For two years now they have been decimating my wintersown swamp milkweed. One good thing about the last nasty winter is they didn't survive it! Whether they were eggs or pupa, they are gone! (Like my rhododendron), but that's another story!
Hi Wendy: So sorry to hear about your infestation. We have not seen this beetle around here but I'll be on the lookout for it. I treat all beetles etc. the same way. It seems to me they all pupate in the earth, so in early spring I cover the area around the plants with plastic. That way, when they emerge they are trapped under the plastic and scorching sun and they are done. I use it to control red lily beetles, cucumber beetles, and weevils. You can hand-pick the ones that survive. I haven't sprung for a rhodo. yet. The ones that are hardy in this zone are relatively new, so I'll see how they do. What a shame to lose yours!!