Nitrogen (N) is a limiting resource for both plants and animals. We expect plant growth to be influenced by N availability and that life history parameters of herbivores will be different in response to plants grown under various N regimes. Cotton plants, Gossypium hirsutum, grown with low N availability were shorter and leaf N concentration was lower compared to those with high N level. Beet armyworm, Spodoptera exigua, development was affected by the N status of cotton plants on which they were reared. Fresh weight of caterpillars reared on cotton plant with lower N was consistently lower than those reared on high N cotton plants. The time to pupation and adult emergence of caterpillars grown on low N cotton plants was longer. The survival rate (% caterpillars pupated) was not statistically significant between treatments. Pupal weight of caterpillars were unaffected by cotton plant quality. In this study, we also compared the life-time damage caused by caterpillars fed on cotton plants with different N levels. The ecological significance of these findings will be discussed.