The homeopathic remedy Tarentula cubensis (Cuban tarantula), used in homeopathy to treat abscesses with burning pains, gangrene, septicaemia, toxaemia, has been grouped by homeopathic authorities with either the mygalomorph or wolf spiders. The original specimen used for preparation of the mother tincture was decomposed, leaving the spider's exact identity in doubt. Investigation of the toxicological and clinical literature, compared with homeopathic materia medica, reveals the brown spider, Loxosceles laeta, indigenous to South America but present also in Mid- and North America, as a more likely source. Venoms of spiders of the genus Loxosceles cause severe necrotic arachnidism, as well as, in some cases, a life-threatening systemic reaction marked by renal failure, disseminated intravascular coagulation, thrombocytopeania, coma and convulsions.