Huge swarms of gentle Giant Mayflies boom in the summertime and are a noteworthy 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 during 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, their darkened wing,s and the yellow and brown pattern on their bodies. They have very, very short life spans at this mature stage of life, mere days really, and so they focus all their energy on reproduction before dying. The best way to ensure successful opportunities for mating is to hang out in large groups for what remains of their lives. Though they are harmless, swarms may disrupt foot or car traffic thanks to wide-eyed passersby.
Females lay their eggs in the water, with soft sediment, allowing the larvae burrow into the bottom silt for shelter. The larvae hide in the sediment and sand. These offspring have an identifiable three-pronged tail and slightly resemble their adult counterparts, but look more like a cross between the adult and a mini-lobster. Giant Mayfly larvae are yellow to brown and black in color. They eat underwater plant material and algae. They in turn are eaten by fish, and when they mature into the subimago phase (not quite adults), they are commonly used by anglers for their own fishing needs.
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.