The Arizona Bark Scorpion

• Scientific nameCentruroides sculpturatus
• FamilyButhidae
• Adult length5 to 8 cm (2 to 3 in)^[3][4]
• ColorUniform pale yellow to tan^[5]
• Medical significanceOnly US scorpion considered a serious hazard^[1]
• Signature abilityClimbs smooth vertical surfaces^[2]
• Core rangeArizona and Sonora; edges of CA, NV, UT, NM^[2]
• LifespanAbout 6 years^[3][6]
• ReproductionLive birth, 12 to 38 young^[2]
• AntivenomAnascorp, FDA-approved 2011^[7][8]
• EmergencyPoison Help 1-800-222-1222^[9]

What is the Arizona bark scorpion?

It is a buthid scorpion, one of roughly 40 to 60 scorpion species that live in Arizona, and the one species among them that public-health agencies single out as medically important.^[10][1] Adults are slender, 5 to 8 cm long, straw-colored, and built for climbing: unlike the ground-dwelling giant hairy and stripe-tailed scorpions, the bark scorpion scales stucco, block walls, tree bark, and even interior walls and ceilings, and it rests upside down under overhangs.^[2][3] It does not burrow. It hides by day in any crevice about 14 mm wide, which is why it turns up in shoes, folded towels, block-wall cavities, and the gap behind a baseboard.^[2][11]

The name comes from its habit of sheltering under loose tree bark, not from any sound. Older references call it Centruroides exilicauda; venom chemistry and genetics separated the two species in 2004, and C. exilicauda is now understood as a Baja California species.^[2][3]

How dangerous is it, really?

Dangerous enough to take seriously, and far less deadly than its reputation. Its venom acts on nerve sodium channels and can cause, in a minority of stings, roving eye movements, drooling, difficulty swallowing, and involuntary muscle jerking, which clinicians grade III or IV and treat with antivenom.^[12][13] Most stings cause intense local pain, tingling, and numbness that fade over 24 to 72 hours with home care.^[14][3] Deaths are rare where medical care is available; the commonly cited Arizona record is two confirmed deaths since 1968.^[3] Children under 10 and adults over 70 have the most severe reactions and should be evaluated promptly for any systemic sign.^[15][16]

Stings are common. Arizona accounted for 68.2% of all scorpion exposures reported to US poison centers between 2005 and 2015, roughly 126,000 of 185,402 cases.^[16] A 2025 study estimated that Maricopa County alone saw about 178,625 envenomations from 2017 through 2021, nearly four times the 45,179 that hospitals and the poison center recorded.^[17] Read the full analysis on Are bark scorpions deadly? and the treatment guidance on the sting page.

How do I know it's a bark scorpion?

Three tells, visible without handling it: thin, elongated pincers; a thin tail about as long as the body, usually held to one side rather than arched; and a small tooth beneath the stinger (the subaculear tubercle).^[5][2] Uniform pale color and the fact that it was on a wall or ceiling are supporting clues. The identification page has the anatomy plate and the comparison page sets it beside the two look-alikes people most often confuse it with.

Where does it live?

Across all of Arizona and into the Mexican state of Sonora, with lower-density populations in southeastern California along the Colorado River, southern Nevada, southwestern Utah, western New Mexico, far-west Texas, Baja California, and Chihuahua.^[2][3] It favors rocky terrain and riparian corridors with mesquite, cottonwood, and sycamore, and it does very well in irrigated suburbs, where shade, moisture, and insect prey are abundant.^[2][18] The habitat and range page has the map.

Explore the reference

• Identify

  Identification

  Anatomy plate, the three tells, size, color, and how to tell a juvenile.

• Compare

  Bark vs. stripe-tailed vs. giant hairy

  Side by side, with the features that separate them.

• Medical

  Sting: symptoms and treatment

  Severity grades I to IV, first aid, what not to do, when to go to the ER.

• Medical

  Are they deadly?

  What 50 years of Arizona data say, including the 2025 Maricopa County estimate.

• Medical

  Anascorp antivenom

  How it works, the trial behind it, who gets it.

• Biology

  Venom

  Alpha and beta sodium-channel toxins, and why the sting feels the way it does.

• Biology

  Habitat and range

  Range map, riparian habitat, why suburbs suit it.

• Biology

  Behavior

  Climbing, crevice-seeking, the 77°F activity threshold, aggregation.

• Biology

  Reproduction and lifecycle

  Courtship, live birth, the ride on mom's back, molts, lifespan.

• Biology

  Diet and predators

  What it eats, what eats it, and the mouse that turned venom into a painkiller.

• Biology

  Why it glows under UV

  The cuticle chemistry, the wavelengths, and the molt caveat.

• Myths

  Myths vs. facts

  Baby scorpions, suicide by fire, aggression, and other things that aren't true.

• Prevention

  The science of keeping them out

  What extension research says works, and what doesn't.

• Kids

  For kids and classrooms

  The fun version, still accurate.

• Español

  Alacrán de corteza de Arizona

  La guía en español.

• Sources

  References

  Every source on this site, tiered.

Why trust this site?

Because you can check it. Every factual sentence carries a numbered citation that links to the source, and the sources are ranked: peer-reviewed journals, university extension publications, government agencies, and poison centers first.^[2][1][17] The editorial policy explains how pages are researched, reviewed, and corrected. Pages that give medical guidance show their review status in the byline; until a named clinician has reviewed one, it says so. The author's own background, including several seasons of nightly field observation in the Phoenix area, is on the author page.