Scorpions are
arachnids, and are extremely
prolific in the
Sonora desert. Exactly how many scorpions there are crawling around here often surprises people who move into developing areas. In the summer, we usually find many more scorpions in or around the house than
spiders and
cockroaches combined. Frankly, I prefer having scorpions to cockroaches.
Although scorpions are awesome and efficient predators, they aren't too dangerous to humans. They only sting when trapped or confused, and their pincers are too small to do any damage. Scorpions are much more dangerous to bugs, their usual prey. Insects are caught and held with the pincers, then stung by the tail. The venom paralyzes the insect, and the scorpion liquifies it with its enzyme-active saliva and chows down. Although scorpions are certain doom for insects, and their venom can kill or maim many small desert animals, they themselves are so small that they are easily preyed upon by all kinds of things, many of which are smart enough not to eat the poison parts.
The sting of even the most poisonous of scorpions does not pose a danger to an adult. However, the sting of some scorpions can be dangerous to young children and the elderly. Stings tend to occur when someone puts on a shoe that has a scorpion sleeping in it, or when someone walks around barefoot in scorpion land. Picking up or touching a scorpion is also not a good idea. Scorpions look so scary that I doubt any toddler would play with one, but keep an eye out just in case.
Generally speaking, the larger the scorpion, the less dangerous its venom is. The largest scorpions, certain varieties of the hairy scorpion, look frightening but their stings do little more than poke holes. The smallest scorpion, the feared bark scorpion (usually between 1/4 and 1/2 inch in length), posseses the most dangerous sting, as noted above. They are found in great numbers in the Sonora desert, and any scorpion you find will probably be either a bark scorpion or a striped (banded?) scorpion.
If you find a scorpion in your house, kill it by smashing it with a shoe. Alternatively, you can catch it and put it back outside, but there are so many of them that it doesn't really affect the ecosystem. If you have just moved into a residence in a developing desert area, never, ever walk around your house barefoot, especially at night. Bark scorpions, and some other species of desert scorpions, have an interesting exoskeleton that glows brightly under ultraviolet light. This makes finding them very easy at night -- wave your light around and look at all the pretty scorpions.
Going on a crusade against the scorpions is not necessary or desirable. They eat just about every other bug you can think of, some of which are much more irritating to you, like roaches, termites, moths, crickets, etc. And if you see something that looks almost like a scorpion but won't stop scrambling about long enough for you to be sure, it's probably a solpugid. Every time I have found a scorpion in the house, it has been sitting very still. Solpugids, on the other hand, never seem to stop moving, so much so that I couldn't figure out what they were until I happened upon an enyclopedia entry. Solpugids are harmless to humans.