A liquid insecticidal composition for use with a electrically powered heated emanation device is described wherein the composition comprises a microemulsion of:0.01 –2.0 wt% pyrethroid insecticide selected from at least one of:cyphenothrin, prallathrin, allethrin, esbiothrin, transfluthrin and/or metofluthrin0 –1.0 wt% natural oil0 –2.0 wt% fragrance1.0 –5.0 wt% surfactant0.1 –3.0 wt % fatty acid ester0.0 –40.0 wt% semi polar or polar organic solvent (derived from petrochemicals)0.0 –30.0 wt% polar organic solvent (not derived from petrochemicals) 0 –8.0 wt% additive(s) and water to 100 wt% of the total wt% of the composition wherein water comprises at least 30.0 wt% of the total composition. A replaceable refill containing the insecticidal composition and a system for emanating the composition from the refill is also described.
