adult Mayflies 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 would be greeted with delight among ecologists and limnologists.