The effects of temperature and prey density on Coleomegilla maculata (DeGeer) feeding onMyzus persicae(Sulzer) were determined to quantify their impact on theC. maculata-M. persicaeinteraction. Seven temperatures ranging from 15.6 to 32.2° C were employed in the study. Nine prey densities per temperature and two predator and prey age classes per prey density were also used.An enzyme kinetic equation was used to describe the change with temperature in the green peach aphid intrinsic rates of increase and theC. maculatalarval and adult search rates. The larval and adult handling rates were determined to be linearly related to temperature over the range studied. The short-term impact ofC. maculataadults and 3rd-instar larvae on green peach aphids was simulated by substituting these equations into two aphid growth rate models. Both models predicted thatC. maculata3rd-instar larvae and adults would be most effective in reducing the aphid population in temperatures above 29° C.