In the Garden:
Middle South
October, 2011
Regional Report

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Though large and fearsome in appearance, the common yellow and black garden spider is harmless to humans.

Most Spiders Get a Bum Rap

When the weather cools, pumpkins begin to appear on porches, and billboards carry news of the state fair, I always think of E. B. White's award-winning children's book, Charlotte's Web, and its lively cast of characters. Who could forget the story of Fern, the soft-hearted eight-year-old; Templeton, the gluttonous rat; Wilbur, the adorable but fearful pig; and his friend Charlotte, the intelligent gray spider?

In the book, Charlotte, an orb-weaver who makes her home above the pig pen, saves Wilbur's life by writing "Some Pig" and other messages of praise in her web. At the story's climax, when Charlotte's work is done and she reaches the end of her natural lifespan, she is hailed as a hero.

Unfortunately, spiders are seldom celebrated in real life. Though only a handful of species are dangerous to humans, nearly everyone fears and loathes all of them.

Most spiders are good guys, though. Many species in our region spin flat, circular webs that help control harmful and pesky insects such as flies, leafhoppers, grasshoppers, mosquitoes, gnats, aphids and thrips. Few have mouthparts that can break human skin, yet they're blamed for the bites caused by fleas, ticks, and mites.

Dangerous spiders in the Middle South, including the black widow (Latrodectus mactans), brown widow (Latrodectus geometricus), and brown recluse (Loxosceles reclusa), do not make orb webs. The two types of widow spiders are more likely to build their irregular, tangled webs (called cobwebs) in a garage, outbuilding, or a crawl space than to reside among the garden's foliage. And the recluse, which roams for dead insects at night, spins a small mat of silk for nesting, not trapping.

When time allows, I like to observe the many orb-weavers in my garden, especially the large yellow and black garden spider (Argiope aurantia). Called the writing spider for the zigzag band of white silk it spins at the center of its web, this species constructs its web in sunny fields or among tall garden foliage where it is protected from the wind.

Despite vivid bands of color, the garden spider is usually camouflaged among the varied foliage. Females have rounded bodies and long legs that measure up to three inches in diameter, while the male is thin bodied and less than an inch long.

On an interesting note, the female of this species consumes the interior portion of her web each night and rebuilds it in the morning with new silk. It's believed the web may have tiny bits of insects and other organic matter that provides nutrition.

I also like to watch funnel web spiders, (Agelenidae), and the much smaller sheet web weaver, (Linyphiidae), that are often found in the landscape. Funnel web spiders are fun to look for because they try to remain hidden deep inside the funnel-shaped webs they build among the plants and shrubs. Unlike the bulky yellow and black garden spider, this species is fast, running out of its hiding place to subdue its prey when an insect becomes tangled in the trap.

Sheet web spiders are tiny, dark colored spiders that spin flat, horizontal webs to catch small insects such as mosquitoes and gnats. When I go out early in the morning to get the newspaper, hundreds of these webs, outlined in dew, glisten on the tops of the shrubs and lawn like sparkling lace handkerchiefs.

Web spiders such as these three species have poor eyesight, but are sensitive to touch. When an insect becomes trapped in their snare, they rush over to wrap it in silken thread, and then bite the insect to kill it. A digestive enzyme from the spider's bite turns the inside of the insect into liquid, which the spider drinks for a meal.

As anyone who has read Charlotte's Web knows, female spiders die after they produce their eggs. The eggs may overwinter as they are, or they may hatch into babies that remain protected in the egg mass until spring.

From the time they are born until they die, garden spiders continually spin silk. Sadly, controlling disease-carrying and plant-destroying insects doesn't win them many popularity contests.

If you are a spider fan, like me, do be on the lookout for black widows, the most dangerous spider in our region. Easy to identify, their shiny black bodies are marked with a red hourglass on the underside of their abdomens. A bite from a black widow can result in severe pain, violent abdominal cramps, muscle spasms, and breathing difficulties. Death, however, is very rare, with mortality in less than 1 percent of all cases, and recovery usually complete within a few days.

The U.S. Public Health Service estimates that venomous wildlife causes human death less often than people expect. Snakes average fourteen fatal injuries annually, bees twelve, wasps ten, spiders six, and scorpions one. As is often true with other dangers, the elderly and young are most susceptible.


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