Technical Abstract: Field studies of the blackmargined aphid, Monellia caryella (Fitch), were conducted on three cultivars, “Cheyenne,” “Kiowa,” and “Pawnee,” of pecan, Carya illinoinisis (Wang) K. Koch. Aphid and natural enemy (lacewings, ladybird beetles, and spiders) densities were determined twice weekly by direct inspection of foliage on each variety during summer of the 2005 and 2006 growing seasons. Honeydew deposition was measured biweekly using water sensitive cards. Aphid phenologies were similar among cultivars; however, “Cheyenne” supported higher densities of aphids that either “Kiowa” or “Pawnee.” Honeydew production was directly correlated with aphid density. Natural enemy densities increased during initial stages of aphid outbreak on all cultivars and the asymptote reached on “Cheyenne” exceeded the action level of 25+ aphids/leaf, and had a lower natural enemy to aphid ratio than that on the other cultivars, indicating that the functional response of natural enemies to increased aphid densities was exhausted sooner on “Cheyenne” than on other cultivars where aphid densities did not exceed the action level. Honeydew appears to be an attractant for natural enemies and cost-benefit calculations were made to quantify the loss of photosynthates to aphids for each cultivar versus the gain in natural enemies that occurred. “Cheyenne” was the least efficient of the three cultivars in the utilization of this defense mechanism. The energy drain per hectare was calculated using aphid density and also by using honeydew measurements; these data showed that energy drain on “Cheyenne” far exceeded that of “Kiowa” or “Pawnee,” using either method. These results suggest that moderate densities of blackmargined aphids efficiently attract natural enemies with little risk of economic damage to the crop.