A Plague of Killer Spiders?

Electron microscope image of a spider's silk spigots
Electron microscope image of a spider's silk spigots
Photo courtesy MicroAngela

Aug 10, 2006 | Post Archive

It may not be unmanageable swarms of locusts or frogs falling from the sky, but the a recent plague of yellow sac spiders has many Austrians spooked. For some, "hysterical" might be a better word for it. Since several biting reports were filed earlier this summer, the yellow and brown striped spider has swept the media off its feet. And as any self-respecting news agency would have it, the sensationalism has led to a wave of public hysteria serious enough to warrant a government statement.

The Associated Press quotes Austria's health minister, Maria Raouch-Kallat: "The bites of the Yellow Sac Spider are indeed painful but not deadly...If you are bitten, please don't panic and in case of discomfort immediately contact a doctor." Those bitten by the Yellow Sac Spider (also known as Cheiracanethium punctorium) report that the spider's bites are definitely painful and cause nausea. As evidence of the Austrian public's level of fear, a local hospital reported that only 8 of its 190 visitors who claimed symptoms were legitimate.

Dr. Kyle Jordan, writing for Pest Control Magazine, points out that all spiders are venomous, only some possess more potent venom than others. According to Jordan, the yellow sac spider:

...is an active hunter, emerging at twilight from its silken retreat to seek out prey. It typically searches among foliage, waving its first pair of legs in front as feelers as it rapidly climbs amid leaves and plant stems. Because of their active searching, sac spiders often enter homes and are commonly seen running up walls. They will loiter near the ceiling, dropping to the ground to escape when disturbed. Each morning, the spider constructs a silken sac in a protected area, such as under a leaf or at the junction of a wall and ceiling. This daytime retreat is where the spider derives its common name.

Zoo.org says that the female yellow sac spider lays 30 to 48 eggs after mating and covers them in a white silken sac. The spider then vigilantly protects the egg sacs, typically located along ceilings and in corners. They warn that

Yellow sac spider bites occur most frequently when the very defensive spider is trapped in clothing. Sac spider bites are not considered as serious as those of the brown recluse or hobo spiders. The severity of bites varies greatly

Dr. Jordan says that there's a strategy to getting rid of the sac spiders: first, eliminate the their sac retreats and the spiders themselves, then rid your home of their prey. He says that, because the spiders are so active, "Physical control is more effective than chemical control...Vacuuming the spiders and their sacs often effectively reduces an infestation."

It would seem that the good people of Austria have little to fear if they take proper preventative measures. And if they don't and happen to get bitten, the worst they have to fear (barring allergic reactions), is the equivalent of a wasp sting and a sore that sticks around a a few weeks to heal and possibly months for the lesion to completely vanish. Not quite a day at the pool, but a little dose of perspective never hurts anyone.(link)

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