are being killed off in the U.S. The culprits are actually their cousins: brown widow spiders. Though the reason behind the killings is unknown, a new study suggests. Brown widow spiders are believed to have originated in either Africa or South America but they have spread all over the world. They were first seen in
Florida in 1935. Since then, they have spread all over the southern states as well as
California. According to , both the brown and black widow spiders are from the same genus, which is made up of five species. Three of those species: northern black widows, southern black widows, and western black widows are all from North America. The difference with the cousins is black widow spider bites are painful and sometimes lethal to people, but bits from brown widow spiders are rarely harmful. As for the brown widow spiders killing their cousins, scientists have yet to figure out why. There’s no competing for resources and no other spider species have been impacted by the brown widow spiders. Read more via .