I have a West facing porch on my new home. In the evening it gets covered with flies/mosquitos warming on the brick... So I hosed the entire thing down a few days ago with both Bifenthrin and Permethrin at HEAVY rates. I even resprayed the brick a few times, letting it absorb in... So why are there still flies/mosquitos all over the place? I understand that these chem's are not repellants... But when they hang out all night, shouldn't I be finding bug carcasses laying on the porch?