Mayflies are more sensitive to the toxic effects of insecticides than many other aquatic insects. Insecticides that are highly toxic to mayflies must be used in a manner that keeps the insecticide out of surface water including ponds and streams. The primary protection is the use of a buffer strip. The pesticides can only be used at a prescribed distance from the water’s edge. Toxicity to aquatic insects may preclude certain uses such as arial sprays over forested areas, that could allow pesticide spray to reach the water.

Imidacloprid, is the most widely used insecticide in the United States. A recent article in Environmental Toxicology and Chemistry, THE NEONICOTINOID IMIDACLOPRID SHOWS HIGH CHRONIC TOXICITY TO MAYFLY NYMPHS, found mayflies the most sensitive of 7 species tested. Imidacloprid at 0.03 ug/liter of water killed 10 percent of the mayflies in their test. This work emphasizes the importance of keeping imidacloprid…