Spiders are arachnids which are creatures that have two body segments, eight legs and no wings or antennae. Many people think that spiders are insects, but insects have six legs. Although not all spiders spin webs, all spiders produce silk from glands in the abdomen, and as soon as the liquid silk comes in contact with the air, it hardens. Spiders feed off insects, and if there is no food supply, they will typically relocate, and strong repellents are available that will deter spiders from your house.
Purchase a bottle of deltamethrin and drione dust at a hardware store; both are also available online. Deltamethrin is a white liquid that is combined with water and sprayed in areas to repel pests. It works particularly well on arachnids like spiders and scorpions. Drione dust is a white powder and is safe and lasts a long time. It kills on contact and works well in crawl spaces, cracks, outlets, holes and attics.
Spray deltamethrin outside along the sides of the house and the borders where the bottom of the walls meets the ground. For the first application, use 1 or 2 gallons, depending on the severity of the problem. You may need to spray more than once for several weeks. Spray around bushes, plants and decks. There is very little odour to this product and it's safe to spray in closets, baseboards and indoors.
Apply drione dust with a hand duster to outlets, cracks, crevices and any open holes. Keep pets and children away from the deltamethrin until it dries and away from any areas treated with drione dust until the spilt dust is removed.
Wear rubber gloves to avoid contact with the products, and use eye and breathing protection when treating confined areas like an attic or crawl space.