A wooly white gall with pink spots on an oak.

Oh, the Gall! Gall-making Wasps

Have you seen a weird lump, bump, and/or projection growing off a leaf or stem of a plant? If so, you might have encountered a gall which is an abnormal growth of plant tissue caused by an invertebrate, fungi, and/or bacteria. Gall-making invertebrates secrete chemicals (like proteins) as they feed, causing plant tissue to form