Make ants one day in advance. For each treat, knead 1/2 teaspoon Gum-Tex into 6 oz. fondant. Tint black.
Roll three fondant balls, each 1/2 in. dia. Flatten slightly and shape to form body sections. Use brush and piping gel to attach sections.
For legs, roll three logs, each 1/16 in. dia. x 1 in. long. Use brush and piping get to attach legs to body. Let dry overnight on cornstarch-dusted cake board.
Make cupcakes. Prepare white batter following recipe directions. Tint 1/3 batter red and 2/3 batter green. Gently stir mini chocolate chips into red batter.
Place two-tone insert in baking cup-lined muffin pan. Use a cut disposable decorating bag to fill center ring of insert 2/3 full with red batter. Use a cut disposable decorating bag to fill outer ring of insert 2/3 full with green batter.
Remove insert and repeat until all cavities are filled. Remove insert. Bake and cool.
Decorate cupcakes. Prepare buttercream icing following recipe directions. Tint green. Use spatula to ice tops of cupcakes smooth. Position ant.