Review: The Sting of the Wild

Justin Schmidt is widely acclaimed for creating the Schmidt Pain Index that ranks the potency of the stings of bees, wasps, and ants, based largely on self-inflicted experience. It naturally follows that a book is in order to explain what most would consider a crazy person's pursuit. The Sting of the Wild, from Johns Hopkins University Press, is an odd combination of memoir and study in the scientific method. Does it succeed as either?

Full disclosure is also warranted here. I have known Justin as a friend, mentor, and colleague for decades, and am truly in awe of how his mind works. He asks questions that no other scientist does, then creates ingenious ways to test his hypotheses. No one I know is as innovative, persistent, and hard-working in the name of basic research. I was hoping that his personality and character would be reflected in this book.

The book contains what may be the best explanation of the attraction of certain people to scientific careers:

"Science is an exploratory process more so than a goal to realize. Yes, there are goals, and these must be clearly defined for funding agencies to support the research, but the real excitement and driving force in science is the adventure of seeking the goal, not in attaining the goal."

That is what I was anticipating from this volume: excitement and adventure. I have heard enough stories from Justin to know that he has a nearly limitless source of material, and is able to engage colleagues easily. So, what happened to that? Why did it not translate well to the written page?

If your usual reading in entomology is Howard E. Evans (Life on a Little Known Planet and Wasp Farm), May Berenbaum (Bugs in the System), or Bernd Heinrich (In a Patch of Fireweed), you will likely be disappointed by this book. Those unfamiliar with scientific terms, or chemical molecular structure, will find the book over their head at times, or at least dry and flat. Anecdotes from the field are lively enough, but too few and far between to sustain momentum of the narrative. The reader is forced to weave together the author's timeline from disparate passages and references, so the autobiographical aspect is also broken.

It stings me to say this about the book because its author is someone who should be admired and emulated. Schmidt is profoundly curious, a quality sadly lacking in too many scholars today, if not outright squelched by an academic environment that demands we be more concerned with "managing" nature than understanding it first. He is not some caricature or dare-devil as the media tends to suggest, but this book does little to change that impression, let alone create an understanding of what drives Schmidt's curiosity.

Despite its shortcomings, I learned a good deal from this book, and that alone may be enough to recommend it, at the very least as something worthy from your local library. A general audience is, unfortunately, not going to flock to this book. It reflects the novelty of the author's life, but lacks relevance to the reader unless he or she is also a scientist or aspires to be one. The complete "Schmidt Sting Pain Index," which makes up the appendix, is not enough to push the whole book into the limelight. The best natural history books ignite in the reader the urge to explore and discover. This one might keep them indoors, as a virtual spectator of other adventurers.

Brown Recluse

The Brown Recluse, Loxosceles reclusa, is without question the most infamous spider in the United States. Frequently maligned as the cause of serious necrotic wounds, and often confused with many harmless species, its reputation is inflated far beyond reality.

Identification

Also known as the “fiddleback” and “violin spider,” Loxosceles reclusa is usually marked distinctively on the carapace. This dark, violin-shaped marking may be vague, or even absent; and many other spiders have similar contrasting patterns. The only way to positively distinguish Loxosceles species is by their eyes. Brown spiders have only six eyes, compared to the usual eight eyes most spiders have. This sextet of ocular organs is arranged in a triangular pattern of three pairs. Understandably, most people don’t want to get close enough to a spider to see its eyes, but that is what is necessary to confirm an identification. Many other spiders are similarly colored, and of similar size. Recluse spiders attain a body length of 5-13 millimeters, with a legspan up to 30-40 millimeters.

Geographic Range

The Brown Recluse is native only to the central and southeast U.S., from Texas to northern Georgia, southeast Nebraska, southwest Ohio, and states in between. There are twelve other species of Loxosceles in North America, two of which are accidental introductions from other parts of the world. The Chilean Recluse, L. laeta, is found in only a few old, historical buildings in greater Los Angeles. The Mediterranean Recluse, L. rufescens, has turned up in many large urban areas, but is again usually restricted to a few highly localized populations. The remaining ten Loxosceles species are confined to the southwest U.S., from south Texas to southeast California and southern Nevada, and are found outdoors more often than in dwellings and other structures. While it is possible for any of the brown spiders to be transported outside their normal geographic range via commerce or travel, the Brown Recluse is less likely to spread than the foreign species.

Bites

The medical significance of the Brown Recluse has been sensationalized by the media and the internet. Various websites display graphic images of the most extreme cases of envenomation, if the pictures even represent spider bites at all. Yes, the venom of Loxosceles is cytotoxic (destroys tissues), and can produce necrotic wounds in some bite victims. However, many other maladies can express similar symptoms. MRSA (Methicillin-resistant Staphylococcus aureus) is one of these. More to the point, spider bites in general are a rare phenomenon. They are simply overdiagnosed. You owe it to yourself to read this article by Dr. Richard Vetter, and insist that your physician rule out those other potential causes if you ever present what you believe is a “spider bite.”

Should you ever present with a suspected or confirmed spider bite, run, don’t walk, away from any physician who applies electric shock to “deactivate the enzymes in the venom.” This is not a practice endorsed by any respected body of doctors, yet I personally know one bite victim in a rural area who received such “treatment” back in the year 2000.

Precautions

It is relatively easy to avoid the prospect of a spider bite by taking simple precautions, such as those outlined in this article from Spiders.us. Simply never put your hands in places you can’t see. Do be careful moving items that have been stored for lengthy periods without disturbance, especially clothes and linens, as spiders frequently hide in garments and blankets. One of the specimens depicted here was in the folds of a blanket that was taken out of storage in a home in Leavenworth, Kansas.

Natural History

The Brown Recluse earns its name for its shy nature. They hide in narrow cracks and crevices, under stones or other objects, from which they spin a thin, haphazard, vaguely sheet-like web. Sometimes they wander out of their snares, especially at night. They are surprisingly tolerant of others of their kind, so large populations may occupy a small area. The family living in one home in Kansas City, Kansas collected 2,055 specimens in only six months. No one in the household was ever bitten, either. Individual recluse spiders in captivity live 2-3 years.

Conclusions

You should really not fear the Brown Recluse, but do give it respect. Exercise caution in places that you do not visit frequently, like the storage shed, cellar, deep recesses of the garage, and similar structures. Do not assume that every spider you see is a recluse. Male spiders of nearly all species, including those normally confined to webs, will wander in search of mates and may stray indoors in their quest for love. Should you really be concerned, take the specimen to an entomologist or arachnologist at a university, natural history museum, or even the public health department to have it properly identified.

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Forks, Thomas P. 2000. “Brown Recluse Spider Bites,” J. Am. Board Fam. Med. 13(6): 415-423.
Kaston, B.J. 1978. How to Know the Spiders (3rd edition). Dubuque, Iowa: Wm. C. Brown Company Publishers. 272 pp.
Vetter, Rick. 2004. “Causes of Necrotic Wounds other than Brown Recluse Spider Bites,” UCR Spiders Site. University of California-Riverside
Ubick, D., P. Paquin, P.E. Cushing, and V. Roth (eds.). 2005. Spiders of North America: an identification manual. American Arachnological Society. 377 pp.

"Is it poisonous?"

Hardly a day goes by when I am not asked some version of this question. Maybe it is phrased “Is it dangerous?” or “Is it venomous?” This illustrates just how paranoid we have become of other life forms on this planet. Let’s clarify the definition of each of these terms, and the relative risks involved with each.

Most of the time, people use the terms “poisonous” and “venomous” interchangeably. What they usually want to know whether a given spider, scorpion, or insect is venomous. Venomous animals possess toxins that they deliver to a victim by biting or stinging. Nearly all spiders are venomous, as that is how they kill their prey. Only a handful of spiders are dangerously venomous to the average, healthy human being. Here in North America, the only spiders confirmed to be potentially dangerous are widows (genus Latrodectus), and brown spiders (genus Loxosceles). This is not to say that the bite from *any* spider cannot spark an allergic reaction in someone hypersensitive to venoms.

Western Black Widow (female)

What is generally exaggerated is the risk of being bitten by a spider. The likelihood of being envenomated by a spider is quite miniscule, especially if you take simple precautions like those suggested in this article at Spiders.us.

Some venomous insects can come as a surprise to the uninformed or uninitiated. Several caterpillar species, for example, have stinging spines or hairs that can cause excruciating pain, at least in some people. Be careful not to touch hairy or spiny caterpillars.

Flannel Moth caterpillar

Ironically, tarantulas in the genus Aphonopelma will kick tiny, barbed hairs off of their abdomen instead of biting in self-defense. The hairs become airborne and, if inhaled or otherwise contact mucous membranes, cause severe irritation or even allergic reactions. Some people who handle tarantulas, or even the molted exoskeleton, may pay for the experience with contact dermatitis.

Wheel Bug adult

Many species of ants other than fire ants are capable of stinging, as can “velvet ants,” wasps in which the female gender is wingless and may resemble a large, hairy, brightly-colored ant. Assassin bugs like the Wheel Bug, and aquatic bugs like giant water bugs (aka “toe-biters”), backswimmers, and water scorpions, have a venomous bite to immobilize prey, but they can bite in self-defense, too. I can speak from experience that it is not pleasant.

Giant Centipede

Centipedes, fast-moving, snake-like arthropods with “too many legs,” are venomous, their first pair of legs modified into fangs they use to subdue their prey or defend themselves. Scorpions, arachnids related to spiders have a venomous stinger at the end of their telson (“tail”), but only the “bark scorpion,” Centruroides sculpturatus, is dangerously venomous. It occurs only in Arizona, western New Mexico, southern Nevada and Utah, and extreme southeast California.

The term poisonous means that an organism is toxic if ingested (swallowed). A startling number of insect species actually are poisonous and it pays to learn which ones, especially if you have curious toddlers prone to putting things in their mouths. Fireflies are very poisonous, as their bodies contain lucibufagins, toxins closely related to the toxins in toads.

Blister Beetle, one of many species

Blister beetles (image above) are aptly-named, for when molested they ooze a liquid substance containing cantharidin, an irritant that can raise blisters on sensitive skin. Even worse, if eaten, they can be lethal. Ranchers must be careful that blister beetles are not accidentally baled in hay. Horses that swallow beetles along with hay can die.

Millipedes, slow-moving, worm-like arthropods with lots of legs, are vegetarians, but most can defend themselves with harsh chemical secretions. Some species, like the one shown below, ooze cyanide compounds to repel potential predators. Others produce substances that can stain, or even burn, the skin.

Flat-backed Millipede

Luckily, many venomous and poisonous insects and spiders are aposematic. That is, they are marked with bright, contrasting “warning colors” such as black and yellow, orange, or white. There are many completely harmless insects that mimic those dangerous species, but when in doubt it pays to avoid handling brightly-colored animals.

While I do want people to find fascination in insects, spiders, and other invertebrates, I also want the public to stay safe and healthy. Be careful out there.

Spider Sunday: A Common "Indoor" Spider

At this time of year, there is one spider that is commonly encountered indoors in the eastern United States and southeast Canada. It has a bi-colored body that makes it conspicuous and different from most other spiders one is likely to see around their residence. Trachelas tranquillus, is sometimes known as the “Broad-faced Sac Spider,” a member of the family Corinnidae.

This is a spider of average size, adult females measuring 7-10 millimeters in body length, males 5-6 millimeters. It occurs from Nova Scotia and Minnesota south to Kansas, Oklahoma, and northern Georgia, preferring deciduous woodlands. In nature, specimens are often found in retreats fashioned from curled leaves; or they are seen occasionally under stones.

I have seen this species hunting actively at night, prowling around porch lights where it may be hunting various insects attracted there. Trachelas does not spin a web, but does lay down draglines to help secure itself during climbs. Females probably also impregnate their draglines with pheromones (scents) so that males can track them down.

© Ken Lebo 2012

Mating usually happens in summer and early fall, after both genders have matured (nice images on the highlighted link). Females create a lens-shaped egg sac, the bottom flat against a substrate and the top slightly convex. The whole package is roughly ten millimeters long and usually attached beneath loose bark, or under a rock.

Besides killing live prey, Trachelas may scavenge on dead insects. Perhaps this is why it prospers when other spiders have either perished or gone into hiding in autumn. This scavenging habit may also influence the outcome in those rare instances when the spider bites a human. Secondary infections from its bite have been recorded, originally interpreted incorrectly as caused by the spider’s venom.

© Sarah Rose

The fact that Trachelas hunts regularly in and around homes and other buildings means it is more likely to have interaction with people. Still, verified cases of bites are infrequent, and usually result in only localized pain and swelling. People sensitive to arthropod venoms, or prone to allergic reactions, should seek medical attention for any arachnid bite (or sting in the case of scorpions).

Further complicating this picture is the confusion of Trachelas with another spider that is completely innocuous, though more intimidating. The Woodlouse Hunter, Dysdera crocata, is a specialized predator of woodlice, known commonly as “sowbugs,” “roly-polies,” or “pillbugs.” This species has exceptionally long jaws and fangs it uses to turn over its armored prey. While it looks dangerous, it is not.

Dysdera crocata © Nick Richter 2010

Dysdera is not native to North America, having been introduced from Europe at some point in our history. It has also become accustomed to prowling around human dwellings, so may be found indoors. It does not climb as well as Trachelas, however, and in my experience the Woodlouse Hunter prefers to hug baseboards.

Dysdera crocata © Sarah Rose

I encourage my readers to appreciate all spiders, but also act responsibly. It is a good idea to try and exclude spiders from entering your home and workplace by repairing worn weatherstripping on doors, mending holes in window screens, and sealing any cracks and crevices that could offer passage for insects and arachnids. Be careful when bringing objects indoors from outside, too, like firewood, gardening implements, children’s toys, and shoes and clothing left outdoors overnight.

Sources: Cox, Shelly. 2011. “Ground Sac Spider,” MoBugs blog.
Eaton, Eric R. and Amanda Howe. 2012. “Trachelas tranquillus (Ground Sac Spider),” Spiders.us.
Jacobs, Steve. 2002. ”Broad-faced Sac Spider,” Penn State University fact sheet.

Spider Sunday: Western Black Widow

The first time I encountered a black widow was in the desert of eastern Oregon. I cannot recall the circumstances exactly, but I was rather awed, given that I had read about them but never seen one until then. Thanks to the book How to Know the Spiders, by B. J. Kaston, I learned the species found in the Pacific Northwest is the Western Black Widow, Latrodectus hesperus.

Eventually, I was able to easily identify black widow webs, even if the spider was not present. Black widow webs are large, three dimensional tangles of extremely strong threads. The whole web can easily occupy a cubic foot or more, and you can pluck the silken strands like guitar strings without them breaking. A funnel-like retreat is usually seen going into a rodent burrow, under a boulder, or some other cavity that would take heavy machinery to break into. Black widows do not want anything to do with larger animals. Only at night are you likely to see the spider out on her web.

Believe it or not, black widows begin their lives as largely *white* spiders. They lose the pale spots and stripes as they age, but because males mature more quickly, in fewer molts, they never lose their pale markings entirely. Even the immature spiders sport at least some semblance of an “hourglass” marking on the underside of their abdomen, so you can still identify them as widows. Since widows sit upside down in their webs, that hourglass marking is usually visible.

The Western Black Widow is the largest North American member of the genus Latrodectus. Females have a body length of 14-16 millimeters as adults, males 7-8 millimeters. Mature females usually lack any red markings besides the hourglass, and that may be broken or even wanting in some specimens. Some individuals may be chocolate brown instead of black.

Mature males are recognized by their swollen pedipalps, which resemble tiny boxing gloves located near the spider’s face. He uses these as intromittent sex organs that fit like a key in the “lock” of the female’s paired genital openings. Contrary to popular myth, the female does not always cannibalize her mate, though sex is a risky business for nearly all male spiders.

Mated females can produce several egg sacs in their lifetime, each containing up to 750 eggs. Few of the spiderlings that emerge will make it to maturity themselves, due to cannibalization by siblings and other natural hazards. Adult females can live more than a year, though.

Western Black Widows are able to secure surprisingly large prey. Their webs are designed to trap prey walking over the ground. When a victim stumbles into one of the sticky trip threads attached to the ground, the thread breaks and rebounds, yanking the potential prey animal into the main body of the web. The trip threads are so elastic and strong that even small vertebrates can be captured in widow webs. I personally witnessed a hatchling lizard struggling in a web. Yes, I intervened.

While black widows have no problem killing prey as imposing as large beetles, they flee rapidly when they sense a larger creature such as a human. The speed at which they can scramble back into their retreat is astonishing. I have had many a photo opportunity cut short when I accidentally bumped a thread.

The Western Black Widow is a very common spider found from extreme southern British Columbia south to Mexico and west to Kansas, Oklahoma, and Texas. It is particularly abundant in drier habitats such as deserts and prairies, though it can be encountered in more damp situations as well.

Because of the timid nature of widows, it is relatively easy to minimize the possibility of being bitten. Simply take these precautions:

• Never leave clothing, shoes, or gloves outdoors overnight. A spider can seek shelter during that time.
• Do not put your hands or feet where you cannot see into, such as holes and crevices, inside the mailbox, or behind large objects that have been in storage for awhile.
• Carefully inspect firewood, houseplants, toys, etc being brought indoors from outside in case a spider may be hitchhiking on the object.
• Do not walk barefoot outdoors, especially at night.

Reactions to bites from widows can vary considerably from one person to the next because immune system responses to envenomation are highly individualistic. The spider may not even deliver much, if any, venom. Still, they typical experience is excruciating. The venom is neurotoxic, meaning it affects the nervous system. This translates to triggering constant muscle contractions that result in severe cramps, especially in the abdomen, legs, and other large muscle groups. One friend of mine had back spasms for months following a black widow bite. One should always seek emergency hospitalization immediately, precisely because one cannot be sure how their body will react. Antivenin is available for treatment, though it is recommended as a last resort by most hospital physicians. Antivenin is produced from horse serum, which can carry its own complications including allergic reactions. Obviously, avoiding bites is preferable to treating them after the fact.

Black widows cannot be easily “controlled.” Contact insecticides have a very low probability of reaching a hidden spider, and killing one spider means it will soon be replaced by another anyway (prime web sites are a coveted commodity). Meanwhile, the spiders will kill plenty of pest insects that could potentially be more trouble than the spiders themselves. By all means, do inspect playground equipment and toys before allowing your children to play outdoors. It all comes back to vigilance and prevention. Take care, but value the work your spiders do.

Spider Sunday: Brown Widow

Spiders are very good at exploiting us humans, and using our vehicles and cargo to conquer new territory. One example of this phenomenon is the Brown Widow, Latrodectus geometricus. Exactly where this species is native to is a matter of speculation. It is known from South Africa, the Middle East (Afghanistan), the Mediterranean (Cyprus), Australia, the southern United States, and even Japan.

Here in the U.S., L. geometricus has been well-known in the southeast, but has been extending its range up the Atlantic Coast (to North Carolina so far) and across the entire southern tier of states (Tennessee, Texas, southern California). There have also been reports from Nevada and Colorado. The specimens shown here were imaged along a retaining wall at an undisclosed location in Redondo Beach, California (a friend’s house).

According to arachnologists, despite the virulence of the venom of the Brown Widow, the species should not be considered dangerously venomous to the average, healthy adult person. The spiders apparently inject less venom than black widows, and the effects are more localized than systemic. One can avoid the potential of a bite simply by not placing his or her extremities where they can’t see, and avoiding clutter in yards, sheds, garages, and other situations where the spiders are likely to occur.

The Brown Widow is very likely to be confused with a completely innocuous spider known as the American House Spider, Parasteatoda tepidariorum. The two are nearly identical in appearance, but the House Spider never has a red hourglass marking on the underside, whereas the Brown Widow does. Like most widows, the Brown Widow prefers to sequester itself deep inside cracks or crevices by day, venturing out into its web only at night. House spiders do not have retreats, so are visible at all times, though usually tucked snugly against a wall or other surface during the day. The House Spider also has a much broader distribution, being found across most of the North American continent. Below is a pair of House Spiders, male on the right.

The egg sacs of the Brown Widow are highly distinctive, being spherical but bearing numerous tufts of silk (see images below). Both the Brown Widow and the House Spider belong to the family of "cobweb weaver," Theridiidae, which only adds to the confusion in identifying them. They both build extensive, tangled snares.

The “spread” of the Brown Widow to the west coast is a relatively recent occurrence, the first specimens being noted in the Los Angeles area in February, 2003 as a result of the Los Angeles Spider Survey being conducted by the Natural History Museum of Los Angeles County. Verified accounts of this species from elsewhere along the Pacific Coast would be welcome. It has been suggested that trucks, cars, and recreational vehicles have mostly been responsible for the assisted migration of this species. That seems reasonable, especially in the case of RVs, which often sit idle for long periods, allowing spiders to establish themselves there.

Sources: Brown Widow Spiders
Santana, Fred. 2007. Brown Widow SpidersUF/IFAS Sarasota County Extension
Levi, Herbert W. and Lorna R. and Herbert S. Zim. 1990. Spiders and Their Kin. New York: Golden Books. 160 pp.

House Centipedes

One of the most confounding, and arguably creepiest, creatures I am asked about at AllExperts.com has to be the “house centipede,” Scutigera coleoptrata. Neither insect nor arachnid, it is variously described to me as spidery, an animated feather, a speeding, ghostly apparition, and plenty of other epithets born out of both fear and fascination.

This species seems to be genuinely domestic, occurring mostly in and around human habitations where these venomous predators prowl in search of other invertebrates to eat. It is thought to have originated in the Mediterranean region, but unless one starts speaking Italian or Greek, you could fool me. International commerce has now succeeded in transporting the house centipede to virtually all inhabited corners of the globe anyway.

Related species in the genus often live in caves, and indeed the long legs and antennae of this animal are characteristic of habitats where visual acuity is much less important than a sense of touch. The lanky build of these creatures also makes them appear much larger than the 25-35 mm body length of the average specimen. Couple that with the incredible speed at which they can travel, and you have the heebie-jeebies come to life. I confess they can even freak me out at times because they can climb walls and scurry across ceilings at about Mach 7.

Fortunately, house centipedes are totally harmless to people and pets (well, if you have a flea circus I guess you’d better be careful). I encourage folks who encounter house centipedes to just let them continue their pest control patrol, like this one is doing, or usher the centipede into a container and release it outdoors in a woodpile, rock wall, or other sheltered situation where it will be equally happy hunting for food and mates. Those approaches are certainly preferable to "Honey, can you get me a shoe? A really big shoe?"

Spider Scare in the News

Last week a news story broke about a potentially dangerous neotropical (New World tropics) spider that stowed away in a crate of bananas from Latin America and ended up in a grocery store in Tulsa, Oklahoma. Credit the media for sticking with the story and getting it right for a change, successfully quelling what could have been needless widespread public hysteria.

Two experts in the case contradicted each other’s identification of the arachnid, and because the specimen was dispatched, there was no way to verify its identity. There are several species in the spider family Ctenidae, collectively known as “wandering spiders” because they do not spin webs to catch prey. Their large size and often aggressive behavior is enough to intimidate a person, regardless of how venomous they may be. The genus Phoneutria includes at least some species that can, rarely, deliver a lethal bite. Species in the harmless genus Cupiennius, however, can be easily mistaken for their deadlier cousins.

Richard S. Vetter and Stefan Hillebrecht addressed this dilemma in the cover story of the summer, 2008 issue of American Entomologist, a journal of the American Entomological Society. The bottom line from the article is that without close examination of a specimen, it is unlikely that an individual spider can be correctly identified. The better news is that fatalities from bites of Phoneutria are very rare, even for “at risk” populations such as the elderly and infants. It is largely one’s immune system response, rather than the toxicity of venom, that determines whether a bite will result in no reaction, a mild response, or a severe trauma.

Many of the reader response comments on the Yahoo version of the story centered on the perceived failure of our government inspection services. Dangerously venomous tropical spiders do not routinely infiltrate our nation, however, and the large volume of foreign shipments to the U.S. precludes comprehensive inspections. It is the price we pay for a “free market” where goods pass unfettered across borders. Collectively, through our demand for tropical fruits and houseplants, we consumers have determined that risks like spiders are an acceptable hazard.