Oak Galls

Published March 30, 2021 at 5:14 AM EDT

The exterior of an oak gall. When the shell is broken, the inside is "fuzzy."

These galls are made by wasps laying eggs in leaf buds.

Oak galls are caused by gall wasps, also called gallflies, are a family (Cynipidae) in the wasp superfamily Cynipoidea within the suborder Apocrita of the order Hymenoptera. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this generally very small creature (1–8 mm) are known worldwide, with about 360 species of 36 different genera in Europe and some 800 species in North America.