All kinds of undesirable pests don’t even need crawl space to make themselves at home – including your home.

Michelle Trautwein hates to break it to you, but your home belongs to the bugs.

They’re in your basement and your attic. They’re scuttling along floorboards and windowsills. They’ve turned your kitchen cabinets into complex ecosystems – complete with scavengers and parasites, predators and prey. And there’s nothing you can do about it.

That is the latest takeaway from Trautwein’s five-year, five-continent effort to understand the creepy crawly roommates with whom we share our homes.

“We’ve been sampling houses all over the world, and it’s true globally,” said the California Academy of Sciences entomologist. “Bugs don’t respect the limitations, the borders we’ve created. They just view our houses as extensions of their habitat.”

These invertebrate interlopers, she continued, are “an inevitability of living on the planet.”

Trautwein and her colleagues have sampled homes in bustling cities and rural villages in the United States, Australia, Japan, Peru and Sweden. Soon, they hope to visit Africa and Antarctica.

In 2012, the team convinced 50 homeowners in Raleigh, North Carolina, to let them look for bugs inside their houses. The scientists spent hours crawling around on the floors of the strangers’ homes, gently swabbing for critters and depositing their finds in tiny plastic vials.

For their latest paper, published Friday in the journal Scientific Reports, Trautwein and her colleagues wanted to figure out what features of a building make it friendlier to bugs. So they scored each home on a number of metrics: degree of cleanliness; amount of clutter; presence of pets, pesticides, dust bunnies; number of windows and doors.

To Trautwein’s surprise, “nothing seemed to make a difference” when it came to bug diversity. Each home had an average of 100 species living in it, regardless of how often the residents cleaned or how many pets they had.