Black beetles ate my Rudbeckia flowers
Last summer tiny black beetles ate the flower buds off my blackeyed susans. By the end of the summer the some of the plants had died off completely. Last year I shook the buds over a bucket of plant oil to knock the bugs off to kill them. How do I keep the beetles from returning?
Doug says you may not be able to stop them from returning. But you can dust with diatomaceous earth to stop them from establishing themselves. If the DE doesn't stop them, dust the plants with Rotenone but do read the label on both - while they are effective, they can both create other issues for you.