Black Widow Spiders in Bakersfield

UC IPM puts it simply: bites from black widows "are quite rare, even where these spiders are very common." Most bites happen when someone reaches into a spot the spider has claimed, usually while cleaning out a garage or picking up stored items. The rest of this guide is about knowing what you are looking at, keeping them out of the places your family reaches into, and what to do if a bite happens.

How to identify a black widow

The spider most people picture is the adult female western black widow. UC IPM describes her as about 1/2 inch long and shiny jet black all over (body and legs), with a red hourglass on the underside of a large round abdomen. The hourglass varies in shape and is occasionally missing, so do not rule out a widow just because you cannot see it.

Juveniles and males

Young widows and males are where people get confused. Per UC IPM:

• Newly hatched spiderlings have tan legs and a mostly white abdomen with a few black spots.
• As they grow, juveniles turn olive-gray or tan with white stripes. The stripes fade as the spider darkens with each molt.
• Males are much smaller than females and keep the striped juvenile coloring. They are seldom noticed.

UC IPM says only larger immature spiders and adult females can bite through skin with enough venom to cause a painful reaction.

Egg sacs and webs

Black widow egg sacs are about 1/2 inch across and creamy yellow to light tan. They are tough and papery. A female typically lays about 300 eggs per sac. The web is an irregular cobweb that is tough and sticky. The spider hangs upside down in it.

Black widow or brown widow

The brown widow is a non-native relative that has spread through Southern California. It matters because a brown widow can look like an immature black widow.

	Western black widow	Brown widow
Adult female	About 1/2 inch, shiny black, red hourglass	About 3/8 inch, mottled tan and brown, with gray
Egg sac	Round to teardrop-shaped, creamy yellow to tan, papery	Covered in spiky silk points, like a large pollen grain
Eggs per sac	About 300	About 130
Bite	Can cause pain and whole-body symptoms	Much milder in most verified cases
In the Central Valley	Found in populated areas almost everywhere in California	Not established here as of UC IPM's 2016 survey

UC IPM says the egg sac is the more reliable way to confirm a brown widow. If you find spiky egg sacs around a Bakersfield home, that would be unusual. A photo is the easiest way to sort out what you have.

Where they live around Central Valley homes

Black widows like dark, dry, sheltered places that nobody disturbs. UC IPM says they usually nest outdoors in holes and crevices and in clutter. They do this around homes and barns and around rock walls, and in garages they build webs near doors and vents. They rarely survive inside the living areas of a home.

Around a typical house in Bakersfield or Oildale (or Shafter), check:

• The bottom corners of the garage door, and garage vents
• Block walls and rock borders
• Gaps where the slab meets the ground
• Woodpiles and stacked pots
• Stored boxes on the garage floor
• Under patio chairs and picnic tables
• Under the handles of trash cans
• Kids' molded plastic toys and playhouses with open, downward-facing spaces

Most of those spots come from UC IPM's description of favored widow habitat. Widows are nocturnal, so you will see more of them on a flashlight walk after dark than at noon.

Bite symptoms and when to get care

A black widow bite often feels like a pinprick or nothing at all, sometimes with a small red mark. UC IPM says symptoms may start within about an hour and can include:

• Pain that spreads from the bite, and rigid stomach muscles (sometimes mistaken for appendicitis)
• Sweating and numbness
• Agitation and fever
• Less commonly, patchy paralysis

The CDC's list for workers adds muscle cramps and headache. It also lists nausea or vomiting and trouble breathing, along with high blood pressure. UC IPM notes that black widow bites do not cause conspicuous swelling or tissue breakdown around the bite, and that in most cases the symptoms resemble the flu and fade in a few days. Small children and older adults are more likely to have serious effects, as are people with health problems.

What to do

1. Stay calm. If it is safe, catch the spider or photograph it for identification.
2. Wash the bite with soap and water.
3. Put a cold damp cloth on the bite, or a cloth with ice. Raise the bitten arm or leg if you can.
4. Do not try to remove the venom. The CDC says not to.
5. Call Poison Help at 1-800-222-1222. It connects you to your local poison center (in California, the California Poison Control System) free, 24 hours a day.
6. Get medical care promptly, as UC IPM advises for any suspected black widow bite. If someone has trouble breathing, call 911.

Doctors have an antivenom. UC IPM says it works quickly, but because it is made from horse serum, physicians must watch for a severe allergic reaction, and UC IPM says American physicians are somewhat reluctant to use it.

Safe removal

For one or two widows, you do not need a professional. Find them at night with a flashlight and vacuum them up or crush them. Vacuum or scrape off egg sacs too, since each one can hold hundreds of spiderlings.

For a garage or shed cleanout, UC IPM recommends:

• Wear gloves when moving stored items or wood, or anything that has sat untouched.
• Keep gardening gloves and clothes in zipper-lock bags so a spider cannot move in.
• Store seasonal items in taped boxes, off the floor and away from walls.
• Stack firewood away from the house and do not carry spiders indoors on wood or plants, or on boxes.
• Keep the foundation clear of trash and leaf litter, and point outdoor lights away from doorways. Lights draw insects, and insects draw spiders.

I would not rely on spraying. UC IPM says insecticides "do not provide long-term control" of widows, both species re-infest treated areas, and young spiders can arrive from far away by ballooning on silk threads. Expect to repeat the cleanup through the year, and see our spider control page for the full approach.

Kids and pets

The risk to children comes from reaching into places widows live. Before kids play, flip plastic toys and playhouses over and check them. Check sandbox covers too, and the underside of picnic tables and patio chairs. Teach them not to reach into gaps in the block wall or under stored items. UC IPM says small children are among those more likely to have serious effects from a bite, so treat any suspected bite on a child as a reason to call Poison Help or a doctor right away.

If you use sticky traps for spiders, put them where pets and children cannot reach, as UC IPM advises. If anyone applies a pesticide, read the label and follow its instructions on keeping children and pets off treated areas. If a pet seems sick after contact with a spider, call your veterinarian.

When to call a licensed company

Call when:

• Widows keep turning up in the same places after you have cleaned up.
• You are finding many egg sacs.
• Someone in the house is at higher risk.
• The problem is in places you cannot safely reach, such as crawlspaces and eaves.

A good visit is mostly inspection and sealing entry points, plus removing webs and egg sacs. Any treatment should be targeted rather than sprayed everywhere.

We only refer companies licensed by the California Structural Pest Control Board. You can verify a license before anyone starts, and compare one-time and quarterly service if you are deciding how much to buy.

If widows keep coming back around your home, ask for a free inspection and a quote before any treatment.