SPRAY 8-inch square pan with cooking spray. Stir boiling water into dry gelatin mix in medium microwaveable bowl at least 2 min. until completely dissolved. Add marshmallows; stir to coat.
MICROWAVE on HIGH 1 min. or until marshmallows are puffed and almost melted; stir gently until marshmallows are completely melted and mixture is well blended. (Creamy layer will float to the top.) Pour into prepared pan.
REFRIGERATE 1 hour. Dip bottom of pan into warm water 15 sec. Loosen edges with knife. Cut into 16 (1/2-inch-wide) strips to resemble worms. Insert 2 candies into one end of each worm for the "eyes." Sprinkle wafer crumbs on large serving plate for the "dirt;" top with the "worms" just before serving.