Studies conducted at the Moorestown, N. J., laboratory from 1935 to 1939 showed that the "milky diseases" of Popillia japonica are playing an important role in reducing populations of these larvae in the field. Living larvae were used as a culture medium since no artificial medium has been found on which the organisms develop to the spore stage. Such grubs, inoculated with the causal agent and held 10-12 days at 86[degree] F, contained 1-3 billion spores. These diseased grubs were then ground and either diluted with water for immediate application or incorporated with powdered talc for storage. Numerous methods of treatment including various dosages of the inoculum and intervals of application were used in field studies. Dosages from 25 million to 1,500 million spores per treated foot, applied continuously and in spots, resulted in successful establishment and subsequent build-up of the disease. Birds and insects are important natural agents of dispersal.