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Order: Ephemeroptera

Status: Not Listed

Classification: Invertebrate


Despite their name, mayflies are active during the warmer months of the year, not just May. They tend to be gray, yellow, or brown and have long, thin abdomens. Mayfly larvae are aquatic and found in nearly all types of water bodies, from streams to lakes. The larva is often used as a bioindicator species to measure the health of water. Mayflies can vary in size, growing anywhere from a quarter-inch (0.6 centimeters) to 1.1 inches (2.8 centimeters).


Mayflies are found throughout North America and worldwide. Most of the nymphs develop in streams and rivers that are relatively clean.


Mayfly larvae feed on detritus and other plant materials. Some may feed on insects. The adults do not feed.

Life History

Females deposit eggs in the water. Mayflies spend most of their lives in the water as nymphs and then emerge as adults for only a short while. Adults will live only a day or so, but the aquatic larvae lives for about a year.


Their status is unknown.

Fun Fact

There are more than 600 species of mayfly in the United States and 3,000 worldwide.


Encyclopedia Britannica

Stroud Water Research Center

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