Nonsteroidal ecdysone agonist stimulates acid phosphatase activity in the fat body in vitro cultures obtained from ligated late-last instar larvae of Corcyra cephalonica. The agonist also stimulates general protein synthesis. This stimulation is both time as well as dose dependent (up to a dose of 1000 ng of the agonist). However, still higher concentrations (1500-4000 ng) tend to depress the degree of stimulation.