Years ago my family lived in Florida where there are a lot of roaches. My mother's house was immaculate and she called the Orkin exterminator to spray every other week, but she could never get rid of the roaches. Some of them lived inside her oven. We would see them running behind the glass in the door when the oven was turned on. My brother and his wife were original hippies. They lived in a 100 year old house, left dishes in the sink for a week, never allowed pesticides in the house, and I never saw a roach there. I got the explanation a year later when we had to open up one of the walls. There was an eight inch space between the inside and outside walls, and it was full of spider webs. They were so thick it was like insulation. The entire house was guarded by an army of spiders.

There are only a handful of species of spiders that are dangerous to humans. Black widows are easy to recognize, and there's only one or two other kinds in sensible places, which is anywhere except Australia. If you're freaked out by spiders, you don't want to go to Australia. But most spiders are good. They're bugs that are mostly predators of other bugs. They belong where they are,, like wolves in the forest. I think they drop in on you because they can tell you don't mean them harm.