Emerging and re-emerging vector-borne diseases such as chikungunya and dengue and associated Aedes vectors are expanding their historical ranges; thus, there is a need for the development of novel insecticides for use in vector control programs. The mosquito toxicity of a novel insecticide and repellent consisting of mediumchain carbon fatty acids (C8910) was examined. Determination of LC₅₀ and LC₉₀ was made against colonyreared Aedes aegypti (L.) and Aedes albopictus (Skuse) using probit analysis on mortality data generated by Centers for Disease Control and Prevention bottle bioassays. Six different concentrations of C8910 + silicone oil yielded an LC₅₀ of 160.3 µg a.i/bottle (147.6–182.7) and LC₉₀ of 282.8 (233.2–394.2) in Ae. aegypti; five concentrations yielded an LC₅₀ of 125.4 (116.1–137.6) and LC₉₀ of 192.5 (165.0–278.9) in Ae. albopictus. Further development of C8910 and similar compounds could provide vector control specialists novel insecticides for controlling insect disease vectors.