How many spiders live around the house?

Probably too many to count. Spiders live everywhere, and tens of thousands can be found in a 1-acre (0.4 hectare) grassy field. There are more than 3,000 species in North America alone. No matter how clean your home is, most have a spider population that feeds on household insects, mites, and stray flies. They often live in dark, neglected areas, like closets, attics, and basements, and behind and under furniture, bookcases, or curtains. Corners and baseboards are two of their favorite locations. Most house spiders are seldom seen except during housecleaning, but some of the larger species mature and become more active from late August to early October. But spider specialists say this is no cause for alarm—very few spider species have venom that can harm humans, dogs, or cats.