Rainfall fluctuations during 1992-1994 significantly influenced plant-herbivore processes. Foliar N and phenolic concentrations were reduced in all species during the much drier summer of 1993 that 1992. The summer drought in 1993 was apparently severe enough to restrict carbon allocation to plant phenolics. In contrast, foliar N levels in oaks were somewhat elevated by the end of the wet 1994 growing season. Total phenol and hydrolyzable tamin levels remained quite low in 1994 when carbon may have been preferentially allocated to growth and not differentiation as N uptake increased during the wet summer following drought. Nevertheless, carbon allocation to condensed tannins was quite high for all species during the wet summer. The especially wet summer in 1994 also prevented soil moisture reductions on the dry treatment plot from affecting foliar chemistry. Insect herbivore damage was directly correlated with rainfall totals over the three-year period. Herbivore damage on oaks was reduced during the 1993 drought, principally because of less impact by leaf skeltonizers. Insect feeding on oaks and maples was elevated during the wet 1994 summer when strip feeding by lepidoptera larvae was at its highest. However, the slightly lower damage on dry than wet treatment plots in 1994 supports the patterns emerging from our weather-related studies. Our findings suggest that herbivore damage at walker Branch appears largely dependent on the response of specific insect feeding guilds to moisture-related changes in the foliar N and plant phenolics.