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The Roommates You Didn’t Know About

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Let’s call it like it is: if you have a house, you probably have spiders.


They may be living in your basement, floorboards, attic, windowsills, or even inhabit your houseplants. But despite their reputation as outdoor pests that “randomly” appeared inside, most of your indoor spiders likely haven’t wandered into your home: Our houses are their natural habitats.

That may not help the arachnophobics sleep better at night, but fear and respect aren’t mutually exclusive. The prospect of having every single spider in your house, while eventually attainable with diligent treatment and a recurring pest control service, isn’t necessarily the key to peace of mind.

Let’s dive into some interesting facts that might persuade you to look at spiders in a new light:

1. Humans and house spiders have history.

Like all modern arthropods, the spiders in your attic are descendants of (pause for horrified shudder) 7-foot-long marine animals that lived about 480 million years ago. True spiders evolved about 300 million years ago, which means they literally pre-date dinosaurs and certainly humans. It feels like they’re often encroaching, but hey, they were here first.


Still, sharing your sleeping bag with spiders on a camping trip isn’t the same as sharing our homes with them. A spider’s evolutionary seniority doesn’t give her free reign over habitats built by and for people.

But ousting spiders from any house is a substantial task. Not only are spiders stealthy and stubborn, but they’ve been living with us for a very long time. In fact, many house spiders are now specifically adapted to indoor conditions like steady climate, sparse food and even sparser water.

2. Putting a house spider outside could kill it.

Ok, so you don’t like them but you’ve tried the pacifist’s approach, caught them in a cup or something, and hoped to set them free outside. That’s where they’re from, right? Though a noble thought, Rod Crawford, curator of arachnid collections at the Burke Museum of Natural History & Culture in Seattle thinks it won’t help them much.


“You can’t put something ‘back’ outside that was never outside in the first place,” he wrote. “Although some house spider species can survive outdoors, most don’t do well there, and some will perish rather quickly when removed from the protective indoor habitat. You’re not doing them a favor.”

In general, Crawford says,

only about 5 percent of the spiders you see inside have ever set foot outdoors.

3. Not all spiders in houses are house spiders.

You’ve accepted that they’ve been in your house from the start… but how did they get there?

Spiders typically colonize buildings, AKA their new habitats, via eggs sacs attached to furniture or building materials. Sometimes though, outdoor spiders wander inside. Many of these are spiders that favor active hunting, like wolf spiders, and may be seen running across floors or walls. If you release one of these outside, you might actually be doing it a favor.

Crawford notes that suspected “wolf spiders” are often just male European house spiders, which tend to roam around more than females do. And although many house spiders weave webs, a few mix things up by actively hunting prey. It’s not always easy to tell indoor and outdoor spiders apart, but it might help to study the eyes more than markings or other features.

Still, the thought of any spider freely waltzing around the home isn’t a pleasant one for any homeowner.

4. Not all house spiders look alike.

To complicate matters further, spiders come in lots of shapes and sizes. The types in your house depend largely on where you live.


One of the most abundant house spiders is Parasteatoda tepidariorum, aka American house spider, native to North America but now found around the world. Measuring 4 to 8 millimeters long, these yellowish-brown spiders have a tall, round abdomen and two rows of four eyes. They build tangled webs, often both outside and inside buildings. On the bright side, they have relatively mild venom and bite humans only in self-defense.

Another widespread species is Tegenaria domestica, aka domestic house spider. It ranges from 6 to 12 mm in length, with a reddish-brown “head” (the cephalothorax) and a pale, speckled abdomen. It builds funnel-shaped webs, and is known to prey on pest insects inside homes.


Steatoda grossa, aka cupboard spider varies in length from 4 to 11 mm. this spider is known for messy webs that contribute to indoor cobweb buildup. It’s also one of several Steatoda species known as a “false black widow” because people commonly confuse it with that highly venomous spider. Not only does it lack the black widow’s red hourglass, however, but its bite is a lot like a bee sting.

5. Spiders don’t use plumbing to sneak inside.

Since spiders are often found trapped in sinks or tubs, many people assume that’s how they got inside. But turns out, modern drains feature sediment traps in their design, preventing spiders from passing.


They probably just got stuck while looking for water. Your house spiders live in water-poor environments, and will try to reach drops of water in sinks or tubs. Once trapped in their ill-fated slick-sided porcelain bowl, they are unable to climb back out.

6. House spiders can actually be helpful.

Though the prospect is awful for some, house spiders can be somewhat beneficial, indoors.


If you want to make sure your house spiders are pulling their weight in your house, check in and under their webs to see what they’ve been eating. Many web-dwelling house spiders drop the remnants of their prey to the floor after eating, which can make an annoying mess but also provide evidence of their small contribution to the household.


For many, one spider inside is still too many.

We get those people, and we get you.

Seeing spiders wandering around inside? It’s time to send them packing.

Call an Edge Service Specialist out today.


Edge provides both residential and commercial services including: Pests, Lawn, Mosquitos, Rodents, Fleas & Bed Bugs.

Click HERE to talk to an Edge expert today. 

If you’d like to learn more about what Edge does, click HERE.


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