Are There Black Widows in California?

Are There Black Widows in California
Picture of Israel Alvarez
Israel Alvarez

Owner @ Insight Pest Management

Table of Contents

Waking up to a spider navigating your bed sheets or crawling across your window sill in the morning is enough to make many people uneasy. While most spider species are harmless to humans, their presence often evokes many different emotions.

However, Southern California is home to L. hesperus, also known as the native Western black widow. This well-known spider species is potentially dangerous for those sensitive to its strong venom. It is then important for all California residents to be able to identify this spider species and use care when finding one in the home.

Key takeaways

  • L. hesperus, or the Western black widow spider, is native to Southern California.
  • The female Western black widow spider has a red hourglass shape on the lower abdomen, and a bite from the female can be dangerous to those sensitive to their venom. The male is smaller in size and is harmless to humans.
  • Female black widow spiders bite when threatened or when protecting an egg sac. Symptoms of a black widow spider bite can include redness and swelling, headaches, nausea and vomiting, severe muscle cramping, difficulty breathing, and, in rare cases, a bite can be fatal.
  • Southern California residents are most likely to see a black widow inside the home during winter when the spiders seek dry, dark shelter.

Black widow spider in California

There are over 3,000 spider species native to North America. However, there are only two native species known to be dangerous to humans. These are the brown recluse and the black widow. Unfortunately, the Western black widow calls Southern California home, meaning residents should always be aware of the potential for black widow bites. In addition, Southern California is also home to an invasive species, the brown widow spider, which can also deliver a painful and potentially dangerous bite.

What are black widow spiders?

Black widows are several species of arachnids belonging to the genus Latrodectus. They are most known for the females’ unique hourglass-shaped marking on the abdomen. Three species of black widow spiders are native to North America:

  • Southern Black widow (L. mactans)
  • Northern black widow (L. various)
  • Western black widow spider (L. hesperus)


While the Western black widow is native to California, southern black widows have also been found in our area. In addition, the brown widow spider, closely related to the black widow, is an invasive spider species that made its way into Southern California in 2003 when it was collected in Torrance.

What do black widow spiders look like?

Black widows are smooth, black spiders. Females measure around ½ inch in diameter and have a leg span of 1 ½ inches. The females have a red hourglass shape on their lower abdomen. Male black widows are smaller, with a ¼ inch diameter and a leg span of ½ inch. Males and juvenile widows are tan in color with white stripes and red dots on the abdomen.

Where do they hide?

Black widows prefer to live outside in areas that provide shelter from the elements, such as woodpiles or crevices in covered patios or fencing. They prefer dark places, so if they do move indoors, they will often take residence in crawlspaces, closets, attics, garages, and basements. They make messy webs that include a horizontal sheet of silk covered by overhanging vertical threads that help trap prey. You will likely find webs between an item and the wall, under furniture, or in dark corners near the floor. If you suspect black widows inside your home, professional pest control and spider control can eliminate them and help prevent re-entry in the future.

How does the black widow survive?

The black widow survives by feeding on other insects trapped within their web and this is why they prefer living outside where the insect population is often thriving. When they are found inside, chances are their web may still be outdoors, around the perimeter of your home, such as in doorways or vents. They hide throughout the day to avoid potential predators but emerge at night and wait for insects to become trapped in their webs. While they are venomous and will bite when threatened, black widows are generally shy and do everything to avoid confrontation in order to survive.

Spider prevention tips

Black widows are most comfortable living outdoors, but they will venture inside to escape inclement weather or follow a food source. These prevention tips can help make your home less appealing to the black widow and reduce your risk of adding a new arachnid roommate.

  • Inspect windows and doors around your home, using caulk to seal any holes and ensure all weather stripping is in good condition.
  • Make sure all exterior doors have sweeps installed to prevent spiders and other insects from entering.
  • Make sure all screens are in good condition and free from holes.
  • Seal any cracks along your foundation, as well as crevices around pipes.
  • Keep your yard well maintained and mowed on a regular basis.
  • Keep plants and vegetation away from your home’s foundation.
  • Keep wood or debris piles away from the foundation of your home.
  • Vacuum and dust your home regularly, using care to eliminate any spider webs.
  • Run a dehumidifier to reduce moisture in the home
  • Use yellow light bulbs or keep exterior lights off at night. This helps deter bugs that black widows feed on.

Keeping your California home free from black widows

Black widows are native to Southern California, so seeing one should not be a surprise. Following these tips, however, will help reduce the risk of this venomous spider moving inside your home and increasing your risk of a potential bite. Because this spider species is native to our area, use caution when working outdoors, such as when moving wood piles. While a black widow is timid and often runs from a threat, when grabbed or cornered, they are more likely to bite. If a black widow bites you or you suspect a spider bite, seek medical attention immediately.

When you need a helping hand

If you find a black widow in your home or want to take extra measures to ensure black widows do not enter your California home, the team at Insight Pest Management is here to help. Our technicians are experts in spider behavior. During an initial inspection, our technicians will not only locate and identify spiders inside but also look and address potential points of entry, helping to ensure they don’t become a concern again.

To learn more about how we can help keep you spider-free, schedule a free evaluation today.

Serving all of Ventura County

Locally owned and family operated, we are a top-rated pest and bug control company that uses state-of-the-art equipment to help ensure that pests are located and eliminated. But it doesn’t stop there! Pest prevention is one of the most important parts of pest and bug control. 

Our expert technicians work to ensure that all potential pest entry points are sealed and offer routine treatment options to help ensure your home or business stays protected from future infestations. You don’t have to share your home or business with pests any longer! If you live in the Ventura County area, let the team at Insight Pest Management help you say goodbye to pests once and for all!

Contact us today to schedule a FREE evaluation!

Ventura County California Map