Arizona Bark Scorpion
The Arizona bark scorpion (Centruroides sculpturatus, included in Centruroides exilicauda), is a small light brown scorpion common to the southwest United States. The range of the scorpion is the Sonoran Desert, though less toxic relatives of the scorpion are located throughout the Southern US. An adult male can reach 8 cm in length (3.14 inches), while a female is slightly smaller, with a maximum length of 7 cm (2.75 inches). Originally described as Centruroides sculpturatus, the species was synonymized with Centruroides exilicauda by Williams in 1980. In 2004 it was separated and renamed Centruroides sculpturatus once again based on DNA evidence and differences in venom. Centruroides exilicauda is native to Baja California while Centruroides sculpturatus is the "Arizona bark scorpion" of the Sonoran Desert.
Diet
The Bark Scorpion is nocturnal, prefers to ambush its prey, and typically feeds on crickets and roaches.
Predators
Bark Scorpions are most often eaten by snakes and tarantulas.
Life Cycle
Bark Scorpions have a gestation period of several months, and are born live, gently guided onto their mother's back. A female Bark scorpion typically gives birth to between 25-35 young, and the young will remain with their mother until their first molt, up to 3 weeks after birth. Bark scorpions may live up to 6 years.
While nearly all scorpions are solitary, the Bark Scorpion is a rare exception: during winter packs of 20 to 30 scorpions can congregate.
Bark Scorpions, like most other scorpions, are incredibly resilient. Lab experiments have frozen the scorpions for weeks, and after being thawed, the scorpion emerged unharmed. During US nuclear testing, scorpions were found near ground zero with no recorded adverse effects.
Habitat
The Bark Scorpion is particularly well adapted to the desert: layers of fat on its exoskeleton make it resistant to water loss. Nevertheless, Bark Scorpions hide during the heat of the day, typically under rocks, wood piles, or tree bark. Bark scorpions do not burrow, and are commonly found in homes, requiring only 1/16th of an inch for entry.
Arizona bark scorpions prefer riparian areas with mesquite, cottonwood, and sycamore groves, all of which have sufficient moisture and humidity to support insects and other prey species. The popularity of irrigated lawns, and other systems which increase environmental humidity in residential areas, has led to an explosion in the number of these animals in some areas.
The bark scorpion is unusual in that it is the only species in the southwest that regularly climbs walls, trees, and other objects with a sufficiently rough surface. Bark scorpions practice negative geotaxis, preferring an upside down orientation, which often results in people being stung due to the scorpion being on the underside of an object.
Venom
The Bark Scorpion is the most venomous scorpion in North America, and in sufficient quantities its venom will cause severe pain (coupled with numbness and tingling) in adult humans, typically lasting between 24 to 72 hours. Temporary disfunction in the area stung is common; e.g. a hand or possibly arm can be immobilized, or experience convulsions. Due to the extreme pained induced, many victims describe sensations of electrical jolts after envenomation.
Fatalities from the venom are rare in the USA, and are limited to small animals (including most pets), small children, and adults allergic to the venom. Extreme reaction to the venom is indicated by numbness, frothing at the mouth, paralysis, and convulsions. Two recorded fatalities have occurred in the state of Arizona since 1968: the number of victims stung each year in Arizona is estimated to be in the thousands. In Mexico, more than 100,000 are stung annually, and at its worst period, the Bark Scorpion claimed up to 800 lives annually during the 1980s.
Anti-Venom
An antivenom was developed for this species, and produced in quantities sufficient to treat individuals within the state of Arizona. This anti-venom is not FDA approved, and has not been highly effective and has side-effects. Production of this antivenom has since ceased, and a Bioclon anti-venom is being tested in its place.
First-Aid
Basic first aid measures can be used to help remediate scorpion bites:
- Clean sting site with soap and water
- Apply a cool compress
- Elevate affected area
- Take Tylenol, Advil, or Benadryl
Natural remedies include using the pulp from prickly pear on the sting site.
Medical Emergency
Since the amount of venom the scorpion injects on a sting varies, Arizona Poison Control will only suggest immediate medical attention in the event of extreme pain or stings involving children.
UV Lighting
Bark scorpions, like most other scorpions, will "glow" when exposed to a blacklight. This is particularly useful in scorpion detection, since Bark Scorpions are active during the night, and can be easily spotted using this method. Unfortunately, powerful UV light is necessary for detection beyond a few feet. Also, newly molted scorpions will not glow under UV light after the first few days of molting.
