House Fly

This fly has a full gray body with black vertical lines on top, and a single, silver stripe on its face. It measures between 1/8 to 1/4 of an inch in length.

Dangers: Since these flies are attracted to garbage, animal feces, compost piles and the like, they are also vectors for harmful bacteria when they infest homes and land on food or food-prep surfaces.

Blow Fly (Bottle Fly)

This fly looks similar to a house fly but it's larger in size, measuring between 1/8 to 5/8 of an inch in length. It is usually black, metallic green, blue, or bronze and has specialized sponge-like mouthparts which it uses for feeding on liquids. This fly typically feeds on decaying meats, carcasses, and garbage.

Dangers: Because these flies feed, breed, and live on rotting organic matter, they can transport some very dangerous bacteria and disease-causing organisms on their bodies and legs; pathogens that can be deposited onto food, dishes, and food-preparation surfaces.

Dark-Winged Fungus Gnat

This is a very small fly, growing only to about 1/8 of an inch, and like its name suggests, it has dark wings. It also has a long, thin body which is gray or black. The larvae of fungus gnats move together across the ground in a snake-like mass.

Dangers: The presence of these gnats may be an indication of water-damaged areas in your home. They are also a big problem for greenhouse owners and mushroom growers.

Deer Fly & Horse Fly

A deer fly is around 1/4 to 1/3 of an inch in length and is light brown to gray. Sometimes, it will have yellow or black stripes. Its eyes are brightly colored and its antennae are longer than its head. A horse fly is larger, growing to between 3/8 and 1-1/8 of an inch, and it is gray or black. Its eyes often have horizontal colored stripes.

Dangers: Though these flies feed on plant pollen and nectar, the females require a blood meal to lay eggs. Bites from one of these two flies can be painful and may leave behind a large, itchy, red welt.