AbstractThe insecticide phosphamidon, both alone and mixed with other chemicals, was tested in the laboratory as a motor stimulant to female spruce budworm moths. For phosphamidon alone, the time to reaction of virgin female budworm (Choristoneura fumiferana) moths was about 40 min. However, small supplements of pyrethrum or synthetic pyrethroids reduced the reaction time to about 3–8 min. The slow reaction to phosphamidon alone could account for the failure of that insecticide to kill gravid females. It is postulated that moths quickly stimulated to flight activity within the canopy would be more likely to acquire a lethal dose of insecticide before the spray cloud dissipated.