'Gallfly' definitions:

Definition of 'gallfly'

noun

Small solitary wasp that produces galls on oaks and other plants [syn: gall wasp, gallfly, cynipid wasp, cynipid gall wasp]

noun

Fragile mosquito-like flies that produce galls on plants [syn: gall midge, gallfly, gall gnat]

noun

Any of various insects that deposit their eggs in plants causing galls in which the larvae feed

From: GCIDE

Gallfly \Gall"fly`\, n.; pl. Gallflies. (Zool.) 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. [1913 Webster]