Both candidate adulticides, Esbiothrin and Bioresmethrin, exhibited quick knockdown 1-h posttreatment. Esbiothrin elicited the fastest knockdown, but Bioresmethrin was more effective at both 1- and 24-h posttreatment than either Esbiothrin or Scourge against both Aedes taeniorhynchus and Culex quinquefasciatus. Mosquitoes treated with Scourge required more time and a higher dosage to respond in a physiological manner similar to those treated with either of the candidate adulticides. More than twice the dosage rate of Cythion was required than either candidate adulticide to cause a similar physiological response in treated mosquitoes.