I do not believe that you can legally use a bug zapper in a food service situation, but the UV glue traps are acceptable, yet my experience has shown me they are next to useless.
I’ve had better luck with simple sticky paper tapes. They look like crap, but they do work without raining down electrocuted insect innards into your food prep area.
Air curtains work nicely, but some customers will pitch a fit when their hair gets blown out of place.
An other option is to adjust your make-up air on your hood so you have a slight positive pressure instead of negative pressure sucking insects inside.