| a small bloodsucking fly, Haematobia irritans, that is a pest, esp. of cattle. |

| horn fly n. A small black European fly (Haematobia irritans), introduced into North America, that sucks blood from cattle, usually biting an animal at the base of the horn. |
horn fly
(Haematobia irritans), insect of the family Muscidae (order Diptera) and a serious cattle pest. Adult horn flies cluster at the base of horns and on the neck and rump of cattle and suck blood. Their attacks cause loss of weight and milk production in affected cattle.
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