1 - please read thru my post here:
How Effective are Seabuckthorn Capsules by themselves
I also have not uncovered anything indicating that SBO actually kills the mites. It's still a good product for skin, imho, but not for that reason.
2 - Borax/boric acid is an insecticide and anti-fungal amongst other things.
Borax - Wikipedia, the free encyclopedia
"Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid...Borax has a wide variety of uses. It is a component of many detergents, cosmetics, and enamel glazes. It is also used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound for fiberglass, as an insecticide, as a flux in metallurgy, and as a precursor for other boron compounds."
Don't get the powder in your eyes, its a dessicant. it works on insects by dehydrating them and cutting up their exoskeletons. It's of limited use with fleas but is supposed to be great for reducing cockroach populations.
Uses of borates:
Rio Tinto Borax : About Borates : Borates in Use
Look toward the bottom of the above page for:
"For Insecticide/Fungicide formulations
For Algaecide/Insecticide/Pesticide formulation
Borax Pentahydrate for Algaecide formulations
Pesticidal Active Ingredient "
It also has other properties for bathing:
Borax Powder Profile
"Cosmetic Use Borax is found in creams, lotions, shampoos, gels, bath salts, and bath bombs. It is an emulsifier, preservative, cleansing agent, and a buffering agent. Commonly used in bath salts, borax has the ability to soften the water, and suspend soap particles in the bathwater. The result is soft, clean, and healthy skin, which is not clogged by the residue of soap particles. When used in collaboration with citric acid in bath bomb or bath salt recipes, the product will produce a fizzing action. It also forms bath or body gel, when mixed with water and guar gum. In summary, Borax has the following uses for body care products:
- Water softener
- Particle suspension
- Buffering agent
- Fizzing action (when used with citric acid)
To use: Simply mix borax into the water portion of your recipe, and heat to a temperature of above 75 °C. Stir until fully dissolved, and then incorporate into your recipe.
Not to be ingested, large doses may be fatal. May cause irritation if exposed to the skin, eyes, or if inhaled. Handle with caution, and keep away from children and pets."
While I don't find, say, an MDs site specifically recommending borax baths, it is common practice as a bath or cleaner for scabies infestation and bed bugs and various creppy crawlies. Technically, you can get tested for excess demodex mites I believe, like a skin s****e test and then a Dr could prescribe an insecticide. But all humans have some demodex mites. Allergic reactions or overpopulation are believed to be causes of or contributors to some skin problems.