See publications of the U.S. Dept. of Agriculture; E. O. Wilson, Insect Societies (1971) and, with B. Holldobler, The Ants (1990); G. E. Ball, ed., Taxonomy, Phylogeny, and Zoogeography of Beetles and Ants (1985); J. H. Sudd and N. R. Franks, The Behavioural Ecology of Ants (1987).