Rhopalosiphum rufiabdominalis (Sasaki), rice root aphid, and Rhopalosiphum insertum (Walker), apple-grass aphid, are trapped regularly in Victorian cereal crops but little is known about their involvement in the epidemiology of barley yellow dwarf virus in Australia. To assist in our understanding of these species, laboratory experiments were conducted to provide comparative biological data for both species. The growth, development, fertility and survival of R. insertum and R. rufiabdominalis were compared at nine constant temperatures between 10°C and 35°C. R. rufiabdominalis proved to be better adapted to higher temperatures than R. insertum in all measures of aphid performance used in the study, including mean relative growth rate, intrinsic rate of increase and rate of offspring production per unit bodyweight. While the lower temperature thresholds estimated for development from birth to adult were similar for both species (R. rufiabdominalis 7.3°C; R. insertum 6.9°C), R. rufiabdominalis developed more rapidly than R. insertum< at each temperature tested. The shortest observed development period (birth to reproduction) was 4.2 days for R. rufiabdominalis at 30°C and 4.7 days at 27.5°C for R. insertum.