true horse flies

(Tabanus spp.)

true horse fly
Photo by Bill Reynolds

Tabanus are is a genus of large, stout-bodied flies known as true horse flies. They are sometimes called true horse flies. There are at least 1,358 species of Tabanus worldwide, but the exact number is unknown. There are more than 100 species in North America north of Mexico, and at least 12 species in Minnesota. Adults are often found near ponds, steams, and marshes. Larvae are aquatic.

Adults are active in the spring and summer. Females feed on the blood of larger mammals. They seldom bite humans, but when they do the experience is painful and remembered. They can be silent when flying, allowing them to land stealthily on exposed skin. Males feed on flower nectar.


The body is usually gray or blackish. The wings usually do not have dark spots, though in some species the wings are entirely black. The eyes of many species are brightly colored or iridescent. Some are bright green, some are striped. The eyes of the male meet, while those of the female are separated. The antennae have only three segments. The third segment is elongated and subdivided, and has a basal tooth-like projection. The fourth segment of the hind leg does not have spurs at the top (apex). The last segment of the foot (tarsus) has 3 pads.


Distribution Map



4, 7, 24, 27, 29, 30.



Diptera (flies)  




Tabanomorpha (snipe flies and allies)  




Tabanidae (horse and deer flies)  


Tabaninae (horse flies)  



Subordinate Taxa


black horse fly (Tabanus atratus)

brown-footed horse fly (Tabanus fulvicallus)

chained horse fly (Tabanus catenatus)

horse fly (Tabanus turbidus)

marginal horse fly (Tabanus marginalis)

Nova Scotia horse fly (Tabanus novaescotiae)

Reinwardt’s horse fly (Tabanus reinwardtii)

sage horse fly (Tabanus sagax)

similar horse fly (Tabanus similis)

striped horse fly (Tabanus lineola)

stygian horse fly (Tabanus stygius)

three-spotted horse fly (Tabanus trimaculatus)


Orthorrhapha was historically one of two infraorders of Brachycera, a suborder of Diptera. However, Brachycera did not contain all of the descendants of the last common ancestor (paraphyletic). It was split into five extant (still existing) and one extinct infraorder. Orthorrhapha is now considered obsolete and has not been used in decades, but it persists in printed literature and on some online sources. A recent revision of the order Diptera (Pope, et al., 2011) revived the name Orthorrhapha, but this has not been widely accepted.






Common Names


horse fly













On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.



The fourth segment of an insect leg, after the femur and before the tarsus (foot).






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Bill Reynolds

  An image of a biter! The dreaded Horse Fly as she waits for the next victim   true horse fly  








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Other Videos
  Horsefly (Tabanus) larva crawling and digging in the mud
Nature in Motion

Published on Aug 6, 2016

This horsefly larva is carnivorous and may take a few years to develop. They are capable of quickly immobilizing/killing animals as large as frogs. Do not handle; it's bite feels like a wasp sting. Adult females feed on mammalian blood; males, which lack mandibles, feed on nectar and plant juices. Adults are a pest to cattle and other livestock. Millions of dollars have been spent trying to control them.

(Insecta: Diptera: Tabanidae)

  Horse Fly (Tabanidae: Tabanus) in Hand
Carl Barrentine

Published on Aug 1, 2010

Photographed at Kelly Slough NWR, North Dakota (31 July 2010).

  Horse-fly bites and wounds me: an experiment and explanation

Published on May 27, 2014

Horse-fly bites and wounds me: an experiment and explanation - I allow a vampire-like horse-fly to bite my hand wounding me to show what can happen. I strongly recommend not performing this experiment because there are horse-flies in certain parts of the world that are carriers of disease. For those horse-flies that do not carry disease, though rare, it is still possible for certain individuals to suffer a case of life-threatening anaphylactic shock from what would otherwise be a "benign" bite.

More info:

More / IMG * videos:

  Horse Fly (Tabanidae: Tabanus) Behavior
Carl Barrentine

Published on Jun 28, 2011

I observed two flies exhibiting this behavior (i.e., employing outstretched forelegs as either a funneling or gathering technique). I'm speculating that this may be a feeding behavior. Could this individual be gathering organic debris on foreleg tarsal setae. These large, biting flies are pollen-eaters, too. Photographed at the Turtle River State Park, North Dakota (27 June 2011).

  Horse Fly (Tabanidae: Tabanus) on Wall
Carl Barrentine

Published on Jun 20, 2010

Photographed at Grand Forks, North Dakota (19 June 2010).




Visitor Sightings

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  Bill Reynolds

Location: Pennington Co. MN

An image of a biter! The dreaded Horse Fly as she waits for the next victim

true horse fly  




Created 6/18/2017.

Last Updated:

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