The LC value of lambda-cyhalothrin was 2.92 mg/ft2, while that of alpha-cypermethrin was 20.99 mg/ft2. Thus the concentration needed was 7 times greater than lambda-cyhalothrin. The knockdown values of permethrin after 10 minutes exposure were very low but the mortality after 24 hours was high. Both deltamethrin and cyfluthrin gave good knockdown values at low concentrations, but the cockroaches recovered 24 hours later.