Lady friend had scabbies she said and impossible to remove all. I had mentioned Perma-Guard for garden which bugs can't defend against. She had idea to try on and called that company. They said it can do so she did and verry happy.
It's a powder fine like talc powder but is a fossil powder shell from anchient fresh water lakes. Not expensive but far more than you can use. Ask that co. where best for you so low cost shipping.
Acts like glass on bugs shell and bug dries out in 2 days. Safe in or on us since so small but you must use food grade type.
Good luck Rich,