Black widow spiders are found in Oregon. Understanding their presence, how to identify them, and where they typically reside can help residents co-exist safely with these arachnids.
Black Widow Presence in Oregon
The primary black widow species found in Oregon is the Western Black Widow (Latrodectus hesperus). This species is part of a larger group of widow spiders distributed across western North America.
Western Black Widows are most common in southwestern and eastern Oregon. They are less prevalent in northwestern Oregon but can be found there, particularly on rocky, south-facing slopes without dense tree cover. They may also be encountered inside homes, especially within the Willamette Valley, and are found in areas protected from rain, including Douglas, Lane, and Josephine counties.
Identifying Oregon’s Black Widows
Proper identification of black widow spiders in Oregon is important for safety.
The adult female Western Black Widow is typically shiny black with a rounded, bulbous abdomen. She measures about 7 to 16 millimeters (0.27 to 0.62 inches) in body length. A distinctive red or orange hourglass-shaped marking is usually visible on the underside of her abdomen, though this marking can sometimes appear as two unconnected spots or be less defined. As females age, their color may shift to a dark brown.
Male Western Black Widows are considerably smaller than females, typically measuring half their size or about 3 to 6 millimeters (0.12 to 0.24 inches). Their coloration differs, often being sandy brown or a lighter brown-gray with lighter stripes on their abdomen. While males may also possess a red or orange hourglass or similar markings, they are generally considered harmless to humans. Juvenile spiders, both male and female, can have pale or white stripes and may be brown, white, gray, or black, developing darker coloration as they mature.
Where Black Widows Live and How to Avoid Them
Black widows prefer to build their irregular, messy webs in dark, secluded, and undisturbed locations.
Outdoors, common habitats include woodpiles, rubble piles, and areas under stones or house eaves. They can also be found in meter and sprinkler valve boxes, hollow tree stumps, burrows, and dense yard debris like tall grass.
Indoors, these spiders frequently inhabit sheds, garages, basements, crawl spaces, and attics. They seek out quiet corners, areas behind furniture, and cluttered spaces such as those containing cardboard boxes or rarely worn shoes.
To minimize encounters, it is advisable to wear gloves when handling wood or cleaning out sheds and to shake out shoes or clothing before use. Reducing clutter in and around the home, sealing cracks in foundations, windows, and doors, and regularly removing spider webs from exterior structures can also help deter them.