The Black Widow spider, a member of the genus Latrodectus, is recognized worldwide for its potent venom and distinctive appearance. These arachnids have garnered a widespread reputation, making them one of the most well-known venomous spiders across the globe. Their existence serves as a reminder for residents in areas where they are common to maintain awareness and caution.
Presence and Range in Oregon
The Western Black Widow (Latrodectus hesperus) is a resident species in Oregon. This species is distributed throughout the western regions of North America, typically found in the state’s drier environments, including areas in Eastern and Southern Oregon.
These spiders favor dark, sheltered locations, building their webs near the ground in places like woodpiles, under stones, or in debris. Residents commonly encounter them in man-made structures such as sheds, garages, meter boxes, and cluttered basements.
Identifying the Black Widow
Visual identification of the Western Black Widow female is straightforward. The adult female is generally 14 to 16 millimeters long and possesses a shiny, black, globular abdomen. The most recognizable feature is a bright red, orange, or sometimes yellow hourglass-shaped marking located on the underside of her abdomen.
The hourglass marking can vary, sometimes presenting as two separate spots instead of a complete figure. In contrast, the male is significantly smaller, often half the size of the female, and is usually a lighter color, such as beige or sandy brown, with lighter striping.
The webs they construct are messy, irregular, and unorganized, unlike the geometric webs of orb-weavers. These sticky, haphazard webs are usually spun in dark, protected crevices near the ground.
Understanding the Bite and Symptoms
Only the female Western Black Widow is medically significant because her fangs can penetrate human skin and deliver sufficient venom. The venom contains alpha-latrotoxin, a neurotoxin that affects the nervous system. A bite may initially feel like a sharp pinprick, followed by localized swelling and redness.
Systemic symptoms, known as latrodectism, can develop within an hour and spread throughout the body. These include severe muscle cramps and stiffness, often felt in the abdomen or chest, along with nausea, vomiting, profuse sweating, and elevated blood pressure. If a bite is suspected, clean the area and apply a cold compress, but immediate medical attention is necessary, especially for children or the elderly.
Prevention and Removal
Minimizing encounters relies on managing their preferred habitats both indoors and outdoors. Seal potential entry points, such as cracks in the foundation, gaps around windows, and utility line openings, to prevent them from entering structures.
The spiders are attracted to clutter, so regularly clearing woodpiles, storing firewood away from the house, and removing debris and trash around the yard are helpful steps. Inside the home, reducing clutter in storage areas like basements, attics, and garages eliminates secluded hiding spots.
When working outdoors, particularly when disturbing wood, rocks, or gardening, wearing heavy gloves is an effective precaution against accidental bites. If a spider or its silk-wrapped egg sac is found indoors, use a vacuum cleaner for safe removal, followed by disposal of the bag outside.