Welcome to the crowd! You're part of approximately 75% of the population who prefers tradition over innovation. I just happen to be one among the 25% who prefers thinking out of the box. If it weren't for the few, the majority would not enjoy the progress of inventions and the learning gained...
It would have to soak through the skin. Perhaps applying something like MSM (methylsulfonylmethane)/DMSO after applying the boric acid could chase it through the skin.
I'm wondering if anyone has tried boric acid for mites. It basically breaks down the exoskeleton of arthropods (insects, mites, spiders, etc.) upon contact, and is harmless to mammals, provided the acidity is not strong enough to cause an acid burn. It is sometimes used for antibacterial...