The Bug Dude presents The Skeptical Entomologist
Hazardous Insects and Spiders
A look at the dangerous to humans posed by common insects, scorpions, and spiders.
INTRODUCTION
If there's one thing that seems to really get people's attention, it's the figure of a spider or a wasp on the wall. In western societies, as many as 55% of women have arachnophobia, and 18% of men are severely afraid of spiders. [1] These fears are justified by those who dislike spiders with the fact that "spiders are dangerous, a black widow can kill a person!" While the bite of a Latrodectus can indeed kill a small child if medical treatment is not sought immediately, this hardly seems to be a valid reason for the image culture has placed on these animals. Only slightly less maligned are bees, wasps, and ants; the former two for their stings, and the latter for their tendency to invade homes. Paradoxically, people love to come across an Asian ladybird beetle (Harmonia axyridis), even though the foul smelling substance it expels onto the skin is, in fact, a poison, and itself is a ravenous predator of aphids (once again emphasizing the notion that perception is everything; our cute symbol of spring is a terrifying hunter).
The purpose of the essay is to argue that insects and arachnids are not as inherently dangerous as they seem. While there are many urban legends (spiders under toilet seats, soldier and camel killing solpugids), some with a basis in truth (the recurring and errant internet meme of the "spider under the toilet seat" has its roots based in the wild west, where outhouses made excellent hunting grounds for Latrodectus spiders), these are largely unsubstantiated and, even it they were true at some point, utterly irrelevant now; in the age of advanced medical technology, human deaths from these animals are incredibly rare.
The Eight Legged Freaks Versus Man's Best Friend
The reason that insects, spiders, and scorpions are maligned by humans may be the fact that they are so different than us. We only have four limbs, while they have a minimum of six. Many eyes, or large, complex globes of ommatidia which watch the world unblinkingly. However, the claims are often based on the animals being seen as "dangerous". I myself have experience in such a claim, being told that if my own progeny came into contact with my P. imperator or G. rosea, there would be dire consequences. How do these magnificent, miniature marvels so compel us with fear to urge us to threaten each other when another willingly keeps them in their home?
It is extremely bizarre (to me anyway, although that may be the Aspergers talking), at least on the face of it, that a country which loves sky diving, roller coasters, a love of guns, of fast cars and rodeos would fear a creature as small as a spider. We could crush a spider without a second thought, and when we weed, we are literally destroying their microhabitat (to quote J. Robert Opppenheimer, "And now I've become death, destroyer of worlds."), and yet they haunt our collective memory to such an extant that few other animals - most notably the shark - rival them in terms of fear factor.
A basic search of "dangerous animals" or "U.S. deaths caused by spiders" brings up horrifyingly specific figures. One website cites, without any real information to back it up, 100,000,000 annually; the site looks to be, fortunately, satire.[2] Distressingly, this seems to be the common theme; "spiders are dangerous, and they should be gotten rid of". One website states that the deaths caused by venomous spiders are eight times as great as deaths caused by both bees and wasps (or maybe it's the other way around; the wording is, actually, rather horrible).[3] To further add to the confusion, the CDC only inflames things by listing three venomous, medically significant spiders instead of the normal two (Latrodectus and Loxosceles reclusa); the added species is the hobo spider (Tegenaria agrestis)[4]. Still, others claim another venomous spider which lives in the United States: Cheiracanthium inclusum, the American yellow sac spider. Once you add in the fact that the occasional wandering spider from Brazil (Phoneutria), a very venomous species, occasionally stows away in shipments of bananas to supermarkets, it would seem we are living in a veritable nightmare.
The Brazilian wandering spider, sometimes called the banana spider.
Of course, spiders aren't the only animals which have to contend with bad publicity. At least as equally feared as spiders, if not more, in some parts of the country are scorpions; in the American southwest, they are everywhere. By far the most feared is Centruroides excilicauda, the Arizona bark scorpion, which is also the only scorpion out of the 80 North American species which can be fatal to humans. But scorpions aren't the only things which give spiders a run for their money; soplugids, better known as camel spiders or sun spiders, are found worldwide, and are (also worldwide) the subject of many, rather gruesome, urban legends. Then you have bees and wasps (the only wasp I would be wary of is the tarantula hawk wasp, for reasons we shall see later), which have given chemical corporations a wide market to sell their wares to.
But how do these animals fare when compared to other animals? The most deadly of the insects and arachnids, the spiders, kill on average 6.6 people annually (this is a rather liberal number; the more conservative estimates are zero); admittedly, these are also the cases in which very young children are bitten, and medical help is not offered to the victim. On average in the United States of America (where the 6.6 people are allegedly killed by spiders), less than 1 person is killed by grizzly bears (it seems an odd thing to say, but it's an average); one person is killed annually by a cougar.
Dogs by far have the highest kill rate of any animal outside of humans. 31 deaths occur annually from dog attacks; the most common culprits of canine crime are pit bulls, rottweilers, dobermans, and German shepherds. People have also been run down by mix breeds, golden retrievers, labradors, St. Bernard dogs, mastiffs, American bulldogs, Alaskan malamutes, and even weimaraners. Yet people absolutely love their dogs. There are even those who claim that, despite continually topping the list in causes of fatal dog attacks, pit bulls are perfectly safe to be kept around small children and infants. This is incredibly alarming when one considers that most of these deaths involved small children, toddlers, and babies.
These are often the same people, mind you, who absolutely hate spiders, scorpions, centipedes, and insects. Why would people hate an animals that only can kill you if you don't seek medical attention, yet leave their small toddlers around an animal with a reputation for turning on its owner?
To push the issue of this cognitive dissonance home, let's recap (these are for the U.S. only):
Dog breeds known to kill humans: pit bulls, rottweilers, doberman pinschers, German shepherds, mongrels, golden retrievers, St. Bernard dogs, bull mastiffs, American bulldogs, Jack Russel terriers, Alaskan malamutes, huskies, weimaraners, schnauzers, labradors, wolf-dog hybrids, great danes, American Staffordshire terrior, chow, pomeranian, airdale terrier, English sheepdog[9]
Spider species known to kill humans: Black widow, brown recluse
Despite it's higher kill count, many people would prefer a dog
to a spider.
As many people would assert, the basis of fear is not only due to the fact they are venomous. The human brain responds differently to different shaped objects. Even though the domestic dog (Canis lupus familiaris) is much more dangerous than a spider is, humans usually do not fear them because they are similar to us. They're bodies contain no rough angles, they don't move suddenly or in a "jerking" manner. The human brain has evolved to find animals with large eyes cute (which is why human babies have seemingly large eyes), a trait often found in dogs. Dogs also display a remarkable ability to react in ways spiders cannot; dogs display some degree of empathy, acting sad when their owner, say, displays signs of depressions. Dogs may even empathize better with humans than any other animal, including humans.[5] Spiders, on the other hand, are solitary. While dogs evolved as social animals whose survival depends on maintaining a position in a highly structured social group, spiders never had any need to evolve such behavioral traits.
This is not to say that venomous insects and arachnids should not be taken seriously. Even if they cannot kill, their venom (wasps, ants, bees, spiders, scorpions), pedipalps (scorpions), and the "mandibles" of soplugids (actually, they are their cherlicerae) can cause intense pain in those who are stung. For example, the sting of the tarantula hawk wasp (genera Pepsis), for example, is extremely painful, and second only to that of the South American bullet ant (Paraponera); when stung by a Pepsis wasp, Justin Schmidt (who devised the Schmidt pain index for the stings of bees, wasps, and ants), described it as so painful the only thing a person can do is scream.[6]
Many venomous spiders have conditions named after them; Latrodectus spiders, for example, cause a condition known as latrodectism in those who have been bitten, and the experience, while not fatal, is extremely unpleasant. Even pet species of arachnids can do some damage; P. imperator does not cause any major damage with its sting, but large ones have been known to break skin with their pedipalps; New World tarantula bites are often treated as minor stab wounds as opposed to spider bites, because the majority of the damage is done by the actual bite itself when compared to the effect of the venom.
Why we fear arthropods lies deep in our evolutionary past. That's right, before the advent of modern medicine, bites form spiders, stings from scorpions or wasps, could very well prove fatal. Studies show that humans are instinctively more afraid of dark colors, sharp angles, and unpredictable movements than smooth curves, bright colors, and predictable behaviors. The former is often found in arthropods, while the latter is found more commonly in birds and mammals (and butterflies; have you ever noticed how people hate moths but love butterflies?). According to psychologist Jon May,
Why we fear arthropods lies deep in our evolutionary past. That's right, before the advent of modern medicine, bites form spiders, stings from scorpions or wasps, could very well prove fatal. Studies show that humans are instinctively more afraid of dark colors, sharp angles, and unpredictable movements than smooth curves, bright colors, and predictable behaviors. The former is often found in arthropods, while the latter is found more commonly in birds and mammals (and butterflies; have you ever noticed how people hate moths but love butterflies?). According to psychologist Jon May,
We like bright-coloured [sic] butterflies and ladybirds, but spiders are dark coloured with long, angular legs... we also are very sensitive to seeing things moving our of the corner of our eye and immediately notice it, and insects move quickly and unpredictably.[7]
It doesn't help much when we see arthropods eating things we would generally consider animals which would eat them. It seems utterly mind-blowing that a praying mantis would catch a hummingbird, or that a spider could kill (and consume) a snake. Yet, these things happen (if Facebook is to be believed, the majority of these things happen in Australia), and their occurrence seems to throw our established "food chain" on it's head (yet another reason to adopt "food webs" instead of "food chains"). However, this really does not violate any natural order; much like any animals, many arthropod predators will take whatever they can catch.
Fear of such animals is also likely driven by a general misunderstanding of them by the public. While a person may be driven to understand the behavior of a dog, or a bird, or a fish, they may simultaneously never give two thoughts to how a spider or a wasp sees the world. As such, these organisms remain an enigma, whose behaviors are as elusive as a half-forgotten dream, who are forever seen as living in the shadows.
Fear of insects and arachnids aren't the only remnants of our evolutionary history; the common fears of heights, enclosed spaces, and the dark once were great assets to our pre-human ancestors. But, in the 21st century, these fears no longer have any survival value; remnants of a dangerous and brutal live in nature, before we had the technology to control the environment, they can only hold us back as we go into the future. While the exotic pet trade is helping to squelch some of these unnecessary fears and negative stereotypes about invertebrates, everybody should try to learn as much as they can about spiders, insects, and scorpions.
Once again, it seems that myths have been cultivated over an animal with a bizarre appearance that the general public knows very little about. To complicate the problem, the History Channel (who's expertise is "history") ran an episode of the pseudoscience show Monster Quest in which "arachnologists" scoured Middle Eastern deserts for giant solpugids, although they predictably didn't find any (which didn't seem to affect their optimism that it exists). As with many other arachnids, enthusiasts are constantly having their time preyed upon by the gullible who have been taken in by these wild falsehoods. As Winston Churchill famously said, "a lie gets halfway around the world before the truth has a chance to get its pants on."
Another common myth about camel spiders is a truly terrifying one (or, it would be terrifying, if it were in any way accurate). This myth claims that they run parallel to military vehicles, emitting a screeching sound as they run. While utterly ridiculous, camel spiders are considered to be the fastest of all land arthropods; they have been known to reach speeds of up to ten miles per hour. They have also been known to make sounds by stidulating their chelicerae, although the resultant sound could hardly be described as a "screech".
Nevertheless, solpugids are indeed an intimidating animal; so intimidating, in point of fact, that when one was found in the house of an English soldier, the entire family evacuated the building.
Meanwhile, in Australia, a golden orb weaver
(genus Nephila) consumes a small bird.
Fear of insects and arachnids aren't the only remnants of our evolutionary history; the common fears of heights, enclosed spaces, and the dark once were great assets to our pre-human ancestors. But, in the 21st century, these fears no longer have any survival value; remnants of a dangerous and brutal live in nature, before we had the technology to control the environment, they can only hold us back as we go into the future. While the exotic pet trade is helping to squelch some of these unnecessary fears and negative stereotypes about invertebrates, everybody should try to learn as much as they can about spiders, insects, and scorpions.
Not to be outdone, a praying mantis (Mantis religiosa)
catches and consumes a hummingbird.
Solifugae - The Myths & the Facts
Even few spiders instill as much fear, as much awe, and as many urban legends as Solifugae. Not an actual species, Solifugae is an order of arachnid, and a single individual is known as a solpugid. They are endemic to desert biomes, although they may also be found in grasslands and wooded areas; there are over 1,000 described species. Many species described are extant, although some are known from fossilized carcasses from the Pennsylvanian. These animals are best known for their impressive chelicerae, which appear as two large, saw-like jaws that dwarf the actual head. These large weapons are used to take down and tear apart their prey, and solpugid bites have been known to break skin and leave ragged wounds. While no species are poisonous, that hasn't stopped them from accumulating a nasty reputation.
A fossilized solpugid.
Their Latin mean translating (roughly) into "fleeing from the sun", they have many colloquial names: sun spiders, camel spiders, wind scorpions, matevenados (deer killers in Spanish), jerrymanders (the name given to them by British soldiers in WWI), rooiman ("red man"), and baardskeerders ("bear cutters"). One of the more intimidating behaviors exhibited by solifugae is its tendency to "chase" after people. Indeed, this is one of the many myths about them returning from Iraq with the soldiers. However, this behavior is not them chasing the soldiers out of any malice or predatory intent; this is simply them seeking shelter from the desert sun. If the soldier mustered enough nerve to sit there calmly, it is likely the solpugid would simply come to rest in the shade the soldier provided.
The photo of two solpugids was authentic, although the
accompanying text was almost entirely fictitious.
The above picture has started circulating around the internet quite some time ago, with the following text:
"Yuck. I sure am glad we don't have these here. Although we probably will after this war...
This picture is a perfect example of why you don't want to go to the desert. These are 2 of the biggest I've ever seen. With a vertical leap that would make a pro basketball player weep with envy (they have to be able to jump up on to a camels stomach after all), these bastards latch on and inject you with a local anesthesia so you can't feel it feeding on you. They eat flesh, not just suck out your juices like a normal spider."[8]First and foremost, this description is inaccurate because it places the range of solifugae as only in the middle east, when species naturally occur in the Americas. As stated earlier, these animals are also found in grassland and wooded areas, so the description is wrong on that count, as well. As far as has been observed, these animals cannot jump, let alone make vertical leaps into the air. They do not secrete any compound from their jaws, either venom or anesthetic, and when they bite you, you definitely feel it. Camel spiders have also never been known to attack camels (or deer).
Once again, it seems that myths have been cultivated over an animal with a bizarre appearance that the general public knows very little about. To complicate the problem, the History Channel (who's expertise is "history") ran an episode of the pseudoscience show Monster Quest in which "arachnologists" scoured Middle Eastern deserts for giant solpugids, although they predictably didn't find any (which didn't seem to affect their optimism that it exists). As with many other arachnids, enthusiasts are constantly having their time preyed upon by the gullible who have been taken in by these wild falsehoods. As Winston Churchill famously said, "a lie gets halfway around the world before the truth has a chance to get its pants on."
Another common myth about camel spiders is a truly terrifying one (or, it would be terrifying, if it were in any way accurate). This myth claims that they run parallel to military vehicles, emitting a screeching sound as they run. While utterly ridiculous, camel spiders are considered to be the fastest of all land arthropods; they have been known to reach speeds of up to ten miles per hour. They have also been known to make sounds by stidulating their chelicerae, although the resultant sound could hardly be described as a "screech".
Nevertheless, solpugids are indeed an intimidating animal; so intimidating, in point of fact, that when one was found in the house of an English soldier, the entire family evacuated the building.
Holding a pet solifugae is surprisingly anti-climatic.
The Spider and the Toilet
Sometimes, urban legends have their origins in real events. One of these is the recurring story of a "new, ultra-venomous" spider which seems to find the underside of toilet seats an excellent place to build a home. The spider is always portrayed as the rather beautiful two-striped Telamonia dimidiata, which is a species of jumping spider from south Asia, which is harmless to humans. The original hoax was created in 1999 by an individual named Steve Heard, because he wanted to see if a fraudulent meme would be propagated despite obvious holes in its central premise. The most recent incarnation of this meme was worded in the following manner:
"Please pass this on to everyone on your email list:In today's highly sanitized world, the underside of a toilet seat would be the last place a spider would set up shop. Not only to regular cleanings keep any prey populations from accumulating in such an microhabitat, the chemicals used to clean would themselves be highly toxic to the spider, and would almost certainly kill them. Why, then does this at least seem plausible to most people who hear it?
According to an article by Dr. Beverly Clark, in the Journal of the United Medical Association (JUMA), the mystery behind a recent spate of deaths has been solved. If you haven't already heard about it in the news, here is what happened.
3 women in Chicago, turned up at hospitals over a 5 day period, all with the same symptoms. Fever, chills, and vomiting, followed by muscular collapse, paralysis, and finally, death. There were no outward signs of trauma. Autopsy results showed toxicity in the blood. These women did not know each other, and seemed to have nothing in common.
It was discovered, however, that they had all visited the same restaurant (Big Chappies, at Blare Airport), within days of their deaths. The health department descended on the restaurant, shutting it down. The food, water, and air conditioning were all inspected and tested, to no avail. The big break came when a waitress at the restaurant was rushed to the hospital with similar symptoms. She told doctors that she had been on vacation, and had only went to the restaurant to pick up her check. She did not eat or drink while she was there, but had used the restroom. That is when one toxicologist, remembering an article he had read, drove out to the restaurant, went into the restroom, and lifted the toilet seat. Under the seat, out of normal view, was small spider. The spider was captured and brought back to the lab, where it was determined to be the South American Blush Spider (arachnius gluteus), so named because of its reddened flesh color. This spider's venom is extremely toxic, but can take several days to take effect. They live in cold, dark, damp, climates, and toilet rims provide just the right atmosphere. Several days later a lawyer from Los Angeles showed up at a hospital emergency room. Before his death, he told the doctor, that he had been away on business, had taken a flight from New York, changing planes in Chicago, before returning home. He did not visit Big Chappies while there. He did, as did all of the other victims, have what was determined to be a puncture wound, on his right buttock. Investigators discovered that the flight he was on had originated in South America. The Civilian Aeronautics Board (CAB) ordered an immediate inspection of the toilets of all flights from South America, and discovered the Blush spider's nests on 4 different planes! It is now believed that these spiders can be anywhere in the country. So please, before you use a public toilet, lift the seat to check for spiders. It can save your life! And please pass this on to everyone you care about."[9]
The story obviously plays to people's irrational fear of spiders. While the origins of this particular chain meme have origins dating only to 1999, similar incidents have occurred in older times. Most notable of these would be incidents which occurred in outhouses before the advent of indoor plumbing; seldom clean, made of wood, and outside, these would have likely seen moderate levels of prey populations. In such conditions, spiders would be likely to be found. The spider in this example would likely be Latrodectus; the immediate environment is shaded, protected, well suited for building its messy webs, and literally crawling with prey items. And when the local farmer needs to "make some room", he may of been unfortunate enough to alarm the resident spider with his genitalia, resulting in a nasty bite that, in a time before medical science became what it is today, was often fatal.
Another, video version of this story has also been making the rounds, being promoted on Facebook and YouTube:
The spiders in the video appear to be a species of huntsman spiders (Sparassidae), which are often quite large and, to those who lack any understanding of spider species, intimidating. They are generally considered to be harmless to humans, with defensive bites causing no major medical issues. That doesn't stop people from (1) fearing spiders even more, and (2) vowing never to use a gas station restroom again.
Bullet Ants and Pepsis Wasps
This is most definitely NOT recommended.
If you know anything about Pepsis wasps (the species in the video is Pepsis formosa), you can probably conclude the man in the above video has balls so hard that, when he falls, they crack concrete. Second only to the sting of a bullet ant, the Pepsis sting is so painful that it is, essentially, unbearable. The only thing which rivals the sting of P. formosa is the bullet ant, Paraponera clavata. P. clavata is famously used in coming of age rituals for some south american tribes. Young men looking to become full fledged men in their tribe must wear the bullet-ant-mittens twenty times.
Donning a glove of angry bullet ants.
Could you do it?
Once again, don't try this at home.
The bullet ants receives it common name because it has often been said that the sting is so painful that it feels as though one has been shot. While this may seem, to most, to be a blatant hyperbole, there can be no mistaking the effects of the neurotoxins on the body - those who are stung clearly feel it, and they feel it deeply. The creator of the Schmidt Pain Index described the Pepsis wasp sting as "blinding, shockingly electric. A running hair dryer has been dropped into your bubble bath." Bullet ants, he contents, feel like "fire-walking over flaming charcoal with a 3-inch rusty nail grinding into your heal."[10] Clearly, if these unscientific but humorous descriptions are correct, these animals are not to be taken lightly.
But are they dangerous? A single animal won't kill a human, no. Once again, while these animals certainly can deliver their venomous goods, they seem to have built up a reputation that is greatly exaggerated. One can't help but wonder why the caliber is never mentioned when a bullet ant is compared to a gunshot wound. It can be easily imagined that it may feel like being shot with a .22, but the vagueness about the description could just as easily imply that it is equal to the pain of being shot in the foot with a .40 caliber pistol. It would be highly unlikely that the sting of a bullet ant would be akin to the pain felt when being shot with a .270 Winchester, but, once again, the vagueness of most of the reports doesn't rule it out. All that is said is that it feels like a "gunshot". It would seem much more likely that the reference to a "gunshot" type pain is a hyperbole, a way to describe a pain that is to exquisite for words.
The sensation of a P. formosa sting is much more defined by those unfortunate enough to experience it. It is quite easy to imagine what it feels like to be unable to do anything but scream (and maybe roll around on the ground like a possessed person). But the sting is also reported as very ephemeral, lasting only minutes. What an oxymoron! A pain so powerful you can only scream, but it's gone in a matter of minutes. Compared to the bullet ant, which takes 12-24 hours to fully dissipate inside the body.
Why do these animals have such powerful stings? As with all biological answers, they are found in the eons of evolution. Also, before we continue into the origins of such powerful chemical weaponry, we should probably note that the black body and bright wings of the P. formosa wasp are warning coloration against predators. It doesn't want to use the built of stores of venom for anything other than hunting tarantulas; biologically speaking, any other use of its sting would be a gross misuse of such a powerful chemical weapon. The venom is primarily for the capturing of prey, spiders such as tarantulas. The wasps venom works in such a way so that it paralyzes the spider for the remainder of its life, while still keeping it alive (wasp larvae like fresh meat); if anything could help bear the pain of such a sting, perhaps it is the knowledge that your fate is much better than the spider's. Schmidt hypothesizes that the reason for the painful sting of the Pepsis formosa (and likewise for the bullet ant) is
"making us hurt far more than any animal that size ought to be able to do. It deceives us into thinking serious damage is being done."[11]In a world in which Darwinian rules reign supreme, and only those most able to adapt and survive pass their genes on to the next generation, the role of such potent venom is quite obvious; if a sting is painful enough to repel a predator, your genes may be more likely to survive into the next generation. In the case of the tarantula hawk wasp, it may be hypothesized that the strength of the venom comes from the concentration of the chemical ingredients; in an environment where water is hard to come by, a venomous organism would find benefits in concentrating the venom so that less of it needs to be used, thus conserving water. The same parallel can be found in tropical and desert scorpions - often, the more dangerous scorpions are found in desert locales.
Hobo Spiders and Yellow Sac Spiders - Wrongfully Accused
In the Pacific Northwest, there exists an invasive species so terrible, so venomous that is has quickly surpassed both the violin spider and the black widow in terms of infamy. It is the very dangerous and very aggressive hobo spider. And it must be something about its new locale that gives it its new power and aggression, because, in their native land of Europe, they're considered quite harmless.As comedian Tim Allen would say, back the truck up. How can an animal be incredibly deadly in the United States, but be harmless in its native land? Once again, falsehoods have left the truth in the dust. Unlike Latrodectus spiders, Pepsis wasps, or bullet ants, the medical effects of T. agrestis and C. inclusum are hotly debated among professional and amateur arachnologists. Hobo spiders have coexisted with humans for centuries, and across America, many people often come into close contact with yellow sac spiders and never notice them, let alone suffer a bite. The major difference between these two species, and the arguments surrounding their toxicity, is that T. agrestis is an invasive species whereas C. inclusum is a native spider. As such, it would seem the hobo spider is automatically more important - and therefore, more dangerous and more frightening - simply because it is new. "Black widows? Seen them lots of times. Brown recluses? Meh, SSDD. Hobo spiders? Now, that's something!"
Hobo Spiders
In the United States, the argument for the toxicity of T. agrestis is based, almost entirely, on three pieces of information; a study involving rabbits, a man who was purportedly bitten by a hobo spider who developed lesions, and the fact that their Latin name agrestis was translated as meaning "aggressive", when it more accurately means "of the fields". Many are quick to take these at face value, but, alas, we do not live in a universe of black and white, and so we cannot assume these to be accurate without looking deeper into them.
Regarding the scientific study, rabbits were submitted to T. agrestis bites and their reactions were recorded.[12] The rabbits developed sores on their skin at the site of the bite. This study was used by several governmental agencies, including the CDC, to assess the danger of this new, invasive spider, claiming it causes necrosis in humans. This then, in turn, led to the assumption that spider bites attributed to L. reclusa were really caused by hobo spiders. Subsequent studies into the toxicity of hobo spider bites has failed to reject the null hypothesis that T. agrestis venom is not medically significant; and, indeed, there have been no confirmed cases of their venom causing such a response.
In regards to the man who was reportedly bitten by a hobo spider and developed necrotic lesions from the venom, one very important fact is often left out: the victim had a preexisting skin condition known as phlebitis, one which made him prone to similar skin lesions.[13] Once again, popular media has not helped the situation even minutely, as Animal Planet's show Infested was quick to jump on the story. Once again, skepticism is needed to determine fact from fiction; while it appears to be a documentary, it is produced for entertainment purposes.
A personal hero of mine, Arlo from Quaoar Power,
conducts a hobo spider bite test.
Yellow Sac Spiders
The other contested spider is the yellow sac spider. Originally classified as a Clubionidae (true sac spiders) but now classified as a long-legged sac spider (Miturgidae), C. inclusum is endemic to North America, commonly found in trees and shrubs. They can have a legspan of one inch when the legs are fully extended. Like the hobo spider, it is nocturnal and does not rely on a web to catch its prey. Because of this, when humans do encounter the American yellow sac spider, it is usually because the spider has wandered into the vicinity of the person; the majority of the time, however, the spider and human never interact, despite their sometimes close proximity to each other.
Like that vast majority of all spiders, C. inclusum is venomous. Often, when a person it bitten, nothing more than local symptoms are reported. It is worth noting that the American yellow sac spider has affected a very important industry in a rather unique way - in 2011, the species was responsible for Mazda's recall of thousands of Mazda6 automobiles; the spiders had built webs which had clogged the fuel ventilation systems. It was never determined what had caused the spiders to build webs in such a unique place.[14]
A yellow sac spider video, courtesy of Quaoar Power.
Scorpions
Scorpions exude a menacing aura that makes them at once frightening, yet mysterious. Nocturnal hunters known for their large pedipalps, the elongated tail, and their eerie glow under a black light, several species are becoming more common to see in the pet trade. The imperial scorpion, Paninus imperator, is about at dangerous as a honeybee, but it's size and coloration make it no less intimidating to any observer. Such an appearance can play a large psychological trick on humans, and many are afraid of picking them up, despite their often docile temperament.
World's deadliest scorpion, the Indian red (Hottentatta tamulus).
Of all described 2,000 species of scorpions, only 20-30 have venom strong enough to be considered medically significant (excluding, of course, the possibility for an allergy to the proteins in the venom).[15] Among these are the Arizona bark scorpion (Centruroides sculpturatus) and the deathstalker (Leiurus quinquestriatus).
A video of a child stung by an Arizona bark scorpion.
What Do We Do From Here?
The question of how to handle the reputations of venomous insects and arachnids is important, because while reputations of some are completely overblown and fictitious, other reputations are well earned. The same rule of thumb for a hobo spider cannot be applies to the deathstalker, and a scurrying camel spider would seem to be infinitely more dangerous than an almost stationary Latrodectus, although this is not the case.
There is nothing simple about changing the perceptions people have, especially when it's something they don't want to deal with. Arachnophobes are a good example; they have an irrational fear of spiders so great that it's a problem simply getting them to talk about them often. And, when one points out the fear is irrational, they may get defensive, accuse you of judging them, and storm out of the room (or hang up violently) in agitation. Many of these same people would look to dogs as a source of joy and comfort, even though dogs are more likely to kill them than any spider is, especially in this age of medical wonders.
It seems the best course of action is to tell those who fear, those who ignore, and those who love these wonderful animals to treat them with respect and dignity, never interact with them unless necessary, and to always remember that they, like us, may simply need some space.
[4] http://www.cdc.gov/niosh/topics/spiders/
[5] http://news.discovery.com/animals/zoo-animals/dogs-empathy-humans-120831.htm
[6] "Tarantula Hawks - DesertUSA". Retrieved 2010-07-26.
[7] http://www.dailymail.co.uk/sciencetech/article-2158452/The-shape-fear--spiders-scare-Humans-hardwired-fear-angular-legs-unpredictability.html
[8] http://urbanlegends.about.com/od/spiders/ss/Camel-Spider.htm
[9] http://www.truthorfiction.com/rumors/b/bushspiders.htm#.UaBmkkBQGSo
[10] http://www.dailymail.co.uk/sciencetech/article-2148089/The-10-painful-stings-planet-self-sacrificing-man-tried-150-different-varieties-science.html
[11] http://discovermagazine.com/2003/jun/featstung#.UaB_NUBQGSo
[12] Vest, D. K. (1987). Envenomation by Tegenaria agrestis (Walckenaer) spiders in rabbits. Toxicon 25(2):221-4.
[13] Vetter, R. S. and G. K. Isbister. (2004). Do hobo spider bites cause dermonecrotic injuries? Annals of Emergency Medicine 44:605-607.
[14] http://articles.latimes.com/2011/mar/03/business/la-fi-mazda-spider-20110304
[15] http://animals.nationalgeographic.com/animals/bugs/scorpion/
[5] http://news.discovery.com/animals/zoo-animals/dogs-empathy-humans-120831.htm
[6] "Tarantula Hawks - DesertUSA". Retrieved 2010-07-26.
[7] http://www.dailymail.co.uk/sciencetech/article-2158452/The-shape-fear--spiders-scare-Humans-hardwired-fear-angular-legs-unpredictability.html
[8] http://urbanlegends.about.com/od/spiders/ss/Camel-Spider.htm
[9] http://www.truthorfiction.com/rumors/b/bushspiders.htm#.UaBmkkBQGSo
[10] http://www.dailymail.co.uk/sciencetech/article-2148089/The-10-painful-stings-planet-self-sacrificing-man-tried-150-different-varieties-science.html
[11] http://discovermagazine.com/2003/jun/featstung#.UaB_NUBQGSo
[12] Vest, D. K. (1987). Envenomation by Tegenaria agrestis (Walckenaer) spiders in rabbits. Toxicon 25(2):221-4.
[13] Vetter, R. S. and G. K. Isbister. (2004). Do hobo spider bites cause dermonecrotic injuries? Annals of Emergency Medicine 44:605-607.
[14] http://articles.latimes.com/2011/mar/03/business/la-fi-mazda-spider-20110304
[15] http://animals.nationalgeographic.com/animals/bugs/scorpion/
