Although cockroaches are drawn to shelters with favorable temperature and humidity, to some extent cockroach aggregates are able to create their own microenvironment. Grouped cockroaches may better survive hostile dry conditions than loners in at least two species. Dambach and Goehlen (1999) found that as a result of respiration and diffusion, individuals of B. germanica are each surrounded by an envelope of water vapor. These individual diffusion fields overlap in aggregated insects, reducing net individual water loss. Aggregation behavior also reduces water loss in G. portentosa; Yoder and Gro-jean (1997) suggest that it is an adaptation for surviving the long tropical dry season of Madagascar. Documentation of seasonal changes in social behavior in the field would provide added support for this hypothesis.
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