O,O-diethyl phosphorothioate O-ester with phenylglyoxylonitrile oxime (Bay 77488) at calculated deposits as low as 0.05% by weight satisfactorily protected woolen cloth against feeding damage by. larvae of the black carpet beetle Attagenus piceus (Olivier) and of the webbing clothes moth Tineola bisselliella (Hummel). The biological data also showed the Bay 77488 residues to be moderately resistant to washing. highly resistant to drycleaning, and persistent through aging for at least 12 months.The oral LD₅₀ to rats is more than 1000 mg/kg.