Scorpions are strange animals. They can live for months on a single meal, slowing down their metabolisms until they're practically in suspended animation, yet can spring back to life almost instantly if they detect prey. They can be frozen overnight and thawed out the next day, none the worse for frost bite. There are about 2,000 varieties of scorpion worldwide, including many varieties that live in the desert, and all of them are poisonous.
But don't worry. Most of them don't have enough poison in their glands, or the right variety of poison, to kill a human being. Most -- but not all.
One type of scorpion that is capable of killing human beings is the Arizona bark scorpion, the most poisonous in the United States (and, ironically, one of the smallest) -- and, yes, it's found in the deserts of Arizona. You'll know if you've been stung by one because it will hurt like -- well, it will hurt about the same as if you stuck your finger in an electric socket and got it stuck there. You probably won't die from it unless you're a small child or have a weakened immune system, but even if you're a healthy and athletic adult you'll want to get to a doctor or hospital for a dose of antivenom as soon as possible, because it can take up to 72 hours for the effects to wear off -- assuming, of course, that you survive.