Insects that make nests have a well developed navigation system that allows them to forage outside the nest and return. Hymenoptera make extensive use of visual cues and use a series of landmarks to navigate back to their nests. German cockroaches do not have nests but they aggregate in a harborage with a defined location. German cockroaches forage outside of the harborage, but return to the same harborage. How do they find the way home?
Rivault and Durier* studied the behavior of cockroaches in an arena where visual and olfactory cues could be manipulated. Moving either the olfactory or the visual cues increased the length of the path a cockroach traveled to return to the harborage. The return path was shortest when both olfactory and visual cues were presented in agreement. When cockroaches encountered a visual cue without the olfactory cues, they investigated the area around the visual cue before moving on. If cockroaches encountered olfactory cues without the visual cues, they also investigated the area before moving on.
This behavior may be adaptive to those environments inhabited by cockroaches. Under high light intensity, visual cues are readily apparent and allow a cockroach to reach a harborage by a direct path. Where low light intensity eliminates visual information, a cockroach must rely on other modalities such as olfaction.
*Colette Rivault & Virginie Durier. (2004) Homing in German Cockroaches, Blattella germanica (L.) (Insecta:Dictyoptera): Multi-Channelled Orientation Cues. Ethology 110, 761—777.