There are both caterpillars and beetles that eat leaves of Eupatorium (and probably numerous other pests). Some of them crawl up and eat during the dark of night. You would have to create a barrier to stop them from finding or scaling the main stem. More than likely they are hiding in the mulch or leaf litter around the base of the plants.

Well I must have an unusual specimen because mine is in full sun, with soil that is sandy loam and very well-drained. I don't water it any more than anything else. I have never noticed that it is droopy or wilting. I have also never gotten ONE seedling! I am jealous of all these posters getting seedlings because I would love to have one or two more of these plants. Mayalena I think you even offered me a seedling at last year's swap, which I didn't take and now I regret it! :) I also love the cloud of white flowers which attract zillions of pollinators late in the season. So odd that we have such different experiences with the same plant sometimes!

I haven't ruled the inside job out just yet. Though there's been 2 weeks since the last heist was pulled. I'm suspicious about the back corner under the bench. Now I have to make time and get down under there and lift a board or two and see if I can find tunneling. In between the two robberies, I did construct an exact fitting screen door made of hardware cloth. But I got lazy the other day and used the window screen instead.

Someone on a different forum suggested I go out at night to see if whatever is eating my echinacea leaves is a "night-time" eater and sure enough, I saw something. Can someone tell me what this is and how I get rid of it?