Gall abundance and biomass was recorded on marked valley oak and blue oak individuals throughout California. Galls, mostly caused by cynipid gall wasps, were identified to species. Sampling effort per tree was recorded as the number of leaves searched for gall wasps. Leaves were taken from two branches per tree using pole pruners, and total galls per tree were summed in each observation. Annual observations of galls on each tree were made from 2000-2006.