Flies

The Vector Control Program provides educational fly consultations to County residents. The Vector Control Program is not a pest control company and does not trap, bait, or remove flies.

About Flies

Most types of flies in San Diego County are nuisance pests. Rarely, some have the potential to cause allergic reactions, contaminate food, or spread disease.

Common types of fly

House Fly (Summer): This fly is the most frequent pest to humans. The common house fly is grayish-black, about 1/4-inch-long, and covered in hair. In two weeks, one female fly may lay more than 1,000 eggs, typically in animal waste, household garbage, piled lawn clippings, or rotting fruit and vegetables.
Lesser House Fly (Cooler weather): The lesser house fly is seen flying around at eye level, hovering in the middle of a room, in a garage, on a patio, and under trees or other covered areas. Larvae develop from eggs laid in moist organic matter.

Flies and commercial poultry ranches

Commercial poultry ranches may serve as a source for fly breeding. Regulations to prevent fly breeding hazards on commercial poultry ranches in the unincorporated area of the County can be found in the San Diego County Code of Regulatory Ordinances.

The Fly Abatement and Appeals Board (FAAB) was established to assist in determining whether a fly breeding hazard exists and what methods shall be used to abate the hazard.

Prevention

Remove attractants

Attractants are things that draw flies to your property. These include dog poop, trash, or anything with a strong smell. Removing attractants will help reduce flies.

Remove breeding sources

Cover garbage: Clean garbage cans regularly and keep lids on tight. Flies like to breed in the "muck" often found at the bottom of garbage cans. If you have dumpsters, it may be necessary to have trash picked up twice a week, especially at restaurants and apartment/condo complexes where there is a lot of trash.
Keep manure dry: Keep manure piles dry, flat, or covered as wet manure may attract flies. Dog poop may attract flies and should be removed, but typically is not responsible for fly breeding as it dries quickly.
Remove grass clippings, straw or hay: get rid of clippings quickly or make sure they stay dry.
Cover compost piles: Keep compost piles tightly covered. Wet, decaying matter attracts flies.

Exclusion and Control

Exclusion

To keep out flies out of your home:

Screen doors and windows with at least 16-gauge mesh.
For small flies, such as fruit flies, use 24-gauge mesh.
Keep screens for windows and doors in good repair and free of gaps or holes.

Businesses may also want to:

Install self-closing doors.
Install high-velocity fans over doors that must remain open.

Control

Other control methods are generally not as effective as removing breeding sources, but may help.

Fly strips are easy to use and can be placed around the home to help catch flies. Fly strips can be purchased at most grocery or home improvement stores.
If using fly traps with fly attractant lures, place them around the perimeter of the property, away from where people spend time, so as not to draw flies towards people.
Fly swatters are effective for occasional flies.
If insecticides are used, be sure to follow the instructions carefully.