Spiders There are over 35,000 described species of spiders worldwide, with about 3,000 occurring in North America. Many species of spiders are household pests. Wherever their food is available, spiders are likely to be found. All spiders are predators, feeding mainly on insects and other small arthropods. In the United States only two spider groups are considered dangerous to man, the widow spiders (Latrodectus spp.) and the recluse spiders (Loxosceles spp.). Both of these groups are composed of several species. It’s unfortunate that many cases of the well-known bacterial infection MRSA (methicillin-resistant Staphylococcus aureus) are still being attributed to spider bites, primarily the brown recluse, by the medical community.