Web Masters

“What would you rather have, spiders sitting in webs where you can see them, or bugs wandering around undetected?” asks Tom Mason.

June 21, 2007 | | Back Issues | Environment | Summer 2007

The puny male approached the huge female with extreme caution. Conflicted by fear and desire, he plucked the web to send out soothing vibrations. Then, by excruciating increments, he crept toward her. She of deadly threat and delicious enticement, waited. At last the male’s weak eyes, all eight of them, discerned her, gloriously plump and ominously fanged. He readied his sperm- filled pedipalps, leg-like structures projecting from his head. With no lingering romance in mind, his goal was to complete the act quickly, then retreat as fast as his eight little legs could carry him. Alas, it was not to be. With blinding speed the female clutched him in her arms and swathed him in layer upon layer of suffocating silk. Then the coup de grâce. Entombed and immobile, he first felt the stab of her fangs, then a stupefying paralysis. The suitor had become the supper. Enzymes injected by the female soon liquified his internal organs. She essentially drank him up!

The murderous drama described to the left did not occur in some distant tropical glade but in my own backyard. The female, a very common cross orb weaver, had built a web stretching from my deck to nearby shrubbery. After almost blundering into it, I spied the fat female in her web and the skinny male lurking in the margins. I hurried to retrieve my camera – then watched the tragedy unfold.

I’ve always been interested in spiders, but with recent research that interest has blossomed into unabashed wonder. There are spiders that build air-filled diving bells under water to allow them to hunt small fish and tadpoles; spiders that spit a mixture of venom and sticky silk to ensnare prey; and spiders that dangle by guy wires and swing filaments tipped with gobs of glue at passing moths. There are spiders that spin orb webs of stunning beauty and others that build bevelled trap doors snuggled on the surface of soil.

Spiders thrive in almost every land habitat except mountaintops and the Antarctic ice pack. There is probably not a human habitation on Earth without its complement of spiders – including yours! Adventurous young spiders carried aloft on gossamer threads even populate the skies above us, entrusting the air currents to deliver them to new homes.

An English study calculated an estimated five million spiders per hectare in a British meadow. Numbers here are probably similar.

Elizabeth Simes of the Upper Credit Field Naturalists marvelled at the webs that festooned a field she visited one late summer morning: “The rising sun was hitting the dewy webs. I had never seen so many. It was a spectacular sight! I had no idea there were so many spiders about.”

Spiders without exception are carnivores, and their entrée of choice? Insects, of course.

Charlotte, perhaps the world’s most loved spider, may have indulged in hyperbole in the quote at the beginning of this article, but according to Wild Cities, a book on urban wildlife: “Estimated mass of insects consumed annually by spiders in Canada: Equal to the weight of the country’s entire human population in 2oo4.” Wow!

Alas, all the celebrated benefits of spiders will not assuage the fears of true arachnophobes. This seemingly primal fear of spiders is a common phobia – one that Hollywood has exploited in such successful films as Arachnophobia and Eight Legged Freaks. When I asked my grade-six students what animals they feared, most hands shot up at the mention of spiders.

Toronto resident and photographer Jon Triffo says that when he was younger, “Even a picture or shape of a spider would trigger some sort of panic response or anxiety.”

His phobia became so extreme he suffered bouts of sleeplessness, worried there were spiders in his room or, more horrifying, his bed. Eventually he was so plagued by sleeplessness and panic attacks, he was no longer able to function and found himself unemployed. His doctor recommended a visit to the Mayo Clinic in New York.

Triffo decided the only cure was to confront his fear head on. He became a spider expert. Basically conducting his own “exposure therapy,” as Triffo learned about spiders, his fear gradually dissipated. He went on to create an online magazine at triffophoto3.tripod.com that features his excellent nature photography, including superb close-ups of spiders. Is he still arachnophobic? “I am indeed, but I’ve become a much more functional arachnophobic. The study of things I fear most, very literally, allows me to sleep most nights.”

However, caution is necessary when dealing with spiders. Almost all spiders are venomous, with poison many times more potent than that of rattlesnakes. However, mitigating the danger is that most spiders are retiring creatures that would sooner hide from us than attack. Moreover, the jaws of most spiders cannot penetrate human skin and the venom they possess, while sufficient to subdue a fly, is vanishingly small.

Still, as everyone is aware, spiders such as black widows can inflict painful, even life-threatening bites. As Des Kennedy, author of Living Things We Love to Hate, notes: “We know that when outhouses were common, a choice hiding place for black widows was under toilet seats, and frequent reports were received of black widows inflicting painful bites on exposed genitalia.”

The chances of this happening to you? Very slight. The black widow, or more precisely a subspecies called the “northern widow,” is rare in Ontario. However, if you need to use an outdoor privy, a glance under the seat may be prudent!

Yellow sac spiders are also of some concern in Ontario. According to Tom Mason, curator of invertebrates and birds at the Toronto Zoo, “they are in every home in southern Ontario,” after being accidentally introduced from Europe in the 198os. “Although the bite is sometimes serious, few people actually get bitten,” says Mason, who considers such bites a concern only to people who have a rare allergy to spider venom.

While researching this article, I looked for spiders inhabiting my home. I found three species. Sure enough, the yellow sac was one of them.

However, to put things in perspective, Terry W. Thormin, curator of invertebrate zoology at the Royal Alberta Museum, writes that he doesn’t think “there has ever been a verified death from a spider bite in Canada.” Moreover he contends the culprit in most “spider” bites is more likely mosquitoes, fleas, bed bugs, chiggers and ticks that “seek out humans for blood meals, something no spider does.”

If you really can’t bear to share your home with hairy eight-legged boarders, Dr. Charles Dondale, the dean of spider experts in Canada, says fumigation in the only solution. However, he adds, “This is a drastic solution.” And it has to be repeated regularly.

Perhaps with spiders it’s best to live and let live. They are pest control agents in miniature. Maybe not in the living room, but in dark corners of your basement they have their place.

“What would you rather have, spiders sitting in webs where you can see them, or bugs wandering around undetected?” asks Tom Mason.

There are 8oo or so species in Ontario, and a world total in excess of 35,ooo. Many, like the ill-fated cross spider I photographed, create the exquisite, spiralled orb webs so common in late summer.

Charlotte was one of these gifted architects: “On foggy mornings, Charlotte’s web was truly a thing of beauty.” On one such morning, “each thin strand was decorated with dozens of tiny beads of water. The web glistened in the light and made a pattern of loveliness and mystery, like a delicate veil.”

The orb spider’s silk, stronger than steel and more elastic than nylon, is squeezed out of nozzle-like spinnerets on its abdomen. It is then woven into intricate patterns almost solely by touch and instinct – orb weaving spiders do not see well. Remarkably, like human construction workers who select different wood for different purposes, spiders use different kinds of silk to construct their webs. Orb weavers use non-stick silk for the spokes and the central hub and sticky silk for the spirals.

Orb webs brought out the poet in a Frenchman named Jean Henri Fabre who studied spider life in minute detail around the turn of the last century.

Describing an evening he took his family outside to see a spider make its web, he wrote. “Big and little, we stand amazed at her wealth of belly and her exuberant somersaults in the maze of quivering ropes; we admire the faultless geometry of the net as it gradually takes shape. All agleam in the lanternlight, the work becomes a fairy orb, which seems woven of moonbeams.”

Fabre also solved the mystery of why spiders don’t get stuck on their own webs. While he noted that they tend to stay on the non-stick strands, he also noticed that they could step in their own glue with impunity. He sacrificed a spider to test his theory that an oily leg coating was the key. He pulled off one of the spider’s legs, first assuring that it did not stick to the web. Then, in what must have been an exacting process, he carefully washed the leg in a solution known to dissolve oils and touched it to the web. It stuck.

Our most common orb web weavers are the brown cross spiders, the large yellow garden spiders, and a pretty creature common in local meadows called the banded argiope. In the middle of many orb webs is a bright zigzag “stabilimentum,” so-called at first because it was thought to stabilize the web. Later it was suggested that it warned birds to avoid wrecking the web, essentially a labour-saving device for the spider. But another recent explanation has to do with insects’ ability to see ultraviolet light. Meadow flowers reflecting this light stand out like beacons, summoning pollinators to sample their tasty nectar. Apparently the stabilimentum also reflects light in the ultraviolet range, serving as an ingenious insect lure.

The ill-fated male of our opening is one of an unfortunate minority. Most males are lucky enough to mate before the female eats them! However, the females’ motives are far from sinister. They need the energy fix to produce healthy eggs. Thus, in a macabre way, the male also benefits – his offspring will be stronger. Why did the female in this instance kill the male before mating? Perhaps she had already mated or perhaps the male simply didn’t have his mojo working!

As tough as they are on their mates, spider mothers are more caring of their children than many vertebrates. Whereas most reptiles and amphibians lay their eggs and depart, spider mothers usually guard their silken egg sac. Some even lug it around with them until the young hatch.

Wolf spiders, common in our area, are even more dedicated. After the young hatch, the mother allows them to clamber up on her back, where they may ride for a week or more. Monsieur Fabre experimented with removing all the little ones from the back of their mother. Then watched as she positioned herself so they could all clamber up her legs and back aboard!

The young of many species disperse by casting their fates to the wind. As Fabre describes it: “The young spiders, born acrobats and rope-walkers, climb to the top of a branch so as to find sufficient space below them to unfurl their apparatus. Here, each draws from her rope-factory a thread which she abandons to the eddies of the air. Gently raised by the currents that ascend from the ground warmed by the sun, this thread wafts upwards, floats, undulates, makes for its point of contact. At last, it breaks and vanishes in the distance, carrying the spinstress hanging to it.”

This process, called “ballooning,” usually carries the tiny spiders only a few metres before they touch down, but some are caught in rising air currents that might transport them hundreds of metres aloft and hundreds of kilometres away. Of course, the little balloonists have no way of controlling their direction and the vast majority likely perish, but some survive to colonize new territory. After the eruption of Krakatau in 1883, the scorched island was quickly re-colonized by spiders that parachuted down from above.

Though the spiders most of us are familiar with make webs to catch prey, many species do not. Some chase prey down cheetah-like and others lie in ambush like leopards. Still others have perfected jumping as a method to capture their food.

These jumping spiders are engaging creatures, the furry plush toys of the spider nation. Their excellent vision allows jumping spiders “to stalk prey in the way cats do,” according to Charles Dondale.

The zebra spider, one of our common jumping spiders, attacks flies on the cliff-like walls of our houses. To do this, says Dondale, “It first glues a thread to the surface and then, as it springs, it pays a safety line behind it. After catching the fly in its fangs, it climbs up the safety line to the starting point.”

You see a butterfly positioned awkwardly on a spray of goldenrod. As you approach, it doesn’t fly away. On closer inspection, you notice a small spider, masterfully camouflaged, jaws clamped on the butterfly – a goldenrod crab spider.

Goldenrod crabs are by far the most common of several crab spider species found in this area. They are either white or yellow and possess the remarkable ability to switch these colours according to the flower they’re on – yellow for goldenrod, white for a daisy. Wavy pink bands run down either side of their backs.

Years ago in Caledon I had a memorable sighting of one of these spiders perched in the lip of a showy lady’s slipper flower. The white background and the pink bars matched the flower beautifully.

Crab spiders are ambush predators. They position themselves on a flower with four oversized front legs spread wide and wait for dinner to arrive. Moths, bees and butterflies are typical fare.

Jean Henri Fabre was offended by idle crab spiders feasting on industrious bees: “The slaughter of the Bee engaged in the hallowed delights of labour has always revolted me. Why should so many admirable lives be sacrificed to the greater prosperity of brigandage?”

One of these “brigands” that I came across in Forks of the Credit Provincial Park had selected a hawkweed bloom as her ambush station. She had used her silk to bend the flower over, revealing pink striping that matched her pink bars perfectly. I wondered if the enhanced camouflage was a deliberate strategy?

Last winter, my brother Dean opened a closet in his Heart Lake-area home – and his heart skipped a beat. On the floor was the largest spider he had ever seen. He called to his wife to look at “the huge spider.” Not easily spooked, she assumed her husband was exaggerating, until she saw it. It was huge! In fact, it was the largest of Canadian spiders – a fishing spider, also known as a “dock” spider. This impressive spider with a leg span from five to nine centimetres, is a common inhabitant of lakes and wetlands throughout the province. In winter it seeks a sheltered refuge, such as my brother’s closet.

Fishing spiders also do not capture prey in webs, though their hunting strategy is similar to the orb weaver. An orb weaver sits very still in its web, constantly sensitive to any vibrations. For fishing spiders, the surface of a quiet body of water is their “web.” They rest several of their legs on the water and wait for vibrations. Surface-skating insects, such as water striders, are fair game.

Fishing spiders can also submerge to capture their prey. Charles Dondale reports that “fishing spiders have been observed catching minnows, tadpoles and aquatic insects underwater, though to submerge they must descend along a plant stem.” These arachnid submariners can remain beneath the surface for up to forty-five minutes.

Being so small, numerous and adaptable, our Canadian spiders are in no danger of disappearing from our midst as so many other animals are in this age of extinction. If you are able to subvert the tidiness imperative – and arachnophobia, you can encourage them on your own turf by including arachnid-friendly brush piles as part of your garden design.

Along with their tremendous pest control services, spiders dazzle us with the infinite creativity of nature. These hunters, stalkers, ambushers, and aerial acrobats are downright fascinating, making spiderdom a wonderful world.

About the Author More by Don Scallen

Don Scallen enjoys sharing his love of nature through his writing and presentations. Check out his blog "Notes from the Wild".

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