If you have spent time walking around the Kaweah Oaks Preserve or one of the other land preserves maintained by Sequoia Riverlands Trust, you probably noticed some strange-looking growths on the leaves, stems, and branches of the oak trees. These oddly shaped, brightly colored growths are called “oak galls” (pronounced gawls) and are formed as a result of the egg-laying process of the gallwasp.
Each spring, the tiny gallwasp deposits its eggs into a part of an oak tree, along with a fluid that induces plant cell multiplication, leading to the formation of the gall. The oak gall provides food and protection for the developing wasp larvae until it reaches maturity and chews its way out of the gall.
There are 11 distinct types of oak galls, each produced by a different species of gallwasp. Try to locate and identify them next time you are out hiking at Kaweah Oaks Preserve!