Combating arthropods with ferrocene-containing synergistic compositions

An arthropodicidal composition containing, as active ingredient, an arthropodicidally effective amount of (1) at least one ferrocene derivative of the formula ##STR77## in which R and R.sup.1 each independently is hydrogen, alkyl, or alkenyl with up to 20 carbon atoms, alkyl or alkenyl with up to 10 carbon atoms substituted by carbalkoxy with up to 4 carbon atoms per alkoxy, benzyl, nitrile, cyanomethyl, cyanoethyl;

• ##STR78## R.sup.2 is hydrogen, alkoxy with 1 to 10 carbon atoms;
• alkyl with 1 to 19 carbon atoms, cycloalkyl with 3 to 12 carbon atoms or phenyl optionally carrying at least one halogen, alkyl, hydroxyl, halogenoalkyl, nitro, nitrile or alkoxy substituent,
• R.sup.3 is hydrogen or alkyl with 1 to 8 carbon atoms,
• R.sup.4 and R.sup.5 each independently is alkyl with 1 to 6 carbon atoms or together are an alkylene radical with 1 to 6 carbon atoms,
• X is oxygen, hydroxyimino or alkoxyimino with 1 to 6 carbon atoms, and
• Y is oxygen or sulphur,
• and (2) a compound selected from the group consisting of
• (A) carboxylic acid esters of the formula ##STR79## in which R.sup.11 is alkyl with 1 to 6 carbon atoms optionally substituted by phenyl or halophenyl;
• phenyl;
• halophenyl;
• or cyclopropyl optionally substituted by alkyl, alkenyl, halogenoalkyl or halogenoalkenyl each with up to 6 carbon atoms,
• R.sup.12 is hydrogen, alkyl with 1 to 6 carbon atoms, halogenoalkyl with 1 to 4 carbon atoms and up to 3 halogen atoms, alkenyl, ethynyl or nitrile, and
• R.sup.13 is phenyl optionally substituted by C.sub.1-4 -alkyl, halogen, phenoxy, halophenoxy, methyl-phenoxy or benzyl;
• furanyl, tetrahydrophthalimido or benzodioxolyl any of which is optionally substituted by halogen, alkyl or alkenyl with up to 4 carbon atoms or benzyl or, together with R.sup.12, forms a cyclopentenone ring which is optionally substituted by C.sub.1-4 -alkyl, furfuryl or C.sub.1-5 -alkenyl, and naturally occurring pyrethroids, and
• (B) phosphoric acid esters of the formula ##STR80## in which X' each independently is O or S,
• Y' is O, S, --NH-- or a direct bond between the central P atom and the radical R.sup.16,
• R.sup.14 and R.sup.15 each independently is C.sub.1-4 -alkyl or phenyl, and
• R.sup.16 is alkyl with 1 to 4 carbon atoms which is optionally substituted by halogen, hydroxyl, nitrile, optionally halogen-substituted phenyl, carbonylamide, sulphonylalkyl, sulphoxyalkyl, carbonylalkyl, alkoxy, alkylmercapto or alkoxycarbonyl;
• alkenyl with up to 4 carbon atoms which is optionally substituted by halogen, optionally halogen-substituted phenyl or alkoxycarbonyl;
• aralkyl;
• phenyl which is optionally substituted by methyl, nitro, nitrile, halogen or methylthio;
• a pyridine, quinoline, quinoxaline, pyrimidine, diazinone or benzo-1,3,4-triazine radical which is optionally substituted by C.sub.1-4 -alkyl or halogen;
• dioxanyl;
• an oxime radical;
• or a radical identical to that to which it is bonded,
• the weight ratio of component (1) to component (2) being from about 0.1:10 to 10:0.1.