Welcome. Your snake may need sometime to settle in like Stefan said. Bugs are not in there diet. Eartworms, nightcrawlers are more their liking. Live guppies are also a good food. Those flopping and flipping little beauties will drive most garters crazy. Check out the care sheet for more info. on keeping your new found friend.
http://www.thamnophis.com/caresheets...ake_Care_Sheet