The most common observed stage of a fly is the winged, adult stage.  The immature stage is a pale, legless maggot.  When full grown, maggots wander from the breeding site in search of a place to pupate.  Many flies complete development (egg-larva-pupa-adult) in a short period, seven to 14 days, and produce numerous generations during a typical season.
Although flies most often are a nuisance during the warm season, indoor overwintering is common with cluster flies and face flies.

BLOW FLIES

Blow flies are fairly large, metallic green, gray, blue or black flies found throughout the state.  These flies tend to be more common that the house fly and sometimes are called the "house flies of the West".  The adult flies spend the winter in homes or other protected sites but will not reproduce during this time.

Blow fly maggots feed on garbage.  They occasionally can be found in homes that are near a carcass of a dead squirrel, rodent or bird they have wandered from.  Blow flies breed most commonly on decayed carcasses and droppings of dogs or other pets.  The adult blow fly is also attracted to gas leaks.

HOUSE FLY

House flies are the best known of the house-infesting flies.  House flies generally are gray, with the thorax marked with broad dark stripes.  Most often there is some yellow coloring along the sides that differentiates them from face flies.

House flies are usually found where humans are present.  Larvae commonly develop in or near man-made sources of food and can be found in garbage, animal waste, culled fruits and vegetables, and spilled animal feed.  The adult flies feed on a wide range of liquid waste but can eat solid foods such as sugar.  To digest solid foods, house flies liquify food by regurgitating.  Because of this habit, house flies can pose serious health threats by mechanically transmitting disease organisms.  During mild winters, house flies may fly and breed continuously, as temperatures permit.

FACE FLY

Face flies are closely related and similar in appearance to house flies but have different habits.  They are more common than house flies, particularly in ruarl areas.
Face flies pass the winter as adults and often seek shelter in upper stories of building such as attics, steeples and little-used upper rooms.  They become active in spring and females lay eggs in fresh cattle manure that is less than one day old.
Adult face flies feed on many types of fluids.  They often are attracted to the eyes, nose and mouth of cattle and have been implicated in the transmission of pinkeye disease to cattle.

LITTLE HOUSE FLY

Little house flies are smaller than the house and face flies but similar in appearance.  Indoors they fly for long periods and rarely rest.  The adult flies lay eggs in decaying organic matter, particularly manure, where the maggot-stage larvae feed.

FLY CONTROL

Sanitation practices that remove breeding areas are fundamental to the control of filth-breeding flies, such as house flies and blow flies.  Remove or cover garbage regularly and clean spilled animal feed and manure.  Face flies, which typically develop in pasture lands, often are difficult to control by breeding area management.

Screening and other exclusion techniques can be a very important management tool for several types of indoor fly problems.  Caulk or cover all openings into a home to prevent flies from entering.  Efforts to exclude flies must be done prior to when they enter buildings.

Insecticides used for control should only be considered as a supplement to other controls.  Serious problems exist with insecticide-resistant flies and many fly populations are now difficult to control with insecticides.
Spot treatments with insecticides applied to areas of high fly activity are most efficient.  For example, flies that tend to rest in dark corners can be controlled by applications to these areas.  Chlorpyrifos (Dursban) is currently the most common insecticide used for fly control and is widely available.

Several types of traps for flies also are available and can supplemnt other controls.  Fly paper and electrocution light traps can kill flies but are only effective in areas where exclusion and sanitation efforts have already reduced the fly populations to low numbers.

Various food-based traps also are for sale.  These traps often contain a protein bait, sometimes with the addition of a pheromone (sex attractant) used by flies.  As with other traps, they can supplement other controls such as sanitation and exclusion.