New York ironweed (V. noveboracensis L.) supports 2 spp. of honeydew-producing Homoptera, an aphid (Aphis vernoniae Thomas) and a membracid (Publilia reticulata Van Duzee), that are tended by Tapinoma sessile Say and Myrmica lobicornis fracticornis Emery and M. americana Weber. The benefits accruing to the honeydew producers from these ant associations are unequal and asymmetric, with aphids benefiting more from association with Tapinoma while membracids benefit more when tended by Myrmica. Survivorship of homopteran colonies is greatest when attended by the appropriate ant and lowest when ants are excluded. There is no evidence that either ant affects aphid growth or fecundity. The size achieved by membracids is increased and the development time is decreased when ants are in attendance. These effects are greatest in Myrmica-tended colonies.