Whiteflies (Trialeurodes vaporariorum) were reared on tomato plants grown at different nitrogen levels. Life history parameters such as whitefly longevity and fecundity increased with higher N-levels in the nutrient solution, whereas the developmental time decreased. Sex ratio, respiration rate, and egg to adult survival were not consistently affected by the various N-treatments. Life table analysis showed that high N-concentrations in the leaves resulted in a shorter generation time and doubling time of the populations and in a higher net reproductive rate (R₀) and intrinsic rate of natural increase (r_m). Hence, overall population growth was faster on high-N plants than on low-N plants.