Bark-ScorpionScorpions are arachnids, related to spiders and ticks. They have four pairs of legs, two lobster-like pincers and a segmented tail with a stinger on the end. Some have multiple eyes, but they cannot see very well, relying instead on vibration and touch to seek out prey and sense danger. Scorpions prefer warm, dry climates and are seldom found above 7,000 feet of elevation. Though a few species can be found as far north as Canada, most live in the southwestern deserts of the United States and Mexico. Of the approximately 90 species in North America, very few are dangerous to people. Here are some of the most dangerous scorpions in North America to watch out for.

Bark Scorpion

By far the most dangerous scorpion in North America is the Bark Scorpion. This species ranges from Arizona, New Mexico and southern California to Sonora and Baja California in Mexico. They are yellow or light brown in color, and the slightly larger males grow to about three inches in length. Bark Scorpions do not burrow. Instead, they seek holes or openings in which to hide. They are commonly found under rocks, logs, tree bark, stacked bricks and piles of firewood. They also invade homes and hide in cellars, attics, kitchen cabinets, under sinks and in bathrooms. Bark scorpions are among the few species of scorpions that are climbers. They climb trees, cliffs, and block or stucco walls. You might even find them in your house on the wall or ceiling. Their venom is potentially lethal if an antidote is not administered in time. It causes excruciating pain, numbness, difficulty in breathing, muscle twitching and convulsions. Most at-risk are children and the elderly. If you are stung, seek medical help immediately. In areas of bark scorpion habitation, an anti-venom is available in both hospitals and drug stores.

Desert Hairy Scorpion

The Desert Hairy Scorpion is the largest scorpion in North America, growing from five to seven inches in length. It is found mainly in southern California and Arizona. Though this species is a burrower, it can also be found under objects such as rocks, logs, woodpiles and boards. Because it is attracted to water, it has been known to invade homes, garages and swimming pool areas. It is sometimes found in attics, crawl spaces, closets, bathrooms or kitchens. Though the venom is not very potent, it can be as painful as a bee or wasp sting. However, those who are stung should be watched carefully, as some people have dangerous allergic reactions to the venom.

Stripe-Tailed Scorpion

The Stripe-Tailed Scorpion, also known as the Devil Scorpion, inhabits the deserts and dry areas in Arizona, New Mexico and southern California. It is a medium-sized scorpion, about two and a half inches in length, with brownish stripes running along its back. It burrows in sandy or gravely soil, but can also be found under surface objects. Sometimes stripe-tailed scorpions crawl into sleeping bags, shoes and items of clothing, so in scorpion-infested areas it is important to shake out clothing and shoes before dressing. Though the sting of this venomous scorpion is painful, it is not considered significantly dangerous to humans.

Though all scorpions carry venom, no other species of North American scorpion is thought potentially harmful to humans. To check for scorpions in and around your home, use a portable UV light, as scorpions glow brightly in black light. Pesticides are largely ineffective against scorpions. Instead, use tongs to capture and remove them. To prevent entry, plug up cracks and holes around your house.

Mario Spencer is a freelance writer based in Denver, CO. If you need assistance with a scorpion problem around your house, Mario strongly recommends Arizona Exterminating Company as a resource.