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'Eight-legged roommate'? It's spider season. Here's why you're seeing more around the house

While the search for wintertime shelter may account for why you're seeing more spiders, experts also say the full-grown arachnids are driven by an impulse to reproduce.

Eric Lagatta
USA TODAY

Fall is around the corner, which means some of nature's spookiest creatures are starting to emerge in droves, providing a free — if unwelcome — Halloween decoration.

If you've been noticing more spiders scuttling around your home, experts say you're not alone. In fact, there are several reasons those eight-legged creepy crawlers always seem to be more prevalent this time of year.

Though spiders are abundant from spring through fall across the United States, experts warn that more may be noticed inside our homes when temperatures start to cool and they seek out warm spaces to take shelter for the winter.

Fall is also the time of year that most arachnids reach maturity and are full-grown, which may account for why you're noticing them more often.

"They are not necessarily more abundant than in the summertime, but individuals are more visible because they are larger," said Anne Danielson-Francois, associate professor of biological sciences at the University of Michigan-Dearborn. "A small web might go unnoticed in your kitchen window, but once that spider has grown to full size and spins a web that covers a quarter of the window, you could not miss it."

But there's one other reason spiders may suddenly be appearing. With that maturity also comes a certain impulse to ... well, procreate.

Here's what to know about spider season.

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So, spiders are mating inside my house?

And beneath your deck, and under that bush in your backyard, and likely many other places in and around your home.

It is what it is!

Our homes are rife with window sills and other small crevices in which spiders can hide, while trash cans and compost bins provide a plentiful food source of scavenging insects, said Lisa Gonzalez, a program manager at the Natural History Museum of Los Angeles County, home to the spider pavilion where about 300 spiders of up to 15 species live.

What's more, structures like houses provide plenty of sturdy attachment points for their webs.

That is to say, our homes are great places for spiders to live, which means it's also where they're going to reproduce.

Late summer and early fall is typically when male webspinners, hoping to put their newly-developed sex organs to the test, leave their webs in search of female mates, Danielson-Francois said. The female spiders, depending on species, typically conserve their energy and remain at their spun homes, waiting on the males to come to them.

What months should I expect to see more spiders inside?

The answer to this question depends on where you live, but most experts say spider activity ramps up as soon as overnight temperatures start to drop.

In the Chicago region, for instance, this time period starts around mid-September through October, or the first hard frost of the year, said Allen Lawrance, associate curator of entomology at the Peggy Notebaert Nature Museum located in Chicago and operated by the Chicago Academy of Science.

Some spiders can also live year-round inside of homes.

In Los Angeles, it's common for people to have cellar spiders (better known as "daddy longlegs") in their homes regardless of the time of year, Gonzalez said.

These cellar spiders hide quietly in a corner, munching on little flies and other small insects that wander by. 

Should I kill them?

No!

The rule of thumb, experts say, should be this: If the spider isn't bothering you, then don't bother it.

Arachnologists do acknowledge that many people are fearful of spiders and may not want them around. But there's no need to burn your house down to rid yourself of the critters; if you can't tolerate their presence, simply use a cup and piece of paper to capture and move the spider outside.

"Don’t feel bad for the spider, they can survive outside quite well," Danielson-Francois said. "With substances in their blood that act like antifreeze, some species can overwinter under tree bark or in leaf litter just fine."

Even Gonzalez said she removes widow spiders, which have venom that can cause problematic reactions if they bite, from her mailbox and underneath patio furniture.

"Every other spider I see in and around my house is welcome to set up camp," she said.

More drastic (and nonlethal) measures include inspecting the perimeter of your home to ensure that all cracks are sealed, window screens are tight-fitting and no gaps exist below doors, Lawrance said. Homeowners can also keep porch lights turned off at night to avoid attracting insects that spiders prey on, he added.

The important thing, though, is to remember that most specides of spiders commonly found inside homes are not dangerous.

"While all spiders do produce some venom to help capture and consume their prey, none of these pose any real threat to humans," Lawrance said.

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Are spiders beneficial to have around?

Yes!

Spiders are predators, so they keep insect populations in check. If left alone spiders provide free pest control, eating more obnoxious pests such as flies, Lawrance said.

"If you can allow an eight-legged roommate, it can benefit you," Danielson-Francois said. "And they provide free Halloween decorations for your home, wherever you prefer them — inside or out."

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Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at elagatta@gannett.com.