Dark gray form of the clematis blister
beetle. Photograph courtesy of Ginny Sawyer. I thought last year would be the end of the carnage in my yard, never to happen again. Overnight, blister beetles stripped an entire clematis vine. They also ate up an Anemone Hupehensis ‘September Charm” in the middle of a shade garden and didn't touch any other specimens. Tried diatomaceous earth which didn’t work very well so I reluctantly resorted to some chemical insect spray. I thought I had eliminated them and the plants started to recover, but the beetles came back two weeks later chewing on both the same plants. Little did I know that this attack was related to the number of grasshoppers I had the year before! I had contacted Dr. Whitney Cranshaw, Emeritus Professor of entomology at Colorado State University and he wrote back: "I suspect the blister beetle involved is the "clematis blister beetle." He recently wrote a sheet on this at: https://webdoc.agsci.colostate.edu/bspm/arthropodsofcolorado/Clematisblisterbeetle.pdf Some interesting highlights from Dr. Cranshaw's paper about the clematis blister beetle:
Why are they called blister beetles? Because they produce a highly toxic compound called Cantharidin which can irritate the skin and produce blisters so be careful removing them. See Dr. Cranshaw's paper for more information about controlling them in your garden. This year they're back again, although I was carefully watching my clematis vine to catch them early. Early application of spinosad did the trick. Here is one of the villains: |