Scorpions are terrestrial arthropods, related to spiders, ticks, and mites, and are native to the United States. Over 90 different species of these nocturnal predators are found within the country’s borders, primarily concentrated in arid and semi-arid regions. While their presence is widespread, the severity of any potential encounter varies significantly depending on the specific species and its geographic location. They are highly adapted to survive in harsh climates, often seeking shelter during the day and emerging at night to hunt.
Where Scorpions Live in the United States
The greatest density and diversity of scorpions occur across the Southwestern United States, including the Sonoran and Mojave deserts. States like Arizona, New Mexico, Texas, Southern California, and Nevada form the core of the US scorpion habitat, boasting the highest populations and the most well-known species. The hot, dry climate and availability of rock crevices and ground cover make this region ideal for them.
The range of scorpions is not exclusively limited to the Southwest. Fewer than five of the 90 species are naturally found east of the Mississippi River. The Striped Bark Scorpion (Centruroides vittatus) is a common species found throughout Texas and extending into states like Oklahoma, Arkansas, and parts of the Midwest, demonstrating a wider tolerance for varied climates.
Identifying Major US Species
Scorpions found in the United States generally fall into two broad categories based on their venom potency, which often correlates with their physical appearance. The most medically significant species is the Arizona Bark Scorpion (Centruroides sculpturatus), which is small and slender, rarely exceeding three inches in length. This scorpion is typically a pale yellow or light tan color, and it is semi-arboreal, meaning it is an agile climber often found on walls, under tree bark, or in rock crevices.
In contrast, the Desert Hairy Scorpion (Hadrurus arizonensis) is the largest scorpion in North America, with adults reaching up to five and a half inches long. This species is easily identifiable by the sparse brown hairs covering its body, which it uses to detect ground vibrations. Despite its intimidating size and powerful pincers, its venom is considered mild and poses little danger to healthy adults. This species is a fossorial burrower, spending its days in deep underground tunnels to escape the desert heat.
Understanding Scorpion Venom and Sting Safety
The potential danger from a scorpion sting is determined by the type of venom injected. Most US scorpion species possess venom that is primarily cytotoxic or hemolytic, meaning it causes localized pain and tissue reaction at the sting site. Symptoms from these stings, such as those from the Desert Hairy Scorpion, are generally limited to immediate, intense pain, mild swelling, and localized numbness or tingling, comparable to a bee sting.
The Arizona Bark Scorpion, however, possesses a potent neurotoxic venom that directly affects the nervous system. This can lead to systemic effects, which are particularly concerning in young children or the elderly. Severe neurotoxic envenomation is characterized by symptoms such as uncontrollable muscle twitching (fasciculations), roving eye movements (nystagmus), hypersalivation, and, in the most severe cases, difficulty breathing.
For a sting from a non-medically significant species, basic first aid involves cleaning the wound and applying a cool compress to reduce swelling and pain. Over-the-counter pain relievers can manage discomfort. If an Arizona Bark Scorpion sting is suspected, especially if systemic symptoms like muscle spasms or breathing issues appear, immediate medical care should be sought. Antivenom is available for severe neurotoxic stings and is administered in a hospital setting.