Which Arizona scorpion is dangerous?

Only the Arizona bark scorpion (Centruroides sculpturatus). Its neurotoxic venom can cause severe symptoms, especially in young children and the elderly. The stripe-tailed and giant hairy scorpions deliver stings comparable to a bee's. If a bark scorpion stings a child, call Poison Control at 1-800-222-1222 right away.

Do all scorpions glow under a blacklight?

Yes. Every Arizona species fluoresces blue-green under UV light because of compounds in the outer layer of the exoskeleton. The only scorpions that do not glow are ones that have just molted, since the new cuticle has not hardened yet.

What is the biggest scorpion in Arizona?

The giant hairy scorpion (Hadrurus arizonensis), which can reach 6 inches. It is the largest scorpion in North America, but its sting is mild — the bark scorpion, at less than half the size, is far more dangerous.

If I find one bark scorpion, are there more?

Usually, yes. Bark scorpions are unusually social and tend to occur in numbers — a single sighting on an interior wall typically means a breeding population in the block walls or landscape rock nearby. A UV inspection after dark tells you quickly.

Arizona Scorpion Identification Guide

Arizona is home to more than 40 scorpion species, but East Valley homeowners really only meet three: the Arizona bark scorpion, the stripe-tailed scorpion, and the giant hairy scorpion. Between them they cover almost every scorpion you will find in a garage, on a pool deck, or in a bathtub in Gilbert, Chandler, Mesa, or Queen Creek.

Telling them apart matters because only one of the three — the bark scorpion — carries venom strong enough to send a person to the hospital. The other two sting roughly like a honey bee. Knowing which species you are looking at changes how worried you should be and how aggressive your control plan needs to get.

Below are the field marks our techs use to identify a scorpion in seconds, plus where each species hides.

Arizona bark scorpion (Centruroides sculpturatus)

The bark scorpion is slender, uniformly tan to yellowish, and tops out around 3 inches. Its pincers are thin and elongated — almost finger-like — and its tail is noticeably skinnier than the other two species. It often rests with the tail curled flat to one side rather than arched over its back.

This is the only scorpion in the United States whose sting is medically significant. The venom is neurotoxic, and a sting can cause intense pain, numbness, tingling that travels up the limb, and in serious cases muscle twitching and trouble breathing. Small children and the elderly face the highest risk, which is why an antivenom (Anascorp) is stocked in Arizona hospitals.

Bark scorpions are also the only common Arizona species that climbs. They scale stucco, block walls, trees, and ceilings, and can squeeze through a gap about 1/16 of an inch wide. If a scorpion is on your wall, your ceiling, or in your sink, it is almost certainly a bark scorpion.

Stripe-tailed scorpion (Paravaejovis spinigerus)

The stripe-tailed scorpion is probably the most commonly encountered scorpion in Arizona overall. It runs 2 to 2.5 inches, with a stockier build than the bark scorpion: thicker pincers, a chunkier tail, and a heavier body. The giveaway is a pair of dark brown stripes running along the underside of the tail.

Stripe-tails are strict ground-dwellers. They shelter under rocks, flagstone, doormats, shoes left outside, and pool toys — they do not climb walls. The sting hurts, but for most people it is comparable to a bee sting: local pain and swelling that fades within hours.

Giant hairy scorpion (Hadrurus arizonensis)

The giant hairy scorpion is the largest scorpion in North America, reaching up to 6 inches. It has a dark olive-brown back with contrasting yellowish legs, and fine brown hairs on the tail and legs that it uses to sense ground vibrations.

Despite the horror-movie looks, its venom is mild — the sting is generally no worse than a bee's. Giant hairies are burrowers, digging tunnels that can run several feet deep, and they actually prey on other scorpions. You will see them more on the desert edges of Queen Creek and San Tan Valley than in established neighborhoods.

The fast way to tell them apart

Use the pincer rule of thumb: thin, delicate pincers signal potent venom, because the animal relies on its sting to subdue prey. Thick, crab-like pincers signal mild venom, because the animal crushes prey instead. The bark scorpion's slender pincers mark it as the dangerous one; the stripe-tail and giant hairy both carry robust crushing claws.

Location confirms it. Anything climbing a wall or clinging to a ceiling is a bark scorpion. Anything 5 inches or longer is a giant hairy. A stocky scorpion on the ground with dark stripes under the tail is a stripe-tail.

All three fluoresce a bright blue-green under a UV blacklight in the 365 to 395 nanometer range — a compound in the cuticle does the glowing. The exception is a freshly molted scorpion, which stays dark until its new exoskeleton hardens. The best hunting window is one to two hours after dusk on a warm night.

How to Identify Arizona's Three Common Scorpions

Arizona bark scorpion (Centruroides sculpturatus)

Stripe-tailed scorpion (Paravaejovis spinigerus)

Giant hairy scorpion (Hadrurus arizonensis)

The fast way to tell them apart

Questions, answered

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