Scorpions are ancient arachnids, featuring eight legs, grasping pincers, and a segmented tail ending in a venomous stinger. Their evolutionary history spans over 435 million years. While often associated with deserts, scorpions have adapted to various environmental conditions. They typically range from half an inch to several inches long and are largely nocturnal, preferring to hide during the day and hunt at night.
Geographical Distribution Across the US
Scorpions are most prevalent across the southwestern United States. States with the highest concentrations and most reported exposures include Arizona, Texas, New Mexico, and Nevada. Arizona reports the highest exposure incidences, especially in urban areas like Phoenix and Tucson, due to the presence of the most medically significant species.
The distribution extends into Southern California and southern Utah. Further east, scorpions are found in notable numbers in Oklahoma, with high exposure incidences reported in cities like Oklahoma City and Tulsa. Less common populations are scattered across other southern states, including Louisiana and Florida, and isolated groups extend as far north as Tennessee and Nebraska.
Common Species and Danger Levels
The United States is home to approximately 75 species of scorpions, but only one is considered medically significant: the Arizona Bark Scorpion (Centruroides sculpturatus). This species is found primarily in Arizona, New Mexico, Nevada, and southern California. It possesses a potent neurotoxin that can cause intense pain, tingling, and numbness in the affected limb, sometimes resulting in temporary loss of motor function. Although a sting is rarely fatal for healthy adults, it poses a greater danger to small children, the elderly, and those with compromised immune systems.
Most other US scorpions are not medically significant, with their stings causing only localized pain, similar to a bee or wasp sting. The Striped Bark Scorpion (Centruroides vittatus) is widespread across the South and Midwest, but its venom is relatively mild. Another common species, the Giant Desert Hairy Scorpion (Hadrurus arizonensis), is the largest in the US, reaching up to five inches long, yet its venom is generally mild.
Where Scorpions Hide
Scorpions seek out dark, cool, and sheltered environments during the day to conserve moisture and avoid predators. Outdoors, they commonly hide beneath rocks, logs, woodpiles, and loose tree bark. They are also frequently found in cluttered areas like landscaping debris, under outdoor furniture, and in the cracks and crevices of building foundations.
When they enter structures, scorpions gravitate toward undisturbed, dark spaces. Common indoor hiding spots include the back of closets, inside wall voids, under sinks, and in cluttered areas of garages or attics. They also frequently hide in items left on the floor, such as shoes, discarded clothing, or bedding.
Prevention and Safety Measures
Protecting a home requires sealing entry points and eliminating outdoor habitats. Scorpions can fit through gaps as small as one-sixteenth of an inch. Homeowners should seal all cracks in the foundation, walls, and around utility pipes and vents using caulk or weather stripping. Installing door sweeps on exterior doors and ensuring window screens are intact also limits access.
Reducing outdoor clutter is essential, including removing woodpiles, rock stacks, and debris from the home’s perimeter. Since scorpions are attracted to insects as a food source, controlling populations of crickets and roaches can reduce their presence. An ultraviolet or “black light” can be used to scan yards and foundations at night, as the scorpion’s exoskeleton fluoresces a bright blue-green under UV light.
Sting Treatment
If a sting occurs, the wound should be cleaned with soap and water, and a cool compress or ice pack applied to reduce pain and swelling. Anyone stung, especially children or the elderly, should seek medical attention promptly. The local poison control center should also be contacted for advice.