There were many adults and larvae of this species in bluebird nesting boxes that were strung from a clothesline under some willow trees. They were suspected of infesting the nest boxes and driving out the bluebirds. I can't imagine a chrysomelid doing anything like that, but even though they were near willows, I don't understand why so many, and especially the larvae, would be in the nest boxes when they weren't even attached to the trees. If it was just adults, I'd think that they'd overwintered in the boxes, but the larvae don't make any sense to me. I suspect that they're Chrysomela scripta or something similar, but am not sure. Any help would be appreciated.