The corn leaf aphid, Rhopalosiphum maidis (Fitch) (Hemiptera: Aphididae), infests maize, Zea mays L., and sorghum, Sorghum bicolor (L.) Moench, throughout the United States. This aphid lives in the whorl, sucks sap, and mottles plant leaves yellow. However, corn leaf aphids can be considered beneficial because they attract lady beetles and other natural enemies that stay to feed on greenbugs, Schizaphis graminum (Rondani), and other insect pests of sorghum and other crops. Effect of temperature on development of corn leaf aphids on sorghum has not been studied. Pre-reproductive period, fecundity and longevity of corn leaf aphids on Tx399 x RTx430 sorghum were assessed at constant temperatures of 10, 15, 20, 25, 30, and 35°C in an incubator at a photoperiod of 14:10 (light:dark) hours. A total of 80 aphids was evaluated at each temperature. Mean generation time and intrinsic rate of increase were calculated. Corn leaf aphids produced more nymphs and lived longer at cooler temperatures. Most nymphs (54.1) were produced per corn leaf aphid at 20°C, with 45.3, 38.3, 28.2 and 0.0 nymphs produced at 15, 25, 30 and 35°C, respectively. Average longevity was 63.4, 41.9, 32.7, 18.5 and 5.7 days at 15, 20, 25, 30 and 35°C, respectively. These data will be used to predict when corn leaf aphids after over wintering are expected to arrive in crop fields and will be used to develop a computer model to predict when greenbugs would become abundant enough to cause economic damage in Texas.