Horned Oak Gall Leaf Galls
When most people think of horned oak galls, they visualize the gnarled, woody stem galls that form on the twigs and small branches of pin oaks. This is understandable since the gall-making wasp, Callirhytis cornigera (Family Cynipidae) that's responsible for directing the growth of the stem galls spends 33 months developing inside individual chambers within these very obvious galls.
The galls grow larger in size with each season. In early spring, as the immature wasps near the completion of their development, the whitish-tan, cone-shaped “horns” that give this gall its...