Outdoor House Fly Control

In almost all cases, flies originate outdoors. Because of this, the first step in successful control of any fly problem is determining where the flies are breeding. This involves inspection, sanitation, exclusion, and mechanical and chemical control, as warranted:

Inspection

Watch the flies. See where they are landing or resting; find out what is attracting them.
Identify the flies. Understanding whether you are dealing with house flies, blow flies, cluster flies, or other large (or small) flies will determine the type of management needed.

If there are a lot of flies, there is probably a breeding site either on your property or a neighboring one. Look for these areas as well. If the source is not on your property and you cannot get a neighboring person or business to cooperate in eliminating the breeding source, of the flies is not on your property try to locate it and have the responsible persons help solve this problem. If cooperation can not be obtained from the other person, it is recommended that you contact your municipal or state health department to seek assistance.
Clean up or otherwise alter any sites that seem to be attracting the flies or where they are found to be breeding.
You will temporarily reduce populations by killing the adult flies, but until you get to the source and eliminate the breeding areas you will not have full control.

The following describes outdoor control methods for house flies. If the inspection found it to be a cluster fly or other large fly, or fruit or other small flies, specific control methods will be somewhat different – although sanitation and exclusion are key to controlling virtually any pest.

Sanitation

To reduce fly attraction and breeding sites:

The house fly can complete its life cycle in as little as a week, so it is necessary to remove wet organic materials and manure, and have garbage picked up at least twice a week to break the breeding cycle.
Keep dumpster areas as clean and as far from the home or building as possible.
Use tight-fitting lids, and clean dumpsters regularly. If plastic bags are used, ensure they are well sealed.
Pick up pet feces regularly and promptly remove other manure and dead or decaying plants Keep dog kennels and outdoor feeding areas clean.
Eliminate areas of pooling, stagnating water and other excessive moisture.
Keep dog kennels clean, and pick up spilled food and water, as this can be a source of food – or rotting – odors that attract the flies.
Keep compost piles far from buildings and properly managed to keep flies to a minimum.

Exclusion

Flies found inside a building have entered from the outside in almost all cases. Therefore, barriers preventing access to the building are the first line of defense.

Seal cracks around windows and doors where flies may enter.
Use well-fitted, small-mesh, well-maintained screens on all doors and windows.
Follow indoor fly exclusion techniques.

Mechanical

While trapping can have limited impact in the open air, they can provide limited reprieve if set away from areas humans will be. The key is to not attract flies toward or through the area, but to set traps to intercept them from coming that way. Some trap options include:

Inverted cone traps containing fly food attractants. These are widely available and can be effective if sanitation is maintained in the area. The fly food attractants can be very foul smelling, so the traps should be placed away from occupied structures.
Insecticide impregnated resin strips can be placed on the inside of garbage can lids to attract and eliminate flies that get into trash. If dumpsters seal tightly, they can be used there as well.
Although they may have little effect in outdoor areas, ultraviolet light traps can be placed in alleyways, beneath trees, and around animal sleeping areas and manure piles to attract and kill flies.

Chemical Control

Chemical control is one component of an integrated fly management program. It is recommended that all other methods be attempted first, because flies have become resistant to many insecticides making fly populations difficult to control with such chemicals. When needed:

Though they will have little to no lasting affect outdoors, some aerosol fly sprays (labeled for flies) can provide quick knockdown and kill of flies, such as such as just prior to picnics and outings.
Insecticide fly baits can be put out in small bait stations to attract and kill flies. This can be particularly effective in dumpster areas if proper sanitation is followed. Always keep baits, and other pesticides, away for possible contact by children, pets, and non-target wildlife.
Properly labeled residual pesticides can be used on areas where flies are seen to rest, such as the outside surfaces of homes and overhangs.
A pest management professional can be hired to apply residual insecticides that may be restricted use, or otherwise unavailable to homeowners.
If insecticides are used, they may have to be reapplied at 2 to 4 week intervals during warm weather.
When using any pesticide, be sure to read the product label and follow all directions.