I've worked in restaurants for years and I can't believe how p!ssed off some people get about a little snail or bug on their lettuce. I mean where do they think that lettuce grows? In a hermetically sealed cabinet??? Vegetables grow OUTSIDE, people, in the elements of rain, dirt, wind etc. They are bound to get a few bugs on them. The suppliers usually sell restaurants "washed lettuce" and restaurants often wash them again. There still isn't a 100% guarantee you won't get he odd 'protein bonus' with your salad. Console yourself with the fact that if you have a live bug on your salad, it means that your vegetables probably haven't been exposed to toxic pesticides.
Now cockroaches and mice are a different matter. They are the product of an unclean, unhygenic kitchen...