Spiders are the target of plenty of fear and anxiety among homeowners, but spiders are actually considered to be among the most beneficial insects in natural ecosystems. Spiders eat many of the most damaging plant pests such as mites and aphids, thereby offering a natural means of pest control. Still, some homeowners prefer to get rid of the spiders they observe in and around their lawns. Pesticides and other sprays can be one element of a successful spider control program, in which case spray selection is the key to effective use.
In general, experts discourage use of chemical insecticides for spider control whether indoors or out; insecticides have a tendency to kill other insects with which the spiders compete for food, ironically making the infestation worse in most cases. Natural control methods such as exclusion and sanitation should be exhausted prior to considering a spray treatment. But, an insecticide can sometimes be necessary in the case of a serious infestation that sanitation and exclusion methods cannot control alone, particularly if you are concerned about spiders that are potentially harmful to humans, such as black widow and brown recluse, coming into the home.
In their guide to home spider control, the University of Minnesota recommends two formulations specifically for outdoor pesticide spray treatment. either chlorpyrifos as a liquid concentrate or a liquid ready-to-use product or diazinon as a liquid concentrate. Other formulations sold for outdoor spider control may contain pyrethrins, resmethrin, allethrin, combinations thereof or still other formulations. Be sure to look for an insecticide that is labeled as being safe for outdoor use on spiders. If you are planning to spray near a garden or other landscaped area, make sure the insecticide is safe for use around the plants in that area to avoid any injury to plants.
Many of the insecticides labeled for spider control can simply be applied to spiders that you observe in you yard. To really control a problematic infestation, it is necessary to direct spray treatments at the areas that spiders tend to frequent. Don't just spray the yard alone; include woodpiles, trash, rocks, compost piles, old boards, lawn debris and any other potential spider hiding spots in your spray program, as well. To prevent spiders from moving from the yard into your home, make sure to also spray any cracks, crevices or other openings on the outside of the home that could serve as an entrance into the home.
Other Control Measures
The reason experts generally recommend an insecticide spray as only one component in an integrated spider control program is that insecticides rarely resolve the problem on their own. Mow and clean the lawn frequently to disturb spider hiding spots. Avoid attracting flies, ants and other insects that spiders feed on to your yard and the area around your home. Replace you standard light bulbs with yellow-colored or sodium vapor light bulb as these do not attract insects as strongly as white incandescent bulbs. These are only a few of the natural control measures that can go a long way in controlling the spider infestation in your yard. In some cases, they may preclude the use of any insecticides at all.