There is another relevant publication: Moritz RFA and Southwick EE 1992 Bees as superorganisms. An evolutionary reality. Published by Springer, Berlin, Heidelberg, New York. ____________________________________________________________________ Michael Haberl Zoologisches Institut der Uni Muenchen Tel: ++49 89 5902-444 Luisenstr. 14 Fax: ++49 89 5902-450 80333 Muenchen, Germany E-mail: [log in to unmask] ____________________________________________________________________