Technical Abstract: Maize, Zea mays L., germplasm with resistance to leaf feeding by southwestern corn borer, Diatraea grandiosella Dyar, and fall armyworm, Spodoptera frugiperda (J. E. Smith) neonates has been developed and released. Laboratory studies were conducted during two years to determine if this resistance extends to older larvae and if larvae initially fed resistant tissue recover when switched to susceptible tissue. Developing larvae of both species were fed selected regimes of resistant and susceptible tissue from field grown whorl stage plants to evaluate for a resistance or a recovery response by the insects. Biological responses to the feeding regimes were obtained by weighing larvae at specified time intervals. Additional data obtained for the fall armyworm were pupal weights, developmental times to pupation and adult eclosion, and adult morphological normality. Results indicated a resistance and a recovery response to larvae of both species depending upon tissue feeding regime. The most interesting response occurred with fall armyworm fed resistant tissue after being initially fed susceptible tissue for 7 d. Although the larvae fed the susceptible and then the resistant tissue gained less weight after the tissue switch than those reared only on susceptible tissue, the number of days to pupation did not differ. However, the pupae of those fed susceptible tissue for 7 d and then resistant tissue weighed only 138.5 mg compared to 182.1 mg for those reared on only susceptible tissue.