''Diachlorus ferrugatus'', commonly known as the yellow fly in the United States or doctor fly in Belize, is a species of highly aggressive biting

horse-fly Horse-flies or horseflies are true Fly, flies in the family Tabanidae in the insect Order (biology), order Diptera. They are often large and agile in flight, and only the female horseflies bite animals, including humans, to hematophagy, obtai ...

of the family

Tabanidae Horse-flies or horseflies are true flies in the family Tabanidae in the insect order Diptera. They are often large and agile in flight, and only the female horseflies bite animals, including humans, to obtain blood. They prefer to fly in s ...

native to North and Central America to Costa Rica.

Taxonomy

The yellow fly was described as ''Chrysops ferrugatus'' by

Johan Christian Fabricius Johan Christian Fabricius (7 January 1745 – 3 March 1808) was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others. He was a student of Carl Linnaeus, and is cons ...

in 1805.

Description

Adult yellow flies are around long with yellow bodies, mid-legs, and hind-legs, and black fore-legs. The eyes are blue-green with purple bands. They fly with little sound, and the first sign of their presence noticed by humans is usually their bite. The larvae are thin white grubs with fine yellow fur, each segment having three pairs of pseudopodia.

Distribution and habitat

The yellow fly ranges from the southeastern United States, where it is found from New Jersey to Texas, to Costa Rica. It is most common near bodies of water, along with trees nearby to hide in.

Spanish moss Spanish moss (''Tillandsia usneoides'') is an epiphytic flowering plant that often grows upon large trees in tropical and subtropical climates. It is native to much of Mexico, Bermuda, the Bahamas, Central America, South America, the Southern Uni ...

(''Tillandsia usneoides'') is a popular hiding spot.

Effect on humans

It is notorious for its propensity to inflict painful bites on people, having been described as the most aggressive fly species in Florida. The female feeds on blood to develop eggs, and is most active in the summer and early autumn during daylight hours, especially in the late afternoon and on overcast days. Flies can even venture indoors. Its presence affects recreational swimming, boating and fishing from April to June. Yellow fly bites leave itchy welts.

DEET ''N'',''N''-Diethyl-''meta''-toluamide, also called DEET () or diethyltoluamide, is the most common active ingredient in insect repellents. It is a slightly yellow oil intended to be applied to the skin or to clothing and provides protection ag ...

is the most useful insect repellent, though may not prevent bites if the yellow flies are in large numbers. In this case, physical barriers such as gloves and headnets are the only truly effective protection.

References

{{Taxonbar, from=Q13587242 Tabanidae Insects described in 1805 Insects of the United States Diptera of North America Taxa named by Johan Christian Fabricius