Mayflies don't bite and adults only live for a day, but you don't want to get stuck in a swarm. Here's what to know about the mayfly insect.
All About the Mayfly Insect: Larvae, Lifespan and More
Published on Mar. 17, 2025
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What Does a Mayfly Insect Look Like?
If you’ve ever seen a reedy-looking bug with two long, antenna-looking protrusions from its abdomen, you might have seen a mayfly. Mayflies have thin bodies and clear, veined wings that resemble those of a dragonfly. They have four wings, although the larger forewings usually overlap the smaller hindwings, which leaves the hindwings difficult to see. Their eyes are large, and their two long abdominal protrusions are called cerci.
Mayfly Lifespan: How Long Do Mayflies Live?
Mayflies are found just about everywhere, including throughout the United States. They’re usually found near freshwater, since their life cycle begins with them as water-based nymphs.
During the nymph stage, they feed on algae and small plants; as adult mayflies, they do not have functioning mouths and cannot eat. This means an adult mayfly insect survives in adulthood for only about a single day — just long enough to reproduce.
Do Mayflies Bite or Sting?
Interestingly, mayflies can pose a problem for people who live near water. Because nymphs often reach maturity around the same time in the summer, they can create massive swarms and thick clouds of bugs. There are so many that they can coat roads and cause cars to slide into each other, they crunch underfoot when walking, and the swarms even show up on weather radar.
Fortunately for humans weathering the swarm, mayflies are not harmful and cannot bite or sting.
How Birds Eat Mayflies?
Mayfly swarms are a gift for many insect-eating birds, including eastern kingbirds and tree swallows. They also provide sustenance for fish, spiders, beetles, dragonflies, and even squirrels.
Do Mayflies Molt?
“This creature landed on my window screen. A few days later, an exoskeleton remained as if it has molted. What is it?” asks Birds & Blooms reader Robert LaPointe.
Kenn and Kimberly Kaufman say, “That’s a fine photo of an adult mayfly insect. In their larval form, these fascinating insects live underwater in lakes or streams for one or two years, sometimes longer. After they crawl up out of the water to emerge as winged adults, they live for only a day or two. Adults don’t have functioning mouth parts, so they can’t eat; they live just long enough to mate and for the females to lay eggs in the water.
And you’re right, they do molt. Other winged insects, like dragonflies or butterflies, only molt their exoskeleton (or “skin”) while they’re still growing in the larval or caterpillar stage. Mayflies are unique in molting once after they reach their winged adult form, which is all the more surprising since their adult lives are so brief.”
Sources
- Missouri Department of Conservation, “Mayflies“
- Arkansas State Parks, “Mayflies: Nuisance or Nutrient?“
- National Wildlife Federation, “Mayflies“
About the Experts
Kenn and Kimberly Kaufman are the official bird experts for Birds & Blooms. They are the creators of the Kaufman Field Guide series and they lead birding trips all over the world.
