There are numerous species of spiders present in the Chicagoland area. Most of the spiders are harmless and help in controlling other insects. The four most common spiders found around Chicago are: the House spider, Jumping spider, Cellar spider, and Yellow Sac Spider. None of which are considered dangerous to man. The two spiders which are to be considered dangerous, Black Widow and Brown Recluse are occasionally observed in the southern portion of Illinois and rarely in the Chicagoland area. For the purpose of identification the following are characteristics that will help in identifying these spiders.

The House Spider - The spider most commonly encountered in the home. Oddly enough the average home is too dry to support this species. Couple the dryness with the small size of new born spiderlings, the mortality rate is about 98%. The house spider selects web sites at random and abandons them if the food supply in the area is not plentiful. The area most common is the ceiling / wall junctures of rooms. Areas that have a high moisture content such as damp crawl spaces etc are likely to be full of these webs. The webs contain the egg sacks of the house spider. Each sack may contain up to 250 eggs. When conditions are favorable two or more egg sacks may be found in the same web. This spider has a body length between 1/4" to 3/8".

The Jumping Spider - This is a hunting spider and is found sitting on walls inside homes. This species of spider is capable of jumping from a few inches up to 6 inches in one leap. They feed on flies and other insects. This species has colorful markings on the surface of the abdomen. Most of these spiders are transported into the home on firewood.

The Cellar Spider - These spiders are quite common in cellars, barns and damp warehouses. Their legs are quite long. Two species are commonly encountered, the long bodied cellar spider, and the short bodied cellar spider. The former has a body length of 1/3 inch, and legs up to 2 inches long. The latter a body length of 1/10 inch and legs about 1/3 inch long.

The Yellow Sac Spider - These spiders build their silk retreats in upper corners and the joints between the wall and ceiling.  Females produce several egg masses, each containing 30 to 48 eggs.   This spider is pale yellow or pale green.  Females have a body length of   3/16" to 3/8", males 1/8" to 5/16" .  Entrance to the home is through faulty screens,cracks around doors and windows, gaps around pipes or any other suitable entry point.  Once inside it prefers to stay where food is readily available.   This spider more than any other species, is responsible for spider bites throughout the United States.  Bites occur when the spider crawls into clothing and is pressed close to the skin.  The bite is generally harmless with a slight swelling, localized redness, and  a burning sensation at the site

Control - Since spiders generally feed off other insects it is imperative that food sources be identified and eliminated.  Spider control is best achieved by treating the upper areas (ceiling/wall junctures) of all rooms with a residual insecticide.  The floor/wall junctures of all rooms must also be treated. Badly infested (lots of webbing & egg sacs) areas such as crawl spaces must be lightly treated with a non residual aerosol.  All webbing should be removed within 3 days of treatment.  The exterior perimeter of the structure must also be treated.  Key areas would be around doorframes, windows and shutters.  These areas would be treated with a residual insecticide  It is advisable to remove any suitable habitat (compost piles, leaves, fire wood), for the crawling insects which the spiders feed upon, from the immediate (10' ) area of the structure.  The cost to treat the average (3 to 4 bedroom) house is $125.00 and a 90 day guarantee will be provided.