308 
Psyche 
[Vol. 90 
Methods 
Emigration raids were observed in three mixed colonies of P. 
lucidus and F. schaufussi Mayr, located in a pine-barrens habitat in 
North Centereach, Long Island, N.Y. The most detailed data were 
collected from a colony monitored continuously from July through 
September, 1976. The emigrations occurred on September 19 and 
20, as the colony moved to a previously-constructed nest, 5.9 m 
southwest of the old site. Movements of individual ants shuttling 
between nests were monitored with hand-held tally counters. Callow 
age was estimated by comparing their degree of pigmentation with 
individuals of known age in laboratory nests (Kwait 1982). 
Results and Discussion 
During the morning and early afternoon of each day, the popula- 
tion characteristics of the emigrations were similar to those described 
for Polyergus nest movements that occasionally occur in the spring 
(Marlin 1971). Thus, only Formica workers functioned as transpor- 
ters, carrying adults and brood of both species to the winter nest 
(Fig. 1). As the afternoon progressed, however, several P. lucidus 
workers periodically joined the emigration. Although these Polyer- 
gus individuals made 5-23 trips between nests, the important point 
to note is the relatively low level of overall activity during most of 
the afternoon (Fig. 2A). But starting about 1600 hrs (EDT), at 
approximately the same time as the onset of slave raids earlier in the 
season (compare Fig. 2A and 2B), groups of 30-69 callow and 
mature- adult Polyergus abruptly surged out of the new nest and 
formed into an organized swarm. This raid swarm backtracked and 
penetrated the old nest, and after several minutes the Polyergus 
workers emerged carrying nestmates (Table 1). On both emigration 
days, the first emigration raid was promptly followed by a second 
raid (Fig. 2A). Activity levels for both species then dropped 
abruptly, as they typically do during slave raids on freeliving colo- 
nies of Formica. 
Aside from our field observations on emigration raids, the only 
other reference to Polyergus carrying adult Formica individuals is 
Huber’s (1810) study in Switzerland, of an emigration into an aban- 
doned Formica nest. A more recent observation of comparable 
behavior stems from studies of P. breviceps- Formica gnava mixed 
colonies in a desert habitat in southeastern Arizona (Topoff et al. in 
