Minnesota Seasons - True Horse Flies (Tabanus spp.)

Overview • Description • Distribution • Taxonomy

Overview

Tabanus is a genus of large, stout-bodied flies known as 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.

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Description

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

Distribution Map

Sources

7, 24, 27, 29, 30, 82, 83.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu, 10/9/2025).

10/9/2025

Taxonomy

Order

Diptera (flies)

Suborder

Brachycera

Infraorder

Tabanomorpha (snipe flies and allies)

Superfamily

Tabanoidea

Family

Tabanidae (horse and deer flies)

Subfamily

Tabaninae (horse flies)

Tribe

Tabanini

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