Abstract: Insecticidal, acaricidal, herbicidal and antimycotic 3-aryl-pyrrolidine-2,4-diones of the formula ##STR1## in which X represents alkyl, halogen or alkoxy,Y represents hydrogen, alkyl, halogen, alkoxy or halogenoalkyl,Z represents alkyl, halogen or alkoxy,n represents a number from 0-3,R represents hydrogen or represents the groups --CO--R.sup.1 or --CO--O--R.sup.2,in whichR.sup.1 represents alkyl, alkenyl, alkoxyalkyl, alkylthioalkyl, polyalkoxyalkyl or cycloalkyl which can be interrupted by hetero atoms, each of which radicals is optionally substituted by halogen, or represents optionally substituted phenyl, optionally substituted phenylalkyl, substituted hetaryl, substituted phenoxyalkyl or substituted hetaryloxyalkyl, or represents optionally substituted phenyl, optionally substituted phenylalkyl, substituted hetaryl, substituted phenoxyalkyl and substituted hetaryloxyalkyl, andR.sup.