Gall Wasps are a diverse species of insect that attack differnt species of oak. Including Coast Live Oak, Engleman Oaks, Valley Oaks, Southern Live Oak and Cork Oaks. These are common oaks that are planted in urban landscapes in Southern California.
There are about 140 differnt species of cynipid wasp that form galls. The damage from these insects are on the twigs, leaves acorns and occasionally petioles. Not all galls on trees are caused by gall wasps. Most species of gall wasps. The same species of gall wasp can produce galls that differ in appear at different stages of there development.
Oak Apples on an Engleman Oak
| The first stage of development can be formed on the Catkins, then a second stage may develop on a more permanent part of the plant like a leaf or a twig. The galls can stay attached for several years after the gall wasps are not active. Other insects may infect these old galls like the filibert weevil. Most of the life cycle of a gall wasp is spent inside the gall. The adult stage is responsible for laying eggs and increasing the insect population.|
Whoolly Bear Gall Wasp