Of the more than 3,000 kinds of spiders in the United States, about 60 species have been implicated as causing medically significant bites to people. Many spiders are not capable of breaking the skin with their fangs while other species contain venom that causes no reaction. Spiders are usually very timid and will only bite in self-defense if mishandled, cornered, or injured. Even when they bite, spiders do not always inject venom. The severity of the reaction to a spider bite will differ among individuals.
Most spider bites are less painful than a bee sting.
Actual spider bites show two puncture marks although the wound is not always obvious. A rather typical reaction may involve localized reddening and various degrees of swelling, itching, and pain. Within a few hours a small red, blue, or black discoloration can develop around the bite site. The area may remain tender for a few days, and eventually a small sore can develop that soon begins healing. Accurate identification of any spider bite can only be made if the spider causing the bite is captured and identified.