A world-renowned toxicology physician who worked at University of Southern California Medical Center estimates that most spider bites in California referred to him were actually the work of other arthropods and that 60% of "brown recluse spider bite" diagnoses came from areas where no Loxosceles spiders were known to exist. Nationwide, some "brown recluse bites" were subsequently correctly diagnosed as Staphylococcus infection, Streptococcus ("flesh-eating bacteria") infection, Lyme disease, herpes simplex, diabetic ulcer, or bites from bedbugs, mites, ticks, small wasps, biting flies, or other spiders.
In addition, in one case where the offending spider was killed in the act of biting, a Californian doctor misidentified the spider as a brown recluse even though the spider had eight eyes, stripes on the cephalothorax, a patterned abdomen, and spines on the legs. In any event, 90% of all brown recluse bites in the Midwest heal without severe problems and millions of people have lived there for years without experiencing bites.