Place some orange slices in a shallow bowl with some water to attract all types of Butterflies to your garden, Monarchs in particular love them. if you are concerned about ants,,, place the oranges and a few rocks in a shallow bird bath and place mint oil all along the base... Ants do not like mint. I do this to my hummingbird feeder that is on a shepherd's hook. The ants stay away from the feeder. - A Not So Secret Garden
"The Monarch is a common poisonous butterfly that eats poisonous milkweed in its larval stage and lays its eggs on the milkweed plant. Monarchs have a wingspan of 3 3/8 - 4 7/8 inches (8.6 - 12.4 cm). Butterflies are beautiful, flying insects with large scaly wings. Like all insects, they have six jointed legs, 3 body parts, a pair of antennae, compound eyes, and an exoskeleton. The three body parts are the head, thorax (the chest), and abdomen (the tail end)."