Crapemyrtle aphids Sarucallis kahawaluokalani are host specific; feeding primarily within the genus Lagerstroemia (Lythraceae). Numerous cultivars of crapemyrtle are used in ornamental plantings and susceptibility to aphid attack differs by cultivar. We fed Chrysoperla rufilabris aphids reared on seven different cultivars of crapemyrtle. Survivorship among pupae and adults was different between cultivars and was found to be dependent on pedigree and mature plant height. In four of seven cultivars the suitability of crapemyrtle as a host to the crapemyrtle aphid was inversely related to the survivorship of C. rufilabris. Six alkaloids have been isolated from crapemyrtle and may be responsible for mediating the tritrophic interaction that we observed.