The Arizona bark scorpion (Centruroides sculpturatus) inhabits the Sonoran Desert, primarily in Arizona and parts of Mexico and the southwestern U.S. While often called “poisonous,” the accurate term is “venomous.” This distinction is important: venom is injected, while poison is ingested or absorbed. It is the most venomous scorpion species in North America.
Understanding Arizona Bark Scorpion Venom
The Arizona bark scorpion’s sting delivers a neurotoxic venom that targets the nervous system. This neurotoxin can cause intense localized pain, often described as an electrical shock sensation, along with numbness and tingling that may spread. More severe reactions include muscle spasms, twitching, abnormal eye movements, excessive salivation, and in rare instances, respiratory distress.
While painful, fatalities are uncommon, particularly for healthy adults. However, young children, older adults, and those with compromised immune systems face a higher risk of severe symptoms. Reaction severity depends on the venom amount injected and the individual’s health and age. Most symptoms improve within 24 to 72 hours, though mild swelling or numbness might persist for up to a week.
Identifying Arizona Bark Scorpions
Arizona bark scorpions have distinct physical characteristics. They are small, typically 1 to 3 inches long, with pale tan to yellowish-brown coloration. Unlike other scorpions, they have slender pincers and a thin, segmented tail that often curls to the side when resting. A small bump, or “subaculear tooth,” is located just beneath the stinger on their tail.
These nocturnal scorpions hunt at night. During the day, they seek shelter in cool, dark, and often moist environments to avoid heat and conserve water. Common hiding spots include under rocks, logs, tree bark, and cracks in walls or concrete. They are skilled climbers, found on vertical surfaces like walls, trees, and inside homes. Under ultraviolet (UV) light, they glow bright bluish or greenish, aiding nighttime detection.
Responding to a Sting
Immediate action after an Arizona bark scorpion sting can help manage symptoms. First, clean the sting site gently with soap and water to reduce infection risk. Apply a cool compress or ice pack for about 10 minutes to reduce pain and swelling. Over-the-counter pain relievers like acetaminophen may be used, but avoid aspirin or ibuprofen as they can worsen bruising or bleeding. Keeping the stung limb elevated and still also helps control pain and minimize swelling.
Seek immediate medical attention, especially for children, older adults, or anyone with severe symptoms like difficulty breathing, widespread muscle spasms, or convulsions. Contacting a poison control center (e.g., 1-800-222-1222 in the U.S.) is also advisable for guidance and monitoring. Antivenom exists but is typically reserved for severe cases, significantly reducing symptom duration.
Preventing Encounters
To minimize encounters with Arizona bark scorpions, implement several preventative measures around the home and outdoors. Seal entry points into buildings by filling cracks in foundations and stucco, and ensure weatherstripping around doors and windows is intact. Scorpions can enter through openings as small as 1/16 of an inch. Installing door sweeps and covering vents with fine mesh screens can also block access.
Outdoor precautions include removing debris like woodpiles, rocks, and clutter from around the home, as these provide ideal hiding spots. Trim vegetation and tree branches away from the house foundation to prevent scorpions from climbing. When outdoors, especially at night, wear shoes and shake out clothing, towels, and shoes before use to dislodge hidden scorpions. Reducing outdoor moisture sources like leaky pipes or standing water also makes an area less appealing.