The Scorpion Found in Arkansas Homes Glows Under UV Light

Quick Take

• Arkansas has only one scorpion species, and its sting won't kill you. However, there is a specific exception that changes everything. See the venom details →
• Scorpions glow blue-green under UV light, yet scientists still can't agree on why. The leading theories turn out to be more surprising than you'd expect. Explore the glowing theories →
• The glowing stops, and the exact moment it does reveals something unexpected about how a scorpion's body works. See when the glow fades →
• Baby scorpions don't hatch from eggs or crawl away at birth. What actually happens is far stranger. Discover how birth works →

Many insects and arachnids in the United States protect themselves with a painful bite or sting. In Arkansas, one of those is a scorpion, whose sharp, painful sting leaves a tingling sensation that can last for hours. For those who aren’t so fond of these stinging arachnids, you’ll be happy to learn there is just one species of scorpion in Arkansas: the striped bark scorpion (Centruoides vittatus). Read on to learn more about the striped bark scorpion, including how it glows in the dark.

What Is a Scorpion?

When most people hear the word “arachnid,” they assume you’re speaking of spiders. There are, however, a number of other critters that fall into this classification, including scorpions. These eight-legged arachnids are predatory and belong to the Scorpiones order. Unlike spiders, they have a pair of grasping pincers and a narrow, segmented tail that curves forward over the back, with a stinger on the end.

There are 2,500 described species and 22 living families recognized spread throughout the world, with the exception of Antarctica. Most species live in desert regions, but many, like the striped bark scorpion, have adapted to live in a variety of other habitats. Striped bark scorpions are the most common species in the U.S. In addition to Arkansas, they also live in Texas, Illinois, Colorado, Mississippi, Missouri, Louisiana, New Mexico, Nebraska, Oklahoma, Tennessee, and parts of Mexico. These arachnids can be found both indoors and outdoors, typically hiding in decaying organic matter, under rocks and logs, and in undisturbed areas of homes. In Arkansas, they can be found statewide, but are most populous in the western half of the state.

Thankfully, most scorpion species don’t pose a serious threat to humans, and healthy adults typically don’t even need medical attention after stings. Only around 104 species have venom that is medically significant to humans, but striped bark scorpions are not among them. Their venom is only mildly toxic. Of course, there are some exceptions if a person is highly sensitive or allergic, so some striped bark scorpion stings may require medical attention.

What Do Striped Bark Scorpions Look Like?

Growing to between 1 and 2.5 inches in length, striped bark scorpions are considered medium-sized arachnids. All arachnids have eight legs, and the scorpion is no exception. Striped bark scorpions are pale yellow to light brown with two long, dark vertical stripes running down their bodies. They have a dark triangular mark over the eye area and a long, slender, curving tail. Females generally have shorter, broader tails than males.

Striped Bark Scorpion Life Cycle

Mating for striped bark scorpions begins in the spring and may continue into autumn. The arachnids birth live scorplings (baby scorpions), with embryos nourished via the placenta before birth. After gestating for eight months, anywhere between 13 and 47 young are born. Once born, the scorplings climb onto their mother’s back to molt. Once molting has occurred, they leave the nest. A typical lifespan is between 3 and 8 years, although some species can live longer.

Scorpions forage for food in cooler temperatures, so they are most active at night. They spend the hot daylight hours in the shade, which allows them to conserve water and energy and remain hydrated. They also have a waxy cuticle covering their bodies which helps to reduce moisture loss.

Spiders, centipedes, crickets, flies, and beetles frequently form part of the scorpion’s diet, along with other insects. Their pincers help them trap and crush their prey after stinging and paralyzing it with their venomous tails, before ingesting it.

Glow-in-the-Dark Scorpions

Nearly all scorpion species, including the striped bark scorpion, glow in the dark under ultraviolet light, also called black light. The phosphorescent blue-green is caused by the hyaline layer of their exoskeleton, which is a tough, thin outer coating made up of compounds that are by-products of the shell-hardening process. These compounds absorb ultraviolet light from the environment, which is re-emitted as blue-green wavelengths on the visible light spectrum. Scorpions stop glowing immediately after molting until their new exoskeleton hardens.

Researchers are not entirely sure why scorpions glow in the dark; some believe it may not serve a critical survival purpose. However, other scientists believe that it helps them detect light, converting UV light from the stars and moon into the blue-green light they see best. Fluorescence is also believed to act as a natural sunscreen.