Guide to Venomous Spiders in California That Bite Humans

Spiders That Bite in California

While the majority of spiders in California are harmless, there are a few spider species that can inflict painful and potentially dangerous bites. Spider bites are quite rare, but it is still good to know how to identify and avoid the spiders that can bite humans.

Black Widow Spider

The black widow spider (Latrodectus hesperus) is probably the most infamous and widely feared spider in California. Here are some key facts about this venomous spider:

• Identified by distinctive red hourglass shape on underside of abdomen
• Females are black and shiny, males are smaller and brown/tan
• Found throughout California in wood piles, tree stumps, sheds, garages
• Nocturnal spiders that build tangled webs
• Neurotoxic venom can cause muscle cramps, nausea, vomiting
• Bites are rare and rarely fatal, but medical attention recommended

Brown Recluse Spider

While not native to California, brown recluse spiders have been found in small isolated populations in parts of Southern California. Identifying features include:

• Light to medium brown in color with dark brown violin-shaped marking on cephalothorax
• Six equal sized eyes arranged in pairs
• Builds irregular webs in garages, attics, warehouses
• Venom destroys tissue leading to painful open wound
• See doctor promptly if bitten

Hobo Spider

The hobo spider (Eratigena agrestis) is in the funnel-web spider family and can be aggressive when threatened. Here are key facts:

• Large brown spider around 1-inch long
• Long legs with alternating dark and light bands
• Found in dark corners of homes, sheds, gardens
• Bites cause mild pain, redness and itching
• Rarely serious, but monitor for infection

Yellow Sac Spider

The yellow sac spider (Cheiracanthium inclusum) is one of the more common house spiders in California that occasionally bites humans. Identifying traits include:

• Yellow to pale green body color
• Dark brown/black mouthparts
• Front legs longer than hind legs
• Nocturnal hunter resting in silken retreats during day
• Bites cause mild stinging, swelling, redness

Signs of a Spider Bite

Here are some common symptoms that may indicate you have been bitten by one of the venomous spiders in California:

• Severe pain at the bite site
• Redness, swelling around bite mark
• Itching, tingling, burning sensation
• Two fang puncture marks visible
• Nausea, vomiting, fever, headaches
• Muscle cramps, spasms near bite area
• In some cases open wounds or tissue damage

Spider bites can be difficult to diagnose due to non-specific symptoms. Seek medical attention if you suspect a serious spider bite, especially if symptoms worsen or spread.

First Aid for Spider Bites

If you are bitten by a spider, here are some first aid tips while you wait for or get medical care:

• Wash bite area with soap and water to help reduce risk of infection
• Apply cold compress to relieve swelling and pain
• Elevate limb if bite is on arm or leg to slow venom spread
• Avoid squeezing bite to prevent spread of venom
• Capture spider safely if possible for identification
• Seek emergency care if severe symptoms like difficulty breathing

Over the counter pain medication, antihistamines and topical antibiotics can help manage mild symptoms. More serious bite symptoms may require antivenom, IV fluids, painkillers or hospitalization.

Preventing Spider Bites

You can take these proactive spider bite precautions when spending time in areas spiders may inhabit:

• Clear clutter in storage areas, corners that attract spiders
• Wear gloves and cover extremities in garden, when moving wood
• Inspect or shake out shoes, clothing before putting on
• Use insect repellent when hiking or in wooded areas
• Install screens on windows and doors to deter entry
• Seal cracks and crevices in home's foundation and walls
• Use a broom to remove webs to avoid direct contact

Spider Bite Treatment

Treatment for spider bites depends on the severity of symptoms but may include:

• Cleaning bite - Thoroughly flush area with soap and water.
• Ice pack - Apply ice wrapped in cloth to reduce swelling and pain.
• Elevation - Keep bite area raised above heart level.
• Pain medication - Over the counter NSAIDs like ibuprofen help relieve pain.
• Antihistamines - Allergy pills reduce itching caused by venom.
• Antibiotics - Prescribed if bite shows signs of infection.
• Antivenom - Given intravenously for severe systemic spider bite symptoms.
• Surgery - May be needed to clean out destroyed tissue from necrotic spider bites.

Monitor for worsening redness, pain and swelling and see a doctor promptly if you suspect a serious spider bite reaction. Call emergency services or get to an ER immediately if you have difficulty breathing, systemic symptoms or open wounds from a bite.

Common Myths and Facts About Spider Bites

There are some common misconceptions about spiders and spider bites. Here are some spider bite myths and corresponding facts:

Myth: All spider bites are dangerous

Fact: The vast majority of spiders have fangs too small or weak to penetrate human skin. Only a handful of spiders in California can cause medically significant bites.

Myth: Spider bites can happen easily in bed or chairs

Fact: Spiders do not seek out humans and prefer to avoid us. Bites almost always happen when handling spiders or walking into webs.

Myth: All spider bites cause nasty wounds

Fact: Only a few spider species have venom that destroys tissue. Most cause mild stinging similar to bee stings.

Myth: Daddy long legs spiders are the most venomous

Fact: Daddy long legs spiders have no venom and cannot bite through skin. Their small fangs are not a danger.

Myth: Spider bites lead to horrific flesh rotting

Fact: Necrotic lesions are rare and limited to brown recluse spiders. Seeking prompt medical care can prevent severity.

When to Seek Medical Care

Most spider bites can be treated at home with first aid and over the counter remedies. Seek prompt medical evaluation if you experience:

• Sudden severe pain spreading from bite site
• Nausea, fever, headaches or other systemic symptoms
• Red streaking from bite area indicating infection
• Large areas of redness, swelling and tender skin
• Open wounds or obvious tissue destruction
• Continued increase of pain beyond 24 hours
• Known bite from black widow, brown recluse or other highly venomous spider

Seeking timely medical care can help treat spider bite symptoms and prevent potential complications or serious effects from venom. Call 911 or emergency services if you have difficulty breathing, chest pain, loss of vision or rapid swelling.

Professional Pest Control

For severe spider infestations or populations of venomous spiders around your home, it is best to enlist professional pest control services. An experienced exterminator can:

• Properly identify venomous spiders around your property
• Determine entry points and habitat attracting spiders
• Use specialized treatments and pesticides to eliminate spiders
• Help spider-proof your home for long term prevention
• Offer advice on bite prevention and venomous species to watch for

Having a pest management plan and treatment can give you peace of mind against the spiders that bite in California.

Coexisting with Spiders

While certain spiders can present risks, the vast majority of spiders are harmless to humans and help control insect populations. Some tips for safely coexisting with our eight-legged neighbors include:

• Learning to identify dangerous spiders in your region
• Keeping yards and homes tidy to avoid attracting spiders
• Not disturbing spider webs or handling spiders
• Sealing cracks, crevices and openings into homes
• Using brooms to remove webs vs hands
• Being mindful when working in gardens, woodpiles
• Shaking out clothing, shoes before putting them on

With proper education and precautions, it is possible to minimize risks from the few spiders that bite in California while peacefully coexisting with the many harmless spider species.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.