Insecticidal agents containing insecticidal active ingredients selected from the group consisting of carbamates, phosphoric (phosphonic) (di)(thio) acid esters, pyrethrins, pyrethroids, .alpha.-alkylphenyl acetates, .alpha.-cyclopropyl-phenyl acetates and chlorinated hydrocarbons, and, to increase the insecticidal action of these active ingredients, triazole derivatives or salts thereof.The triazole derivatives have the formula ##STR1## where R denotes unsubstituted or halogen-substituted phenyl, or ##STR2## Y denoting hydrogen, halogen, alkylmercapto of 1 to 6 carbon atoms, alkenylmercapto of 2 to 6 carbon atoms, or unsubstituted or halogen-substituted phenylmercapto, X denoting halogen, and n denoting one of the integers zero, 1 and 2, with the proviso that n does not denote zero when Y is halogen.