From Longman Dictionary of Contemporary Englishhorseflyhorse‧fly /ˈhɔːsflaɪ $ ˈhɔːrs-/ noun (plural horseflies) [countable] HBIa large fly that bites horses and cattle
Examples from the Corpus
horsefly• He watched her crash a magazine against the wall, trying to bat a horsefly.• Gnats the size of horseflies buzzed around our ears. 