Short answer: An Arizona bark scorpion is about 2 to 3 inches long, pale yellow to tan, and slender, with thin pincers. It's the scorpion you'll find climbing walls, ceilings and trees. If a scorpion is on a wall or ceiling in a desert home, assume it's a bark scorpion.
Common desert scorpions compared
| Arizona bark scorpion | Giant hairy scorpion | Stripe-tailed scorpion | |
|---|---|---|---|
| Size | About 2–3 in. | Up to about 6 in. | About 2–3 in. |
| Look | Pale yellow, slender | Yellowish-tan, dark hairy tail | Light body, dark stripes on tail |
| Where you find it | Walls, ceilings, trees, indoors | Burrows in loose soil, rarely indoors | Under rocks and debris |
| Sting | Severe pain and numbness; can be serious | Painful | Painful, generally not dangerous |
Source: Arizona Pest Control's guide to Tucson-area scorpions.
Why the bark scorpion matters most
It's the most venomous scorpion in the United States and the one most likely to end up inside, because it climbs. The large hairy scorpions people find in the yard look scarier but are far less of a concern.
Outside Arizona
In San Antonio and El Paso, the striped bark scorpion is the one homeowners see most. Its sting is painful but less dangerous than the Arizona bark scorpion's. It climbs well too, so sealing works the same way.
Common questions
Do bark scorpions glow under blacklight?
Yes. All scorpions glow blue-green under UV light, which makes them easy to spot at night.
Are big scorpions more dangerous?
Usually not. The small, slender bark scorpion is far more venomous than the large hairy scorpion.