Abstract: Certain benzoyl chloride phenylhydrazones have been found to be active against insects and mites. The benzoyl ring and the phenylhydrazone ring can be substituted with a halogen atom, a nitro group, or an alkyl group of from 1 to 6 carbon atoms, inclusive. A new class of pentahalobenzoyl chloride phenylhydrazones is described, particularly pentafluorobenzoyl chloride phenylhydrazones. A further new class of alkylbenzoyl chloride phenylhydrazones, particularly p-toluoyl chloride phenylhydrazones are also described. The compounds are prepared by reacting a benzoic acid phenylhydrazide with phosphorus pentachloride to obtain a benzoyl chloride (dichlorophosphinyl)phenylhydrazone that is reacted with phenol to produce the desired benzoyl chloride phenylhydrazones. Certain of the compounds can be prepared by direct chlorination of a benzaldehyde phenylhydrazone. Methods of use and compositions are described.