As you've probably been informed, scorpions are actually not insects, but arachnids, like spiders. There are some thirty species of them in the desert southwest. All scorpions are venomous, but in most cases the venom is so mild that it does not seriously endanger a healthy adult. Curiously, the largest and ugliest of the Arizona scorpions, the giant desert hairy scorpion (5 1/2") shown in the sketch above, has a venom which is mild compared to that of the much smaller bark scorpion (2-2 3/4").
The sting of the bark scorpion can be fatal, especially to the very young or the very old. However, fatalities are rare and common sense is your best protection. Scorpions use their venom primarily in the capture of prey. If you leave them alone, chances are they will leave you alone, but it is wise to check your shoes before you put them on and shake out the sleeping bag or blankets just in case.
Scorpion in striking pose, USFWS photo by Gary M. Stolz
The photo above, taken by Gary Stolz of the U.S. Fish and Wildlife Service, demonstrates how difficult it can be to spot a scorpion against its natural background.
If you are stung by a scorpion it is a wise precaution to consult a physician. Since the dangerous bark scorpions live under tree bark and amid leaves and plant debris, it is especially necessary to be on the lookout for them when tramping through cottonwood or mesquite groves, particularly in riparian areas.
If you are stung by a scorpion, wash the wound with soap and water and apply an antiseptic. A cool compress may relieve some of the discomfort. Consult a physician.
Scorpion with young clinging to parent
If you believe you've been stung by a bark scorpion more aggressive action may be necessary and you should contact a poison control center immediately and go to a health care facility if you are advised to do so. Though the bark scorpion sting may cause little redness or swelling, it is extremely painful. Since the venom is a neurotoxin, it affects the whole body rather than just the bite site, and it may produce fever, blurred vision, numbness or tingling sensations, muscle twitches, increased heart rate, and restlessness or hyperactivity.
Soffer, Ruth. North American Desert Life. Dover Pictorial Archive Series. New York: Dover Publications, Inc. 1994.
Sovak, Jan. Insects. Dover Pictorial Archive Series. New York: Dover Publications, Inc., 1994.
Stoops, Erik D. and Jeffrey L. Martin. Scorpions and Venomous Insects of the Southwest. Phoenix: Golden West Publishers, 1995.