The pervasive effects of climate change on the biosphere are increasingly evident with many well-documented impacts on species ranges and phenological events. As ectotherms, the phenologies of plants and insects are highly sensitive to changes in temperature. The vast majority of studies of climate change effects on terrestrial organisms have focused on the responses of individual organisms to changes in temperature and precipitation patterns. Far fewer studies have examined the effects of climate change on biotic interactions, yet studies are vital for our understanding of how climate change has (and will continue to) alter communities and ecosystems. This talk explores how changing temperatures differentially alter the phenologies of members of a simple trophic community (cowparsnip, its insect herbivore – parsnip webworm, and its parasitoid wasp – Copidosoma sosares) across an elevational gradient, resulting in phenological matches in warmer years and mismatches in colder years. In cooler years, cowparsnips at higher elevations largely escape herbivory; in warmer years, cowparsnip populations at higher elevations experience reduced fitness due to substantially increased levels of herbivory.