Eye Gnats

The District's eye gnat program utilizes baited bottle traps to “trap out” and reduce the abundance of eye gnats to tolerable levels. These traps are located at golf courses, parks, and agricultural areas. Eye gnats are very small (1.5-2.5 mm long) flies, primarily a nuisance pest that does not bite, but are a vector of the very contagious conjunctivitis or “pinkeye."

Eye gnats are prevalent in the southern United States, primarily in parts of California and Arizona. In the Coachella Valley, they have been a problem since agriculture was first introduced to the valley.

Breeding Sources

Eye gnats are very common in warm, dry regions. The majority of eye gnats develop in light, well drained, sandy soils that are freshly plowed and contain abundant humus or vegetable matter (such as cover crops or manure), and sufficient moisture. 

Life Cycle

Females get the protein necessary for egg production from exposed mucus. The eggs, about 0.5 millimeters in length, are deposited in batches of up to 50 on or below the surface of the soil. After two days, larvae will develop and feed on a variety of decaying organic matter. The larval stage, under optimum conditions, requires about 7 to 12 days, the pupal stage about 6 to 7 days, totaling approximately 21 days from egg to adult, or 28 days from egg to egg.

Eye gnats do not bite.

They swarm around the head with an annoying persistence, darting at the eyes, mouth, nose, or wounds of humans or other animals. Their labium contains a spine that helps introduce pathogenic organisms to the eye. In this way, eye gnats can aid in the transmission of acute bacterial conjunctivitis (pinkeye) and yaws to humans and anaplasmosi organisms to cattle.

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PDF icon Flies and Gnats brochure (printable)561.06 KB