Definitions for gall wasp
Random House Webster's College Dictionary
any wasp of the family Cynipidae, the larvae of which form characteristic galls on plants.
Origin of gall wasp:
gall wasp, gallfly, cynipid wasp, cynipid gall wasp(noun)
small solitary wasp that produces galls on oaks and other plants
Any insect of the Cynipidae family, whose larvae damage trees, particularly oak trees, creating galls on the branches.