Animals live in groups for a wide variety of reasons. The main benets are related to anti-predator behaviour, foraging, mate nding, and/or reduction of energetic costs.
In this paper we present a game-theoretical model that supports the waste recycling hypothesis. This hypothesis posits that the organic waste materials produced by the members of a group represent a valuable resource that is communally inherited and utilized by group members.
Under this hypothesis and on the example of cockroaches, we determine evolutionarily stable strategies of social behaviour and quantify conditions on natural parameter values such as food availability under which the group formation is benecial.