1. Novel manipulations of local climate were employed to investigate how warmer winters with either wetter or drier summers would affect the Auchenorrhyncha, a major component of the insect fauna of grasslands. Direct and indirect effects of climate manipulation were found.
2. Supplemented summer rainfall resulted in an increase in vegetation cover, leading to an increase in the abundance of the Auchenorrhyncha.
3. Summer drought, however, caused a decrease in vegetation cover, but this did not lead to a corresponding decrease in the abundance of the Auchenorrhyncha.
4. Egg hatch and the termination of nymphal hibernation occurred earlier in winter warmed plots; however, the rate of nymphal development was unaffected.