Spiders are actually fairly harmless to have in and around your home. Some people even like having them around because they often help keep the level of other household insects in check by eating them; they actually can do a pretty good job of this, within reason of course. Still, you need to be aware of some of the problems they can present. First, a spider infestation is not good; if you think seeing one is bad, imagine seeing thousands of them scurrying all over the place and all over everything. It is not a pretty site. Also, while most are harmless, beware the Black Widow and Brown Recluse both of which, when provoked can inflict painful and serious venomous bites.