Bark Scorpions of the Southwest

Bark Scorpions of the Southwest

The Bark Scorpion only averages from one to three inches long -- yet in the 20th century, the sting of the bark scorpion killed more people in Arizona than the all types of poisonous snakes within the state grouped together (Gouge et.al, 2007; "Bark Scorpion," Arizona Highways Magazine. 2005). In this century, thanks to increasing awareness of the deadly nature of the sting of this creature, no one has suffered a fatal attack, and it has been thirty years since a documented fatality has been recorded in Arizona. However, it is important for everyone who may come into contact with a Bark Scorpion to be aware of the terrible risks posed by the scorpion to humans, and to gain a sense of its habits. Even when it is not fatal, the sting of a Bark Scorpion can pose a serious risk to humans.

The Bark Scorpion is especially dangerous to infants and small children, and has most often attacked humans who were picking up firewood or rocks. The scorpion likes to find shelter from larger predators like birds in such concealed areas, and to shelter from the sun during the day. The animal's official name comes from the scorpion's habit of seeking shelter beneath the underside of wood pieces, but it is also known as the Crevice Scorpion because it also hides in the crevices of trees and stones (Gouge et al., 2007).

Although scorpions as a whole "are commonly thought of as desert animals" they may be found in grasslands and savannahs, forests, and caves, but the Bark Scorpion is most common the desert states of the U.S. including California, Arizona, Nevada, southern Utah, and southwestern New Mexico and the Baja Peninsula (Gouge et al., 2007). Bark Scorpions, like all scorpions are classified as venomous arthropods in the class Arachnida, the same class that includes poisonous and nonpoisonous spiders. Scorpions have an elongated two-parted body and a segmented tail tipped with a stinger. They have four pairs of legs with pliers-like pincers on the end. These pinchers are used for grasping. The body's two parts are called the cephalothorax and the abdomen. The cephalothorax is covered above by a head shield "that usually bears a pair of median eyes and 2 to 5 pairs of lateral eyes at its front corners" (Gouge et.al, 2007). On its underside, the scorpion has pectines or feelers "used to sense the texture and vibration of surfaces....The abdomen consists of 12 distinct segments, with the last five forming the metasoma" or 'tail.' At the end of the abdomen is the telson, "which is a bulb-shaped structure containing the venom glands and a sharp, curved stinger to deliver venom" (Gouge et.al, 2007).

The scorpion's preferred temperature is a night above 70F. Scorpions are active at night, and spend their days where it is cool and moist. Scorpions have extra layers of fats on their exoskeleton to retain water. Scorpions get most of their water from their food. They feed on a variety of insects, spiders, centipedes, and even other scorpions. One unique feature of the Bark Scorpion is, while most scorpion species are solitary in nature, they may be found in groups of 20-30. Also, much to the distress of many homeowners (where bark scorpions also make their homes) "the bark scorpion is also one of relatively few species that are able climbers" (Gouge et.al, 2007). Because of their small size, the Bark Scorpion is sometimes called the Home Scorpion, because it is the species most commonly found in infested homes.

Another annoying feature of the pest for humans is that scorpions are immune to most pesticides. Exterminators are necessary to control them within human structures, often using the species' glow under the glare of UV light to spot them (Hedding, 2007). Furthermore, the Bark Scorpion's sociability makes the scorpion more prolific. "Scorpions have a complex mating ritual in which the male uses his pedipalps to grasp the female's pedipalps...The sperm from the male is contained within a structure called a spermatophore, which is deposited by the male on a surface over which the female is pulled. The male sweeps his pectines over the ground surface to help locate a suitable place to deposit his spermatophore. The female draws the sperm into her genital pore, which is located near the front ventral (under) side of her abdomen" (Gouge et.al, 2007). The one positive aspect of scorpion mating for humans is that scorpion gestation can take up to a year. Females give birth to 25-35 young, and remain with their young from 1-3 weeks. Scorpions molt periodically through their life cycle, and the animals usually live from 3-5 years (Gouge et.al, 2007).