What are oak galls?
Oaks are attacked by many gall-making insects, primarily wasps. In general, galls arise when insects lay eggs in expanding buds or young leaf or stem tissue early in the season. Galls form when insects introduce growth regulating chemicals that interact with plant hormones. The insect then develops inside the resulting gall. Each gall-making insect incites its own distinctive gall; some may be on stems, others on leaves, bark, buds, flowers, or even acorns. Some are spiky, others fuzzy, disk-shaped, or round. They range widely in size and color. A few other oak galls we have come across this season have included the jumping oak gall, gouty oak gall, wool sowers gall, horned oak gall, vein pocket gall, and now the wooly oak gall. For the most part, galls are a cosmetic or nuisance problem, and not a hazard to the tree though some that attack stems can be injurious. Many gall-makers attack plants early in the season, long before anyone is even thinking about attempting to control them.
