
Scientist seeks samples of new spider species
Brown widow may move into Central California
brown widow pic
Scientists at UC Riverside say the brown widow spider may move into Central California this summer. Brown widows look similar to black widows but behave differently, mainly that they are not solitude like black widows. There can be hundreds in one area, like a barn or garage. Also their bite contains a much higher amount of venom than a black widow. - photo by Photo Contributed

A UC Riverside scientist is asking for the public’s help to track the distribution of brown widow spiders in California. Brown widows' range expanded rapidly in Southern California since their introduction in 2003, he said, and they may move northward this summer into Central California.

"The brown widow is spreading like wildfire," said UC Riverside urban entomologist Rick Vetter. "It takes over urban backyards; it's a very prolific pest. People find them by the hundreds in places where they haven't seen spiders before."



"I’ve gotten three females from Sacramento and three females from Washington (state)," Vetter said. "I’ve gotten no other spiders from those areas, so I don’t know if they will be another infestation area or not."




Vetter is asking the public to assist in his brown widow spider research by carefully following instructions for collecting and sending brown widow spider specimens to the university. Potential spider collectors should study the photos on his website at to learn the characteristics of brown widows. 





The brown widow poses less of a health threat than black widows, but Vetter said there are several reasons why people should be concerned about their potential northward migration. The typically larger number of spiders may cause homeowners to apply more pesticides, which could cause groundwater contamination.

Currently little is known about biological control of brown widow spiders. Vetter said the best way to control them is by going around with a flashlight at night and smashing the spiders with a shoe or other object.

Black widow spiders prefer low hangouts, but it is not yet known whether brown widows will adjust to higher posts in California. If the spiders take up residence in fruit orchards, for example, they could pose a problem for farm workers.


Brown widows could potentially congregate in agricultural shipping containers or packaging. There are still many things scientists don't know about brown widows.

"That's why we want to figure out where they are," Vetter said.