gall wasp

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various wasps of the family Cynipidae whose larvae produce distinctively shaped galls on oaks and other plants.

Century Dictionary and Cyclopedia

1. n. A hymenopterous gall-insect; one of the Gallicolæ, Cynipidæ, or gall-flies.

Wiktionary

1. n. Any insect of the Cynipidae family, whose larvae damage trees, particularly oak trees, creating galls on the branches.

GNU Webster's 1913

1. n. (Zoöl.) See Gallfly.

WordNet 3.0

1. n. small solitary wasp that produces galls on oaks and other plants