Thanks for asking, Bob. A small wasp (called a cynipid wasp) lays her eggs into the stem of the coast live oak in late fall. Between March and May, the plant tissue begins forming a growth (called a gall) around the eggs. The gall can be green or red, smooth, glossy. By late summer, they are creamy white and by fall, galls are beige. Females emerge and if you look closely in my photo, you will see the exit holes. There are many kinds of galls, and people nickname this type as "oak apples". Galls are very fascinating!
