Common Name: Black Horse Fly

Scientific Name: Tabanus atratus

Kingdom: Animalia
Class: Insecta
Order: Dipter
Family: Tabanidae
Genus: Tabanus
Species: T. atratus


Tabanus atratus is one species of the 1000 plus species found in the genus Tabanus.  Tabanus is a genus containing species of  biting horseflies. Tabanus atratus, or Black Horse Fly, is distinguished from house flies and other flies by their unusual antennae. They have 3 antennae segments with the 3rd segment being long and clearly visible. 

  The Black Horse Fly is mainly found in the eastern United States, although it has been collected throughout the entire continental United States.  It is able to survive in a wide range of habitats, although they cannot survive in extreme climates such as mountain tops or deserts.  They are usually found near water, since the female requires a moist environment in which to lay her eggs. Because flies are present all over the world in such large numbers and they can be harmful to animals and humans they are considered pests. Millions of dollars have been spent trying to control the Black Horse Fly because it can transmit blood borne diseases in humans and animals and is a serious problem to livestock

 The Black Horse Fly is active and feeds during the day. The males feed on the nectar, plant juices, and pollen of plants.  The females search for host, usually a large mammal, to feed on their blood in order to nourish their eggs.  The larvae are carnivorous and eat great quantities of other insect larvae, other invertebrates, and small vertebrates. The Black Horse Fly in all it’s metamorphosis stages: egg, larva, pupa, adult, provides food for birds and it’s natural enemy the Horse Guard Wasp. The adult horse fly escapes it predators by being agile and a fast, strong flyer.

 Despite their harmfulness to humans and livestock, the Back Horse Fly plays a role, although not as well known as the role of bees, in the pollination of plants and they provide food for other animals in their environment.  I was amazed to learn that the eyes of the horsefly contain thousands of facets, or lens segments.  Their iridescent eyes also look impressive.  Another amazing fact is that each female will lay three to four masses of one hundred to a thousand eggs each.

Author: Amber H

Date Published: 2/2012

Sources: “Tabanus Atratus.” Web. 5 Feb. 2012

Long, W. 2001,“Tabanus Atratus.” Animal Diversity Web. Web. 6 Feb. 2012. <>

“Fly.” Funk & Wagnalls New Encyclopedia. Vol. 10. Funk & Wagnalls. 297-298.
“Horse-Fly.” Web. 5 Feb. 2012. <>