Flies are among the most common household pests in the country and there's virtually no way to avoid them. Not only are flies bothersome, some also pose a risk to your health. At Terminix, we believe that the more you know, the easier it is to control pest infestations.

Here you will find some interesting fly facts, information, and photos to help you get a better understanding of these common pests. You'll also get answers to some of the most commonly asked questions we hear about flies, including:

What are flies?

True flies are from the order Diptera, a group of insects that uses one pair of wings for flight. Like their cousins (and fellow members of the order of Diptera) mosquitoes, flies can be irritating pests and certain types of flies even carry disease-causing pathogens.

What do flies look like?

While it may seem like a simple question, identifying a fly isn't always easy. Flies come in all shapes and sizes. However, all flies share some common characteristics including:

  • One pair of wings
  • Large, moveable head
  • Large eyes
  • Six legs
  • Mouthparts adapted for a liquid diet
  • Middle segment of the thorax is enlarged

fly photo

How do flies fly?

Flies are unique insects in that they have one set of wings. To take flight, flies use drumstick-like organs called halteres along with their wings to gain altitude, maneuver, speed up, and stop.

Fly habitat and common behaviors

Unfortunately, flies are common just about everywhere. From urban settings to the most remote and rural spaces, flies are always present. Common fly behaviors like gathering in large groups, buzzing around, and landing randomly can be irksome to people and animals. Flies can be found anywhere they can source food although they prefer damp, humid areas.

What do flies eat?

A fly's diet contains a variety of substances – many of which are less than appealing to humans. House flies and fruit flies love trash bins, rotting piles of plant matter and/or meat, animal feces and more. Female horse flies feed on blood, while the males dine on nectar and pollen.

Fly reproduction and life cycle

A fly's life cycle is incredibly short compared to human lives. During their short lifetime, flies go through a complete metamorphosis that includes the following stages:


Female flies commonly lay their eggs on rotting material, feces, and other food sources. This allows the newly-hatched larva to begin feeding almost immediately.


During the larval stage, the eggs may hatch into larva in as little as seven to eight hours. Fly larvae are what's commonly referred to as a maggot, which is small, pale in color, and wriggling. Maggots also lack the wings of an adult fly.


During the larval stage, the fly molts several times, and will create a puparium, or pupal case, during the last molt. The adult fly will develop while inside the pupal case and emerge in 3-6 days.


Once a fly pupa hatches, the adult fly feeds, mates, lays eggs, and ultimately dies. An adult female fly can lay between 75 to 120 eggs in a single batch and is capable of laying up to six batches of eggs during the course of her lifetime.

How long can flies live?

There is a common misconception that flies only live for 24 hours. The reality is that a male house fly's lifespan is typically just 15 days while the female of the species lives slightly longer at 25 days.

Are flies seasonal?

While flies can be found inside homes and businesses year-round, they prefer warmer temperatures. So, if you live in a colder climate, you'll experience fewer flies in the winter and see an increase in spring, summer, and fall.

What are common types of flies in the U.S.?

There are five categories of flies you'll encounter in the US including filth flies, small flies, overwintering flies, biting flies and non-biting gnats and midges. Each of these groups of flies has their own distinctive characteristics.

Within these groups, common types of flies found throughout the US include:

House flies

Easily identifiable, house flies are common carriers of disease-causing pathogens and bacteria. House flies fall under the category of filth flies and have a long history of contaminating food and serving as a menace to human hosts.

Fruit flies

Fruit flies are one of the most common small flies. Like their bigger cousins, fruit flies are attracted to overripened fruits and vegetables, as well as feces. Fruit flies can breed indoors or outdoors. These pests are one of the most commonly found flies within the category of small flies.

Cluster flies

Although cluster flies are parasitic, they usually live outdoors and only feed on earthworms. However, they can make their way indoors and infest your home during colder months. Cluster flies belong to the overwintering flies group. They look similar to house flies, but have slightly different behavior.

Drain flies

Those tiny flies around your drain are likely drain flies, sometimes called moth flies, and they're a common pest that is attracted to standing water. They'll often infest bathroom and kitchen areas due to the abundance of moisture and organic matter, such as food and even hair, that they'll use to feed.

Horse flies

Although they look like giant house flies, female horse flies can bite and will happily feed on your blood. Horse flies are part of the biting flies group. Their name is derived from their tendency for biting not just humans, but also horses and cattle, spreading disease-causing pathogens.


Sometimes referred to as shadflies or lakeflies, mayflies are not actually true flies. True flies belong to the order of Diptera (meaning “two wings"). By contrast, mayflies have four wings.

What are common fly predators?

Some of the most common creatures that eat flies are frogs, spiders, birds, and lizards. Some plants even dine on the flesh of flies, such as the Venus FlyTrap and pitcher plant.

Do flies bite?

Not all flies bite, however, there are a few that do. Mosquitoes, deer flies, black flies, and horse flies can all bite humans. Besides leaving behind painful, itchy welts, most also feed on blood.

How to identify biting flies

It's easy for most people to identify mosquitoes. Horse flies and deer flies are also fairly easy to identify. However, some biting flies can be so tiny they're virtually invisible, such as the no-see-ums (or biting midge flies) found in hot, humid areas of the country. The only indication you may have of a biting fly is the welt they leave behind.


Can flies kill you?

Although many flies don't bite, in the instance you are bitten, it can have serious consequences. You may have an allergic reaction that ranges from mild itching to severe swelling, pain, and itching. Black flies, however, are particularly dangerous and deaths have been reported.

And while many flies do not bite, their penchant for feeding on waste and decaying matter means that these pests can carry more than 1 million types of bacteria on their bodies. In turn, they can transmit bacteria and disease-causing pathogens just by landing on your countertop or food. As a result, flies can contribute to the spread of diseases like cholera, shigellosis, E. coli, and typhoid fever – all of which can prove fatal in humans if not treated.

How do you treat fly bites?

There are a variety of ways you can treat fly bites, including applying a cool compress to the affected area and taking antihistamines. Severe allergic reactions require immediate emergency care.

Do flies carry disease-causing pathogens?

Yes. Given that flies feed on human and animal waste, as well as rotting food, they pick up various bacteria and disease-causing pathogens on their body and transmit them when landing on other surfaces. The common house fly harbors 65 illnesses that infect people such as, food poisoning, dysentery, and diarrhea. Flies can also pass on the eggs of parasitic worms to people and animals.

What is the difference between a fly and a gnat?

Although gnats may look like a smaller version of flies, they are not the same species. Flies are generally much larger than gnats. However, you may see fruit flies, gnats, and fly larvae all in the same location.

Why are flies in my house all of a sudden?

The main reason flies enter your home, or any structure, is to seek food. Once they've found a way in through an open window, door, or crack, they'll invade. They're attracted to leftover food on the counter, trash, and even wet drains.

What is the best way to prevent flies?

By far, the best way to avoid a fly infestation is to keep your home clean. Regularly remove the trash, wash dishes, and immediately refrigerate leftover food. Make sure that window and door screens are firmly in place and seal up any cracks or other openings to keep flies outside.

How do I get rid of flies in my house?

If you find them in your home, it's important to get flies under control right away. Enlisting the aid of a professional pest control company is the best course of action. If you choose to use any DIY or over-the-counter pest control treatments and remedies, take care to read and follow the instructions on the product packaging.