This giant desert hairy scorpion (Hadrurus arizonensis) measures nearly 5 inches long when stretched out. The species lives in the Sonoran and Mojave Deserts of Arizona, California, southern Nevada, and far southwestern Utah, and also in the Mexican states of Sonora and Baja California. The Latin name breaks down to mean “thick-tailed (scorpion) from Arizona”.

I remember the first time I ever saw a live scorpion after moving to Arizona. It was one of these, a giant desert hairy scorpion (Hadrurus arizonensis) and it was just a few months after I moved into my new rental house in town, crawling across the tan carpeting which it was disconcertingly well-camouflaged upon. My sister and brother-in-law were also visiting me that day and saw it too. The original plan for sleeping arrangements was that they would use their sleeping bags and camping mats upon the floor rather than the uncomfortable hide-a-bed couch with the horizontal bar frame running across the thin, foldable mattress. That changed upon seeing the large arachnid. The uncomfortable mattress suddenly seemed much more tolerable given the fauna that was clearly possible upon the floor carpeting.

Giant desert hairy scorpions are the largest scorpions in North America, reaching 5.5 inches (14 cm) long as adults. The individual photographed here on my driveway last night is roughly 5 inches long when fully spread out. Despite their large size and scary appearance, these scorpions are not considered to be particularly venomous, with most people who are stung rating it as approximately equal to that of a bee sting. While allergic individuals might suffer dangerous reactions to the venom, most people are not badly affected, although obviously avoiding stings is still superior to being hit. It is thought that one reason for why many smaller scorpion species have much more dangerous venoms than the larger ones often do is because larger scorpions are capable of physically overpowering their prey. Therefore they don’t need venom as potent to disable their targets, while smaller and weaker scorpions have evolved more dangerous venoms to aid in food procurement. From an evolutionary standpoint, venoms in most animals are usually designed to be for prey subduction first, and self-defense is secondary, although there are clearly cases where venoms are used primarily for self-defense and not in obtaining food, such as in honeybees.

Almost all scorpion exoskeletons fluoresce under ultraviolet light – I think I read that only two or three species do not. (I am assuming this is correct.) The reasons for fluorescence are unknown but it makes them extremely easy to find at night with a simple UV flashlight. Much, much easier than it would be using normal white light. All scorpions are nocturnal and this plus their coloration makes them difficult to find without the aid of UV lighting.

There are around 1500 different scorpion species globally, with about 70 of them living inside the United States. While a couple of types live in surprisingly cold climates such as Wyoming, the large majority of US scorpions live in warm and dry climates of the desert southwest, with a range of others living in more humid southeastern climates. The giant desert hairy scorpion lives between 7 and 10 years on average in the wild, with captive individuals often living 20 years. Their large size, relatively nonvenomous status, and significant fat reserves make these beasts a desirable food source for a variety of larger desert animals, including kit foxes and elf owls. I imagine that members of the Fab Four Fox Family (gray foxes) that visit me to drink the water I provide for wildlife several nights a week would be equally ready to eat this scorpion should they come across it. And of course, for good measure, I like to post a photo of the extremely cool trait of fluorescence under ultraviolet light when I see one.