asymmetrically methylated imidazolidine ring were synthesized. Their affinity to the nicotinicacetylcholinereceptor of housefly Musca domestica and insecticidalactivity against the housefly were measured. The compound with a 5R-methylated imidazolidine ring demonstrated intrinsic activity comparable to that of the unsubstituted compound. Most of the compounds were synergized by oxygenase inhibitors