Back to Pest Database


Mayfly photo by Jim Moore,
Photo by Jim Moore

Common Name: Mayfly
Latin Name: Many species in various genera
Common Family Name: Mayflies
Latin Family Name: Ephemeroptera

Other Names: Shad flies, lake flies

Origin: Many species of mayflies are native insects in North America.

Biology: These are aquatic insects in their immature stages, as the larva (called naiads) live at the bottom of lakes and streams, feeding on small animals, vegetation, or organic debris. They also become a major food source for other aquatic organisms such as fish. In warm weather the adults emerge in large numbers, and they are attracted to lights and may gather on structures in enormous numbers. Once the insect acquires wings it may fly a short distance, land on a surface, and molt once more to the adult stage, leaving the old exoskeleton stuck to the surface. It is possible that these disintegrating skins can become a cause of inhaled allergenic reactions as they blow in the wind. Adults generally live 1 to 3 days.

Identification: Mayflies are easily identified in the adult stage by the presence of 2 pairs of wings, with the forewings much larger than the hind wings and held vertically over the body. There also is a very long pair of thin cerci protruding from the hind end.

Characteristics Important in Control: There is no need to control these insects, other than exclusion from structures by maintaining windows and doors screened or closed. Reducing exterior lighting, or changing white lights to yellow bulbs, will reduce the attraction of the insects to the structure.