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Psyche 
[Vol. 94 
Fig. 1 . Outbound path of Polyergus scout, consisting of a linear phase, followed 
by a circuitous (searching) phase. Scales of distance are shown at the lower left 
corner. N = north; P = location of Polyergus nest; F = location of Formica nest. 
a Formica nest, the scout’s return route paralleled its outbound 
course, but was displaced about 1 m to the east. The slave raid back 
to the Formica colony was displaced an additional 2 m to the east. 
Because the scout was not marked, we can not be certain that the 
slave raid was led by the same individual. Nevertheless, our previous 
studies with marked scouts (Topoff et al. 1984) indicate that success- 
ful scouts of P. breviceps typically run (at least intermittently) at the 
head of raid swarms. 
Importance of Scouts for Slave Raids 
Materials and methods 
To determine the importance of scouts for initiating slave raids, 
another aluminum-flashing fence (15 cm high, 7 m radius, and con- 
taining four exits spaced at 90-degree intervals) was constructed 
around a second colony of P. breviceps. Every afternoon, from 1400 
hr to 1800 hr, the perimeter of the enclosure was continuously moni- 
tored for the presence of scouts. For each scout, we recorded the 
time of arrival at the fence and the compass direction in which it was 
travelling. Each scout was then removed and placed in a holding 
container until the end of the day, at which time all the captured 
