Adults are a true nuisance; although the do not bite, they are attracted to eyes and any wet areas on the body such as mucus, pus and blood on and around wounds and exposed genitals of animals; capable of spreading some diseases of man and animals such as “pinkeye” (conjunctivitis).
Adults are small (1/16 to 1/8 inch), dark gray to black-bodied flies with clear wings, somewhat similar to tiny houseflies.
Chloropid flies may be confused with fruit flies (Drosophila), but can be separated by characteristic antennal structures: the chloropid flies have a simple hair-like projection (arista) on the last antennal segment, whereas the arista on Drosophila are feathered.
Biology & Life Cycle
Clusters of eggs are deposited on or in the soil by female flies. Larvae resemble tiny maggots and develop through several stages (instars) over 7 to 11 days in warm weather. Larvae pupate close to the soil surface and emerge as adults in about a week. Development from egg to adult can occur in about 21 days, but takes longer during colder winter months. They can occur year-round and may be locally abundant at certain times of the year, such as spring and fall, when conditions are favorable for their development.
Habitat & Food Sources
Adults have lapping mouthparts capable of and rasping (scarifying) because of spines covering the mouthpart (labella). Larvae develop in a variety of habitats such as decaying plant and animal matter and plant rootlets, particularly in freshly disturbed, well drained and aerated sandy soils. Female flies attack animals while males are attracted to flowers. Adult females can be collected with a fine-mesh aerial net by swinging it around ones head while walking through infested areas.
The control methods in the past included poison bait and different types of attractant baits that were placed in mostly agricultural fields. For the last ten years, the District has used 8,000 to 10,000 traps each season, supplied with liquid egg bait to attract and remove eye gnats from agricultural areas and country clubs, without using hazardous ingredients. The eye gnat traps are made of two-quart clear plastic jars joined by a black collar with a clear funnel in the upper jar. The traps are secured with a metal wire to wooden stakes in agricultural areas or trees in country clubs. The traps are serviced on a weekly basis and refilled with the liquid egg bait. Removing leaf litter, weeds, grass clippings, and flowers, before decaying, are of a great help for eye gnat prevention.