Efficacy studies were conducted with Aquaprene™ emulsifiable concentrate (EC) (33.6% active ingredient [AI]) and wettable powder (WP) (40% AI) (S)-methoprene insect growth regulator formulations against larval Ochlerotatus taeniorhynchus in small field test plots. Aquaprene EC was applied at 7.18 and 9.57 g/acre. Approximately one thousand 4th-stage larvae were added to each plot before treatment, and 24 h later pupae were collected to determine emergence inhibition. At both applications rates, Aquaprene EC was extremely effective (99%) at significantly reducing adult emergence in the studies. Two application rates ((S)-methoprene at 2.4 and 4.8 g/acre) of the Aquaprene WP also were evaluated against Oc. taeniorhynchus at 1, 3, 7, and 14 days after treatment. Emergence inhibition and statistical analysis showed that significant differences were found between the (S)-methoprene rates of 2.4 and 4.8 g/acre at each posttreatment assessment. The (S)-methoprene rate of 4.8 g/acre was effective in controlling adult emergence for up to 14 days after treatment.