Nitrogen and phosphorus flow in litterfall and throughfall were studied in two California Quercus species (the evergreen Q. agrifolia and deciduous Q. lobata ) before, during, and after an outbreak of the California oak moth, Phryganidia californica . All of the foliage of both oak species was removed by the herbivore during the course of this outbreak. During the outbreak, total N and P flow to the ground more than doubled from Q. agrifolia and increased to a lesser extent from Q. lobata over the previous year. The composition of the litter during the outbreak year. The composition of the litter during the outbreak year shifted so that in Q. agrifolia , almost 70% of the total N and P flow to the ground moved through frass and insect remains, while in Q. lobata , approximately 60% of the N and 40% of the P moved through frass and insect remains.