A compound of formula: ##STR1## wherein W represents one or two substituents selected from halo, alkyl, alkoxy, alkoxyalkyl, haloalkyl and haloalkoxy, or W represents a bidentate group linking adjacent carbon atoms selected from alkylene and alkylenedioxy; Z represents a fluoroalkyl group of up to two carbon atoms; Y represents a substituted aryl group where such substituent is selected from halo, alkyl, aryl, aralkyl, aryloxy and arylamino; and either X' is hydrogen and X is selected from hydrogen, halo, hydroxy, alkoxy and aryloxy, or X and X' together represent a second bond between the adjacent carbon atoms. The compounds have useful insecticidal properties.