Bake the cake and cupcakes and allow them to cool fully.
While they are baking and cooling, prepare the frosting and tint it with gel food coloring.
Place the sheet cake on a large cake board.
Use a spatula to spread a thin layer of green icing on the top and sides of the cake. It does not have to be smooth.
Fill a piping bag with green icing and attach Wilton Tip # 21 (star).
Pipe little stars all over the cake until fully covered.
Remove liners from cupcakes. Place these cupcakes on top of the green icing in the formation of a caterpillar.
Fill a piping bag with blue icing and attach Wilton Tip # 21 (star). Pipe little stars all over the first cupcake. This will be the caterpillar's rear end.
Fill a piping bag with orange icing and attach Wilton Tip # 21 (star). Pipe little stars all over the second cupcake.
Fill a piping bag with red icing and attach Wilton Tip # 21 (star). Pipe little stars all over the third cupcake.
Fill a piping bag with purple icing and attach Wilton Tip # 21 (star). Pipe little stars all over the fourth cupcake.
Fill a piping bag with yellow icing and attach Wilton Tip # 21 (star). Pipe little stars all over the fifth cupcake. This will be the caterpillar's face.
Stick two eyes on top of the yellow cupcake.
Fill a piping bag with black icing and attach a small round tip. Pipe a smile below the eyes. Stick two red m&m candies on both sides of the smile.
For the antennas, cut out 2 small red circles out of thick cardstock paper and stick each to a lollipop stick. Push these sticks on top of the yellow cupcake.
Pipe patches of green icing grass on the empty space of the cake board.
Stick flower candies on the cake as well as the cake board. Enjoy!