Recluse Spiders
The brown recluse spider (Loxosceles reclusa) is widely known for the potency of its venom.  While most bites cause only small, hard bumps that are slightly sore, disappearing in a few days, rare cases of serious medical problems have been associated with bites from these spiders.  The venom of other recluse spiders is thought to be less potent in humans bitten by them.  Species of recluse spiders found within the United States include: