The difference between Northerns (N. s. sipedon) and Midlands (N. s. pleuralis) is mainly pattern. Midlands have 30 or less bands/blotches from head to vent while Northerns have more. Also, midlands have lateral blotches that are narrower than the light interspaces between them. As far as ventral pattern, Midlands usually always retain a pattern of paired half-moons while Northerns ventral patterns are more scattered or even totally absent. How are your babies doing for you?