Larvae of Aedes polynesiensis and Ae. malayensis were treated with tetracycline for 2 generators. After treatment, females were screed for susceptibility/refractoriness to infection by subperiodic Brugia malayi. No change was seen in the normally refractory nature of Ae. malayensis. Several refractory females were found in the normally susceptible Ae. polynesiensis. In addition, the number of infective filarial larvae was much lower in the treated group when compared with an untreated control.