What killed them? I lost some several years ago to sawfly larvae, they completely decimated the plants in 2 days, just as buds were starting to arise. That happened 2 years in a row, after that I started treating with systemic in spring and found 1 treatment was enough to protect them during the time the larvae emerge. Since then I've stopped using chemicals, but haven't had any problems since. I had grown Columbine for several years and had never seen them attacked like that, and now it seems to have stopped. It may have had something to do with several really mild winters we had during that time.
