They are everywhere. Home, work, in restaurants, offices.....holy cow it's like how we got invaded by the killer Asian beetles a couple years back.
There is an idea - could he rub it behind his ears to keep them away? Or wear the fly strip like a tie?
We have them. The best way to get rid of them is too trap them.
Take a ball jar and ring. Put an inch or so of apple cider vinegar in it, cover top with plastic wrap and screw on the ring. Take a toothpick and poke holes in the plastic. Large enough for them to fit through, but not much bigger. They go in, can't get out, as easily, drown or just hang out until they die.
Put it out on the counter where a fruit bowl may be. Get rid of fruit or move it to another place. Its not instant, but it just as effective or even more so, than just catching them with your hands. Make sure you remove the fruit that is attracting them though.