Females of Scambus buolianae did not lay eggs when deprived of food in the form of host tissues throughout adult life. Greatest egg-production and longest life resulted when that food was continuously available. Average egg-production was reduced to under one-third, and longevity reduced to two-thirds or one-half, in females that were permitted to feed on host body fluids only intermittently or that were deprived of them after the first 15 days of adult life. No eggs were laid by females deprived for the first 20 days, and longevity was reduced to one-third. However, absence of host body fluid as food during the first 15 days only did not significantly reduce egg-production or length of life. Tests showed females of S. buolianae have distinct and similar relative preferences for different host species as sources of body tissues for food. Both sexes showed distinct and similar preferences for species of wild flowers as sources of carbohydrate. The results support earlier findings and show that the presence or absence of suitable foods for the adults may determine whether or not an introduced parasite can establish itself, and can influence the effectiveness of existing parasites as biological control agents.