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Caught in the web

Caught in the web

For the most part they scamper unseen doing the dirty work of insect control.

However, when they are spotted inside a home or in other human-occupied spaces, spiders can elicit reactions worthy of B-movie acting roles from shrieks of terror to throwing breakable objects at a swiftly moving target.

Whether deserved or not, the arachnid has conjured up stories in our minds about close encounters in showers and doorways and along walkways near hedges. This year is no exception. The stories are hitting at a rapid-fire pace with some claiming there are more than ever; others claim the number of poisonous Hobo spiders is on the rise.

While people may speculate about the spider population, and have tales of close encounters to prove it, entomologists at Oregon State University and the Oregon Department of Agriculture said this is just a normal year and that area arachnophobes need not fear an imminent invasion.

“I have not noticed any increase in spiders,” said James LaBonte, an entomologist with the Oregon Department of Agriculture. “This time of year the spiders have grown to be adults so they are bigger and more obvious. Secondly, the reproductive season is underway, so the males are roaming in search of mates.”

The size and lifespan of a spider are related to its diet. Orb spiders, such as those that spin webs in bushes and across windows live a short time and grow fat quickly. Once they are born in the spring, hatchlings find a home, build webs and eat through the summer. By fall, they mate, lay eggs and die.

Ground-dwelling spiders such as the common European house spider and Hobo spider live on the ground and hunt. These spiders can live for several years if uneaten by predators, squished by a grossed-out child or poisoned by the hiss of an insecticide can.

At Oregon State University, Christopher Marshall is an entomologist and serves as curator of the university’s arthropod collection. While there may be horror stories of close encounters with the “deadly” Hobo spider, he said they are often confused with the similar and much more common house spider.

“They are both in the same genus…but the house spider is actually larger,” Marshall said. “The house spider is incredibly abundant and because it is larger, they notice it more and it seems more fearsome. People quickly jump to the conclusion that this must be a Hobo spider.”

The Hobo spider is also known as the Aggressive House Spider, an unfortunate name for a relatively docile creature, Marshall noted.

“This is a translation of its Latin name,” he said with a laugh. “I don’t know when it was named that but if we could go back and change that, we would. It definitely doesn’t deserve that moniker.”

Also up for debate is the toxicity of spider venom. A spider’s fangs are rarely big or strong enough to penetrate human flesh, according to Marshall. Of those that can and do deliver venom, the amount of venom and its level of toxicity depends on many factors.

“Venom is a complicated mix of protein and poison,” he said. “How powerful a venom really is can depend on the food source, climate, natural predators and other factors.”

Many people who claim spider bites do so without proper evidence. Someone that wakes up with localized pain or swelling, sees a spider in the room and say it is the culprit. It can be, but more often it isn’t, said Marshall.

In order to corroborate a bite with an actual spider, Marshall said people must overcome their fears.

“You need to shore up your fear of spiders and get a container and capture it,” Marshall said. “It’s like a crime scene. People try to go from memory and they tell the specialist ‘it was a brown spider and it was huge.’ That doesn’t really help us.”

When a spider bites a person, there may be local pain or swelling that is reduced with ice. Hobo spider bites are more severe although typically not deadly according the Centers for Disease Control and Prevention.

Symptoms include muscle pain and cramping, nausea and vomiting. A purple, pus filled blister may form in more serious cases. Typically, only 50 percent of people bitten by Hobo spiders are injected with venom, according to the CDC Web site.

Once captured, LaBonte said spider specimens can be brought to the Oregon Department of Agriculture building at 635 Capitol Street NE for identification. He also said dead, intact spiders can be placed in a leak-proof container with a small amount of rubbing alcohol and mailed to the same address.

For those with the heebie-jeebies over creepy crawlies, spider season is nearly complete. LaBonte said with mating season nearly over, orb spiders die and ground spiders take refuge for the winter.

Neither expert had predictions for next year’s population, although they weren’t expecting major changes. If a spider-free home is desired, both discouraged the use of poisons, instead suggesting that mid-valley residents exercise caution when working around stationary objects and keeping the inside of the home as free from insects as possible. Instead of killing spiders, Marshall said to take them outside where they do far more good for the home.

“Believe me, they don’t want to take up residency,” he said about the 8-legged creatures. “They are probably trapped inside and as freaked out about you as you are of them.”

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