Black to dark brown in colour with green or black eyes.
The males have contiguous eyes, which easily differentiates them from females where the eyes are widely separated.
A horse–fly’s bite can be very painful. Unlike insects that pierce the skin, horse–flies have mouth parts that work like miniature knives, which they use to slash open the skin with a scissor–like motion.
Eggs are laid in masses ranging from 100 to 1000 eggs on a vertical surface overhanging water or wet ground favourable to larvae development. The eggs hatch in 5–7 days.
They overwinter in the larval stage and pupate during the spring and early summer.
Adult life cycle is 30 to 60 days.
Mating is initiated in the air and completed on the ground where the female then deposits an egg mass sometimes with a shiny or chalky secretion, which aids in water protection.
The males are mainly pollen and nectar feeders.
Tabanids are most active during daylight hours.
As with mosquitoes, it is the female fly that is responsible for biting.
Relentless attacks on livestock can result in reduced weight gain.