Answer: I think the bark is sloughing off on its own due to a systemic problem rather than being torn off by a critter. I don't know if it is caused by insects (look for tiny holes where the foam is being produced), or if it is a fungal or bacterial infection. I'm not sure there's much you can do, even if you find the cause because it has already invaded the tree. Your cooperative extension might be able to help, or at least know whether there is some local problem with mimosa trees. Contact the extension office at 3003 S Loop W # 220 Houston, TX 77054, (713) 349-0880. Best wishes with your tree!
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