A common question we get at the extension office has to do with little round balls falling out of trees. Sometimes they are fuzzy, and sometimes they are smooth. The fuzzy balls falling to the ground are called woolly oak leaf galls. They are usually attached to the lower surface of an oak leaf and fall off the leaf. The smooth BB like gall is called the live oak pea gall. When I first encountered these galls, I wondered what made them. After a little research, I found out that are many of types of galls on trees and they can be caused by insects, fungi and even bacteria. Most are harmless and are more interesting than they are detrimental. The galls we will be learning about in this article are all formed by insects.
The most prolific insect that causes galls is called a gall wasp. Most gall wasps are in the Cynipidae family and are called cynipid wasps. These wasps are very small and all, but a few species are less than 1/4 inch in length. Their color varies greatly. Some species are black, others are red, yellow, or amber. The larvae are legless and both larvae and pupae are white in color. (READ MORE)