There are provided novel substituted 3-aryl-pyrrolidine-2,4-dione derivatives of the formula (I) ##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,A represents hydrogen, or represents alkyl, alkoxyalkyl or alkylthioalkyl, each of which is optionally substituted by halogen, cycloalkyl which is optionally interrupted by hetero atoms, or represents aryl, arylalkyl or hetaryl, each of which is optionally substituted by halogen-, alkyl-, halogenoalkyl-, alkoxy- or nitro,B represents hydrogen, alkyl or alkoxyalkyl,or in whichA and B together with the carbon atom to which they are bonded form an optionally substituted saturated or unsaturated cycle which can be interrupted by oxygen and/or sulphur.R represents the groups ##STR2## in which L, M as well as R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 have the meaning given inthe text of the application.The new compounds (I) have highly pronounced insecticidal, acaricidal and herbicidal properties.