My butterfly bushes have bark falling off the branches
Inspecting the butterfly bushes after this winter, the bark on the branches that are coming out of the ground are all loose - like they will fall off and leave the branches "bare." There was mulch around the roots over the winter. Will this harm the bush? Can insects hurt the bush? Are we losing our bushes? What can we do to protect the bushes? I did prune the bushes in the fall after they had bloomed.
This article has some general information on butterfly bushes. https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-pruning-how-to-prune-a-butterfly-bush.htm
Also, this article will tell you a bit more about peeling bark: https://www.gardeningknowhow.com/ornamental/trees/tgen/peeling-bark-on-trees.htm
Finally, assuming that you have a Buddleia (there are several plants that go by the common name of butterfly bush,) that peeling bark is natural as the plant grows older.