Not long ago, entomologists with North Carolina State University surveyed arthropod populations within 50 homes on the east coast in order to better understand indoor ecosystems. For those not aware, the phylum Arthropoda is the most species-rich phylum in the animal kingdom, and it includes all insect, arachnid, centipede, millipede, and crustacean species. The researchers meticulously inspected every nook and cranny inside the selected homes and collected samples of every arthropod specimen they encountered. The survey procedure and its results were published in the first ever study on arthropod diversity within homes.

At the end of the survey, the researchers had collected more than 10,000 specimens from 550 rooms within 50 houses of varying architectural styles located in different residential areas. With the exception of four bathrooms and five bedrooms, each room within all 50 houses contained an abundance and diversity of arthropod species, which surprised the homeowners and researchers alike. Flies, spiders, beetles, wasps and ants accounted for ¾th of the arthropod population within each of the 50 homes. Occasional home invading arthropods like silverfish, book lice, and ladybugs were also common in each home. While most of the participating homeowners believed that bugs would be most abundant in their basement, bathroom, kitchen or attic, the researchers were surprised to find that living rooms contained the greatest diversity of arthropod species including many pests.

The relative spaciousness of living rooms provides arthropods with a variety of concealed spaces that make for ideal harborages. Also, unlike other rooms, living rooms have the most windows, doorways and entry points that a variety of arthropod species can exploit to enter homes. The arthropod community on second floors and in attics was much less diverse due to a fewer number of entry points, and most terrestrial arthropods cannot easily travel to higher floors after invading homes at the ground level. This study also disproved many common beliefs about indoor pests, such as the belief that cockroaches congregate in kitchens, and that cobweb spiders favor basement or cellar environments. In reality, both cockroaches and cobweb spiders disperse throughout the ground level of homes. In fact, brown-banded cockroaches prefer to find shelter at the highest points within structures including attics.

Have you ever spotted an arthropod skitter across your living room floor while you and others were present in the room?