Businesses, apartments and single-family homes in urban and suburban areas all contain some amount of cockroaches. Manmade structures provide domestic cockroaches, mainly the German cockroach, hidden areas where they maintain a sizable population. At night, cockroaches leave their hiding places in order to forage and mate in various areas of a structure, and their activity peaks around two to four hours after sunset. Studies on indoor German cockroach populations show that roaches know their way around the homes that they inhabit. In fact, German cockroaches likely know the inside of your home better than you do, as roaches are aware of nearly all food and shelter sources within a home, including areas of a home that are inaccessible to humans.
German cockroaches are not the smartest animals on earth, but when it comes to arthropods, cockroaches have a surprisingly advanced spatial mapping ability. Researchers who have tracked German cockroaches traveling through structures during the night have found that the insects always take the most efficient route to resources, indicating that German cockroaches have the ability to more or less memorize the layout of a home. While cockroaches live in groups, only individual cockroaches that know the location of resources leave the group in order to retrieve food sources. These foraging cockroaches are able to efficiently forage within a home due to their ability to reference learned visual and olfactory cues from past foraging trips. Researchers refer to this ability as “path integration,” and this process involves the updating of information concerning new sources of food and shelter. For example, when a German cockroach locates a new source of food, the reward of this discovery enhances the odors and nearby landmarks associated with the new food source. It is hard, if not impossible to tell if cockroaches have the ability to refer to past memories, but there is no doubt that German cockroaches can reference past experiences of finding food while foraging within households.
Have you ever found a large group of cockroaches in an area of your home that you rarely visited?