The effects of nitrogen fertilization on the biology of the cassava pink mealybug, Phenacoccus manihoti Matile-Ferrero, were investigated in the laboratory. The experiment was carried out on cassava potted plants at three nitrogen fertilization rates: 0, 90 and 180 kg N ha-1. The results showed that mealybugs grown on cassava plants receiving the highest nitrogen fertilization rate had a significantly shorter development time, longer longevity and higher fecundity than mealybugs in the other treatments. The survival rate of the total nymphal stages was not significantly different among nitrogen fertilization treatments. The mealybugs that fed on plants fertilized at the highest nitrogen fertilization level had highest body weight and size than mealybugs in the other treatments. The net reproduction (Ro), generation time (T) and intrinsic rate of natural increase (rm) of mealybugs feeding on plants treated with the highest nitrogen dose were higher than those for mealybugs in the other treatments. Thus, an appropriate nitrogen fertilization level for minimum mealybug damage should be applied since increasing the nitrogen application level leads to an increase in the P. manohoti population on cassava.