1Heat oven to 350°F (325°F for dark or nonstick pan). Make, bake and cool cake as directed on box for 12-cup fluted tube cake pan.
2Cut cake as shown in diagram A. Freeze pieces uncovered 1 hour for easier frosting. Stir food color into frosting. Arrange cake pieces on tray to form inchworm as shown in diagram B. Frost cake, attaching pieces with frosting.
3Attach one M&M's™ chocolate candy to each vanilla wafer with frosting; attach to end of cake for eyes. Press 3 candies into frosting for mouth. Gently push 1 pretzel stick into flat end of gumdrop; repeat. Insert pretzels stick into cake for antennae. Arrange remaining gumdrops along edge for feet. Store loosely covered.