Over the last week or so we have started to see some cooler night temperatures, which to me have certainly been refreshing, especially compared to the warm, summer days we are still experiencing. Our six and eight legged friends though probably haven’t been enjoying the drop in temperatures as much and you may have noticed have begun to move into your homes. I have noticed in my own home an increase in the number of flies and spiders that have sought refuge inside. In my home they usually get the heave-ho back outside, or they meet with an untimely demise.
So, what can be done with spiders to keep them out of the home? First off, most spiders are harmless and are in fact beneficial because they prey upon flies, crickets and other insects. They generally won’t attempt to bite humans unless held or accidentally trapped. Moreover, the majority of spiders have fangs too small or weak to puncture human skin.
Routine, thorough house cleaning is the best way to eliminate spiders and discourage their return. A vacuum cleaner or broom effectively removes spiders, webs, and egg sacs. Spiders also prefer quiet, undisturbed areas such as closets, garages, basements, and attics. Reducing clutter in these areas makes them less attractive to spiders.
Large numbers of spiders often congregate outdoors around the perimeter of structures. Migration indoors can be reduced by moving firewood, building materials, and debris away from the foundation or entryways. Shrubs, vines and tree limbs should be clipped back from the side of any buildings.
You can install tight-fitting window screens and door sweeps to exclude spiders and other insects. Also, make sure to inspect and clean behind outdoor window shutters. Consider installing yellow or sodium vapor light bulbs at outside entrances as well. These lights are less attractive than incandescent bulbs to night-flying insects which, in turn, attract spiders.
To further reduce spider entry from outside, insecticides can be applied as "barrier treatments" around the base of the foundation. Pay particular attention to door thresholds, garage and crawl space entrances, including foundation vents. Carbaryl or any of the synthetic pyrethroids such as cypermethrin, cyfluthrin, or lambda-cyhalothrin are effective, but may need to be reapplied periodically throughout the summer. Wettable powder or microencapsulated ("slow-release") formulations are most effective.