1974] 
Jeanne & Fagen — Stelopolybia 
163 
us choose his measurement of thorax width as a measure of body size. 
Confidence that this indeed is a good indication of body size is gained 
from the fact that the cube of the queen/worker ratio for this dimen- 
sion closely approximates the ratio of the reduced body weights of the 
two castes. The ratio of queens to workers for this character is 1.37 
and 1.34 for V. germanica and V. rufa , respectively, and compares 
with 1. 1 5 queen/ worker ratio for alitrunk length for S. areata 
(Table IV). Thus there is considerably greater separation of queens 
and workers with respect to average body size in Vespula rufa and 
V. germanica than in S. areata. 
In the subfamily Polistinae the degree of polymorphism appears to 
range from virtually none to the degree of dimorphism shown by 
S. areata. Almost nothing has been done biometrically with the sub- 
family, with the exception of Richards and Richards’ analysis of 
certain characters in some of the South American species (Richards 
and Richards 1951). The primary aim of Richards and Richards’ 
analysis was to find reliable morphological characters that could be 
used to distinguish queens from workers. Queens were defined as 
having sperm in the spermatheca. In some species the two castes 
differed most significantly in the number of hamuli, while in others 
wing length, vertex width, mesonotum length, or shape of the first 
abdominal tergite were more reliable. Of the characters measured 
by Richards and Richards probably mesonotum length comes closest 
to being an indicator of body size. At any rate, it is most comparable 
to alitrunk length, used in the present study. If we use as an index 
of queen/worker dimorphism the ratio of average mesonotum length 
for queens to that for workers, the two species analyzed by Richards 
and Richards have values considerably below the ratio of queen to 
worker alitrunk length for S. areata (Table IV). Small but sig- 
nificant differences with regard to at least one character were found 
by Richards and Richards to exist between queens and workers in 
Polybia bistriata, P. occidentals occidentals , Protopolybia pumila , 
P. minutissima, Brachygastra scutellaris, and Polistes canadensis 
(Richards and Richards 1951). 
Conclusion 
Stelopolybia areata thus appears to have achieved a high degree of 
queen/worker dimorphism relative to other species of Polistinae that 
have been studied. Other species in the genus have been mentioned 
in the literature in this connection. Queens of S. flavipennis , for 
