1987] Topoff, Bodini, Sherman, & Goodloe — Polyergus 265 
— i 1 1 1 1 1 i 1 r 
N — *■ PHTH DF 5CDUT 
JULY 13 
Fig. 2. Comparison of routes taken by Polyergus scout during outbound trip, 
return run, and subsequent slave-raid. Scales of distance are shown at the lower left 
corner. N = north; P = location of Polyergus nest; F = location of Formica nest. 
scouts were placed at the nest entrance. This procedure for eliminat- 
ing scouting was repeated for 19 consecutive days during the period 
July 2-July 20. Starting on July 21, and continuing until August 4, 
the fence was removed to permit unlimited scouting. Without the 
barrier, it was not possible to determine accurately the number of 
scouts departing each day. During this phase of the study, we simply 
verified that scouting occurred, and noted the time of raid onset. 
Results 
A comparison of the frequency of slave raids by P. breviceps with 
and without scouts is summarized in Table 1. The Table does not 
include data from days when scouting was prevented by rain or 
heavy overcast. Slave raids occurred on only 2 of 11 days (18%) 
during the period of scout removal. The two raids that occurred on 
7/12 and 7/20 were stopped at the fence (by sealing the exits) to 
ensure that no Formica pupae would be brought back to the nest. 
When the fence was removed to permit scouting, the frequency of 
slave raids jumped to 69%, as 9 raids were conducted on 13 different 
days (x 2 = 7.4, df = 1, P < 0.01). All but one of these raids resulted 
in the capture of Formica brood, and the only unsuccessful one 
(July 23) was aborted by an abrupt thunderstorm. 
