Cockroaches ARE nocturnal.
More Info: If you see a cockroach during the day, it may have been crowded out of its lair. Cockroaches choose to live in groups coming out at night to hunt for food. They will eat anything organic, and that includes non-food items such as paper. They prefer to gather in shelters that are moist, warm, and of course dark.
Cockroaches Are Dangerous
Most people who find cockroaches in their homes are mortified. They’re small. They’re just bugs. If you think an aversion to cockroaches is slightly dramatic, you need to reassess your thinking. Depending on the species, cockroaches are known to transmit food poisoning by passing along organisms such as Salmonella spp. and Shigella spp. They also are known to transmit the hepatitis virus, coliform bacteria, Staphylococcus spp., and Streptococcus spp Wait, there’s more. Cockroaches may contribute to the spread of dysentery and typhoid.
“Cockroaches.” University of California Agriculture and Natural Resources. N.p., n.d. Web. 15 Dec. 2011. www.ipm.ucdavis.edu/PMG/PESTNOTES/ pn7467.html
“Found a cockroach? think like a roach.” New York State Integrated Pest Management Program. N.p., n.d. Web. 15 Dec. 2011. http://www.nysipm.cornell.edu/publications/ roach/think.asp