Laboratory bioassays using 3 formulations of Bacillus thuringiensis israelensis, SAN 402 I, IPS-78, and R153-78 were conducted with 3 species of mosquito: Aedes polynesiensis, Ae. pseudoscutellaris and Ae. aegypti. Another formulation, Bactimos was tested with only Ae. aegypti. Additional bioassays were performed with Ae. polynesiensis in 0.5% salt water. The presence of salt did not deter the action of the bacterium. The 3 mosquito species proved to be susceptible to the various formulations, Bactimos being the most active formulation followed by R153-78, IPS-78 and SAN 402 I.