Technical Abstract: Two laboratory bioassays were conducted to determine the effect of feeding selected whorl leaf regions of a resistant and a susceptible maize, Zea mays L., hybrid on fall armyworm, Spodoptera frugiperda (J. E. Smith), growth. In one bioassay, larvae were fed fresh excised whorl leaf tissue. In the other, they were fed reconstituted diets containing lyophilized leaf tissue from three leaf regions of both hybrids. Results of the two bioassays were similar. Differences in larval weights were found for larvae fed tissue from different leaf regions within and across hybrids. The largest differences were found within the resistant hybrid, showing that regions of the same whorl leaf differ in suitability as a food source for larval growth.