Gnats come in many varieties
I want to discuss some small gnats that are frequently found in homes or businesses. Most pest control companies won’t control flying insects, but they should let you know if they are present so you can take care of them if they are found in your home or business. The following four groups of flies are very common in New Mexico. If you have a food service facility, you don’t want them around and you probably don’t want them in your home.
Fruit flies (Drosophilidae)
Fruit flies are usually found in the kitchen where they feed and breed on food spilled in out of the way places such as behind or under appliances or similar areas. These small flies have distinctive red eyes, which you can see with a hand lens. They are tan or brown in color and about one-eighth-inch long. They are also known as pomace flies and vinegar flies. They can be serious pests when found in food handling establishments as they breed in and feed on fruits, vegetables and any moist, decaying organic material. They have been known to cause intestinal problems and diarrhea when fruit containing their larvae are eaten. They will also breed in discarded fruit juice and soft drink cans and in unsecured bottles of wine. They are also very prolific as the female can lay about 500 eggs that will hatch and reach adulthood in as little as eight days. In your home you can control fruit flies by totally eliminating all breeding material. They are attracted to acetic acid (vinegar), so put some drops on duct tape or glue boards. Or you can just fill a small paper cup with vinegar and the flies will dive in.
Hump-backed flies (Phoridae)
Phorids are small flies, about an one-eighth-inch long and tan to dark brown in color. They have a distinct hump-backed shape thorax, hence their common name. They do not have red eyes as fruit flies do. When these flies are disturbed, they will run along the surface they are on rather than fly away.
These flies breed in any moist organic material including dirty mops, garbage, decaying fruits and vegetables and dead animal matter. They are also known as coffin flies because of their presence where dead bodies are found, including inside of coffins. There are over 220 species of phorid flies in the United States. You have to eliminate the food source and breeding areas in order to control them in your home or business.
Moth flies (Psychodidae)
Moth flies are small flies with hairy wings that resemble small moths. They are also called filter flies and drain flies. They are usually found in the bathroom. They will breed in the gunk buildup in drains and will often be found in the tub, on shower curtains or on the wall. They are poor fliers and seem to just hop around. The larvae live in gelatinous material in sink and floor drain traps, in sewer treatment plants and in septic tanks. They will also breed in damp crawl spaces under a house. If you have a commercial building, you can put duct tape sticky side down on drains to see which ones they are breeding in. You need to keep your drains clean to control these flies as they have a very short life cycle. They can go from egg to adult in a little over a week in some areas.
Fungus gnats (Sciaridae)
Fungus gnats are very small flies with long legs and long antennae and distinctly patterned wings. They are dark brown or black in color. They are generally found in over-watered house plants where the larvae feed on fungus in the potting soil and moist organic material. The best way to control them is to let the plants dry out almost to the point of wilting before re-watering. That will kill the larvae in the soil. Then put an inch of aquarium gravel on the soil to prevent female fungus gnats from laying any more eggs in the potting soil. You can also place a yellow sticky trap on a stick in the soil to catch the adult gnats.