We conducted an 8-year field survey to link extreme high-temperature events to the shift in dominance hierarchy of two worldwide cereal aphid species (Rhopalosiphum padi and Sitobion avenae), which may respond rapidly through evolutionary or plastic responses to thermal extremes due to their short generation duration, clonal structure and high thermal sensitivity. To further understand the mechanism involved in this change in species’ dominance, we characterised aphid heat tolerance and demography of the 2 species sourced from relatively mild (Xinxiang) and hot (Wuhan) locations in a common garden design and compared the same measures in up- and down-selected lines of the two aphid species. All the datasets are the raw data for our three parts in this research, field survey, common garden test, and artificial selection experiment.