Although spiders don't have a large human fan base, they should at least get the nod for reducing the number of other bugs in your house. These swiftly darting carnivores are not in your basement just to cause you grief: All they're after is food, and the presence of spiders in your home means that there are fewer spider-coveted insects than there once were. If you still want the spiders gone, try preventive measures, natural repellents or commercial solutions to rid your basement of unwelcome arachnids.
Prevent New Infestations
Without a food source spiders won't stay, so your first line of defense is to keep your basement clean and free of spider snacks. Sweep up dust and food crumbs, taking care to move appliances for increased access to hidden areas. Apply caulking where necessary to keep new spiders as well as spider meals from entering. Ensure that the outside of your house is free from leaves and other bug habitat materials such as excess grass; instead, surround your house with cedar mulch, which spiders don't like. Reduce the availability of spider hiding spaces in your basement by minimizing clutter and eliminating unnecessary items, such as empty boxes and bags.
Spray with Peppermint Oil
Fortunately, an effective spider repellent comes with a pleasant fragrance and is non-toxic. Spiders don't like peppermint and are driven away by its smell. Fill a spray bottle with water and add 15 drops of peppermint essential oil, or enough to adequately scent the water. Then spray potential spider entry points such as cracks, gaps, window sills and doorways.
Try Other Natural Repellents
Vinegar works much like peppermint oil to repel spiders, although the fragrance is not as pleasant. The procedure is the same, however: Mix vinegar with water and spray wherever you think spiders can enter your basement. Also try leaving chestnuts around or rubbing citrus peels where spiders frequent, or soak tobacco in water for another spider-combating spray.
If entry prevention fails and natural remedies don't work, try a pesticide designed for spider control. Spray the outside perimeter of your house, and if necessary inside, as well as along the baseboards and behind furniture where spiders could hide. Use a pesticide container that includes an attachment such as a small spray tip to access cracks and crevices where spiders might crawl. Also available are insecticide dust treatments that cover larger areas. Be sure to read labels or inserts to learn about toxicity risks and safe procedures before you begin.
Make Use of Traps
Traps are an effective method for gathering information about your spider population. If you have safety concerns, such as a cat that likes crawling into dark hiding places where dangerous brown recluse spiders might hide, commercially available spider traps can confirm the presence of such spiders in your home so you can take extra precautions. Traps can also give you a sense of whether your spider population is decreasing as you employ various methods of control.