Read about adding mustard to the mop.

A half-inch trowel for months? That's wild.

Heard lots of devs saying the same thing lately.

Ever notice how lots of good processes, like pickling or compost, have a funky middle stage?

That part about the gunk sloughing off is what made me think of something. The oil might work by smothering the mites, but it also traps heat against the skin. On a hot day, that could actually cook the skin and cause a burn or blister. I've seen similar things with other animals. Maybe try something like petroleum jelly instead. It still smothers them but won't heat up as much in the sun. Just a thought, because a bad burn on top of mites would be awful.