Expert Wants Your Brown Recluse Spiders

Published in the Contra Costa Times on July 7, 2007

Expert Wants Your Brown Recluse Spiders

THE MASTER GARDENER article on brown recluse spiders has generated quite a bit of heated debate throughout the area, with many respondents certain that the spiders are here and are a problem.

In an effort to find out for certain, Dr. Richard Vetter of UC Riverside's Department of Entomology, has generously offered to positively identify any spider suspected of being a brown recluse.

If you find a spider that you believe fits the description, please capture it carefully in a small container with a tight lid, and bring it to the Master Gardener office at 75 Santa Barbara Road, second floor, in Pleasant Hill, 8 a.m. to 5 p.m., week days.

The office is directly behind the library on Oak Park. Directions can be found at http://cecontracosta.ucdavis.edu/. Please label the container with the address where the spider was found, and include your phone number so that you can be notified when the spider is correctly identified. The following information was provided by Vetter.

Description of a brown recluse spider:

Six eyes arranged in pairs, with one pair in front and a pair on either side. (Most spiders have eight eyes.)
A dark violin shape on the cephalothorax (the portion of the body to which the legs attach).
Uniformly light-colored legs, no stripes, no bands.
Uniformly colored abdomen which can vary from cream to dark brown depending on what it has eaten. However, it will never have two colors of pigment at the same time.
No spines on the legs, only fine hairs.
Recluses make small retreat webs behind objects, never out in the open.
It is about 3/8-inch in body length. If the spider body is larger than 1/2-inch, it is not a brown recluse.

Bethallyn Black is director of the Contra Costa Master Gardeners, a program associated with the University of California Cooperative Extension and supported by Contra Costa County. Reach her at bblack@ucdavis.edu, or 925-646-6586. Send general questions for the Master Gardener to mgcontracosta@ucdavis.edu.