Photograph by Matt Bertone
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This false bombardier beetle will often wander into U.S. homes and roam around looking for prey (or a way to make it back outside).

Photograph by Matt Bertone

Wealthier Homes Have More Kinds of Bugs

The new research supports a "luxury effect," in which higher-income neighborhoods host more biodiversity.

You’re never really home alone.

Even when you think you're enjoying a few moments of blissful solitude, entomologist Misha Leong likes to remind people, you have more tiny roommates than you think.

“Ecologists spend most of their time studying these far-off, exotic places, but we rarely think about the wildlife inside our homes,” says Leong, a postdoctoral fellow at the California Academy of Sciences. “We’re actually surrounded by wildlife, especially bugs, when we’re indoors.” (Related: "500 Kinds of Bugs May Be Living in Your House")

Now a new study shows that wealthier homes have more types of arthropods—which include insects and spiders—than less expensive homes.

Though Americans love the great outdoors, we're spending more and more time in the great indoors—about 90 percent of our time, according to recent estimates.

And scientists know relatively little about the ecology of the habitats we have created for ourselves. A 2003 study showed high-income neighborhoods have a higher diversity of vegetation than lower-income neighborhoods, a phenomenon that ecologist Ann Kinzig calls the "luxury effect."

Since then, researchers have delved more into the luxury effect, studying how individual and neighborhood income affects biodiversity.

The Bugs in Our Midst

Leong and colleagues, however, wanted to take the luxury effect indoors. As part of a larger project on indoor arthropods, the researchers sampled 50 randomly selected homes in Raleigh, North Carolina, that covered the region's economic spectrum.

“We didn’t go through drawers or closets looking for secrets,” Leong laughs, “but we did spend a lot of time on our hands and knees sweeping up samples.”

If You're Scared of Bugs, Don't Watch This Behind the scenes at the Smithsonian's Insect Zoo, entomologists care for a plethora of insects, including giant cockroaches, tarantulas, and even a giant 300-legged centipede. Video.

Sampling each room took around half an hour. The researchers didn’t count the total number of arthropods in homes, just the number of species represented. The average home contained 61 distinct arthropod families, some of which could live their entire lives indoors. (See "7 Bug and Spider Myths Squashed.")

The data showed wealthier homes had an average of a hundred types of arthropods, compared with 50 types in less wealthy homes—even when the size of the home was taken into account, according to the study published August 2 in the journal Biology Letters.

Though the reasons are unknown, it may be because wealthier homes tend to have larger yards with more plant species, which, in turn, support more arthropods.

Nature Deprived

“This study is part of the brand-new world of urban ecology," says Jeff Ackley, an urban ecology fellow at Arizona State University who wasn't involved in the study.

Such research is "building a new view of cities” that includes not just the areas surrounding our homes but also our indoor ecosystems, he says.

Ackley also sees the new results as a social justice issue. "Some neighborhoods aren’t just impoverished financially, they’re also impoverished in biodiversity,” Ackley says.

By the way, lest you suddenly feel an urge to vacuum your home to rid yourself of your invisible insect squatters, Leong has words of reassurance. (Related: "What Should You Do If You Find a Spider in Your House?")

“Many of these species are completely harmless," she says. "And even homes that looked completely clean still had lots of insects."

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