by Gordon Grice
In the desert of the American Southwest, windscorpions and widows thrive—both love heat. The two predators compete for the available insect prey, and they also readily devour each other. The windscorpion is an avid eater of widows. It chews them into scribbles of skewed legs and pulp, sucking down body fluids that literally are poisonous enough to kill a horse, but that have no adverse effect on the windscorpion. However, even windscorpions have a less-than-sterling record against the widow, which frequently snares and eats them. In many deserts around the world, true scorpions make this a three-way rivalry. Seven-inch scorpion husks have been found in widow webs.
A widow’s most dangerous enemy is another widow. An adult female will fight any other female who crowds her, and the winner often eats the loser. I am told that staged fights between widows are still a popular entertainment in Mexico: children put the widows on a stick and pass it around so everyone can see. Sometimes one female ties another up and leaves without killing her. I’ve seen this happen several times with widows in captivity, and in the wild I once came across what looked like a black pearl wrapped in silk on a red fence. When I peeled off the silk, the pearl unfolded its legs and rushed away. Another time I saw a female widow bind another and bite her on a leg joint, just as she would do to a prey item, and then leave without feeding. Soon the beaten widow stretched her legs, shrugged off her fetters, and walked away, becoming the only arthropod I’ve ever seen survive a widow’s bite.
The widow gets her name by eating her mate, though this does not always happen. When a male matures with his last molt, he abandons his sedentary web-sitting ways. He spins a little patch of silk and squeezes a drop of sperm-rich fluid onto it. Then he sucks the fluid into the knobs at the ends of his pedipalps and goes wandering in search of females. When he finds a web, he recognizes it as that of a female of the appropriate species by scent—the female’s silk is laden with pheromones. Before approaching the female, the male tinkers mysteriously at the edge of her web for a while, cutting a few strands, balling up the cut silk, and otherwise altering attachments. Apparently he is sabotaging the web so the vibratory messages the female receives will be imprecise. He thus creates a blind spot in her view of the world. This tactic makes it harder for her to find and kill him. Then he’s ready to approach her. He distinguishes himself from ordinary prey by playing her web like a lyre, stroking it with his front legs and vibrating his belly against the strands.
I came upon one courtship in progress. The male was brown and white. A broad white bar marked the midline of his back; the hourglass on his belly was white. He tapped his two front legs on the web before him like a blind man tapping his cane. The female was near the tubular retreat in a sheltered corner of her web. She responded by staying still. He approached and turned to bicycle his hind legs, roping her legs with fine silk. She stirred briefly, as if settling in her sleep, the strands of web he’d thrown sliding off her; he fled to the far side of her web and hung there licking the tips of his claws. The next time he approached, the female responded to his leg-tapping with a tap of her own foreleg—the same move she would make if she suspected prey at hand. Its impact on the web sent him running again.
He never gave up, but approached her time after time. Sometimes he retreated for no reason visible to me. Sometimes she seemed momentarily hypnotized by his tapping routine; other times she tensed as if she had detected prey and were “listening” to the vibrations of her web for a direction. I counted over one hundred retreats before an appointment forced me to leave. The next morning I looked at the web. The female was nowhere in sight. At the center of the web hung a small bundle of silk from which a number of translucent legs protruded. I removed the bundle carefully, the web tearing with its characteristic dry crackle. Once I had unwrapped the male’s body, I found little structural damage to the exoskeleton. It had turned golden instead of brown with the loss of blood and organs. The palps were still dark and round and probably full.
No explanation for the female black widow’s unpredictable response has held up for long. Sometimes she eats the male without first copulating; sometimes she snags him as he withdraws his palp from her genital pore; sometimes he leaves unharmed after mating. Scientists used to assume the female only ate the male if she had already mated with a different male, or if she was particularly hungry. But no such pattern has proved true. Recently fed virgin females sometimes eat males.
I have witnessed male and female living in apparently platonic relationships in one web. Sometimes the male’s attempts to mate, and the female’s attempts to run him off, last for days or weeks before some decisive ending occurs. Occasionally a male will devour a female in captivity. Whether this occurs in the wild I don’t know, but such abortion of future generations obviously couldn’t be very common.
Captivity may play an enormous part in our understanding of widow mating—or, rather, our misunderstanding. In the wild, a male will quickly run away after mating. A researcher named R. G. Breene found that captive males, if removed from the container of a female, could breed repeatedly, fertilizing the eggs of a whole series of females. He proposed that this outcome is the normal one, and that sexual cannibalism, while it does happen occasionally, is fairly unusual. The high incidence of mate-eating found by scientists in laboratories, says Breene, can be explained by the sealed containers used in labs. The male can’t escape as he naturally would, and sooner or later he gets eaten. Breene has even suggested that John Henry Comstock, the arachnologist who popularized the name black widow around 1900, was observing under just such misleading conditions and used his misinformation to foist the “widow” name onto the general public. Breene suggests males eaten in the wild are generally malnourished or sick. Though he doesn’t go this far, his notion would allow us to see the female’s cannibalistic brand of romance as an instance of natural selection, with the female scourge culling imperfect males from the gene pool before they mate, or at least before they mate again.
Breene’s position is weakened by the more-than-occasional observation of sexual cannibalism in the wild—I’ve seen it several times, and so have others. I used to keep a male and female of breeding age in a mustard jar together, and they never injured each other, disproving Breene’s idea that the captive situation invariably produces cannibalism. And then there’s the red-back.
The red-back widow of Australia enacts a startling variation on the motif of mate murder. When the red-back male has inserted the tip of his palp into the female’s genital pore, he does a somersault, bringing his abdomen to the female’s fangs. She bites him and begins to digest and suck out his innards while they are still copulating. He sacrifices himself, perhaps helping to ensure protein and calories enough for the female to lay eggs.
Then again, scientists have not been able to show an increase in egg-laying among females who have eaten males, which are, after all, skimpy—often the female outweighs the male by a factor of fifty. Another theory is that the males hold the females’ attention longer, and are allowed to copulate longer, by offering their bodies as a sort of diversion. Their self-sacrifice reduces the mating opportunities of rival males.
None of the widows I’ve been around has sacrificed itself the way the red-back sometimes does, but the strategy should still work. A female whose time is taken up by an elaborate series of threats and retreats before mating doesn’t have time to receive other prospective mates. A freshly mated female who’s busy eating suitor number one may not want to be disturbed at her meal by suitor number two. In this view, the most genetically successful males are those who occupy the female’s attention longest, even if it means sticking around to become a meal.
Mating is the last thing a male does. Once he’s left his web to seek mates, he never eats again; and whether he finds females or not, he is already wasting away, collapsing toward his preordained life-limit, which is marked by the coming of the cold.
Many widows will eat as much as opportunity gives. One aggressive female I collected on the back porch of my parent
s’ house had an abdomen a little bigger than a pea. She snared a huge cockroach and spent several hours subduing it, then three days consuming it. Her abdomen swelled to the size of a largish marble, its glossy black stretching to a tight red-brown. With a different widow, I decided to see whether that appetite was really insatiable. I collected dozens of large crickets and grasshoppers and began to drop them into her web at a rate of one every three or four hours. After catching and consuming her tenth victim, this bloated widow fell from her web and landed on her back. She remained in this position for hours, making only feeble attempts to move. Then she died.
The widow’s appetite is connected to its reproductive prowess: the more a female eats after mating, the more eggs she can lay. I rarely find a black widow in the wild with more than two or three egg sacs, but in captivity, where the spiders’ work of fighting the elements and repairing the web is reduced and the prey abundant, I’ve seen them produce many more. Some widows lay eggs until their bellies shrivel like raisins and they die. When an egg sac is taken away from a widow, she lays a new clutch that night. As long as the female widow keeps eating, she can make more eggs, but the last clutch or two in a long series are usually sterile. The greatest number of sacs I have seen one female produce is nine, of which six hatched a normal number of spiderlings. From the seventh a small brood of a dozen hatched. The eighth and ninth sacs proved sterile.
The female starts her egg-laying ritual by spinning the beginnings of the sac—a short stem from which hangs a flat patch of webbing like a lace doily. Working belly-up, the widow lays her egg mass on the lower surface of this patch. The egg mass slowly squeezes out of the genital pore in the middle of the belly. It is a gooey substance in which no individual eggs are visible, and it comes out in a nearly perfect orb. The process resembles the blowing of a bubble with chewing gum, but can last hours. The egg mass, which is the color of butterscotch pudding or a little lighter, sticks to the silk platform.
After resting, the widow returns to work on the sac. Hanging beneath the egg mass in the usual belly-up position, she pokes the spinnerets that tip her abdomen at the edge of the platform and squirts silk at it. This silk is fine; as it comes out and adheres to the platform, you can see the individual fibers accreting into a lacy tangle. The edge of the structure always has spaces like those in lace, but the rest is solid; somehow, the silk dries into an unbroken, waterproof fabric. Its texture is like nothing else the widow spins; it is somewhere between paper and linen. As she adds to the platform, it grows to resemble an inverted goblet; then the goblet rounds in to form an orb, which does not touch the inner orb of the egg mass except at the original point of attachment. You can see the darker egg mass inside the sac by holding it in front of a light.
After the egg sac dries, it usually has a smooth surface with a single nipple at its starting point. Its color darkens a bit; the darkest become light brown or manila, and others remain almost white. Its fabric is tough; when you tear into it, you can see intricate layers within. The egg mass inside slowly dries, resolving itself into individual eggs that look like the grains of sand in an hourglass.
I worked as a groundskeeper at a hospital one summer when I was in college. One day I was cleaning out a cement pit that opened onto the basement laundry. The pit was full of dead leaves and discarded containers and other trash, and the vents from the laundry poured steam onto me as I swept. Whiptail lizards as long as my hand would streak out of the trash and lodge a few feet from their original hiding places. One ran across my boots. I ran after him and dug through the pile of junk where he went to ground.
I forgot the harmless reptile when I turned over a five-gallon plastic bucket and found it filled with the web of an immature female widow, who hung at the center of the bucket, the bright hourglass nearly covering the ventral surface of her slender abdomen.
She did not seem to have noticed that I had turned her world upside down. I was shocked. I had been thrusting my hands into such junk all afternoon. I aimed the handle of a rake at the spider pool-cue style and with a tap converted her to a paste on the bottom of the bucket. I felt pleased about having dispatched her so economically, but soon I regretted it. She was, after all, a good-looking specimen, and I could have enjoyed watching her with a safe layer of glass between us. I told myself I had prevented the possibility of anyone else’s getting bitten, but, since no one but me would find himself cleaning out this hole in the ground in the near future, my rationalization didn’t entirely convince me.
I forgot this moral dilemma when I found a second widow. And a third, and a fourth and fifth. I captured them in discarded paper cups and styrofoam Big Mac containers (this was before McDonald’s became environmentally concerned). They were all immature, all colored brown and white except the one I had killed. I stashed them in some sunless corner so that I could retrieve them after work. Later, when I told my boss about seeing black widows, he said, “I hope you killed them.” I changed the subject.
I took those widows home after work and installed them in terraria. As the summer passed, I found other widows at the hospital. I found them on three sides of the building; I found them low and high; I found them at various ages.
One day I was cleaning out a latticed stone wall. I suppose it was designed to throw a lovely dappled shadow on the walk, but what it actually did was provide crevices for trash to lodge in when the wind got stiff. I reached into the wall’s triangular holes to fish out candy wrappers and floral-print Dixie cups that must have come from the hospital’s family room. The wall was thick; my hand went in up to the middle of my forearm. In a dazzling display of intelligence, I was working bare-handed.
I thrust my hand into the next triangular space and felt my finger brush something desiccated and velvety. I pulled my hand out immediately. I had no idea what I had touched. I had never felt anything like it. I looked into the hole.
A female widow hung in a torn web with dry leaves and a few scraps of shredded paper. It was the widow’s abdomen I had touched, but, because she had not re-treated at my intrusion, I knew she was dead. I pulled everything out of the hole.
The widow’s exoskeleton was in good shape, but it was dry. Her leaking blood had made a sugary crust where abdomen joined cephalothorax. She had simply died, as widows do after laying their last egg sacs. That last egg sac hung in the web too. It still held its globular shape, but its crisp beige had gone a little gray with age. A single pinhole showed that the spiderlings had left. I tore the sac open. The tiny individual eggs were visible, each broken open so that its shape was ruined, a neatly halved orange rind instead of a spherical orange. These shells had dried to a sandy grit. The web also held the wrapped carcasses of a few young black widows. They had been eaten by siblings or maybe by their mother in her last languid days.
The remaining spiderlings must have dispersed soon after hatching that spring, as young widows do after their infant phase of cannibalism. After crawling out of the wall, each produced a few filaments of web, which caught the wind; when the filaments had spun out long enough, the wind lifted strand and spiderling and carried them as far as it wanted to take them. This strategy for dispersal is called ballooning; it is common in spiders. Human balloonists have encountered ballooning spiderlings high in the atmosphere; scientists have found spiderlings hundreds of miles from their birth sites.
In the case of the black widow, it’s not unusual for the spiderlings to land very close to the mother’s nest, so that a parabola of new webs springs up on the ground downwind from the point of origin. A few years of this pattern of dispersal can infest miles of open ground. The widows can exist so close to each other because, even though they’re cannibals, they seldom leave their own webs. Infestations of this size crop up in grassy fields, and farmers have burned off stretches of pasture to destroy the black widows. Putting sheep or pigs on the fields is also supposed to clear them of widows. Sheep react only slightly to widow venom, probably because of their long evolutionary history of grazing low in the spidery grasses
. Pigs are not immune, but a layer of subcutaneous fat tends to keep poisons out of their bloodstreams, so that they often survive the bite of a widow. Their rooting destroys widow webs. The U.S. Navy once arranged for men to clear an infested field with flamethrowers.
What I had been seeing at the hospital that summer was the dispersal of the widows in reverse. I had found the young early and then, near the end of the summer, discovered their nest of origin. Of course, some or all of the young widows I had found may have come from other nests; I’ll never know. But all the females I found there that were old enough to show their adult colors had the same pattern as the dead mother—no red marks except the double triangle on the belly.
The last few weeks of the summer I often noticed the wind. It made the roof of the building creak; it sent trash scudding around corners. It eddied into odd nooks of the building to deposit dirt and dead leaves. It stopped short, dropping things from high up—pine needles, dust, scraps of paper on which were written the names of diseases and drugs, bits of newspaper, dandelion seeds on their tufted parachutes, bits of animal fur, bits of gossamer.
