Races B, C, D, and Great Plains of the Hessian fly,Mayetiola destructor(Say), were used to infest wheat cultivars Seneca, Monon, Knox 62, and Arthur 71, all of which have different genes for resistance. The cultivars were grown in standard green-house flats and placed in chambers at 15, 18, 21, 24, or 27+1°C. Results showed that cultivars with different specific genes for resistance grown at several temperatures react differently when infested by various races of Hessian fly. Most of the resistant cultivars showed an increase in infestation and tillering as temperatures were increased. However, tillering varied depending on the race, the cultivar, and the temperature used. High tillering could potentially be an important form of tolerance in some cultivars helping to offset some of the losses caused by the Hessian fly.We propose that a constant temperature of 27°C be considered as a screening tool to aid entomologists and plant breeders in selecting resistant wheat cultivars that are stable to Hessian fiy infestations at high temperatures.