There are over forty species of scorpions in Arizona but the only one that's considered dangerous to humans is the bark scorpion however there are lots of them. The popularity of irrigated lawns and other systems which increase environmental humidity in residential areas has led to a significant increase in the number of these animals. They hide during the day typically under rocks, wood piles and tree bark. Roaches, spiders, crickets and other insects are their main prey. Bark scorpions do not burrow and are commonly found in homes as they require only 1/16th of an inch to enter. Bark scorpions can climb walls, trees and other objects with a sufficiently rough surface. They prefer an upside down orientation which often results in people being stung due to the scorpion being in the underside of an object; check your shoes and clothes before putting them on.
It's hard to tell the difference between the bark scorpion and many other species that are approximatly three inches long and light in color so it's best to assume the worst. Their venom can cause severe pain coupled with numbness and tingling typically lasting between 24 to 72 hours. Temporary disfunction in the area stung is common; e.g. a hand or possibly arm can be immobilized or experience convulsions. It also may cause the loss of breath for a short period of time. Due to the extreme pain induced, many victims describe sensations of electrical jolts after being stung.