Schools near lakes often attract large numbers of flying insects to night lights as does general security lighting on buildings. Spiders will build webs under eaves, in corners or on shrubbery. Spider populations will fluctuate from year to year, but will be highest in the late summer. Indoors, the highest numbers will be in storerooms, crawl spaces and basements. Because there is so little food available indoors, spider populations will be limited unless they have an easy time migrating from outdoors.
Poisonous spiders are very rare in Wisconsin.
There is only one site in Racine where Brown recluse has been found breeding and the Northern Black widow is not common anywhere in Wisconsin. If hunting spiders are being found inside in large numbers, check door sweeps, electrical openings, vents and other areas on the outside of buildings and seal up these access points. Keep vegetation along foundation to a minimum, preferably a 24 inch band that is vegetation free. Vacuum indoors to remove webs and egg cases. For indoor nesting species, remove clutter in storage rooms.