Prepare cake mix according to package directions. If desired add orange or green food coloring to batter. Cool on racks completely.
Meanwhile, divide candy coating evenly among three small microwave-safe custard cups. Microwave, one at a time, on 100% power (high) for 1 to 2 minutes or until softened. Stir until melted. Stir in a small amount of violet, orange, or green paste food coloring into each. Cool slightly. Place each in a small heavy plastic resealable bag. Seal and cut the tip from one of the corners of each bag. Make spirals and squiggles on a waxed paper-lined cookie sheet. Chill in refrigerator for several minutes or until set. Keep refrigerated.
Tint vanilla frosting with small amounts of yellow and green paste food coloring for a lime green color.
Wash all rubber or plastic animals and insects. Dry thoroughly.
Assemble cake using lime-colored frosting. Decorate with animals, insects, spirals and squiggles. Makes 1 cake (12 servings).