Spiders ambling across the ground floor of a house are a common occurrence. Depending on how much of a nuisance they are, you may want to consider some pest control methods. First, a little background information on spiders so you can tell what species you're dealing with:
There are several species that like to visit homes. Black Widows and Brown Recluse spiders are the most notorious because they are poisonous.
The Black Widow Spider
Only the female Black Widow bites. She is about a half inch long, black (hence the name), and sports a red hourglass on the underside of the abdomen. There are also Brown and Red Widow spiders in various parts of the US; these only sometimes have the noticeable hourglass.
The Brown Recluse Spider
The Brown Recluse is also about a half inch long, sometimes shorter. The spiders are brown (again, the name is a giveaway) and can be identified by their violin-shaped markings beneath the thorax (middle section).
Though the Black Widow and Brown Recluse Spiders are poisonous, they are not that much of a threat in most cases. Black Widow Spiders are very reclusive, tending to gravitate toward places where people aren't. Brown Recluse spiders are rare except in the lower Midwest in the US. The Brown Recluse also tends to stay away from people.
The Aggressive House Spider
The only other kind of spider that invade houses in the US and can harm humans is the Aggressive House Spider, identifiable by a brown body with V-shaped chevrons on its abdomen. These spiders can give you a ulcerous wound. They can move quickly and are over an inch long.
Most other types of spiders are harmless in your house. Although we are going to talk about some spider control methods, know that spiders are actually beneficial creatures. In their natural outdoor habitat they eat other pests. In your house, spiders will munch on those annoying house flies and fruit flies. Consider this before you go to extreme methods to eliminate them.
Nontoxic Spider Control Methods:
Indoors, get rid of their webs. Cleaning is the best method of spider prevention, so go through your home vigorously sweeping, dusting, and vacuuming. Do this weekly for a couple of months to destroy existing nests, not giving spiders time to rebuild and lay eggs.
Outdoors, get out the hose. Use the water to knock webs and spiders out from under the eaves. Repeat weekly or as necessary. Keep grass and weeds that grow near the house cut low, and likewise keep shrubs near the house small and neatly maintained.
Dealing with Spider Bites:
Spider bites are not usually dangerous, but if you believe a poisonous spider may have been responsible, try to capture the culprit for identification (squished spiders can usually still be identified). A visit to the doctor is necessary if you feel abdominal pain or serious pain from the bite. (Take the spider remains with you.)
People with mattresses laying directly on the floor are more susceptible to spiders running through and biting them in their sleep. If you think you're being bitten in your sleep, wash all of your bedding. Consider raising your bed from the floor.