Science & Technology

Even If You Don't Kill Spiders, You Might Be Doing Them Harm

When you find a spider in your bathtub, it's understandable to want to kill it. It has too many legs, hardly any torso, and it broke into your house without even knocking! But entomologists — that's scientists who study insects — argue that there might be a better way to proceed with an eight-legged visitor.

Related Video: Why Spiders Are Awesome

Why Not Go For the Death Smoosh?

Well, for one, spiders are just inevitable. North Carolina entomologists looked through 50 different homes, and all of them had spiders — the only question was what species they were and how good they were at hiding from their human overlords. Even if you kill every spider you see, your home will still have a whole furtive spider civilization in its cracks and crevices: A typical home has between 50 and several hundred spiders.

This is a blessing in disguise, though. Spiders are good houseguests! They almost never bite humans. In fact, they prefer to avoid us altogether. And in a way, they function like free, invisible groundskeepers in our houses, trapping and killing other even more obnoxious pests. Off too many spiders, and you could find your house buzzing with flies ... or potentially disease-carrying mosquitoes that, you know, thirst for human blood.

It's also just more humane not to kill spiders, who are really a lot like us. Consider this factoid, from British researchers that created a free app for tracking arachnid sightings. They received almost 10,000 crowdsourced spider reports and found that the vast majority of them were about male spiders scurrying around in the evenings, probably looking for mates. Almost brings to mind male humans, doesn't it?

The Best Peaceful Approaches

Ok, so if you don't want to kill them, but you also don't want to share a shower with them, then you can just scoop them up and toss them outside. Right? Yes and no. This is the sink-or-swim approach, and it works great for spider species native to your area. For immigrant spiders, however, this can basically be a death sentence, according to arachnid expert Rob Crawford at the Burke Museum of Natural History.

Spiders are only built for hyper-specific environments, so much so that a species that originated in London will die outdoors in Seattle, an almost identically gloomy city. And your house has more non-native spiders than you think. "The American house spider (Parasteatoda tepidariorum) [is] probably native to northern South America," Crawford told LiveScience in 2016. "It undoubtedly lives outdoors just fine if your backyard is in Brazil or Guyana."

You do have a few other options, including moving them somewhere else indoors. Even if you don't have a Spider Party Room, there are places spiders can live unobtrusive lives in any home: a crawl space, a basement, a garage, etc. Crawford says indoor relocation, once you trap the spider between a glass and a piece of cardstock, is the most humane move, as it's almost guaranteed not to kill the spider.

Of course, you can also ignore them. Usually, when you see a spider, it's an accident, or the spider is trapped. You can assume the former and just carry on with your life — although if the spider's in a bathtub, it might be having trouble scaling the slick ceramic walls. Here, instead of washing it down the drain, try draping a towel over one side of the tub and giving it some space. The towel's textured surface will function like a spider ladder, and when your return, the spider should be gone.

Optionally, you could also do some caulking. If you're seeing a lot of spiders, the issue is likely with gaps and cracks in your walls. Even spiders that seem big can fit through small holes. Caulking can do a lot to keep your spiders thriving but out of sight.

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Rather not get too close to an eight-legged visitor? This specialized insect catcher keeps you several feet away from the critter while you harmlessly catch it for relocation. That's an affiliate link; if you use it to make a purchase, Curiosity will get a share of the sale.

Written by Mae Rice September 25, 2018

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