Activity of insecticides against the preemerged adult cat flea in the cocoon (Siphonaptera: Pulicidae).

The activity of insecticides against the adult cat flea, Ctenocephalides felis (Bouché), inside the cocoon (preemerged) was determined by spraying the cocoons directly and observing subsequent emergence of adults over the next 14 d. Direct sprays of 0.5% trimethacarb wettable powder (WP) and chlorpyrifos emulsifiable concentrate (EC) and WP provided greater than 70% kill. The order of activity against the preemerged adult exposed to direct sprays was organophosphates greater than carbamates greater than pyrethroids. In general, pyrethroids and proprietary aerosols failed to kill preemerged adults. Even though most sprays did not kill preemerged adults, they stimulated adult emergence from cocoons. Preemerged adults placed in the nap of carpet were not killed by chlorpyrifos, diazinon, or propetamphos sprays; the carpet protected them effectively.