For the first time, Toxorhynchites rutilus rutilus (Coquillett), a predatory species of mosquito, was reared on a non-living diet of a commercially available food for tropical fish. Larvae reared on the non-living diet required an average development time of 107.5 days from egg to pupa compared with 15.6 days for larvae that were fed a diet of larvae of Aedes aegypti (L.). The daily survival rate of larvae reared on the non-living diet was 0.9901+0.0098, a value slightly less than the survival rate of 0.9973+0.0075 for larvae fed Ae. aegypti. Even though the daily survival rates for the 2 groups are about equal, the longer development time required for the non-living diet groups resulted in only ca. 24% pupation vs. ca. 98% for the group-fed larvae. Pupae reared on the non-living diet were much smaller (29.3+3.6 mg) and produced smaller adults than pupae in the control group (50.+2.0 mg), adult longevity and fecundity of the small adults did not differ significantly from the control. The significance of the above findings are discussed relative to the use of Tx. r rutilus as a biological control agent for container-breeding mosquitoes.