Are you worried about pink, hairy globs growing on the underside of your oak's leaves? Don't. They are the egg clusters (called galls) of the harmless crystalline gall wasp. The female lays her eggs just under the surface of the leaves, and these colorful galls form. They don't hurt the tree and the tiny wasps that will hatch in late winter won't hurt you.

Photo courtesy of Mariposa Master Gardeners