Horse flies (family Tabanidae)

Cydistomyia doddi Female horse flies, such as this Cydistomyia doddi, feed on blood.

The noisy, biting flies that Australians call March flies are commonly called horse flies in other parts of the world.


Females of most horse flies require a blood meal to develop their eggs. Most feed on mammals but some species feed on birds, amphibians or reptiles. Some are pests of humans and stock. If the flies are very abundant, blood loss can be a problem for stock. In Australia horse flies are only known to transmit a nematode to kangaroos and wallabies. One Australian species is known to cause sensitisation, with severe reaction to subsequent bites in humans.

Adult horse flies feed on nectar and sometimes pollen, and can be good pollinators. In some Australian species, the females only feed at flowers and do not suck blood. Horse fly larvae are predators of other invertebrates usually in soil in wet areas.


Horse fly Horse flies sometimes have patterned wings.

Length 6-20 mm. These are robust flies with large eyes, short, segmented antennae and a strong proboscis.
Horse flies belong to the Family Tabanidae. There are approximately 3,000 species of horse flies known worldwide, 200 of which are found in Australia.

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