They should be fine. Did you cut off the rotten part. The bugs are eating what's rotted, but more than likely they won't touch the healthy tissue. If you cut off the rotted tissue and discard it, you shouldn't have a problem.

I'm in zone 7a and I leave my cannas out all year round. Of course they die back in the winter. Yours are probably safe now if temps are above freezing. But they wont' really begin to grow well until temps get really warm. They like it hot.

In the fall, you'll want to dig them and bring them in after a killing frost. Just whack off the stalks and store again. If you want to bring them in before a frost, that's fine too. It won't hurt, but most people want to enjoy them as long as they can.