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Black Flies

Black Flies - Biting Insect Library

Black flies, also known as “buffalo gnats” or “turkey gnats” can be quite annoying to people and mammals. What are black flies attracted to? Much like mosquitoes, both the male and female Black Fly feed on nectar. It is only the female Black Fly who bites since she requires blood for the development of her eggs.

Black Flies can be found throughout the world from the warm tropics to the cold regions of the Arctic Circle.

Description | Breeding | Geography | Control | Interesting Facts


What are black flies? Black files, also known as “buffalo gnats” or “turkey gnats” can be annoying to people and mammals. Although they are called Black Flies, they can be gray, brown, or yellow in color. The “buffalo gnat” nickname came from their hump-like body.

What are black flies attracted to? Much like mosquitoes, both the male and female Black Fly feed on nectar. In terms of the Black Flies' breeding cycle, it is only the female Black Fly who bites since she requires blood for the development of her eggs. Depending on the species of Black Fly, the female will seek warm-blooded creatures such as humans, animals, and birds for her bloodmeal, or she may prefer cold-blooded animals. If you are tired of being what black flies are attracted to, then a mosquito trap may be the answer.

Unlike most mosquitoes, however, females will bite in the middle of the day. As the female bites, she injects saliva into the skin, which is highly irritating and leads to swelling and itching. Some species of Black Flies have painful bites, often prompting a burning sensation in the victim.

It is not just the pain of the bite that is a concern with Black Flies. They can be vectors, or transmitters, of diseases around the world, including onchocerciasis (river blindness) and mansonellosis in humans, bovine onchocerciasis in cattle and horses, and leucocytozoonosis in wild birds. There is a possibility that they could also transmit encephalitis, but this has not been confirmed to date.


Breeding Habits

The lifespan of Black Flies is short, lasting only 2-3 weeks. The Black Flies breeding ground is clear running water. The female Black Fly will not lay her eggs in polluted water. Females deposit from 150 to 500 eggs in submerged vegetation, and the eggs hatch in four to five days, making the Black Flies breeding cycle very fast. The eggs proceed through the larval and pupal stages before becoming adults.

In warmer regions the Black Fly’s life cycle is continuous and each stage is short in length; in some cooler regions, it will overwinter in the larval stage; while in much colder regions, the Black Fly usually spends the winter in the egg stage.

There can be anywhere from 1 to 6 generations in a year, depending on the region’s temperature and the Black Fly species.



Where do Black Flies live? Black Flies can be found throughout the world from the warm tropics to the cold regions of the Arctic Circle. Their main criteria appear to be clean water and a sufficient supply of bloodmeal hosts, which means Black Flies live virtually everywhere.

Control efforts for the Black Fly are hampered by the vastness of their range and the variety in their breeding locations. Some states in the U.S. spray insecticides to combat Black Flies, while others prefer not to put anything into its now-clean rivers and streams, fearing that insecticides could harm beneficial insects or fish. Another form of outdoor black fly protection is the mosquito trap.

Control Black Flies

Black flies are attracted to certain habitats and environments. The best way to control these pests is by ensuring that your property isn’t drawing them in and giving them everything that they need to survive.

Black flies are drawn to water. Making sure that you’re not fostering an environment that contains moving water is a key component to controlling the insect. A garden stream or a pond with a fountain might make your backyard paradise complete, but they are the perfect breeding habitats for black flies.

It’s important to also clear brush or vegetation that hangs close to the water. Black fly larvae can attach themselves to branches and other areas around the moving water. They need the water to breed, but they need drier spots to hang out on.

Keep in mind that the male insects feed off nectar, rather than blood like the female, so it can be a downfall if you have a luscious garden with many flowers. You can implement plants and greenery in your yard that don’t contain nectar to try and deter these bugs.


Interesting Facts

Deceased farm animals have been found along streambeds and riverbeds, the victims of large swarms of Black Flies. It is felt these bloodsucking insects cause toxemia or anaphylactic shock in the animals. In some cases, rapid blood loss may also have been a cause of the death. An animal may breathe in the flies through its nostrils in such large amounts that suffocation of the animal results.

Animal victims of Black Flies have included horses, cows, birds, hogs, sheep, turkeys and chickens, and even dogs and cats.

Children are often the targets of these bloodsucking insects while nearby adults may not be bothered by the Black Flies at all.

River blindness, or onchocerciasis, can be found in Africa, Mexico, Latin America, and some countries of South America.

By removing pollutants in our streams and rivers, we are actually creating inviting breeding grounds for Black Flies. (But we still must continue to clean up our streams and rivers despite that fact!)

Black Flies are known to travel up to 10 miles from their breeding sites in search of a bloodmeal.

Black Flies seem to prefer the head area of its bloodmeal host, although these bloodsucking insects will also bite under clothing.

Black Flies are attracted to humans largely through the carbon dioxide we exhale, but these bloodsucking insects are also attracted by dark colored clothing, perfumes and sweat.

The smell of exhaled carbon dioxide also attracts these bloodsucking insects to livestock and other mammals.

Over 250 species of Black Flies have been found in North America, while there are about 2,000 species throughout the world.

Humans can develop severe allergic reactions to the bite of a female Black Fly, requiring medical attention.

Black Fly larvae are considered an important part of the food chain of streams and rivers.

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