A botfly, also written bot fly, bott fly or bot-fly in various combinations, is any fly in the family Oestridae. Their lifecycles vary greatly according to species, but the larvae of all species are internal parasites of mammals. Largely according to species, they also are known variously as warble flies, heel flies, and gadflies. The larvae of some species grow in the flesh of their hosts, while others grow within the hosts' alimentary tracts.
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