Wandering spiders often end up trapped indoors


COLORADO SPRINGS, Colo. — OK, here’s the good news: Arachnids that you’ll find in your home this time of year are in search of a few things, and none of them are you.

Warmth, moisture and, er, spider companionship are at the top of their lists.

“This time of year, you see a surge in the number of particularly male spiders coming into the home desperately looking for females,” said Paula Cushing, curator of invertebrate zoology at the Denver Museum of Nature and Science. “When the males mature, even web-building males, they stop building webs and they have just one thing on their minds.”

But that doesn’t mean there will be a legion of spiders in your home.

“Males locate females by increased wandering. They’re a lot more active so they’re moving around more, and with that increased activity they can sometimes make their way into our homes,” she said.

“I don’t think a spider thinks very much. They’re just by happenstance making their way inside.”

Whether or not you see them, you live with spiders — lots of them — year-round. About 10 percent of the world’s roughly 35,000 known species of spiders live in North America.

Three native U.S. species are poisonous to humans: the black widow; the brown recluse; and the hobo spider, according to the Centers for Disease Control. In fact, the little visitors aren’t trying to set up house, said Whitney Cranshaw, a professor of entomology and extension specialist at Colorado State University in Fort Collins.

“These are spiders who wander into the house,” he says, “often making the wrong turn, and can’t get out.”

At the top of the list are the funnel weavers, so named because of the hollow, oblong web in which they live.

With legs outstretched, the average funnel weaver can grow to about an inch in length. Males can cut a gruesome image.

“Being brown and having wacky looking palps are two things that tend to upset people,” Cranshaw said. “Any brown spider, people just assume it’s a brown recluse, and they never are.”

Other common fall wanderers include the “roly-poly hunter,” the Bold Jumper jumping spider and the wolf spider, less common indoors than the funnel weaver, for which it’s often mistaken.

Wolf spiders bodies can grow to up to an inch.

“It’s rare to see more than one wolf spider in your house,” Cranshaw said. “They don’t breed in there. They’re just lost.”

Black widows thrive in the American South and West, according to the CDC.

“Whether or not you’ve seen black widows around the home, I guarantee you, you have them,” Cushing said. “Black widows are very timid spiders. They don’t tend to bite people unless they’re seriously provoked, unless you put your hand actually on them.”

Female black widows are a glossy black and the males are brown; both have the distinctive red hourglass marking on their belly.

If you find a black widow inside the home, dispatch or carefully remove it, especially if you have small children, Cushing said.

“Don’t worry about black widows outside the home. If you have kids, teach them what a black widow looks like. You know, ‘Bad spider, don’t touch,’” she said. “The rest of them, a big old wolf spider, if you pestered it enough … you’d feel a pinch and maybe some localized pain, but that would go away after a few minutes and not cause any more problems,” Cushing said.

To cut back on the number of spiders in your home, close any obvious gaps along floorboards and at windows and doors, and minimize landscaping near the house.

Cushing cautions against pesticides. Although she advocates for carefully returning the spiders to the wild, she suggests placing sticky traps, available at hardware stores, on the floor near exterior doors, in basements, in the kitchen and bathroom and around radiators — anywhere there might be dripping or pools of precious water. Reducing clutter can help, too.

“They seek out hiding places to build nests and retreats, so if you have a lot of clutter on the floor, that’s a stable habitat,” she said.

Keep in mind, too, “it might come back, especially this time of year because of the temperature gradient,” she said.