Hi Talon! Welcome to Thamnophis. Are any of your garters wild caught and specifically the female? Two years is a good amount of time for a animal to become established in their enclosure. And also to become tolerant of handlings however all specimens are individuals with their own personalities. Was she in a shed cycle? Was she recently fed? The other garters, are they in close proximity to her? Then the main question is what type of encolsure is she in and what are the temperatures like in there. Ambient, basking spot, and warm and cool side temps? How are you heating the enclosure? These are the questions we need to check into. Then overall, we need to remember that these animals are captives but they have wild instincts.