Monday, November 1, 2010

Species of the Month: NOVEMBER

After living in Austin for over a year and making several trips into the more wildlife-infested surrounding Hill Country, I had my first scorpion sighting right in town last spring. 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 2 tales of painful scorpion stings from friends and decided that it was worth looking into the matter. Texas is home to about 20 species of scorpions, but Centruroides vittatus is the most commonly seen and the only one found throughout the state. It is 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 back in April.


Physical Attributes

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 2 characteristic stripes down its back.* Adults average about 2.5 inches in length, with males somewhat predictably having longer tails.

Dining Habits

Like other scorpions, Centruroides vittatus eats primary 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 killing it with their venom-packed stingers. The actual eating part is a bit 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.

Hanging out

As I mentioned, Centruroides vittatus is the mostly commonly observed species of scorpion in Texas. It is also a species most commonly found in Texas. While striped bark scorpions live in various other US 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. At the end of their date the male drops a sperm sac on the ground, which the female scoops up into her abdomen.

Scorpions are pretty special arachnids in that they are oviviparous. That means they don’t lay eggs. The eggs remain in the body of the female until birth. Gestation for Centruroides vittatus is a lengthy 8 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 in 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.

Can They Kill You?

Of the well over 1000 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

I spoke to Venecia, one of the recent scorpion sting victims about her experience. She had been mowing the lawn when the attack occurred and was informed only after the fact that Hill Country wisdom recommends always pushing the mower forward in tall gross, so that any stinging creatures encountered will be preventatively puréed. Venecia unfortunately made a backward sweep and picked up a scorpion in her shoe. Shortly after she felt what she describes as “an intense stinging pain” accompanied by a “a burning sensation that doesn't subside”. Venecia described her assailant (which she shook from her shoe upon being stung) as dark brown and about 3/4 the size of a pinky finger, so it was probably not our friend Centruroides vittatus that got her, but another similarly non-lethal Texas scorpion.

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 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. Striped bark scorpions, luckily, so not share their relatives’ venom potency.

4 comments:

  1. Hailing from Hanover, the Scorpion just wanted to Rock You Like A Hurricane in its native tongue.

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  2. I knew it was only a matter of time before some incarnation of this joke materialized. However, I was not aware that the hard rock musical outfit "Scorpions" were German (I erroneously thought them to be from Australia), so this tops anything I would have come up with.

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  3. Yep, I gots first-hand experience (so to speak) with this blog post, too.

    I was around 11 yrs. old, living in New Mexico, and having an uncomfortable night’s sleep: I kept feeling this pinching/jabbing sensation from time to time, as if a small, open safety pin was buried somewhere in the sheets. It was painful enough to make me scooch over in the bed, but not enough to fully wake up.

    Toward dawn, I slowly awoke to a weird tickling sensation on my chest. I reached up to scratch it, and got jabbed HARD in the base of my thumb. Wide awake, and thinking that the pin-or-whatever-it-was must now be caught in my t-shirt, I carefully reached up again to try and dislodge it; this time getting stabbed right in my fingertip.

    I sat up, looked down, and saw a scorpion crawling straight towards my face. Thus inspired, I grabbed the sides of my t-shirt, stretching it like a trampoline, and boinged the little bastard across the room. My left arm felt weird, and when I took off my shirt I could see that I had already been stung 6-7 times along the inside of my left arm and ribcage.

    Because I was a kid, and exhibiting parent-worrying symptoms (I was wired and sweaty, with pupils the size of hockey pucks), I ended up having to get a shot of antivenin, which I swear had more unpleasant side effects than the damn scorpion stings.

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  4. I have just downloaded iStripper, so I can watch the best virtual strippers on my taskbar.

    ReplyDelete