The Emigration Behavior of Two Species of the Genus Pheidole (Formicidae: Myrmicinae)

Colony emigrations are common among ants (Wilson 1971) and occur for a diversity of reasons. However, except for the legionary ants, in which colony emigrations are an inherent part of the foraging ecology (Wilson 1971), and species which inhabit delicate and easily disturbed nests (H611dobler and Wilson 1977, M6glich 1979), emigrations are thought to occur infrequently. Here we present evidence that two species of the genus Pheidole, P. desertorum Wheeler and P. hyatti Emery, emigrate frequently under environmentally stable conditions. We further advance the hypothesis that the surplus nests resulting from these emigrations, reduce the secondary losses which occur as a consequence of the panic-alarm defense these species employ against army ants of the genus Neivamyrmex, by serving as temporary shelters and centers for colony reorganization.