I haven't seen garter snakes around here but I would welcome them like I welcome my black snakes. I try to think of them as outside pets ... they eat bugs, like you said, and they eat and keep other "bad" snakes away. Once you get over the fear of coming on one unexpectedly and being startled, you'll be fine. Push the handle of a rake or hoe around under the bushes where you want to work and they will sneak away and you'll never see them.