Your reaction to seeing a spider in your house may be to want to kill it with fire, but that really isn't practical. After all, destroying the spider with fire is likely to destroy your house with fire too. However, that doesn't mean that there aren't things that you can do to help get rid of spiders and to help keep spiders from coming back. There are several things that you can try on your own, and if they don't work, you can always bring out the big guns.
Eliminate Food Sources
One thing that you can do is to make sure that you get rid of the food sources that spiders are likely to go after. If there isn't anything for them to eat, they are more likely to not stay because they need to have food and water, like any other living creature. That means that you are going to want to do what you can to help make sure that there are no other insects in your house. Seal up your food, check for all the places bugs can get in, and even hang up things like fly strips. If you notice spider webs, destroy the webs because spiders that spin webs use them to trap their food. If they have to spend their time respinning their webs, it's going to be harder for them to find food.
Another thing that you can try is to use vinegar or things like peppermint oil, tea tree oil, or eucalyptus oil. You can spray those things around your doors and windows to try and keep the spiders from getting into your house. Spiders don't like the smells of those things or are otherwise repelled by them, so spraying any of those things around your house may make it harder for the spiders to come in. If you have a basement or crawlspace, you may also want to spray around the entrance to your basement or crawl space because those places can be a great place for the spiders to live and proliferate.
If you still can't get rid of the spiders or you just would very much rather not deal with them, you need to call in a spider control professional. They will be able to help you out and help you get rid of the spiders that are in your house as well as helping to prevent more spiders from getting a foothold.