Spiders:

Spiders are predatory arthropods of insects. Unlike the horror movies, spiders do not attack humans unless provoked to bite by handling, whether intentionally or not. All spiders have 2 body regions like ticks: an unsegmented abdomen and a cephalothorax. Unlike ticks, a spider's abdomen is constricted at the base, but, like ticks, spiders have 8 legs and no antennae. So, if your bug has 8 legs and a constricted abdomen, it's a spider.

Looks like:

Photo: Hobo Spider. Whitney Cranshaw, C.S.U.