 they won't eat you. They don't even harm you. What they do is they get attracted by the CO2 that is coming out of your mouth, congregate around there. The reason why you probably have a gnat problem is that your vegetable beds and your blueberries are too wet. There's a lot of moisture going on over here. You want to keep your beds moist, not wet. Imagine a wrung-out sponge. That's what a moist soil should be like.