Loree O’Hagan’s new home in Great Cacapon, West Virginia, came with four bedrooms, a wrap-around deck, a view of the mountains—and a family of feral cats. That last detail wasn’t mentioned in the seller’s disclosure report, but O’Hagan and her husband got an inkling on moving day, when they spotted...

Wherever you are in the U.S., a coyote may be taking up residence less than a mile away. If you live in the city, you’re more likely than your rural cousins to encounter raccoons. And regardless of geography, you probably share your home with dozens of species of insects and spiders. These facts...