DIVISION OF LABOR IN A NEST OF THE SLAVE- 
MAKING ANT FORMICA WHEELERI CREIGHTON 
By Edward 0. Wilson 
Biological Laboratories, Harvard University 
It is a well known fact that most of the dulotic Formica 
are not “host-specific.” They normally employ several 
species as slaves and are apparently governed in their 
choice at least in part by the species that happen for- 
tuitously to be accessible to the colony. F. subintegra 
Emery, for instance, most commonly enslaves F. fusca 
Linn., but I have seen it associated in cabinet series with 
F. lasioides Emery, F. neogagates Emery, and F. scham- 
fussi Mayr, while Creighton (1950) records it in addition 
with F. montana Emery and F. pallidefulva Mayr. Ac- 
cording to Forel (1928, p. 12), the slave workers may 
retain some of the behavioral traits peculiar to their species. 
He notes that in Europe Formica pratensis Retzius workers 
reared from pupae by F. sanguinea Latreille tend to con- 
struct the form of nest characteristic of their own species. 
Talbot and Kennedy (1940) have made observations sug- 
gestive of the same behavior in F. fusca enslaved by F. 
subintegra. When sanguinea workers kept in observation 
nests were induced by Forel (op. cit., p. 126) to rear 
pupae of Polyergus rufescens (Latreille) and several com- 
mon Formica so that all these species coexisted in the 
same nest, differences in behavior were noted: “the F. 
exsecta and fusca were distinguished by their activity in 
working, the Polyergus by their complete idleness, the 
sanguinea by their skill, and the pratensis by their clumsi- 
ness.” 
During a recent field trip through the western United 
States, I was able to study in some detail a remarkable 
compound colony of the slave-maker F. ivheeleri Creighton 1 
and two slave species (F. neorufibarbis and F. fusca) in 
which behavioral differences were so strong as to produce 
1 A tentative determination, since the status of this species relative to 
F. subintegra is still uncertain; see the preceding article by Wilson and 
Brown. 
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