Lifeform of the week: Striped bark scorpions are deep in the heart of Texas
I lived in Austin, Texas for over a year before I had my first scorpion sighting. It occurred not during one of my forays into the wildlife-infested surrounding Hill Country, but right in the middle of town. The animal wandered into a classroom where I was learning German, causing much surprise and standing up from chairs amongst the students. The scorpion was escorted out of the building before any stinging ensued, but since then I’ve heard two tales of painful scorpion stings from friends and decided that it was worth looking into the matter. It turns out Texas is home to about 20 species of scorpions, but Centruroides vittatus – the striped bark scorpion – is the most commonly seen, and the only one found throughout the state. It’s one of a small handful of scorpion species recorded in the Austin area, and its appearance is satisfactorily similar to that of the creature that briefly attended my German class that spring day.
Like spiders and ticks, scorpions are arachnids. As such they have eight legs. Additionally they are equipped with a set of lobster-esque pinchers in the front and a long tail, complete with venomous stinger, in their rear half. The striped bark scorpion is yellowish to tan in color and wears two characteristic stripes down its back.* Adults average about 2.5 inches in length, with males somewhat predictably having longer tails.
Centruroides vittatus subsists on the standard scorpion diet, which is composed of various insects. They eat a lot of things you probably don’t much care for, including centipedes, flies, and spiders. They subdue their dinner by grasping it with their pinchers and then delivering a lethal dose of venom from their stinger. The actual eating part is a bit more complicated. Scorpions have tiny mouths, so they do most of their digesting externally by coughing up digestive fluids onto their prey and then sucking up the liquefied remains. If it helps, you can think of it as akin to drinking a nutritious smoothie.
As mentioned, Centruroides vittatus is the mostly commonly observed species of scorpion in Texas. It is also most commonly found in Texas. While striped bark scorpions live in various other U.S. and Mexican states, Texas is headquarters for these critters.
Being as they are not mammals, they must resort to behavioral thermoregulation. They tend to be more active at night and spend their days seeking shelter in cool, damp places (Texas summers are too hot even for scorpions). This can be any number of locations, from the undersides of logs and rocks to your air-conditioned apartment.
Courtship and mating
Scorpions have a fancy mating ritual where they pair off, grab each other by the pinchers and do a little dance. If the date goes well, the male then drops a sperm sac on the ground, which the female scoops up into her abdomen.
Scorpions are pretty special arachnids in that they are viviparous. That means they give birth to live young instead of laying eggs. Gestation for Centruroides vittatus is a lengthy eight months, after which about 30 baby scorpions emerge. The mother carries the new brood on her back for a few days until they are ready to care for themselves, which you must admit is pretty cute by arachnid standards.† Striped bark scorpions live for about 4 years and will generally reproduce several times in their life.
At the disco
Centruroides vittatus, as well as other scorpions, glow under ultraviolet light (the ‘black light’ seen in certain nightclubs). Needless to say, this is pretty cool. However, it is not always advantageous to the animals. I noticed that several pest-control websites sell a product called a “scorpion UV flashlight,” presumably used to find and stomp the little guys after nightfall.
Can they hurt you?
They sure can. While no reasonable scorpion would mistake a human for their desired meal, they will sting you if you inadvertently surprise them during their normal activities. Since they sometimes conduct their affairs in your yard, your home, or the discarded jacket you’re about to put back on, these encounters are an inevitable part of life in the Hill Country.
Can they kill you?
Of the well over 1,000 known species of scorpion, only about 25 have venom toxic enough to kill a human.‡ Centruroides vittatus is not one of these species. As with bee stings, some people may have an allergic reaction to the venom. In these cases, death due to anaphylactic shock can occur when treatment is not sought. If difficulty breathing is one of the post-sting symptoms, paramedics should definitely be called to the scene. Such incidents are rare, though. In most cases, the sting of the striped bark scorpion just yields about 20 minutes of sharp pain followed by another day or so of mild discomfort. An ice pack helps.
Don’t mow the lawn backward, and other sage advice
One of the scorpion sting anecdotes I heard involved yard work. Hill Country wisdom recommends always pushing a lawnmower forward in tall grass, so that any stinging creatures encountered will be preventatively puréed (a suggestion the storyteller heard only after she’d picked up a scorpion in her shoe during a backward sweep).
In addition to modifying your lawn mowing style, the best way to avoid run-ins with scorpions around your house is to not create a lot of comfortable sheltering spots for them. Leaving logs, stones, building materials, and trash around your yard can attract scorpions (not to mention rats, cockroaches, and raccoons). It’s also not a good idea to bring firewood into your home unless it’s going directly onto the fire. And you might consider a bit of weather stripping while you’re at it. In addition to keeping the scorpions out, you’ll waste less electricity.
* Technically, this would be “the upper surface of the abdomen,” but if I start using proper anatomical terminology to describe this thing, we’ll likely be here all day.
† Drinking blood (ticks), cannibalizing mates (spiders), etc.
‡ These belong to the family Buthidae, which is coincidently the same family in which Centruroides vittatus is classified. Striped bark scorpions, luckily, do not share their relatives’ venom potency.