The Average American Home Has About 100 Different Bug Species

If you’ve been feeling lonely lately, we’ve got good news for you: You’re never really alone. Even in a seemingly empty house, you’re sharing a space with hundreds of bugs. The interior of a house is a veritable arthropod jamboree, according to scientists who identified hundreds of species in a survey of 50 homes. The findings were published today in the journal PeerJ.

The study was part of the Arthropods of Our Homes project, which aims to explore the diversity of itsy-bitsy life in American houses. The term “arthropod” refers to animals with exoskeletons, segmented bodies, and jointed legs, and includes insects, arachnids (like spiders, ticks, and mites), and other bugs like centipedes.

After recruiting volunteers for house checks, in 2012 the researchers scoured 50 detached homes in Raleigh, North Carolina, looking for any kind of arthropod, living or dead. (They didn't survey apartments because of the easy transit bugs can have between dwellings.) All told, the researchers found more than 10,000 specimens.

According to lead author Matt Bertone: "Nobody had done an exhaustive inventory like this one, and we found that our homes host far more biodiversity than most people would expect."

To be a little more specific: The team found an average of about a hundred arthropod species per house. Many of these were the kind of bugs you’d expect: flies, beetles, spiders, book lice, and ants. Others seemed to have gotten lost in the wrong neighborhood.

"Many of the arthropods we found had clearly wandered in from outdoors, been brought in on cut flowers or were otherwise accidentally introduced,” Bertone said in the press statement. "Because they're not equipped to live in our homes, they usually die pretty quickly."

"The vast majority of the arthropods we found in homes were not pest species," Bertone continued. "They were either peaceful cohabitants—like the cobweb spiders (Theridiidae) found in 65 percent of all rooms sampled—or accidental visitors, like midges and leafhoppers (Cicadellidae)."

We’ve all got a few more housemates than we realized, but that’s certainly no cause for alarm. "We share our space with many different species, most of which are benign,” Bertone said. “The fact that you don't know they're there only highlights how little we interact with them."