1984] 
Carpenter & Ross — Po/istinae 
249 
swarm-founding species (Jeanne, 1980). Such morphological differ- 
ences between reproductives and non-reproductives may vary 
between colonies of the same species (Richards and Richards, 1951; 
Jeanne and Fagen, 1974; this paper) and within colonies over the 
course of a normal cycle. Moreover, although morphological caste 
differentiation is not pronounced in the Polistinae, behavioral and 
functional differentiation is well developed (West Eberhard, 1978). 
Lack of pronounced morphological caste dimorphism has been 
taken to indicate a less advanced level of eusociality in the Polistinae 
relative to the Vespinae (e. g. Iwata, 1976). However, by other crite- 
ria of social complexity (mode of suppression of nestmate reproduc- 
tion, colony size, duration of colonies), the swarm-founding 
Polistinae are at a comparable level of sociality to the Vespinae 
(Jeanne, 1980). The difference in degree of caste dimorphism 
between the two groups of highly social wasps undoubtably reflects 
ecological constraints of the environments in which they have 
evolved (Richards, 1971), with the strong queen/worker dimorph- 
ism of the Vespinae part of an adaptive syndrome linked with winter 
hibernation and a short colony life cycle (Richards, 1971). The dif- 
ferences in adult size between queens and workers of some polistine 
species suggest that in these species caste differentiation is either 
pre-imaginal, or that males preferentially mate with females possess- 
ing certain morphological attributes (or that only these females are 
receptive to mating). These competing hypotheses must be tested in 
species in which caste dimorphism has been firmly established. 
Although dissection and morphometric study of individuals col- 
lected with nests are likely to remain the primary methods of analy- 
sis of social structure in tropical polistines, the information 
provided is limited. A proper understanding of the social biology of 
these wasps requires in-depth behavioral studies of natural colonies. 
Acknowledgements 
Deborah R. Smith of Cornell University assisted in collection of 
colonies. M. C. Day of the British Museum (Natural History) 
arranged the loan of Brachygastra larvae. We should like to thank 
Janice S. Edgerly of Cornell University for the figures of the larva 
and G. C. Eickwort of Cornell University for critical review of the 
manuscript. Field work in Suriname was supported by grants from 
Sigma Xi, the Explorers Club and the Griswold Fund of the 
Department of Entomology of Cornell University. 
