Insect Identification logo

Black Horse Fly (Tabanus atratus)

Detailing the identifying qualities of the Black Horse Fly, including physical features and territorial reach.

 Updated: 2/5/2018; Authored By Staff Writer; Content ¬©

  Black Horse Fly  
Picture of Black-Horse-Fly
Picture of Black-Horse-Fly Picture of Black-Horse-FlyPicture of Black-Horse-FlyPicture of Black-Horse-Fly

Large Black Horse Flies are notorious biters of horses and all things smaller, including humans, leaving behind painful sores on its victims.

Black Horse Flies are about an inch long, making them highly visible and somewhat intriguing to watch. They are fast fliers despite their hefty size. Females feed on blood, and they are not averse to taking it from anything that has it. Their mouth parts cut open flesh, allowing blood to ooze out. They use a proboscis to sponge up the blood, leaving behind an open wound. These wounds can become infected, which poses a threat to livestock health. They are also very painful bites for humans. Males do not bite and do not drink blood. Males actually drink flower nectar and spend their days looking for females to mate with.

Males and females are both completely black, but males have huge eyes that touch each other at the center of the face; the eyes of females are separated. It's the size of the eyes that strikes curiosity in most people that see them. The color of the eyes may vary depending on the lighting. Facets comprising each eye reflect light, so sometimes their eyes appear black, sometimes silver (see photo gallery) and sometimes shades of their surroundings.

This species is found in the eastern part of the continent. Females lay fertilized eggs on or near water sources. Maggots (larvae) feed on other aquatic insects and worms. Chemicals, home remedies, and special collars exist as methods used to deter the presence of Horse Flies, especially in stables.

Picture of the Black Horse Fly
Picture of the Black Horse Fly

Black Horse Fly Information

Category: Fly or Mosquito
Common Name: Black Horse Fly
Scientific Name: Tabanus atratus

Taxonomy Hierarchy

 Arrow graphic Kingdom: Animalia
  Arrow graphic Phylum: Arthropoda
   Arrow graphic Class: Insecta
    Arrow graphic Order: Diptera
     Arrow graphic Family: Tabanidae
      Arrow graphic Genus: Tabanus
       Arrow graphic Species: atratus

Size, Identifying Tags and Territorial Reach

Size (Adult, Length): Size (Adult, Length): 20 mm to 28 mm (0.78 inches to 1.092 inches)
Identifying Colors: black
Additional Descriptors: huge, plump, eyes, large,

North American Territorial Reach (Though Not Limited To): Alabama; Connecticut; Delaware; Florida; Georgia; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; New Hampshire; New Jersey; New York; North Carolina; Ohio; Pennsylvania; Rhode Island; South Carolina; Tennessee; Texas; Vermont; Virginia; West Virginia; Wisconsin; New Brunswick; Newfoundland and Labrador; Nova Scotia; Ontario; Prince Edward Island; Quebec; Mexico

A Note About Territorial Reach: Keep in mind that an insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above. Insects are driven by environmental factors, food supplies and mating patterns and do not nescessarily work within hard-and-fast territorial lines like we humans do.

Images Gallery


BugFinder: What is it?