Although this plant can be very invasive, and the sap, if it gets on the skin and is hit by sunlight, can cause a nasty reaction (photodermatitis), it is a magnet for insects. Here you can see a couple of hairstreak butterflies, and various flies and wasps. I have seen flowerheads covered with about 15 different species of insects, including honey bees and butterflies. As well, the larvae (caterpillars) of the gorgeous Black Swallowtail butterfly, are frequently found on this plant.