Flies are normally associated with garbage and filth, as the insects always seem to be found buzzing around dumpsters and carcasses of dead animals. Known for their ability to rapidly increasing populations, the pervasive insects have a worldwide presence and are found in any region that experiences warm temperatures.

Types of Flies

The United States is home to thousands of species of flies, several of which are nuisances in and around the home.

The main fly pests include:

house flies
House Fly
fruit fly
Fruit Fly
drain fly picture
Drain Fly
horse fly
Horse Fly

blow fly closeup
Blow Fly
crane fly
Crane Fly
cluster fly
Cluster Fly
phorid fly or humpbacked fly
Phorid Fly

horse fly
Horse Fly
black fly
Black Fly

The insects primarily pester inhabitants by constantly zipping around and landing on individuals while remaining just out of reach to be swatted. In addition to being annoying, flies can affect personal health by spreading harmful bacteria and viruses.

Several of the species even inflict sharp, painful bites to victims. These unwanted guests can gain entry into the home relatively easily, but completely eliminating them can prove quite daunting.

What do Flies Look Like?


Flies have stout, rounded bodies, which are usually dark colored (some have shiny, metallic coloration). Size varies by species, but in general, flies measure between a quarter of an inch and half an inch long.


A set of large eyes nearly encompass the entire head and are composed of over 4,000 slightly angled lenses, which allow the insect to see the same image from various perspectives. Though their eyes sound impressive, flies have poor eyesight.


The insects primarily use their antennae, located between the eyes, to locate food.


A pair of shiny, translucent wings extends from the midsections of flies and measure about the same length as the body (hindwings reduced to tiny knobs).


Flies have three pairs of legs, which produce a glue-like substance that aids in sticking to surfaces.

Where Do They Live?

Flies live and breed around their food sources, which can be animal excrement, rotting carcasses, and decaying food/organic matter found in garbage receptacles. The pests remain active during the day and rest during the evening.

When in the home, flies typically cling to walls and ceilings while at rest. When active, the pests generally remain close to accessible food sources, such as fruit bowls and open trashcans.

Flies prefer warmer climates and usually die off as winter approaches and temperatures drop (unless within a heated structure).

What Do Flies Eat?

Decaying fruits and vegetables, animal excrement, and rotting carcasses provide sufficient sustenance to flies. These food sources double as shelter for larvae, which feed on their surroundings throughout their development. Adult flies are also attracted to sugary foods, such as plant nectar and fruit juices, that provide additional nutrition. Females of biting fly species, like the black fly and horse fly, also need to consume blood in order to produce eggs.

Life Cycle

How Long Do Flies Live in Homes?

The length of a fly’s lifespan depends on its living conditions. Warm homes with food sources help flies live longer than they would outdoors. On average, most of these insects live two to three weeks in houses.

life cycle illustration
click to enlarge


Depending on the species, adult flies tend to live between one week and two months. Due to their relatively short lifespans, flies reproduce constantly during breeding seasons, which take place during the warm spring and summer months.


Female flies lay eggs in batches of hundreds at a time, and the offspring hatch in a matter of days. Eggs are laid in waste and decaying organic material, which newly hatched larvae feed on during development.


After several days of development, larvae (maggots) leave their surroundings to pupate (in soil), which can take a few days or several weeks.


Flies emerge from the pupa stage as adults that are ready to begin the reproduction process. Under optimal conditions, flies may progress through the development process in under a week. Adult flies die off before winter, but larvae overwinter inside their food-supplied harborages and emerge as adults in the following spring.

Flies survive in various ways—depending on the species, they may scavenge for food, suck blood, or live off of crops or other insects. The larvae of cluster flies, for instance, will make their way inside earthworms where they will develop for up to two weeks before emerging. Species such as house flies are unable to eat solid food, so they must first liquefy it with saliva which they then drink up.

Problems Caused by Flies


As insects that thrive on waste products and decaying organic matter, flies pick up harmful bacteria, like listeria, salmonella, and E. coli, which can be transmitted to other surfaces the pests touch. Flies land frequently and may spread pathogens to various surfaces. The pests can contaminate food by direct contact or indirectly by contaminating cooking utensils and food-prep areas. Eating contaminated food can cause individuals to develop typhoid fever, hepatitis, and dysentery.


In addition to spreading disease, certain flies inflict painful bites. Biting flies collect protein from humans by using their sharp, scissor-like mouthparts to slash skin and suck blood. Unlike mosquito bites, fly bites themselves are painful.

Various species of flies bite, and any insect that feeds on the blood of other mammals may spread disease-causing pathogens. Some of the most common biting species in include horse, deer, and black flies. Other household pests, such as fruit flies and house flies, do not bite.

Afterwards, bites leave irritating welts, which may itch for several days. Individuals with allergies may experience extreme swelling and inflammation around bite sites.

Signs of Infestation

Detecting a fly infestation is relatively easy and straightforward, as the insects do not avoid humans. Even when at rest, the insects are usually within plain sight clinging to ceilings or walls.

Most flies remain active during the day, which makes them easier to spot.

A fly infestation is apparent when multiple flies are seen inside a residence at one time. If flies seem to continually increase in numbers, they are breeding in the home.

Learn how to get rid of fly infestations.


Keeping doors and windows closed (or properly screened) is the first step in keeping flies out of the home. Seal gaps around windows and doors.

A critical part of fly control is sanitation. Maintaining a clean, sanitary household also helps keep the insects away. Any items that may attract flies as a food source or egg laying medium should be removed whenever possible. Regularly emptying waste and throwing out old foods that may be sitting out makes the home less hospitable for the pests.

A homeowner may also choose to utilize fly paper or traps and may wish to call in a pest control professional if flies become a nuisance.

If a structure becomes infested, removal can be difficult for untrained individuals, and professional pest control service is advised. Pest control professionals can provide multi-level solutions, which eliminate flies and prevent them from returning.