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A summer storm rolls through, the desert smells like rain, and you step outside to check the yard. Something black and armored is crossing the patio. It has two chunky claws up front and a long, thin tail trailing behind it like a piece of wire.
Many Arizona homeowners have the same first thought: giant scorpion. Look at the tail before you panic. If it’s thin and whip-like with no bulb at the end, you may have met a vinegaroon, also called a giant whip scorpion.
The short answer is that vinegaroons have no venom and no stinger. They can pinch, and they can spray a vinegar-smelling acid if you bother them. If you leave one alone, it’s very unlikely to cause you any trouble. Here’s what they are, how to tell one from a scorpion, and what to do if one shows up near your door.
What Is a Vinegaroon?
A vinegaroon is an arachnid, so it’s related to spiders and scorpions, but it isn’t either one. Whip scorpions have their own group. The species that lives in southern Arizona was described in 2018 and named Mastigoproctus tohono, after the Tohono O’odham people, who have long lived in the same part of southern Arizona and northern Sonora.
Adults are usually about 2 to 3 inches long, not counting the tail, and dark brown to black. They walk on six legs. The front pair of legs is long and thin, and they use those like antennae to feel their way around in the dark, since their eyesight is weak.
Why They Show Up After Monsoon Storms
Vinegaroons spend much of the year sealed inside underground chambers. Researchers Justin and Li Schmidt studied one population near Willcox for more than 20 years. They found that vinegaroons stayed underground until the first summer rains, usually in late June or July, and then dug out to hunt and find mates. In all those years of visits, the Schmidts didn’t spot one above ground before the season’s first rain.
Justin Schmidt is better known for something else. He created the Schmidt Sting Pain Index, which rates how much insect stings hurt, and he took a lot of stings to build it. When the man nicknamed the “King of Sting” spends two decades studying a desert animal, it’s worth a second look before you reach for a shoe.
Vinegaroon or Bark Scorpion? How to Tell Them Apart
This is the part that matters most for your family. The Arizona bark scorpion does have venom, and its sting can be serious, especially for small children. Here’s how the two compare:
| Vinegaroon | Arizona Bark Scorpion | |
| Tail | Thin and whip-like, with no stinger | Thick and segmented, often curled up, with a stinger at the tip |
| Color | Dark brown to black | Light tan to yellowish |
| Front claws | Short, thick, and chunky | Long and slender |
| Under a UV blacklight | Doesn’t glow | Glows blue-green |
| Venom | None | Yes |
If you aren’t sure what you’re looking at, don’t touch it. Take a photo from a safe distance and keep kids and pets away until you know. If it turns out to be a bark scorpion, ACTION’s guide to Arizona scorpion season has tips for making your home less inviting to them.
Where You’re Most Likely to See One in Arizona
Most Arizona vinegaroon sightings come from the southeastern part of the state, including the Tucson area and the grasslands and foothills to its south and east. They prefer soft soil they can dig into.
Sightings in the Phoenix metro area appear to be much less common. If you live in the Valley and find something with a tail near your door, a bark scorpion is the more likely suspect. It’s worth confirming, because the two call for very different responses.
Should You Get Rid of a Vinegaroon?
Usually, no. A vinegaroon eats the same pests most homeowners want fewer of. Researchers have recorded them eating crickets, beetles, cockroaches, spiders, and even scorpions. During monsoon season, winged ants and winged termites are on the menu too.
That last one overlaps with ACTION’s home turf. Termites are ACTION’s specialty, and Arizona’s subterranean termites often swarm after summer rains. A vinegaroon snacking on a few swarmers is fun to picture, but it won’t protect your house. Seeing winged termites near your home can be a sign of a colony nearby, and that’s a good reason to schedule a termite inspection.
If a vinegaroon wanders inside, move it the way you’d move a spider. Put on gloves, slide a container over it, and slip a piece of cardboard underneath. Release it outside, away from the house, near some soil or brush. Keep it away from your face, and don’t squeeze it. Squeezing is what triggers the spray.
When It’s Worth Calling a Pro
One vinegaroon isn’t a pest problem. It’s a visitor. A few situations are worth a call, though:
- You can’t tell whether it’s a vinegaroon or a scorpion, especially if you have kids or pets at home.
- You keep finding scorpions, crickets, or cockroaches indoors. Predators go where the food is, so a yard with lots of night hunters may also have lots of insects for them to eat.
- You see winged termites, discarded wings, or mud tubes near your foundation. These are common early warning signs of termites.
Not Sure What’s Crawling Around Your Yard?
ACTION Termite & Pest Control has served Arizona since 1969 and is the official pest control provider of the Phoenix Suns. Whether you found a vinegaroon, a bark scorpion, or signs of termites, the team can help you figure out what you’re dealing with. Check the full list of service areas to find your local team.
📞 Call ACTION today at (602) 899-2222, or (520) 524-6624 in Tucson, to schedule your free inspection and take ACTION against pests.