Navigation Links
Are brown widows displacing black widow spiders around southern California homes?

Brown widow spiders are relatively new to North America, where they were first documented in Florida in 1935, and even newer to southern California, where they were only recently discovered in 2003. However, in the last decade they have been so successful that they may be displacing native black widow spiders. If so, the overall danger to homeowners may decrease because brown widow spider bites are less toxic than those of native western black widow spiders.

In "The Prevalence of Brown Widow and Black Widow Spiders (Araneae: Theridiidae) in Urban Southern California," (DOI: a soon-to-be-released article in the July issue of the Journal of Medical Entomology, the authors describe the results of their efforts to document the presence of brown widows in southern California by performing timed searches in various habitats, such as urban properties, agricultural lands, developed parks, and undeveloped natural areas. They also included the native western black widow spider to compare the abundance and habitat selection of the two species.

"The brown widows really burst on to the scene in a very short time, and we found brown widows in many habitats where we expected to find black widows," said corresponding author Richard Vetter (University of California, Riverside). "There may be some competition where brown widows are displacing black widows because there is some habitat overlap. There are also places where only brown widows were able to make homes, but in other habitats the black widows still predominate."

After collecting data at 72 sites, which involved 96.8 hours of collecting, the authors found 20 times as many brown widows than black widows outside homes, especially under outdoor tables and chairs, and in tiny spaces in walls, fences and other objects. Neither spider is found in the living space of houses.

"Homeowners would benefit to know about the hiding places of brown widows, displaying care when placing their hands in nooks and crannies," the authors conclude. However, they should also keep in mind that even if the chances of being bitten do increase, the dangers are lessened because the brown widow bite is less toxic than that of the black widow.


Contact: Richard Vetter
Entomological Society of America

Related biology news :

1. Chemical fingerprinting tracks the travels of little brown bats
2. Mesquite trees displacing Southwestern grasslands
3. Black flies may have a purpose after all
4. Wiley-Blackwell launches new open-access journal: Food Science & Nutrition
5. Black brant geese show lifetime relationship good for goose and gander
6. Flying jewels spell death for baby spiders
7. Crabs, insects and spiders vulnerable to oil spill, but also resilient
8. Velvet spiders emerge from underground in new cybertaxonomic monograph
9. Vampire jumping spiders identify victims by their antennae
10. New paper examines poison resistance in snakes around the world
11. New data suggests interferon-free therapy around the corner for HCV patients
Post Your Comments:
(Date:6/16/2016)... FRANCISCO , June 16, 2016 ... size is expected to reach USD 1.83 ... by Grand View Research, Inc. Technological proliferation and ... banking applications are expected to drive the market ... ) , The development of advanced ...
(Date:6/9/2016)... June 9, 2016 Paris ... Teleste,s video security solution to ensure the safety of people ... during the major tournament Teleste, an international ... and services, announced today that its video security solution will ... to back up public safety across the country. The system ...
(Date:6/2/2016)... The Department of Transport Management (DOTM) of ... Dollar project, for the , Supply and Delivery ... IT Infrastructure , to Decatur ... Identity Management Solutions. Numerous renowned international vendors participated in the ... was selected for the most compliant and innovative solution. The ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... WA (PRWEB) , ... June 23, 2016 , ... ... announces the release of its second eBook, “Clinical Trials Patient Recruitment and Retention ... recruitment and retention in this eBook by providing practical tips, tools, and strategies ...
(Date:6/23/2016)... June 23, 2016   Boston Biomedical , ... compounds designed to target cancer stemness pathways, announced ... granted Orphan Drug Designation from the U.S. Food ... gastric cancer, including gastroesophageal junction (GEJ) cancer. Napabucasin ... to inhibit cancer stemness pathways by targeting STAT3, ...
(Date:6/23/2016)... 2016 A person commits a crime, and the ... track the criminal down. An outbreak of foodborne ... Administration (FDA) uses DNA evidence to track down the bacteria ... far-fetched? It,s not. The FDA has increasingly used a complex, ... foodborne illnesses. Put as simply as possible, whole genome sequencing ...
(Date:6/23/2016)... ... June 23, 2016 , ... ... and Mold) microbial test has received AOAC Research Institute approval 061601. , “This ... introduced last year,” stated Bob Salter, Vice President of Regulatory and Industrial Affairs. ...
Breaking Biology Technology: