Insecticidal benzofuran derivatives

A compound of the formula ##STR15## wherein R is selected from the group consisting of hydrogen, optionally substituted alkyl, alkenyl and alkynyl of up to 8 carbon atoms, optionally substituted cycloalkyl or cycloalkenyl of up to 8 carbon atoms, optionally substituted aryl of 6 to 18 carbon atoms, optionally substituted benzoyl and optionally substituted optionally substituted benzoyl and optionally substituted heterocycle, the optional aryl, aralkyl, benzoyl and heterocycle substituents being at least one member of the group consisting of halogen, thiazolyl, alkyl and alkoxy of 1 to 6 carbon atoms haloalky, --CN,--NO.sub.2, aldoxycarbonyl,--CONH.sub.2, --OCF.sub.3 optionally substituted alkylamino or dialkylamino of 1 to 4 or carbons, --OR", --SR" in which R" is alkyl or alkenyl of 1 to 6 carbon atoms, or heterocyclo, or said optional substituent is alkylenedioxy, Alk.sub.1 and Alk.sub.2 are individually optionally substituted alkyl of 1 to 8 carbon atoms, X is --O-- or --S-- and R' is hydrogen or halogen in any position on the phenyl and the geometry of the double bond is E or Z or a mixture of E and Z the optional alkyl, alkenyl, alkynyl, cycloalkyl and cycloalkenyl substituent being at least one halogen.