SINCE the discovery in 1936 of its insecticidal properties, 2:4 dinitro-6-cyclohexylphenol1 has been widely used in the United States for the control of tetranychid mites. Successful control has been obtained of Paratetranychus citri (McG.)2,3 and of Tetranychus telarius (L.) on citrus, cotton4 and hops5; on all these crops damage by red spider is of considerable economic importance, and this substance is the only synthetic compound which has been successfully applied to control on a large scale. It is of interest that 4:4' dichloro-diphenyl-βββ-trichloro-ethane (D.D.T.) is of no use as an acaricide. Later work has established that the phytocidal effect of dinitro-ortho-cyclohexylphenol can be diminished by use of its dicyclohexylamine salt without impairing its properties as an insecticide or acaricide.