Hundreds of Tiny Roommates

Study Surveys the Insects in Raleigh-Area Homes
May 11, 2016

Sorry, North Carolina, you are not alone in your homes.  

That, perhaps, should not come as a surprise. Hardly a week goes by where we don’t find a bug or spider hiding in a dark corner of our kitchen or bedroom, but many people probably don’t wonder how many others there might be—while many others don’t want to know.

Fly eating cream cheeseFor those who would rather not know how many creepy-crawlies walk around our homes, turn back now. New research from NC State University, the California Academy of Sciences and the North Carolina Museum of Natural Sciences have inventoried the arthropods living in North Carolina homes and found that on average, there are about 100 species in every home.

While studies have tackled the arthropods—insects, spiders, mites, centipedes and anything else with a jointed exoskeleton and no backbone*—in the home before, this work is the most exhaustive. The results are reported in the journal PeerJ.

Matt Bertone, an NC State University entomologist, and his colleagues surveyed 50 homes in the Raleigh area, scouring each room for arthropods living or dead. They spent six months searching for all the bugs these homes had to offer as part of the Arthropods of Our Homes Project.

All told, they found 579 morphospecies—a biology term meaning species that are different-looking enough from each other that they can be easily told apart—of arthropods living in the 50 homes. Each home contained anywhere from 32 to 211 morphospecies from 24 to 128 arthropod families. Only five of the 554 rooms searched did not yield a single arthropod.

That may seem like a ton of bugs, but Bertone says they are not setting up shop in our homes. Many simply wander in from outside or catch a ride on something we bring in ourselves and actually have a hard time surviving indoors.

Also, most of the arthropods living in our homes are not pests but just trying to make a living; doing their own thing. If the 100 arthropods-per-home figure surprised you, that’s because most of those, you would never see.

Distribution of Arthropods in HomesThe most common species found in many homes were ants, spiders, flies beetle and booklice, which are not actually lice but small insects that feed on mold and other fungus and can be good indicators that your home has the right conditions for mold growth.

By now you’re probably thinking one of two things: 

1.“Gross! I’ll never eat or sleep in my home again!” Or…

2.“So the arthropods are there, what’s the big deal?”

The big deal is that now that we know what is actually living in our homes, Bertone and his colleagues can ask how our homes impact the arthropod world and what these creepy critters are doing in our homes anyway.

Each home, we now know is a vibrant ecosystem with dozens of species making a living for themselves, and while some of them might be random visitors, many morphospecies make appearances in a lot of homes. Cobweb spiders, for example, were found in 65 percent of all the rooms Bertome and his colleagues sampled.

Michelle Trautwein, chair of the Dipterology (the study of flies) Department at California Academy of Sciences and co-author of this study, says these common species might play an important role in the ecosystem of our homes.

Just like our digestive systems don’t work without a few billion bacteria to help us, maybe our homes don’t work right without bugs and spiders. They might fight off parasites or eat other less friendly arthropods. 

Maybe their purpose long ago was to clean. They could round up food scraps or eat up smudges. Maybe their purpose is just to freeload, hanging out on the walls all day watching CSI reruns. 

In that case, maybe you could ask them for rent money, but the chances of getting any are, like the arthropods themselves, tiny.

*Crabs, shrimp and lobsters are all arthropods as well, so the next time you have a nice seafood dinner, just remember you’re eating giant delicious sea bugs!

— Daniel Lane

Daniel Lane covers science, medicine, engineering and the environment in North Carolina.