Insecticidal compounds of the formula: ##STR1## in which A is chloro and B is hydrogen or A and B are both fluoro, X is oxygen or sulfur and one of R.sup.1 and R.sup.2 is or includes an optionally substituted 5-membered heteroaryl ring, their method for preparation and formulation, insecticidal compositions thereof, and their use to control insects, are disclosed and exemplified.