The toxicities of malathion-, permethrin-, and fipronil-treated plant foliage against laboratory colonies of adult Aedes aegypti and Aedes albopictus were evaluated. The exposure times significantly affected the percentage knockdown of mosquitoes. Fipronil-impregnated plant leaves caused higher mortality than malathion- and permethrin-impregnated leaves at the same application rates. Aedes albopictus was more sensitive to the 3 kinds of insecticides than Ae. aegypti. The method for bioassay of mosquito adulticides using plant foliage has been described, and the advantage and disadvantage of leaf bioassay method has been discussed and compared with other existing methods.