When people refer to “house spiders,” they generally mean any spider that has taken up residence inside a human dwelling. This broad term encompasses various species, and understanding their natural origins helps clarify why they frequently become indoor inhabitants.
Native Environments of Common Indoor Spiders
Most spiders encountered indoors originate from outdoor habitats. For instance, the common house spider (Parasteatoda tepidariorum) lives in sheltered outdoor locations such as nooks on cliffs, cave entrances, or hollow logs. The giant house spider (Eratigena atrica) primarily inhabits caves or dry forests, often found under rocks or in gaps between stones.
Cellar spiders, known for their long legs, typically reside in cave openings, cliff crevices, and other protected, often damp, natural areas. Hobo spiders (Eratigena agrestis) are commonly found outdoors in rock retaining walls, under landscape rocks, in cracks in soil or concrete, and within vegetation near foundations. They often construct funnel-shaped webs in these low-traffic areas.
Wolf spiders (Lycosidae family) are robust hunters living on the ground in leaf litter, burrows, suburban gardens, woodlands, and wet coastal forests. These diverse outdoor settings represent their preferred ecosystems before human structures become an option.
How Spiders Find Their Way Inside
Spiders enter homes through various small openings. They can slip through cracks in foundations, gaps around windows and doors, or open windows and utility pipe entry points. Even small tears in screens or unsealed window frames can serve as access points.
Beyond direct entry, spiders frequently hitchhike into homes on items brought inside, including firewood, potted plants, storage boxes, camping equipment, or toys left outdoors. Spiders also seek shelter from harsh weather conditions like extreme cold, heat, or heavy rain. Sometimes, their entry is simply accidental as they explore their surroundings, only to find themselves inadvertently inside a building.
What Makes Homes Attractive to Spiders
Once inside, homes offer conditions that entice spiders to stay. Consistent indoor temperatures provide refuge from outdoor extremes, allowing spiders to avoid cold winters or scorching summers. This stable climate helps them survive and reproduce. Homes also offer shelter from natural predators.
Another significant draw is the availability of food. Spiders feed on other insects, and homes often harbor a steady supply of flies, mosquitoes, cockroaches, and ants, creating an abundant food source. Finally, human dwellings provide numerous quiet, undisturbed places for spiders to build webs or hide, such as corners, basements, attics, garages, or cluttered areas. Access to standing water in sinks or bathtubs can also be a factor for some species.