1981] Topoff, Rothstein, Pujdak, & Dahlstrom — Army Ants 157 
were able to monitor the time of onset and the duration of each 
night’s raid, in addition to the emigration frequency. This colony 
was released from a laboratory nest at 1900 hr on August 7. Because 
this was statary day 15, most of the pupae were fully pigmented. The 
colony promptly moved into a subterranean nest beneath a small 
hole in the desert floor. The first raiding column appeared shortly 
after 2200 hr, at which time 9.0 g of Novomessor brood and termites 
were placed near the raiding front. The army ants removed the 
booty in less than 1 hr, after which all surface activity ceased. For 
the next seven nights, the colony was either not active on the surface 
or, at best, conducted brief raids (each of which was immediately 
followed by artificial feeding) but no emigrations. On August 15 we 
arrived at the study site after 2200 hr, and found the colony 
emigrating 25 m to the NW. Because previously-collected food was 
being transported to the new nest, but no larvae had yet appeared, 
we considered the emigration to be in an early stage. Accordingly, 
10.2 grams of booty were placed near the emigration column, 1 m 
from the old bivouac. This resulted in recruitment of ants both from 
the short column leading to the old nest, and from the longer 
emigration column. All of the artificially-placed food was taken 
back to the old nest, and the emigration was aborted. 
On August 19 (nomadic day 1 1), after 2 days of not having been 
fed, the colony conducted its only successful emigration. The move 
took the colony 19 m to the N, beneath an Ephedra bush. On 
August 25, we excavated the colony and forced it to shift its statary 
bivouac. This procedure verified that the colony’s larvae had 
pupated. Thus, throughout a nomadic phase lasting 14 days, the 
colony conducted only one completed emigration. On 4 nomadic 
nights no raiding occurred. During the 10 nights in which raiding 
took place, the median time for raid onset was 2200 hr, and the 
median duration of each raid was 1.5 hr. 
The control colony, which was also released from the laboratory 
at the end of a statary phase, exhibited more typical patterns of 
nomadic behavior (Table 2). During a 15-day nomadic phase, the 
colony emigrated on 1 1 nights. Some degree of raiding took place 
on every nomadic night. The median time of raid onset for the 
control colony was 1850 hr, and the median duration of raiding was 
9.7 hr. 
