In greenhouse studies, four nitrogen (N) rates were applied to potted grape plants. Foliar N increased significantly as applied N increased, and there were significant differences in N content between leaves taken from lower, middle, and upper node locations on the vines. In leaf cages,Tetranychus pacificus(McGregor) responded to increasing foliar N with significantly (P<0.05) increased fecundity and shorter immature developmental time only during the second year of the study. There appeared to be no relationship between foliar N and immature survivorship, ovipositional duration, or female longevity.