Spiders enter a home for one of two reasons: they’re either looking for a place to stay for the winter, or they’re looking for food—namely, insects—in your home. If you notice more spiders during the fall months, it’s because they’re looking to hide indoors for the winter.
The vast majority of spiders in the United States are not dangerous to humans. Many are actually beneficial, as they eat a number of common insect pests; in fact, the presence of spiders often indicates the presence of another pest you might not have seen yet.
Signs of a Spider Problem
A solitary spider scampering across your bathroom floor once in a while is pretty much unavoidable. But if you see many spiders at once, or see spiders frequently, that may indicate a problem.
The most common household spiders in North America include the orb-weaver spider, the cellar spider, and the house spider, also known as the hobo spider. The house spider’s bite, though not life-threatening, has been attributed to isolated cases of necrotic ulceration (death of the tissues surrounding the bite).
The brown recluse, the black widow, the brown widow, and the red widow, all native to the South, are the only North American spiders that are venomous to humans—and even these species are shy and tend to bite only if provoked or startled. If you are bitten by one of these spiders, or if you’re bitten by any spider and are unable to identify the species, seek medical help. Try to bring the spider with you to have it properly identified by a professional.
Habitat Modification and Mechanical Control
- Sealing: Properly sealed windows and doors will keep spiders from wandering indoors. Spiders can exploit even the smallest entrance into a home, so inspect carefully during the early months of fall and spring.
- Firewood: Because many outdoor spiders seek shelter in firewood, it’s a good idea to inspect any pieces of firewood before bringing them inside.
- Vacuuming: A vacuum cleaner is your best weapon against spiders in your home. Make sure you get any egg sacs you see near the web—they look like small, fluffy white balls.
- Pesticides: You can dust residual pesticides, such as Sevin® , into cracks, crevices, and any other points of entry that you think spiders might find. To apply, fill a plastic squeeze bottle with pesticide and squeeze it into these spots. This method is called a barrier treatment.
- Boric acid (borax): Sometimes sold as a pesticide under the name Niban®, borax is a nontoxic option for barrier treatment. Spiders that come into contact with borax may not die from it, but they will avoid returning to that area in the future.
Keeping Spiders Away
- Control of other pests: If you keep other pests and insects out of your home, you will make your house that much less attractive to spiders.
- Window treatments: Efficient blinds keep light from leaking through windows at night, reducing the number of insects attracted to the light at night and reducing the number of spiders that follow those insects.
- Sodium porch lights: Low-pressure sodium lamps contain bulbs that produce different spectrums of light than what insects are usually attracted to. Replace your typical outdoor white light bulbs with low-sodium bulbs, and you may notice fewer bugs and spiders near your porch lights.
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