Mayflies: Ephemeroptera

Physical characteristics: Adults are 0.55 to 0.86 inches (14 to 21.8 millimeters). Their wings are spotted. The larvae have mouthparts that look like miniature elephant tusks. They use these tusklike jaws for burrowing in the mud. The large abdominal gills are fringed and used, in part, to create a water current inside the burrow, as a way to maintain a steady flow of oxygen-rich water and food particles.

Geographic range: The brown mayfly lives in western Europe, including Great Britain and Scandinavia, and areas south of the Arctic Circle, ranging east to central Siberia.

Habitat: The larvae prefer the still waters of ponds, lakes, slow-moving rivers, and the mouths of rivers that are not too cold.

Diet: The larvae strain bits of algae and plant materials from the water with their mouthparts and legs.

Behavior and reproduction: Larvae burrow in muddy and sandy bottoms or in fine gravel.

Brown mayflies are valued by fly fishermen, who tie flies that imitate the body form of both larvae and adults. (Illustration by Patricia Ferrer. Reproduced by permission.)

Males fly in small to large mating swarms in the evening next to bodies of water. Females lay their eggs while they float downstream on the water surface. The life cycle is completed within two, or, rarely, three years, depending on water temperature.

Brown mayflies and people: Brown mayflies are valued by fly fishermen, who tie flies that imitate the body form of both larvae and adults.

Conservation status: This species is not threatened or endangered. ∎