The invention comprises benzyl phenyl sulphides of the formula: <FORM:0790199/IV (b)/1> in which (a) one of the phenyl radicals X and Y is substituted by one or more lower alkyl, lower alkoxy, alkenyloxy, or nitro groups and may be additionally substituted by one or more halogen atoms when the other radical is substituted by one or more halogen atoms or lower alkyl, lower alkoxy, or nitro groups; (b) Y is substituted by one or more lower alkyl, lower alkoxy, or nitro groups when X is unsubstituted; (c) X is substituted by one or more nitro groups and by one or more halogen atoms when Y is unsubstituted; (d) X is substituted by one or more halogen atoms or nitro groups when Y is unsubstituted; provided that (1) if X is unsubstituted or is substituted by one or more chlorine atoms only then Y is not substituted only by one or more nitro groups, (2) if X is substituted by one lower alkyl group only, then Y is not substituted only by more than one lower alkyl group. The groups "lower alkyl" and "lower alkoxy" contain 1 to 8 carbon atoms inclusive. The compounds are prepared by reacting a halide of the formula: <FORM:0790199/IV (b)/2> with a thiol of the formula: <FORM:0790199/IV (b)/3> in the presence of an alkaline condensing agent such as potassium hydroxide in aqueous alcohol or sodium ethoxide, X and Y having the meanings given above. Compounds of the above general formula are mentioned wherein X is unsubstituted or is p-methyl-, p-ethyl-, p-methoxy-, p-allyloxy-, p-chloro-, p-iodo, p-fluoro, p-nitro -, 4 - chloro - 2 - methyl -, 4 - chloro - 3-methyl -, 5 - chloro - 2 - methyl -, 2:4 - dichloro - 3 - methyl -, 2:4 - dichloro - 5 - methyl-, 4 - methyl - 3 - nitro -, 2 - methoxy - 4 - nitro-, 2 - chloro - 5 - nitro -, and 4 - chloro - 2 - nitrophenyl, and wherein Y is unsubstituted or is p-methyl -, p - methoxy -, o -, m - or p - chloro-, p - bromo -, p - fluoro -, p - iodo -, p - nitro-2:6 - dichloro -, and 4 - methoxy - 3 - nitrobenzyl. Examples are given. The compounds are used in acaricidal compositions (see Group VI). The Provisional Specification relates to benzyl phenyl sulphides of the above formula where Y is substituted by one or more halogen, lower alkyl, lower alkoxy, nitro or amino groups and Y is unsubstituted or is substituted by one or more of the substituents given for Y. Specifications 713,984, 738,170, 745,360, [Group VI], 748,604 and 758,926 are referred to in the Provisional Specification.ALSO:An acaricidal composition comprises a diluent or carrier and as active ingredient a benzyl phenyl sulphide of the formula <FORM:0790199/VI/1> in which (a) one of the phenyl radicals X and Y is substituted by one or more lower alkyl, lower alkoxy, alkenyloxy, or nitro groups and may be additionally substituted by one or more halogen atoms when the other radical is substituted by one or more halogen atoms or lower alkyl, lower alkoxy, or nitro groups; (b) Y is substituted by one or more lower alkyl, lower alkoxy, or nitro groups when X is unsubstituted; (c) X is substituted by one or more nitro groups and by one or more halogen atoms when Y is unsubstituted; (d) X is substituted by one or more lower alkyl or alkoxy groups and one or more halogen atoms or nitro groups when Y is unsubstituted; provided that (1) if X is unsubstituted or is substituted by one or more chlorine atoms only, then Y is not substituted only by one or more nitro groups, and (2) if X is substituted by one lower alkyl group only, then Y is not substituted only by more than one lower alkyl group. The groups "lower alkyl" and "lower alkoxy" contain 1 to 8 carbon atoms inclusive. Compounds of the above formula are mentioned in which X is unsubstituted or is p-methyl-, p-ethyl-, p-methoxy-, p-allyloxy-, p-chloro, iodo, or fluoro-, p-nitro-, 4-chloro-2-methyl (or 3-methyl)-, 5-chloro-2-methyl-, 2 : 4-dichloro-3(or 5)-methyl-, 4-methyl-3-nitro-, 2-methoxy - 4 - nitro -, 2 - chloro - 5 - nitro -, and 4-chloro-2-nitro-phenyl, and wherein Y is unsubstituted or is p-methyl (or methoxy, bromo, fluoro, iodo, or nitro)-, o, m- or p-chloro-, 2 : 6-dichloro-, and 4-methoxy-3-nitro-benzyl. Examples of these are p-chlorobenzyl p-methoxyphenyl sulphide, p-fluorophenyl p-methoxybenzyl sulphide, 2 : 6-dichlorobenzyl 2 : 4-dichloro-3-methylphenyl sulphide, 4-methoxy-3-nitrobenzyl p-chlorophenyl sulphide, and p-nitrobenzyl 4 - chloro - 2 - nitrophenyl sulphide. The composition may be in the form of a dust, dispersion, emulsion, smoke, mist, or aerosol. It may contain a water-miscible organic solvent such as acetone. It may be in the form of a solid dispersed phase in an aqueous oil emulsion and the oil may be paraffin oil. The composition may comprise the active ingredient with an emulsifying agent and an organic solvent such as xylene and, if desired, a vegetable or mineral oil. The carrier may be a pulverulent solid, e.g. kaolin. For smoke compositions the carrier comprises an ignitable slow-burning substance so that a smoke containing the active ingredient is generated on ignition. For mists and aerosols the active ingredient may be dissolved in a mixture of a vegetable oil and cyclohexanone or acetone and the solution may be dispersed by mechanical means or by incorporating a volatile propellant such as a mixture of chloro-fluoro derivatives of methane and ethane. Specifications 713,984, 738,170, 745,360, 748,604 and 758,926 are referred to in the Provisional Specification.