WSU Extension

Pestsense

Widow spiders

(revision date: 1/11/2019)


Use Integrated Pest Management (IPM) for successful pest management.

Biology
The western black widow (Latrodectus hesperus) female is a velvety jet black with two reddish markings on the underside of their abdomen resembling an hourglass. Males and immatures are striped with white and yellow. Adult female black widows are about 1 1/2 inches in diameter including legs and are commonly found in firewood, old lumber, dry crawl spaces, outbuildings, rock piles, or hay bales. The bite of the adult female is more toxic than that of juveniles or males. However, black widows are shy spiders and reluctantly bite only when bothered. If bitten by a suspected black widow spider, seek medical attention. Also, bring the spider to an expert for correct identification. For more information, see the following publication: Common Spiders of Washington EM113E at http://pubs.wsu.edu..
Management Options

Non-Chemical Management
  • Because most spiders are occasional to frequent visitors to our living space, we must make special efforts not to make it easy for them to gain access. For example, decreasing space in door thresholds, securing window screens and using any other measures to “bug-proof” the home would help eliminate entrance pathways for spiders. Many spiders are brought in with firewood, so collect wood with gloves and inspect wood thoroughly for their presence and carefully remove them.
  • Use of mechanical devices such as fly swatters, shop vacs, brooms, etc. will help eliminate spiders.
Select non-chemical management options as your first choice!

Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

Pesticides are a temporary fix unless efforts are made to prevent their entry into the house. Spraying spiders of this sort outdoors is not usually advised and extremely temporary in nature unless performed by a pest control company on a regular basis.

Images
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Caption: Black widow
Photo by: Roger Akre