Black widow spiders are venomous arachnids, known for their distinctive appearance and potent neurotoxin. Belonging to the genus Latrodectus, their bites can cause uncomfortable symptoms. Understanding their presence and characteristics can help alleviate apprehension.
Presence and Distribution in Oregon
Black widow spiders are found in Oregon, with the Western Black Widow (Latrodectus hesperus) being the most common species. This spider thrives across western North America, including various parts of Oregon. They are more frequently observed in the drier, warmer areas of southwestern and eastern Oregon, but can also be found in northwestern Oregon, particularly on rocky, treeless, south-facing slopes.
These spiders prefer dark, secluded, and undisturbed environments, building their webs close to the ground. Common outdoor habitats include woodpiles, under stones, in sheds, and within meter and sprinkler valve boxes. Indoors, they may inhabit basements, garages, and other cluttered areas. While occasionally found inside homes, especially in the Willamette Valley, they generally seek shelter in less trafficked spaces.
Identifying Black Widows
Identifying a black widow spider primarily involves recognizing the female, as she is larger and has the most distinctive markings. Adult female Western Black Widows are typically shiny black, measuring about 14 to 16 millimeters (approximately half an inch) in body length. Their most recognizable feature is a prominent red or orange hourglass-shaped marking on the underside of their rounded abdomen.
The hourglass appearance can vary, sometimes appearing as two separate triangles, unconnected dots, or being faded. Female black widows often hang upside down in their webs. Their webs are irregular, tangled, strong, and sticky, typically constructed in dark crevices or corners near ground level.
Male black widows are considerably smaller than females, usually lighter in color, ranging from tan to light brown, with different abdominal patterns. Immature spiders also exhibit varying coloration, often appearing with gray, brown, or white patterns that darken as they mature.
Characteristics of a Black Widow Bite
A black widow spider bite may initially feel like a slight pinprick or go unnoticed. Within 15 minutes to an hour, a dull, localized pain typically develops around the bite site, which can then spread. This pain may intensify and radiate, often leading to severe muscle cramps and spasms, particularly in the abdomen, back, or chest, depending on the bite location.
Other symptoms can include nausea, vomiting, sweating, headache, and elevated blood pressure. While a black widow bite can be painful and cause systemic symptoms, fatalities are rare in healthy adults. However, young children, the elderly, and individuals with compromised immune systems may experience more severe reactions. Bites generally occur when the spider feels threatened or is accidentally disturbed, as they are not inherently aggressive.