The responses ofMaruca testulalis(Geyer) larvae, which favor or hamper its colonization of a plant, were studied on three cowpeaVigna unguiculata(L.), Walpers, cultivars, ‘VITA l’ (susceptible), ‘VITA 5’ (moderately resistant), and ‘TVu 946’ (resistant). Larval responses studied were orientation, feeding, utilization of ingested food, and development. Attraction and arrest–stay of first instars to the plants indicated that orientational nonpreference of the larvae contributed to the resistance of ‘TVu 946’ and ‘VITA 5’ cultivars toM. testulalis. Results from studies on food intake, utilization of ingested food, larval growth, and development indicated that antibiosis was also partly involved in the resistance of ‘TVu 946’ and ‘VITA 5’ stems and pods.