How to Manage Pests
Pests in Gardens and Landscapes
Twohorned oak gall wasp—Dryocosmus dubiosus
The two horned oak gall wasp is a cynipid wasp that forms
an oblong or round, seedlike gall. Galls occur on the underside
of oak leaves, usually on a leaf vein.
Leaves appear scorched. Leaf margins are brown and dead beyond location of the gall. Some galls drop
from leaves, leaving only scorched foliage. The gall wasp has two annual generations. The easily overlooked late-winter or spring generation lays
eggs in oak catkins, causing catkins to distort into a club shape. Second-generation wasps develop in
As with other gall wasps, no control is known or recommended. Because parasites are believed important
in helping to limit this pest to occasional outbreaks, spraying may do more harm than good because pesticides
can kill parasites and predators of gall wasps.
on undersides of leaves