The Sacramento Region's Guide To Dangerous Spider Identification

What You Need To Know Most

It isn't easy to properly identify a black widow or brown widow when they are young spiders. There is a large variation in physical characteristics as these spiders grow from spiderlings into adults.

If you want to know for sure what spider you're dealing with, and you're able to catch it, we recommend sending the specimen to us or to an entomology department at a university. A glue board or similar trap can help you do this. We don't suggest capturing one of these spiders by hand—for obvious reasons. You may also take a photo of a spider you're finding in your home or on your property and send it by email.

Webs

One of the most helpful ways to distinguish a dangerous spider from a spider that isn't dangerous is to examine the webs they create. Here are a few characteristics of widow spider webs:

• The webs created by widow spiders are made of strong threads. When you snap a thread, it might make a plucking noise. That's how strong it is.
• Widow spiders don't make pretty webs. Their webs are tangled. This is for utility. A widow spider is looking to capture a large insect or small mammal. While it can eat flies, their webs aren't designed to capture tiny insects.
• You'll find black widow spider webs near the floor of storage areas or in your garage. Outside, they're likely to be found close to the ground in sheltered locations such as under a deck, in a brush pile, or under a stack of scrap wood.

Spiderlings

Both the brown widow and the black widow start out as brown spiders. While the brown widow nymph looks a lot like what the adult will look like, a western black widow spider nymph looks nothing like an adult female spider of the species. If you see a spider with a bulbous abdomen that is brown with white, red, or yellow stripes, you might be looking at a widow spider nymph.

Adult Females

When a female widow spider reaches her adult stage, she will look more like what you would expect her to look like. Females have the recognizable hourglass pattern on the bottom of their abdomens. Brown widows tend to be tan with an orange hourglass, but there is some variation. A brown widow spider can be so dark that you might think it is a black widow. It may also have an hourglass symbol that is dark enough to look like it might be red. Female black widows are black and shiny with a bright red hourglass symbol. They're usually fairly easy to identify.

Male Widow Spiders

If you see a male widow spider, you might not realize it. They don't have the same recognizable coloration and markings as the females and they are much smaller. It is certainly helpful to be able to pick out a male black widow or brown widow in a lineup of spiders, but there are no easily identifiable traits to point out.

We highly recommend doing some image searches and looking at photos of black and brown widow spider nymphs. If you do, keep in mind that there is a lot of variation, so looking at one picture isn't going to be enough to help you positively identify these dangerous spiders on your property.

Quick Spider Prevention Tips

In light of how difficult it is to identify dangerous spiders, we recommend taking precautions around any spiders on your property, and any webs that look tangled.

• Wear gloves when working out in your yard.
• Wear footwear, particularly at night.
• Be cautious around brush and wood.
• Use a broom to remove webs; don't ever use your hands.
• Destroy any paper-like egg sacs you find attached to webbing.