Be careful when reaching under stones, logs, or firewood, or when reaching behind undisturbed household items such as cabinets, furniture, and boxes. Black widows, brown recluses, and other spiders tend to inhabit such undisturbed areas.
Reduce the amount of potential nesting sites around the home. These include woodpiles, lumber stacks, rock piles, brush, high weeds and grasses, and discarded human-made items. Frequently cleaning and moving stored items in basements, storage areas, and garages will reduce the number of spiders by disturbing their habitats. Vacuum spiders and their webs from behind objects, under tables, and in wall and ceiling corners. Close openings in exterior walls and install weather stripping and thresholds at the bottom of doors. Leave firewood outside until you are ready to place it in a stove or fireplace. Firewood that is stored inside, even for short periods of time, will begin to warm, and any overwintering spiders hiding there will become active and may crawl out from under bark and crevices in the wood.
Some spiders will collect in large numbers on buildings with bright exterior lighting. The lights attract a variety of flying insects on which the spiders feed. Spider populations can be reduced by spraying a high-pressure water stream onto the building, and by switching from mercury vapor to sodium vapor exterior lighting.
Unfortunately, most insecticide sprays, whether they are applied to the interior or exterior of a building, do little to control or prevent spiders from entering. If spiders are sprayed with an insecticide, they will eventually die; however, it is still advisable to remove those spiders by the means previously mentioned rather than by applying a pesticide. If you have a confirmed infestation of either black widow or brown recluse spiders in your home, contact a licensed pest control company, the Penn State Department of Entomology, or the Penn State Extension office in your county for additional information.
Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.
Authored by: Steve Jacobs, Sr. Extension Associate
March 2002. Revised 2006