Experiments conducted on the European corn borer (ECB),Ostrinia nubilalis(Hübner), in 1981 and 1982 showed that caged moths did not discriminate between corn,Zea maysL., in the fresh silking stage and sunflower,Helianthus annusL., in the pollen shedding stage for egg laying. ECB larvae which hatched from eggs that were laid on sunflower, however, were largely unable to establish themselves and/or survive on that crop. Once the stalk tissues had been penetrated, however, the amount of activity was essentially identical between the sunflower- and corn-reared larvae. Development of ECB larvae was slower on sunflower than on corn. ECB moths exhibited an oviposition preference for the underside of the sunflower leaves, but an occasional egg mass could be found on the head. ECB larvae almost always penetrated the sunflower stalk at the base of the petiole, but an occasional larva was found to have entered the plant through the soft head tissues.