There are not many insects that thrive dining on milkweed. Its sap is a bitter (I guess) latex that is poisonous to most, but a hardy few not only gobble the leaves up but use the poisons as a defense against predators.. If you have interest in how that all plays out, Monarchs and Milkweed: A migrating butterfly, a poisonous plant, and their remarkable story of coevolution, has a lot of great information. Aside from monarchs, the other insects that do well on the plant that I see often are milkweed bugs, milkweed beetles, and these milkweed tussock moths.
It is not unusual to find a pair of Euchaetes egles or many eating together but this was probably the most intimate pair I have seen yet. They reminded me of Lady and the Tramp in Tony’s Restaurant. 🙂
All those bristly hairs are an additional part of their protection from predators as they go down pretty scratchy. However, not all insects predators are deterred by the toxins. This mantis seems to be enjoying a meal of milkweed bug