The two medically important spiders in the United States are the black widow and the brown recluse; most other spiders are harmless to people, and deaths from spider bites are very rare. The CDC’s guidance on venomous spiders names these two as the venomous spiders to know, and notes that bites can cause effects from minor to severe. Saela Pest Control, a residential and commercial pest control company based in Orem, Utah, offers spider control for homes and businesses. This guide explains how to recognize each spider, where it hides, what a bite can do and when to get help.
Black Widow
Black widows are shiny black spiders with a red or orange hourglass-shaped mark on the underside of a large, round abdomen. UC IPM’s guide to spiders describes them living in dark, dry, sheltered and relatively undisturbed places such as woodpiles and garages, where they build an irregular, tough, sticky cobweb. The CDC adds eaves and fences, and notes that most bites happen when a spider is trapped or touched rather than because it attacks. UC IPM says death from a black widow bite is very unlikely, and medical treatment can relieve the symptoms.
Black widow venom causes pain at the bite that then spreads, and the CDC lists these possible effects of a venomous spider bite:
- Pain radiating from the bite
- Muscle pain or muscle cramping
- Nausea and vomiting
- In more serious cases, difficulty breathing
If you think someone has been bitten by a black widow, wash the bite with soap and water, apply a cold compress and seek medical attention right away, as the CDC advises. If you can do it safely, keep the spider for identification, which UC IPM also recommends.
Brown Recluse
The brown recluse is a brown spider about the size of a quarter, including its legs, with a dark violin-shaped mark on its back and six eyes arranged in pairs instead of the usual eight. University of Kentucky entomologists report that it lives throughout the south central and Midwestern United States, and UC IPM notes it does not have breeding populations in California. Indoors it hides in crevices, corners and wall-floor junctions, especially behind clutter and stored items, and in shoes, clothing, closets and boxes.
Most brown recluse bites happen when a spider is accidentally trapped against bare skin, for example while putting on a shoe, glove or piece of clothing. According to the University of Kentucky, the bite is often painless at first, and most bites stay localized and heal within three weeks without serious complications.
According to the CDC and the University of Kentucky, possible effects of a brown recluse bite include:
- Little or no pain at first
- Reddish to purplish color or a blister at the bite
- Fever, chills or sweating
- Headache
- Nausea and vomiting
- In uncommon cases, a slow-healing wound that needs medical care
If you suspect a brown recluse bite, the University of Kentucky advises applying ice, elevating the area and seeking medical attention. Because brown recluses hide in clutter and some, especially adult females, avoid sticky traps, it also recommends professional spider control along with reducing clutter and sealing the cracks where the spiders shelter. Our guide to what to do if you’re bitten by a spider covers first steps in more detail.
Wolf spiders are often mistaken for brown recluses because they are large and brown, but UC IPM describes them as active ground hunters that are generally not of medical importance; their bite can hurt, and most spiders are beneficial predators whose jaws are too small to bite people at all. Because identification decides the right response, Saela’s protocols come from Dennis Weiss, Saela’s board-certified entomologist, who holds the Entomological Society of America’s Board Certified Entomologist credential.
Every Saela plan includes a 50+ point property inspection covering nesting sites, attics and basements, which are the places these spiders hide. In a February 2024 Google review, Paul Rugg wrote that his Saela technician “did a great inspection and noticed some areas that needed attention.” If you’ve seen a spider you think is a black widow or brown recluse, book a call to have it identified.
Who wrote this article?
Devin Hutchings (Marketing Director at Saela Pest Control) wrote this article.
Devin leads Saela’s marketing and growth strategy. He brings more than 15 years of marketing experience across Uber, C.R. England, Lugg, and Neighbor. His background spans customer acquisition, retention, and developing marketing channels for service businesses and consumer marketplaces.
