The last thing that you should consider using is one of those UV zappers or electrical fly swatters.
What happens when one of those gadgets zaps an insect?
Current passes through the insect's body, the insect presents a resistive load and the current causes it to heat up.
Part of the internal fluid inside the fly will boil and that will cause a huge spike in internal pressure and thus the insect's body will rupture.
Only part of the insect will be heated up and most of the fluid will be expelled as an invisible cloud of drops that will fall out over an area a couple of metres across.
Those droplets will be full of the bacteria that are present in the insect's gut.
When I was living in Germany, some consumer show examined the surfaces in the vicinity of a zapper in a restaurant and they found bits of congealed fly insides all over the surfaces near to the zapper and they also pointed out that anyone in the vicinity of a zapper when it had just zapped a fly would be inhaling the droplets - germs included.
Not in my kitchen thank you.
Presumably the heat would also kill the germs...?
No, not at all. It only takes a tiny proportion of the fly's internal fluid to boil and burst it apart. The germs in the fly's gut will survive that. You can find live bacteria on the ground in a circle around the zapper. As was shown on German TV.