Entomologists collected specimens of arthropods [wikipedia.org] from "free-standing houses" (not apartments, duplexes or row houses) in North Carolina [wikipedia.org]. Among the organisms found, the great majority were not considered harmful to humans or their belongings, with only "a minority of the homes" harbouring pests. The authors characterise the household fauna as "a mix of closely synanthropic [wikipedia.org] [link added] species and a great diversity of species that wander indoors by accident." The latter are thought to die soon after becoming trapped in a house.
Their work was published in PeerJ [peerj.com] and the North Carolina State University has a blog post promoting it [ncsu.edu]. PeerJ interviewed [peerj.com] one of the authors.