Hatch, fly, have sex and then die, such is the 24-hour life span of an adult mayfly. Pictured above is probably the largest mayfly hatch that I’ve ever seen. The beach stank the next morning with their decaying corpses, even after scavengers of all types had feasted on their remains. After sex the female mayfly flies over the lake to lay her eggs and then dies in the water. While the male mayflies die on the sand. In their larval stage mayflies are fierce predators, but in their pictured adult stage they don’t even have a digestive system. They’re just a sex machine. Queue your James Brown. In Ohio, the mayflies (also called midges) are called Canadian Soldiers because they come across Lake Erie in huge swarms, like some kind of invading force from the north. The swarms are so thick that driving can become hazardous because they cover the pavement and make it slippery.