Powders containing 4 or 5% of DDT in pyrophyllite freed treated dogs of the dog flea, Ctenocephalides cants, the cat flea, C. felis, and the sticktight flea, Echidnophaga gallinacea, and protected them from reinfestation for 4-7 days. The dog and cat fleas left the host within 10-15 min. and died in 3-5 hrs.; the stick-tight fleas died on the host. The animals showed no ill effects from the treatment.