From the inception of commercial vineyards in California, insects and mites have been a problem. The abundance of pests may be attributed to the fact that most grape pests were native to America, and the extensive plantings and mild climate favored development of a considerable number of pests. Some of the insects have remained a problem in the vineyards to the present time, while other species have become less important. The introduced grape phylloxera, Daktulosphaira vitifoliae (Fitch), and the native grape leafhopper, Erythroneura elegantula Osb., were present in the early years of viticulture and are still considered major problems. Insects such as the sphinx moths, Pholus achemon (Drury) and Celerio lineata (Fabr.), and the western grape rootworm, Adoxus obscurus (Linn.), which previously caused considerable damage to vines, have become minor problems, whereas the omnivorous leaf roller, Platynota stultana Wlshm., the orange tortrix, Argyrotaenia citrana (Fernald), and the western grapeleaf skeletonizer, Harrisina brillians B. and McD., have become serious pests.