The striped mealybug, Ferrisia virgata (Cockerell) (Hemiptera: Pseudococcidae), is a cosmopolitan pest of a variety of agricultural crops including cotton. To investigate the biological control potential of the predatory ladybird Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) against this pest, we evaluated its developmental and reproductive fitness when feeding on F. virgata reared on pumpkin fruits or on cotton leaves and compared this to a diet of Planococcus citri Risso (Hemiptera: Pseudococcidae) reared on pumpkin fruits. F. virgata and P. citri reared on pumpkins were equally suitable prey for the pre-imaginal stages of C. montrouzieri. Duration of total immature development was 1 day longer in C. montrouzieri offered F. virgata reared on cotton as compared with F. virgata or P. citri reared on pumpkin, whereas no significant difference was observed in survival rates. Diet significantly influenced the reproductive fitness of C. montrouzieri. Females offered P. citri reared on pumpkin had significantly shorter pre-oviposition periods and higher fecundity and fertility than those given F. virgata reared on pumpkin or cotton leaves. F. virgata grown on cotton leaves supported the reproduction of C. montrouzieri better than F. virgata reared on pumpkin. Our study established that C. montrouzieri can successfully complete its development and reproduction when fed exclusively on F. virgata and indicates its potential as a biological control agent of this emerging cotton pest.