The Milkweed plant has a special leaf because many species of insects depend on it as their primary food source. Monarch Butterfly caterpillars eat it exclusively. We have a few milkweed plants growing near our house and we keep them purely for this purpose. I don't know if these caterpillars are monarchs but we were interested to find this little group of troopers going after this milkweed leaf. On the backside they are all lined up cooperating with each other, delighting in the feeding of their ravenous little bodies.