Tuesday, July 29, 2014

The Sting

A honeybee gathers pollen from lavender flowers. Most of Malibu's insects are relatively benign, but summer is peak season for stings and it can be helpful to know what's out there and how to deal with any unfortunate encounters. Photo © 2014 S. Guldimann

“Beware the Jabberwock, my son!
      The jaws that bite, the claws that catch!
Beware the Jubjub bird, and shun
      The frumious Bandersnatch!”

—Lewis Carroll, Jabberwocky

Around here, shunning the ichneumon, velvet ant, and especially the tarantula hawk might be sound advice, too.

I was on a walk recently with visitors from Colorado. They marveled at how few biting bugs we have in the Santa Monica Mountains. It’s true, mosquitoes and black flies are mercifully few, but we still have quite a few stingers, many of them strange enough to be entirely at home in Wonderland. 

Let’s meet some of them, shall we?

With Scorpio, the largest and brightest of the summer constellations, dominating the night sky, it seems appropriate to start with this celestial creature's terrestrial counterparts. Although we tend to describe them as bugs, scorpions aren't insects, they're arthropods in the family ArachnidaAlthough there are four scorpion species in the Los Angeles area, the varieties most often found in Malibu are Paruoctonus sylvestrii, the common California scorpion; and Vaejovis spinigerus, the striped-tailed scorpion.

Paruoctonus sylvestrii, the common California scorpion, zeroes in on supper. This was a fairly large specimen—almost two inches long. Photo © 2014 S. Guldimann

Our scorpions rarely exceed two inches in length, but they are fierce nocturnal predators, able to subdue insects nearly their own size. Fortunately, they aren’t reportedly aggressive towards humans and prefer to avoid confrontation. In fact, although scorpions are common in the Santa Monica Mountains, many residents have never seen one.

The best way to spot these elusive arthropods is at night with an ultraviolet light, because the scorpion’s entire exoskeleton fluoresces under UV light—a recent theory proposed by biologist Douglas Gaffin of the University of Oklahoma suggests the fluorescent pigments may act as a light receptor for the scorpion—an eyeless way of seeing. Here's a link to a 2012 article in New Scientist.

An inexpensive UV flashlight makes it easy to spot scorpions at night. Although, ignorance is perhaps bliss. I was astonished to discover just how many scorpions are out there and I have no intentions of ever sitting on the ground again at night. Photo © 2014 S. Guldimann

I’ve been on several nighttime scorpion walks in the Santa Monica Mountains and I am astounded to find how many scorpions are out there. The fact that stings are so uncommon is a testament to the shy and retiring nature of these reclusive hunters.

Most stings occur when humans inadvertently disturb scorpion hiding places, including woodpiles and garden furniture. Scorpions have also been know to seek shelter in shoes left out overnight on the doorstep or in the folds of beach towels and other laundry left out to dry.

None of Malibu’s scorpion species are regarded as a dangerous and both the common scorpion and the striped-tail are apparently popular species in the pet trade. Both have a painful sting—victims compare it to a wasp sting—but it only poses a health hazard to individuals with severe allergy to the venom. 

Scorpions are beneficial, eating many times their own weight in insects, so peaceful coexistence—whenever possible—is the best way of dealing with them. Besides, they're all around us, whether we know it or not. 

There's another seldom seen Malibu resident with a painful sting: the soil centipede. This beastie is a type of Strigamia centipede. It's fast moving, lives under rocks and garden pots and will bite anything that it senses is a threat. Soil centipedes are eyeless and don't actually have teeth or stingers—they "bite" their prey—and the hand of any gardener unlucky enough to come in contact with them—with a pair of specialized legs that are used like fangs and connect to venom sacs in the body. It's a painful bite but reportedly not dangerous.

The soil centipede just wants to be left alone. For something that is nearly six inches long and bright red it's remarkably good at keeping out if sight and  moves fast when disturbed. Its first line of defense is to get out of the way, rather than to bite, although it does that with fierce efficiency if it feels threatened. This centipede was under a potted plant, where it was living a (presumably) happy life eating insect larvae. I carefully put the pot back and left it to go about its business. Photo © 2014 S. Guldimann

Scorpions and centipedes are all very well, but the serious sting awards go to three members of the wasp family. These insects are usually shy and reluctant to sting, but when they do they have a formidable weapon.

The female Netelia ichneumon wasp has a painful sting, used to subdue caterpillars.  It's been described as comparable to the sting of a yellowjacket or a bee. However, this is a beneficial wasp and it is reportedly only aggressive if handled. The Netelia in the photo is a stingless and benign male that somehow ended up in the house. This species is largely nocturnal, and often drawn to porch and garden lights. Photo © 2014 S. Guldimann

The velvet ant is actually a wingless wasp, and like its distant relative the Netelia it also has an impressively painful sting. Biologist Justin Schmidt, who has been stung by just about everything possible, famously developed a pain scale for insect stings. If the sting of the yellowjacket—the most common and aggressive stinging insect in Malibu and just about everywhere else in North America—is a 2 on the 1-4 Schmidt pain scale, the velvet ant is probably a 3. Children are at the greatest risk for encounters with this wasp, since it's brightly colored, pretty, furry and tempting to touch. Fortunately, allergic reactions are reportedly relatively rare. Like the ichneumon wasp, only the female of the species stings. The male is small, winged and easily mistaken for some sort of inconspicuous fly. Photo © 2014 S. Guldimann

Of all the Malibu-area bugs that bite or sting, the tarantula hawk—or pepsis wasp—is the queen. This wasp has a sting described by insect biologist and sting pain index creator Justin Schmidt as "Blinding, fierce, shockingly electric. A running hair dryer has been dropped into your bubble bath." 
 That's enough to make anyone cnidophobic. The wasp in the photo is feeding peacefully on milkweed nectar, and is shown only a little larger than life. Despite that legendarily horrific sting, it's not an aggressive species, but I was glad that I had a telephoto lens and didn't have to get too close. This wasp is usually rather rare in Malibu, since development has increasingly eliminated tarantula habitat, but for some reason, 2014 seems to be a banner year for the species. Most stings happen when the victim accidentally disturbs, steps on, or brushes against a wasp. Wearing gloves while gardening can help prevent unpleasant encounters. Photo © 2014 S. Guldimann

All three wasps are eye-catching and have vivid coloring, probably intended to warn would-be predators to stay away. It's a warning humans would do well to heed. The Tarantula Hawk has the distinction of being second only to the bullet ant on Schmidt's pain scale. He rates the sting of this wasp as a 4, and adds “…immediate, excruciating pain that simply shuts down one’s ability to do anything, except, perhaps, scream. Mental discipline simply does not work in these situations.” 

This spectacular insect really does prey on tarantulas, which is why it is armed with such a formidable weapon. The female tarantula hawk paralyses the tarantula with her sting and lays her eggs in the unfortunate arachnid, which she will drag to a preselected and prepared hole or burrow, where it will serve as a food source for the next generation of tarantula hawks. And you thought Malibu politics were nasty. 

On a practical note, wearing gloves and shoes while working in the garden can help prevent some encounters with stingers. Many Malibu bee stings happen on the beach, where bees congregate on the wet sand to find salt. A pair of flip flops can help prevent beech bee stings, but some bites and stings are unavoidable—yellowjacket wasps win the award for general orneriness and often appear to sting without provocation, and even in Malibu in the middle of the worst drought in decades, mosquitoes are still out for blood.

Anyone experiencing swelling, hives, breathing problems, or any other sign of a serious allergic reaction from any type of sting should seek immediate emergency medical assistance. Even without a serious allergic reaction, stings can be surprisingly painful and, in some cases, take days to stop hurting or itching.

It's a good idea to keep Benadryl in the first aid kit for sting emergencies. Anyone with sting allergies should make sure they have an up-to-date EpiPen on hand, as well. Here at the Malibu Post we like  "sting ampules."  These are tiny, individual tubes of benzocane that are easy to carry and can be applied to give temporary relief from all kinds of stings. I've never seen them at a store, but Amazon sells a cheap and effective brand).  Cortizone cream, Caladryl lotion and the kind of first aid cleansing spray or wipes with Benzalkonium Chloride and Lidocaine are also  helpful. Ice helps reduce the pain and swelling from most types of sting, although some respond better to heat. In all cases prevention is much preferable to any sting remedy, no matter how efficacious.

The beautiful and deadly tarantula hawk embodies the dichotomy of the insect world: they share our world—or, rather, we share their world, since there are a lot more of them than there are of us, but often they inspire fear because they appear strange or have the ability to defend themselves with powerful chemical weapons. Most stinging "bugs" are beneficial and serve an important function in the local ecosystem. Learning to coexist is important, and offers us a look at a world as weird and alien as anything in fiction, and sometimes also a glimpse of something rare and surprisingly beautiful.

Suzanne Guldimann
29 July 2014


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  2. Where can i look for scorpions in Santa Monica

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