Moth-proof garment bags?

I'm battling a casemaking clothing moth infestation in Massachusetts. Has anyone found garment bags for hangers that are truly moth-proof? Everything that I have found has a large (e.g., 1.0" x 0.5") hole for the hangers, plus they are all flimsy garbage. I don't mind paying, but I could use some advice about where to go and what to buy. Thank you.