DIVISION OF LABOR WITHIN THE WORKER CASTE 
OF FORMICA PERPILOSA WHEELER 
(HYMENOPTERA: FORMICIDAE)* 
By Carlos Roberto F. Brandao 
Museu de Zoologia, Universidade de Sao Paulo 
Sao Paulo, Brasil 
Introduction 
Polymorphism, in the study of social insects, is defined as the 
existence within an individual colony of two or more phases or 
castes belonging to the same sex, without particular regard to their 
genetic or environmental origin (Wilson, 1953). The adaptive result 
of the development of female polymorphism is the division of labor 
within the colony. In most ants this division is clearly seen between 
reproductive and non-reproductive caste, but less evident within the 
worker caste (Oster & Wilson, 1978). The present article utilizes the 
Fagen & Goldman (1977) method for estimating the total repertory 
size of behavioral categories of each worker subcaste listed on an 
ethogram or behavioral catalog. 
Ethograms are the essential first step of the comparative study of 
behavior (Wilson, 1974). A behavioral catalog of Formica perpilosa 
Wheeler, a weakly polymorphic species of the neogagates group 
(Buren, 1968), was constructed in order to investigate behavioral 
differences between the major size groups, defined here arbitrarily 
as three worker subcastes. Formica perpilosa is a common ant in the 
southern United States and northern Mexico (Gregg, 1963). It feeds 
mainly on plant exudates and tends membracids of the genus 
Pubilia (LaBerge, 1952). Its physiology has been relatively well 
studied by Schumacher & Whitford (1974), Kay & Whitford (1975), 
Whitford, Kay & Schumacher (1975) and Schumacher & Whitford 
(1976). The genus Formica is of unusual interest because its species 
are either monomorphic or weakly polymorphic and thus span the 
early stage of caste evolution. Yet close studies of the polymorphic 
species have not been undertaken. 
* Manuscript received by the editor October 10, 1978. 
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