The influence of parasitism byBathyplectes curculionis(Thomson) on growth, food consumption, and food utilization byHypera postica(Gyllenhal) larvae from the early 3rd through the 4th instars was studied at 22 and 30°C. At both temperatures, total growth was greater in unparasitized than in parasitized larvae. The total food consumption by unparasitized larvae at 22°C was higher than that by parasitized larvae, but at 30°C it was not significant. The food consumption per larva per day was higher at both temperatures for unparasitized larvae than for parasitized. There were no significant differences in the dry weight-fresh weight consumption index or in the approximate digestibility of alfalfa by parasitized and unparasitized 3rd and 4th instars, at either temperature. The efficiency of food digestion by both types of larvae decreased with age, the decline being more pronounced at 30°C than at 22°C. The net efficiency of conversion of ingested food to body matter was slightly higher for parasitized than for unparasitized larvae. At 22°C this difference was significant, but at 30°C it was not.