Q We have a big spider problem. They cover the deck and siding with their webs and leave dark stains. It's unsightly and the spots are difficult to remove. How do we stop spiders from targeting our house?
A You can't, at least not for the long term. Spiders don't have it in for your house so much as they are interested in the insects (their prey) that live near it. To help control spiders outdoors:
• Clean up brush piles, wood piles, accumulations of leaves and other potential harborage areas near the home.
• Cut grass and weeds near buildings. Remove any webs and crush egg sacs.
• Knock down webs with a broom or hose them off, and crush or destroy egg sacs.
Supplement these nonchemical efforts with an insecticide spray around the outside of the home. Choose a product that is labeled for exterior use. Be sure to treat cracks and spaces where spiders are likely to hide. Remember that insecticides are a short-lived control measure. For maximum effectiveness, spray insecticides directly at spiders.
The stains to which you refer sound like spider scat. They can be difficult to remove on outdoor surfaces, especially if baked by the sun. Try scrubbing the area with a detergent and water solution. Apply the cleaning solution and let set for several minutes. Scrub with a stiff brush or nonabrasive scrubber. Be sure to test the cleaners and scrubbers in an inconspicuous area first, to make sure they don't mar your siding.
Includes information from entomologist Jeff Hahn at the University of Minnesota Extension Service
