Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Clickable Guide
Moths Butterflies Flies Caterpillars Flies Dragonflies Flies Mantids Cockroaches Bees and Wasps Walkingsticks Earwigs Ants Termites Hoppers and Kin Hoppers and Kin Beetles True Bugs Fleas Grasshoppers and Kin Ticks Spiders Scorpions Centipedes Millipedes


Species Tabanus atratus - Black Horse Fly

Black Horse Fly - Tabanus atratus Black horse fly - Tabanus atratus - female Some type of fly? - Tabanus atratus black horse fly - Tabanus atratus - male Black Horsefly - Tabanus atratus Big Black Fly - Tabanus atratus Black Horse Fly - Tabanus atratus Black Horse Fly (Tabanus atratus)? - Tabanus atratus - male
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon (Orthorrhapha)
Infraorder Tabanomorpha
Family Tabanidae (Horse and Deer Flies)
Subfamily Tabaninae (Horse Flies)
Tribe Tabanini
Genus Tabanus
Species atratus (Black Horse Fly)
Other Common Names
mourning horse-fly (1)
Synonyms and other taxonomic changes
Tabanus atratus Fabricius, 1775
Explanation of Names
atratus - Latin for 'clothed in black' (2)
one of 107 spp. in genus Tabanus n. of Mex.
Adult: 20-25 mm (Long 2001); 20-28 mm (3) (4) (very large)
Color black, including wings, or nearly black, brown-purple. Prominent mouth parts. As in other members of this genus, eyes of male meet in middle (holoptic) and those of female are separated (dichoptic):

Larva white to tan, similar to other tabanids, with twelve segments and retractable tracheal siphon for respiration (Long 2001). (Another reference (5) states that larva of this species is striking in appearance, whitish, banded with black, up to 50 mm long.)
TX-FL-ME-ND / se. Can. / n. Mex (6)
Primarily found in the eastern United States, although it has been collected throughout the entire continental US. (Long 2001)
Very wide range of habitats; generally near aquatic environments (Long 2001)
Apr-Dec in TX & FL (BG data)
Females feed on mammalian blood, while males, which lack mandibles, feed on nectar and plant juices (Long 2001). This species especially prone to attack cattle and other livestock (1) (5).
Life Cycle
Requires moist environments in which to lay eggs, and mammals to feed on (Long 2001). Eggs laid on vegetation overhanging permanent water (3):
Larvae said to live "along the margins of ponds and ditches" (7). Larvae require two years to complete life-cycle (4)(5); males short-lived, females survive through fall (4).
Although Tabanus atratus do not often bite humans, when it does happen it leaves painful memories. This fly can also transmit bacterial, viral, and other diseases such as surra and anthrax, to both humans and other animals through its bite. (Long 2001)
The effect of T. atratus on livestock can be a serious problem. Blood loss and irritation from the flies can severely affect beef and milk production, as well as grazing. Livestock usually have no way of avoiding the painful bites, and millions of dollars have been spent trying to control these pests. (Long 2001)
Print References
Arnett, p. 871--description (8)
Comstock, p. 306 (1) (BHL link)
Eaton and Kaufman, pp. 284-285, (photos male and female) (9)
Evans, p. 236 (3)
Marshall, photos 443.6, 443.7 (male and female) (7)
Milne and Milne, plate 427, p. 653 (description) (4)
Swan and Papp, pp. 604-605, fig. 1288 (5)
Internet References
Long, W. 2001. "Tabanus atratus" (On-line), Animal Diversity Web. Accessed April 23, 2012 at
Works Cited
2.Dictionary of Word Roots and Combining Forms
Donald J. Borror. 1960. Mayfield Publishing Company.
3.National Wildlife Federation Field Guide to Insects and Spiders & Related Species of North America
Arthur V. Evans. 2007. Sterling.
4.National Audubon Society Field Guide to Insects and Spiders
Lorus and Margery Milne. 1980. Knopf.
5.The Common Insects of North America
Lester A. Swan, Charles S. Papp. 1972. Harper & Row.
6.The horse and deer flies (Diptera: Tabanidae) of Texas
Goodwin and Drees. 1996. 1996. Southwestern Entomological Society.
7.Insects: Their Natural History And Diversity: With a Photographic Guide to Insects of Eastern North America
Stephen A. Marshall. 2006. Firefly Books Ltd.
8.American Insects: A Handbook of the Insects of America North of Mexico
Ross H. Arnett. 2000. CRC Press.
9.Kaufman Field Guide to Insects of North America
Eric Eaton, Kenn Kaufman. 2006. Houghton Mifflin.