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Spiders

 

Photo by Brenda-Starr
Photo by jasleen_kaur
Wisconsin is home to more than 1,100 of the categorized 40,000 species of spiders in the world. Spiders take various shapes and forms as well as colors and behaviors. Regardless of the individual species, all spiders consist of eight legs and feature two-piece bodies made up of the cephalothorax (front) and abdomen (the bulbous rear). The cephalothorax contains a multiple-eye arrangement (the number varying by species), mouth parts and the legs while the abdomen holds the silk-producing facilities of the spider.

The common house spider is usually the spider most often encountered indoors. It is a nuisance pest, probably more because of its webs than the spider itself. This spider is found worldwide and is common throughout the United States and Canada. The house spider randomly selects its web sites and creates a tangled web. If a web does not yield prey it is abandoned, another site is selected, and a new web is built. Survival is low in modern homes with low humidity and few insects, higher in garages, sheds, barns, warehouses, etc. because of more prey and generally higher humidity, and highest outdoors in protected places. Inside structures, house spiders are most likely to be found in upper corners, under furniture, in closets, angles of window frames, basements, garages, and crawl spaces. Outside they are often around windows and under eaves especially near light sources which attract prey. House spiders are nuisance pests but pose no threats to humans.

Long-bodied cellar spiders are commonly referred to as "daddy-long-legs" because of their very long, thin legs and as their name implies are found in dark and damp places. There are about 20 species of cellar spiders in the United States and Canada. Cellar spiders build loose, irregular, tangled webs in corners. They hang upside down on the underside of the web. The webs are not cleaned but instead a new web is continually added. This habit can result in extensive webbing in a relatively short time. The spiders and their webs are usually found in dark and damp places, such as cellars, basements, and crawl spaces. They can also be found in the corners of garages, sheds, barns, and warehouses, on eaves, windows, and ceilings, and in closets, sink cabinets, and bath-traps. Cellar spiders seem to fare better in areas with higher relative humidity. Cellar spiders do not pose a threat to humans. While they are commonly found in homes, they usually stay in one place. They are not known to bite. Urban legend has it that their venom is of the most deadly of spiders, but their weak mouthparts keep them from injecting venom into humans. While it is correct that they cannot successfully bite, their venom is not very potent.

Jumping Spiders. The common name comes from their jumping ability and habit which they use to capture prey. They are an occasional nuisance pest indoors, and some colored species may cause concern when people mistake them for Black Widow spiders. About 300 species of jumping spiders are found in the United States and Canada. Jumping spiders do not construct snare webs but do build web retreats which are loosely woven, saclike, composed of several envelopes and usually have two openings. Unlike most spiders, jumping spiders are active during the daytime and seem to like sunshine. They are hunters and have the keenest vision of all spiders, being able to detect and react to movement up to 18" in away; however their night vision is very poor. They can rapidly move both sideways and backwards for short distances. As their name implies, they are excellent jumpers. Retreats may be built under furniture, in drapery folds, between books on bookshelves, in cracks found in wood floors, around door and window molding, etc. Outside retreats may be found under loose bark, between leaves, etc. Indoors, spiders will usually be found hunting around windows and doors because more insects are attracted to these areas and their vision is best in sunlit areas. Outdoors, jumping spiders are commonly seen running over tree bark, under stones and boards, on bushes, fences, decks and the outside of buildings, especially sunny areas. While they can bite, the jumping spider bite is not poisonous. They are not considered dangerous.