warble fly

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several large hairy flies of the family Oestridae, especially of the genus Hypoderma, whose eggs, which are laid on the lower body and legs of cattle and certain other mammals, hatch into larvae that form warbles under the skin.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any member of the genus Hypoderma of large flies, parasitic on cattle and deer.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun hairy bee-like fly whose larvae produce lumpy abscesses (warbles) under the skin of cattle