A choice test revealed that Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), adults deposited ≈3 times more eggs on wheat (Triticum spp.), seedlings than on barley (Hordeum spp.) or rice, Oryza sativa L., seedlings. On a barley seedling, 49.4% of eggs were deposited on either the abaxial leaf surface or the coleoptile and first leaf sheath (C&FLS), where newly hatched larvae die due to their inability to migrate into the interspace between leaf sheaths. In comparison, only 14% of eggs were deposited on the abaxial leaf surface or C&FLS on a wheat seedling. The average death rate of Hessian fly larvae in seedlings of an apparently susceptible barley line was 60%, compared with only 10% in seedlings of a susceptible wheat cultivar. The development of Hessian fly larvae was also much slower in barley seedlings than in wheat seedlings. It took 12 d for Hessian fly larvae to finish the first and second instars in susceptible barley seedlings, compared with 10 d in susceptible wheat seedlings under the same conditions. These results indicate that barley is not a good host for the Hessian fly. Our results also confirmed that rice is a nonhost for the Hessian fly. The resistance mechanism in rice was different from that in R gene resistant wheat. Hessian fly larvae grew a little and died more slowly in rice seedlings, whereas Hessian fly larvae died quickly without growth in resistant wheat.