Milkweed comes in many sizes, flower colors, and growth habits for North American Gardens. The adult moth occasionally is observed on milkweed or dogbane, although you might not be impressed enough to notice it. I thought that was a good thing since my butterfly weed is usually covered with aphids. Where there is one large milkweed bug, there are usually more. Milkweed bugs and milkweed beetle are late season pests. Or should I still be concerned with the ants? And lastly, i am in Elk River just nw of you. December 2018 2. In the larval stage of their life cycle, monarch butterflies feed exclusively on milkweed plants, herbaceous perennials in the genus Asclepias. I have recently found a tropical milkweed that the monarchs absolutely love. 20 Common Tomato Problems. The milkweed flowers range in colors from yellow to orange to red-orange. Then you know your’re getting the variety that work well in your climate.