Experiments were conducted to determine the effect of Hessian fly,Mayetiola destructor(Say), larval feeding on one susceptible and two resistant wheat,Triticum aestivumL. em Thell., cultivars. The stem number, plant and crown weights, and soluble crown carbohydrates were measured in susceptible ‘Monon’ (with the H3gene) and resistant ‘Abe’ (H5gene) and ‘Caldwell’ (H6gene) wheat infested with biotype E Hessian fly larvae. All plant variables were significantly different between infested and control ‘Monon’ wheat, and no significant difference in plant variables was detected in the resistant wheats 4 wk after infestation. Of the four carbohydrates analyzed, only fructan in ‘Monon,’ and fructose in ‘Abe’ differed significantly between the two treatments. These data support the use of resistant genes in plants to control the Hessian fly, in that essentially no damage was observed in the resistant wheat, whereas susceptible ‘Monon’ was damaged severely.