Is the root of a perennial plant growing in northern Africa. It contains a volatile oil, resin, and pyrethrin, and is similar in nature to black pepper. It is a local irritant. It is a specific for bed-bugs, and the best remedy ever used for their destruction (Stiles). The pyrethrum powder, pyrethrum roseum, is dusted wherever the bugs exist, and they are exterminated. It should be used once every week for three weeks, in order to kill any bugs that may have hatched out in the meantime.