Spider identification

External Links

The World Spider Catalog

This routinely-updated website provides a current listing of the taxonomic names of every described spider (over 41,000) in the world. It gives the entire taxonomic history of every species so a user can determine older, outdated names.


This website provides a wealth of images of arthropods of all kinds. It is maintained by people who have extensive experience, and the identifications are typically accurate. Using this site can be very useful for viewing additional images of a particular species in order to get a feel for the variation one might see within one species. However, be aware that specimens may be presented from a wide geographic area, so the color variation seen on the website may be much broader than one would ever see in Central Valley spiders in California.

Identifying brown widow spiders

This document shows how to distinguish between the brown widow spider, Latrodectus geometricus, and the western black widow spider, Latrodectus hesperus. Although these two spiders look very different as adult females, the immature stages of the western black widow are routinely confused for the striped pattern of the brown widow. As of 2010, brown widows have not been found in California's Central Valley and have never been found in grapes.