1978] 
Brandao — Worker Caste of Formica perpilosa 235 
usually act as soldiers. This is not true in the present case, where 
another kind of specialization was revealed. 
In the complete dimorphic species there is no behavioral overlap 
between the castes. Each category can be easily distinguished from 
the others morphologically and behaviorally. 
Majors of Zacryptocerus varians (members of one of the nine 
genera in which complete dimorphism is easily recognized) function 
primarily in defense (Wilson, 1976) and deserve the title of soldiers. 
Yet they sometimes wash and manipulate larvae and pupae. But 
during a high intensity attack, majors block the nest entrance with 
their saucer-shaped heads and are more persistent and effective than 
minors in forcing the enemy back to the entrance and finally out of 
the nest. 
Dr. Edward O. Wilson, reviewing the manuscript, was kind 
enough to suggest that F. perpilosa majors represent an early stage 
in the evolution toward repletes, as seen in Proformica and Myr- 
mecocystus (Wilson, 1971). The specialization shown by perpilosa 
majors (see Table 2) agrees with this view. 
F. perpilosa seems to occupy, from the viewpoint of evolution of 
division of labor, an intermediary position between monomorphic 
and completely dimorphic species. 
Acknowledgments 
I am indebted to the “Fundagao de Amparo a Pesquisa do Estado 
de Sao Paulo” for a scholarship (Biologicas 77/1208). I wish to 
express my appreciation to my parents for supporting my visit to 
Harvard University; and to Prof, and Mrs. B. Patterson, Dr. and 
Mrs. W. L. Brown, Jr., and Dr. E. E. Williams for their kind 
hospitality. 
I am specially grateful to Dr. E. O. Wilson for the opportunity to 
learn ant rearing techniques, for the suggestion of the problem, 
assistance and uses of facilities during the research and critically 
reviewing the manuscript. I thank Dr. and Mrs. B. Holldobler, 
Gary Albert, Hiltrud Engels and specially Katherine Horton and 
James Traniello for advice and help with the ethogram method, and 
also the latter for showing me his unpublished data on Amplyopone 
behavior; Mr. O. Schmidt for conducting the repertory estimations; 
Dr. Francisca C. do Val for critically reading the manuscript. 
