The Collaborative International Dictionary
Gallflies
Gallfly \Gall"fly`\, n.; pl. Gallflies. (Zo["o]l.) An insect that deposits its eggs in plants, and occasions galls, esp. any small hymenopteran of the genus Cynips and allied genera. See Illust. of Gall.
Wiktionary
gallflies
n. (plural of gallfly English)