We compared the biological performance of a new ‘biotype’ of Diuraphis noxia (Mordvilko) from eastern Colorado to that of two D. noxia clones from western Kansas using three wheat varieties as host plants; ‘Trego’, a susceptible variety, and ‘Stanton’ and ‘Halt’, two varieties with different sources of resistance to D. noxia.  Nymphal survival for the two Kansas clones on Trego was 96% and 90%, respectively, compared to 67 % and 43% on Stanton, and 65% and 57% on Halt.  In contrast, the Colorado clone had 60% survival on Trego, 43% on Halt, and 85% on Stanton.  Aphid developmental times varied little among varieties; the largest effect of antibiosis was on aphid reproduction, measured as the number of nymphs produced by an apterous virginopara during the period required for her first born nymph to mature.  Fecundity of the Kansas clones was much lower on Stanton and Halt than on Trego, but that of the Colorado clone was equally high on all three.  We also contrasted plant growth and damage development using naturally developing aphid colonies of the Colorado clone and one Kansas clone on individual plants of all three varieties.  Collectively, the results suggest that the Colorado clone has completely overcome the resistance expressed in Stanton, but only resistance to aphid reproduction in Halt, and not resistance to nymphal survival.  The improved nymphal survival on Stanton appears to been achieved at a cost in terms of reduced survival on Trego.  These results suggest a different genetic basis for D. noxia antibiosis effected via reduced nymphal survival and that effected via reduced adult reproduction.