by Gordon Grice
For now, though, we understand almost nothing about the venom and its attendant array of human suffering.
The necrosis-causing toxin serves no known purpose for the recluse itself. In this respect, the recluse resembles the unnecessarily virulent black widow. But the recluse’s case is even stranger.
Most spiders have a venom component that paralyzes or kills insect prey, and the recluse is no exception. But the chemical in recluse venom that hurts people isn’t the same one that debilitates insects. The black widow’s toxin has an obvious use in catching prey; it just so happens that this toxin can affect large animals. The recluse is dangerous because of an extra, apparently functionless, toxin in its venom. The recluse venom doesn’t even work the way a rattlesnake’s does, serving to make good on threats delivered by a warning system. The recluse gives no warnings.
The recluse spiders became notorious in the United States in 1957. They didn’t arrive here in that year; they had always been around. People had been bitten, some badly injured or killed, by recluses. But, as with the black widow, doctors and scientists didn’t believe such a danger existed, and that fact kept the general public uneducated, compounding the danger. There’s a big difference in the histories of human interactions with the two spiders, however, and in the recluses’ case the blame can’t be laid entirely on incredulous scientists. The other factors include the recluses’ habits, its looks, and the cold facts about plumbing.
Before the United States became a country, European settlers here had gathered some information about the black widow. Many of the Native American tribes knew the gleaming spiders as dangerous, and some tribe members shared that lore with Europeans. I don’t know whether any of the tribes had lore about the recluses, but if they did, it doesn’t seem to have been recorded by Europeans. There was no tradition of fearing the recluse.
This is where the looks of the two spiders play a part. The widows are distinctive. Their sleek, sematic coloring makes them easy to recognize. The recluses come in several shades of dull. There’s a tan species, and several brown ones, and some brown and tan ones, and so on. They don’t have distinctive marks. Several recluse species have a violin shape on the carapace, but that mark isn’t distinctive. It appears on the back of a certain wolf spider, and a harmless running spider—that’s only to list two spiders I’ve seen sporting it in my own house. Other spiders also share the mark. It’s no more distinctive than the name Smith.
Another barrier to identifying the recluse as a danger was its initially painless bite. People weren’t likely to associate the right kind of spider with the bite unless they saw it in the act. Add to this the venom’s unpredictability. Even though it kills some people, the majority have no symptoms, and a majority of those who do have symptoms notice a necrosis instead of systemic effects. Other venomous animals, like the rattlesnake and the black widow, cause varying but far more predictable symptoms.
All these factors kept the general public from developing much knowledge about recluses. That doesn’t mean nobody knew about them; an occasional person had a nasty experience with a bite and made a sharp observation. Cases like that go back at least to the 1870s in the United States. At the time, however, scientists and doctors greeted reports of deadly spiders with irritable lectures on the gullibility of the public. There is actually nothing your average scientist hates more than information from nonscientists, all of whom he assumes to be unwashed, idol-worshipping degenerates good only for working on cars. The thing your average scientist despises second most is a fact that doesn’t fit his theory—an odd position for somebody who supposedly works from empirical data. But most scientists are human.
Until the early part of the twentieth century, the experts smugly proclaimed there was no such thing as a seriously toxic spider in the United States. Proof of the black widow’s killing potential then led most experts to go around saying to impressionable journalists that there was only one poisonous spider in the United States.
In 1934, the same year Dr. Blair published his account of the widow bite that nearly killed him, a scientist named Machiavello published the hard facts on a critter from Chile, the corner spider. This spider hides in clothes and sheets and bites people when they unknowingly squash it. The symptoms it produces include necrotic lesions.
The corner spider is a member of the genus Loxoceles, the gang I’ve been calling the “recluse spiders.” In other words, certain spiders in the United States were occasionally getting accused of biting people and causing spots of necrosis; a closely related spider in South America had been proved to cause exactly such spots; and most American scientists persisted in believing the only dangerous spider in the United States was the black widow. The widow got blamed for a lot of recluse bites, and necrotic lesions were considered a symptom of widow bite. (The widow can, in fact, introduce infections that rot the skin as a recluse bite sometimes does.)
Of course, some scientists weren’t hog-tied by such prejudices. Some of them documented a few spiders that can cause some mild systemic symptoms in humans. But the biggest influence on this kind of research was indoor plumbing. Widow bites occurred in outhouses far more often than anywhere else. In the 1950s, indoor plumbing was rapidly replacing outdoor facilities across the country, and the number of widow bites dropped dramatically. When it did, doctors noticed how many of the spider bite cases they treated were of the kind that had once been a minority, the kind in which the patient suffered a necrosis. Why should the usual sweat-and-pain widow cases vanish while the odd skin-rot cases persisted? It was as if an ocean had receded, leaving a previously submerged boulder prominent on the beach. Science was ready to believe some other spider capable of injuring humans. In 1957, proof of necrotic symptoms caused by recluse bites reached medical journals, and the information quickly spread to newspapers, magazines, and popular books.
When recluses first received a lot of press, they were often described in ridiculously inaccurate terms. One book referred to them as “large, hairy spiders.” One of those three words is correct. I imagine that mistake arose because of the large, hairy wolf spiders that wear fiddlelike marks on their backs. It’s even possible to find books from that period that refer to the recluse as a member of the genus Latrodectus. But Latrodectus only includes the widows, which are as dissimilar from recluses as humans are from giraffes.
For the last forty years the popular press has been spouting science’s revised company line: There are only two dangerous spiders in the United States. As usual, the assumption that we know everything has got us into trouble. In 1996 JAMA: The Journal of the American Medical Association reported that another spider has caused necrosis and death in humans. The spider’s scientific name is Tegenaria agrestis, and its common names include hobo spider and the mellifluous aggressive house spider. The species was described long ago. Its genus, in fact, is found around the world. It simply wasn’t recognized as dangerous because everyone knew there was only one dangerous spider around—and later, make that two dangerous spiders. Symptoms of the hobo’s bite were often called the work of the recluse, just as the widow long took the blame for the recluse’s handiwork.
The truth is, nobody knows how many kinds of dangerous spiders exist. There are a number of proven human-killing spiders around the world besides the ones known in the United States—the Australian trap-door spider, a certain Brazilian wandering spider, a few tropical tarantulas. The diversity of these spiders shows a wild venom can crop up anywhere in the spider family tree. It shouldn’t surprise anybody if we discover another deadly one in another forty years.
At a recent conference, one scientist had just come back from the forests of Central America, and he was showing off specimens he had collected. He had dozens of species from the recluse genus, none of them ever described before.
I used to come to the shed in the summer to hunt vermin. In the northeast corner I could usually find the web of a plump female black widow spider stretched between the sheet metal walls and the welded steel studs. I wou
ld toss a cricket into the web to draw the widow out. She would come cautiously from her hiding place, tapping a long foreleg in front of her, and when the cricket made a few kicks that confirmed her diagnosis of food in the web, she would come for him in rushes separated by pauses when she would listen with her legs. As she moved, her abdomen shivered like a soap bubble near bursting. She moved belly-up, the hourglass on her abdomen red as a double wound in the dim light. Once she was out in the open, I could capture her.
I suppose something about the placement and shape of the building drew the wind into that corner. The young widows must have come in riding the wind every year, for I captured and removed new adults each summer.
It was always easy to find bait for them. Generally a few crickets would be popping around on the cement floor, disturbed by the flood of light when I opened the door. There were pill bugs crawling the floor along the walls (drained shells of pill bugs hung in the lower reaches of the widow web like dirty tassels on a shawl). I could always scare up a few more pill bugs by pouring water into the fissure in the cement. There would be a trail of ants entering the shed on one side and exiting on another, carrying nothing visible and going somewhere for no reason discernible to me. Occasionally a thumb-sized cockroach would race across a cardboard box, its burst of speed beginning with a sound like a striking match, and after it had passed from sight its hieroglyphic tracks remained in the dust.
A few mud dauber nests clung flat to the crossbeams. They were made of pale mud dried harder than brick (once I tried to crush one with a brick, and the brick yielded first). Eye-high on the sheet metal I might notice the egg case of a mantid—a hard, ridged structure shaped like a burial mound.
The place was crawling with life, but the situation was about to change.
The shed needed to be organized. I hadn’t been inside it for several years.
Wasp nests still clung to the crossbeams, but no wasps stirred the dusty air. When I tapped a nest, it crumbled. On another nest I found a wisp of spiderweb. There were no crickets visible, and none singing out of sight. There were no roaches, no ants, no pill bugs, no egg cases on the walls. The corner where the widows used to make their webs held nothing. Along the walls there were little tangles of spider web, apparently without structure. These were not the work of widows; the texture was wrong.
But I had work to do. I lifted an old box of tax records. Something tickled my fingers.
I dropped the box and turned it over. A dozen small spiders covered the bottom of it, and a few more lay in the spot where the box had been. The spiders were brown. Their legs were stringy, an average adult set spanning an area slightly larger than a quarter. Most of them did not react to my intrusion, but the two that did moved very fast, darting around to a sheltered side of the box.
I brushed frantically at my arms where they had touched the box. I knew the spiders by their movement: they were recluses.
I went out into the sunlight and examined my fingers where I had felt them touched. I couldn’t see any bites.
I returned to the shed wearing gloves. Under every shelf, in every drawer, behind every wall stud, in every crack were the brown spiders, most of them dormant in the afternoon heat. They rested in sleeping bags of silk. When I disturbed them they ran away in arcing paths, their stringy legs working in sequence so fast they resembled the guttering of fire in a stiff wind. Everywhere there were wisps of web. I found a few cottony disks of webbing. Inside these lay orange masses of eggs. There were also the spiders’ discarded skins, which were hard to distinguish from the spiders themselves except that the skins’ legs were flung back straight.
I captured one spider in a jelly jar. There was no point in taking two. When you put two recluses into a jar, you soon have only one. At the kitchen table, where the light was good, I could see the violin-shaped mark on the spider’s carapace, a dark-brown pattern against the light-brown background.
The movement of the specimen before me had identified it well enough, but I looked with the magnifying glass anyway. Rimming the head was a crescent of six simple white eyes. There were two in front and two on each side. These were not the large, brilliant eyes of a jumping spider, who spots insects in the air and leaps to catch them as they land. Nor were they the meager eyes of an orb weaver who waits in a snare for prey. They were the eyes of an ambush predator, one that kills whatever happens by. They were the eyes of a recluse.
The recluse hunts by sight, attacking moving objects. You can fool it into grabbing a stick dragged along the floor in front of it. The spider seizes its prey, injects its venom, and then retreats. As the spider waits at a distance, the venom paralyzes the prey. This combination of speed and paralyzing venom explains how the recluse kills larger, stronger predators. When the prey is well paralyzed, the recluse seizes it again and chews a hole in its exoskeleton. It injects digestive acids from its stomach and drinks the liquefying prey.
I recalled the strange lifeless quiet of the shed. My mind settled on the mud dauber wasps I had often seen there: whippet-thin predators that specialize in hunting spiders to feed their hatchlings. A biochemist had told me once about his adventures collecting brown recluses so he could research their toxin. He had seen a recluse climb into the nest of a mud dauber. The spider backed out a moment later dragging the wasp, the spider’s fangs still buried in the wasp’s face.
On the island of Guam, in the decades following World War II, the native birds and lizards began to disappear. Entire species unique to the island went extinct. The cause of this ecological apocalypse turned out to be the brown tree snake, an exotic species that somehow established a population on Guam. Probably humans brought them in accidentally. The brown tree snake doesn’t cause environmental chaos in Southeast Asia and Australia, where it’s native. There other predators and parasites check its numbers. But in a new place, freed from its enemies, the brown tree snake made a sudden, enormous impact.
The little shed wasn’t as isolated from outside populations as an island is. Since new arthropods could crawl into the shed anytime, the “extinctions” weren’t permanent. Still, the similarity is more than an analogy; the same principle of populations interacting in separate pockets applies in both. Instead of a brown snake, a brown spider had brought on this miniature apocalypse. The spider’s aggressive predatory style wiped out every other species. Of course, a predator that exterminates its prey must pay the consequences.
The following year, nothing lived in the shed.
Soon enough the cockroaches and ants and crickets would be back. Perhaps the crickets would eat the skins the recluses had left behind. The skins were the only thing left now; they lay everywhere like the cast-off coats of untidy children. If I pried one loose from the web-strands that anchored it to a wall stud or the underside of a shelf, a breeze too light to be otherwise noticed would send it scudding across the floor. I opened a toolbox and saw dozens of skins shivering like palsied hands.
Here’s what must have happened over the years: A single recluse wandered into the shed and laid her disk of eggs. They hatched, a brood of indiscriminate predators ready to eat anything small enough, and as they grew larger, so did their prey. The recluse will seize prey items many times its own size. It will eat its own young and its sexual partners.
The recluses reproduced slowly. A recluse needs perhaps five years to grow to its full size—a very slow rate for spiders and other small creatures. The black widow, for example, reaches maturity in about three months, and rarely lives past two years. The fast-running recluse lives a long, slow life. It winters in crevices, sealing itself from the cold with a pocket of webbing. Put it in a jar without food or water and its slow metabolism will sometimes last months.
Eventually every creature that could possibly be eaten by a recluse was extinct in the little world of the shed— every creature except the recluses, which now numbered at least in the thousands. They had never shied from spilling kindred blood, but now they became systematic cannibals, eating nothing but their own sibling
s and cousins. Finally there were only a handful left, and they crawled out to find fresher hunting grounds.
Recluses regularly take over abandoned buildings this way. Their life span, long for an arthropod, causes their generations to overlap, creating a gradually building population. The takeover typically requires twenty-five years in a reasonably solid building. In a poorly sealed building, the takeover can occur in five years.
A more typical spider species has an annual cycle. Most individuals of such a species will hatch, reproduce, and die within a year. The size of next year’s population will depend on this year’s crop, a few variable factors like weather, and the species’s rates of reproduction and survival, both of which are influenced by many other factors in the environment. It’s immensely complicated, but things get even harder when you’re dealing with the recluse, whose cycle naturally works in booms and busts. And these changes in population aren’t general across a geographic region—they’re going on constantly in independent little pockets, like abandoned buildings.
These irregular cycles of conquest, overpopulation, and self-extermination aren’t side effects of living with humans. In the wild, recluses take over cliffs of flint or limestone. You can scrape a knife into the crevices of such stone and scare out dozens of recluses in a few minutes. In the desert, their numbers balloon inside the dried skeletons of plants. I remember glancing at a stack of firewood one time and seeing an odd hint of motion, a slight shift of texture that let me know some abundance of arthropods crawled there. Looking closer at the relief map of the bark, I saw nothing; then, after a moment, the arcing trajectory of a recluse’s run; then several. I kicked over a chunk of wood and exposed scores of them.
