What is this spider with a white dot on its back?

"I found a spider with a white spot on its back. What is it?"

A spider with a white dot on its back is most likely one of several common, harmless species found across the U.S. Here's how to narrow it down.

The bold jumping spider is the most likely culprit

The most common match is the bold jumping spider (Phidippus audax). It's a compact, fuzzy black spider with a large white spot (sometimes three spots) on its abdomen, and green or blue mouthparts. It moves in quick bursts on walls, fences, or windowsills during the day. Bites are rare and, if they do occur, typically cause only mild redness or swelling.

Other possible species 

A few other spiders share similar markings:

• Zebra jumping spider (Salticus scenicus) — tiny, with black and white banding across its body and legs. Harmless and commonly found near windows.

• Eastern parson spider (Herpyllus ecclesiasticus) — a fast-moving ground spider with a distinctive white-gray marking on its dark abdomen. It can bite if handled, though it's not considered dangerous.

• False widow spider (Steatoda grossa) — a smooth, bulbous spider with faint white patches. Less common indoors, but worth knowing about. Its bite can cause localized pain, though it's far less venomous than a true black widow.

What to do about a spider with white dots on its back

Most spiders with white markings are harmless and actually help keep other insects in check. That said, if you're regularly seeing spiders indoors, or you're not sure what you're dealing with, it's worth getting a professional opinion from a spider control expert. An Ehrlich technician can identify the species and let you know whether any action is needed