06/16/2026
They have arrived at the campground! Luckily we do not get them as bad here as they are closer to the lake in town.
The mayflies have returned! Mayflies typically return to Northern Ohio and the Lake Erie shoreline, including Sandusky, in late May through July. They hatch in massive swarms once water temperatures reach the upper 60s. While they are a nuisance, their return is a positive indicator of Lake Erie's water quality and a great food source for local fish.
Why They Swarm: Millions of mayfly larvae emerge from the sediment at the bottom of Lake Erie and hatch into adults. They are incredibly sensitive to pollution, so a large hatch means the lake's ecosystem is healthy.
Where They Go: They are highly attracted to bright lights, causing them to cover streetlights, buildings, cars, and homes, particularly within a mile of the shoreline.
Lifespan: Adult mayflies only live for 24 to 72 hours, with their sole purpose being to mate and lay eggs.
Harmless but Messy: They do not bite or sting. However, their sheer volume and the mess they leave behind can be overwhelming, sometimes requiring streetlights to be shut off in towns like Port Clinton to prevent driving hazards.
Key facts about these "briefly winged" creatures include:
No Mouthparts: Adult mayflies don't eat. Because their adult lifespan is so brief, they lack functional mouthparts and a digestive tract.
Two "Adult" Molts: Mayflies are the only insects that molt after developing wings. They emerge from the water as a subadult (or dun), rest for a few hours, and then molt one final time into a mature reproductive adult.
Aquatic Childhood: The nymph (or naiad) stage can last anywhere from a few months to two years. They live on lakebeds or streambeds, eating algae and plant debris.
Sometimes They Swarm: Around late spring and summer, hatches can be massive. Swarms are sometimes so dense near large bodies of water that they appear on weather radars and require street sweepers to clear them away.
