Brown recluse spiders are hunting spiders, so they spend most of the time on the ground. They hide during the daytime and sleep, and at night they come out to hunt. They usually do not climb unless they are running from something. They can walk upside-down, but most brown recluses walking on ceilings have probably come from the upstairs floor. The blood cannot flow through their legs while they walk, so they must stop every few seconds to allow the blood to flow.