Function of cockroach (Orthoptera:Blattidae) aggregation behavior

Data were gathered to test three hypotheses concerning the function of the aggregation behavior of the German cockroach, Blattella germanica (L.). The first is that aggregation serves to ameliorate a harsh environment and promote individual survival and growth rates with increased group size, in contrast to the increases suggested in previous literature. Bioassays demonstrated that information concerning the sexual composition of a population is present in residues left by the population and that this information may be exploited by other individuals. This result is consistent with two hypotheses, i.e., that roaches aggregate for purposes of mating, and that they select habitats based on information available from conspecifics. Bioassays also showed that a natural population of roaches, which had been subject to mortality due to control efforts, displayed a stronger aggregation response than did the laboratory strain. This result is consistent with the hibitat selection hypothesis.