Like Don said, stick with fish. Ribbon Snakes do not eat crickets. Also, it is unlikely that the snakes are three months old - Ribbon Snakes aren't usually born in November.

Ribbon Snakes also eat small amphibians, but the difficulty with this is that wild-caught amphibians can carry parasites. When the snakes get bigger you may be able to covert them to frozen/thawed pinkies that are scented with fish, though I'd see to it that at least 50% of their diet is fish.

Tim

Western Ribbon that I found in October 2010:

Third Eye