Borax has been used as an insecticide for over half a century. Read more at wikipedia: The primary use of borax for the eradication of mites is for soaking clothes and household objects. It can take 8 hours for clothes, bed linen, and other objects to be completely cleared of mites. Borax is also added while washing clothes for its toxic properties against mites. Borax is similar to boric acid. The main difference is that borax is not generally a contact killer for mites where boric acid is. Borax makes for good poison that is eaten.