Deer flies (also known in some parts of the

mid-Atlantic United States The Mid-Atlantic is a region of the United States located in the overlap between the nation's Northeastern and Southeastern states. Traditional definitions include seven U.S. states: New York, New Jersey, Pennsylvania, Delaware, Maryland, Virg ...

as sheep flies) are bloodsucking insects considered

pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...

to humans and cattle. They are large flies with large brightly coloured

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

, and large clear wings with dark bands. They are larger than the common

housefly The housefly (''Musca domestica'') is a fly of the suborder Cyclorrhapha. It possibly originated in the Middle East, and Cosmopolitan distribution, spread around the world as a commensal of humans. Adults are gray to black, with four dark, lo ...

and smaller than the

horse fly Horse flies and deer flies are true flies in the family Tabanidae in the insect Order (biology), order Diptera. The adults are often large and agile in flight. Only females bite land vertebrates, including humans, to hematophagy, obtain blood ...

. There are 250 species of deer fly in the genus ''Chrysops''. Their distribution is worldwide, though they have not been reported in

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

, or

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

. Deer flies lay between 100 and 800 eggs in batches on vegetation near water or dampness. During the larval stage, which lasts one to three years, they feed on small creatures or rotting organic matter near or in the water. After a pupal stage, they emerge as adults in late spring and summer. While male deer flies collect

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

, female deer flies feed on

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...

, which they require to produce eggs. Females feed primarily on mammals. They are attracted to prey by sight, smell, or the detection of

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

. Other attractants are body heat, movement, dark colours, and lights in the night. They are active under direct sunshine and hours when the temperature is above 22 °C (71.6°). When feeding, the females use scissor-like

mandibles In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

and

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

e to make a cross-shaped incision and then lap up the blood. Their bite can be painful. Anti-coagulants in the saliva of the fly prevents blood from clotting and may cause severe allergic reactions. Parasites and diseases transmitted by the deer fly include

tularemia Tularemia, also known as rabbit fever, is an infectious disease caused by the bacterium '' Francisella tularensis''. Symptoms may include fever, skin ulcers, and enlarged lymph nodes. Occasionally, a form that results in pneumonia or a throat ...

anthrax Anthrax is an infection caused by the bacterium '' Bacillus anthracis'' or ''Bacillus cereus'' biovar ''anthracis''. Infection typically occurs by contact with the skin, inhalation, or intestinal absorption. Symptom onset occurs between one ...

anaplasmosis Anaplasmosis is a tick-borne disease affecting ruminants, dogs, and horses, and is caused by ''Anaplasma'' bacteria. Anaplasmosis is an infectious but not contagious disease. Anaplasmosis can be transmitted through mechanical and biological vector ...

equine infectious anemia Equine infectious anemia or equine infectious anaemia (EIA), also known by horsemen as swamp fever, is a horse disease caused by a retrovirus (Equine infectious anemia virus) and transmitted by bloodsucking insects. The virus (EIAV) is endemic in ...

, hog cholera, and filiariasis.

DEET ''N'',''N''-Diethyl-''meta''-toluamide, also called diethyltoluamide or DEET (, from DET, the initials of di- + ethyl + toluamide), is the oldest, one of the most effective, and most common active ingredients in commercial insect repellents. ...

is not an effective repellent. Predators of the deer fly (and other Tabanidae) include nest-building wasps and hornets, dragonflies, and some birds, including the killdeer. They are difficult to control because insecticides cannot be applied in the sensitive wetlands where their larvae typically develop. Additionally, adults may have developed a significant distance from where the eggs were laid. Trapping devices and protective clothing, such as long-sleeved shirts and hats, can help avoid the annoyance and bites of aggressive deer flies.

Photos

File:Chrysops caecutiens-s.jpg, File:Deerfly 8.jpg, Deerfly from coastal Georgia, US

References

External links

Penn State University's Deer Fly site
{{Taxonbar, from=Q1434069 Tabanidae Tabanoidea genera Taxa named by Johann Wilhelm Meigen de:Goldaugenbremse nl:Goudoogdaas

Photos

See also

References

External links