Swarms of Giant Mayflies occur in the summer and are a sign of the season in the eastern part of the continent.
Giant Mayflies are common in the Eastern United States and can appear in large quantities in the summer months. They represent one of the largest Mayfly type insects in North America and dwell in, and around, water sources. Adult Giant Mayflies can be identified by their twin filament tails, darkened wings and yellow and brown patterned coloring on their bodies. They have very short life spans at this stage of life, mere days, and focus all their energy on reproduction before dying.
Females lay their eggs in the water, which is easier for the larvae burrow into. The larvae hide in the sediment and sand. Giant Mayfly larvae are yellow to brown and black. They have an identifiable three-pronged tail and slightly resemble their adult counterparts, looking more like a cross between the adult and a mini-lobster. They eat underwater plant material and algae. They are eaten by fish and when they mature into the subimago phase (not quite adults), they are used by anglers for fishing.
Scientific Name: Hexagenia limbata
Other Name(s): Mayfly; Golden Mayfly; Green Bay Fly; Big Michigan Mayfly; Great Leadwing Drake
Size (Adult; Length): 18mm to 30mm (0.70in to 1.17in)
Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.