1981] 
Droual & Topoff— Genus Pheidole 
145 
D-Jn25-I 
NEST 
MOVEMENT DATE 
1- 2 7/12 
2- 3 7/15 
3- 4 7/16 
4- I 8/5 
1- 4 8/6 
4-2 8/15 
2- 3 8/17 
I METER 
NEST 
MOVEMENT 
DATE 
1-2 
7/10 
2-1 
7/31 
1 -3 
8/1 
3-4 
8/4 
4-2 
8/5 
2-4 
8/14 
D-JI 30-1 
/ N 
NEST I NEST 4 
NEST 
MOVEMENT 
DATE 
1-2 
7/31 
2-3 
8/3 
3-1 
8/7 
1 -3 
8/11 
3-4 
8/15 
4-1 
8/16 
I METER 
Figure 7. Patterns of emigrations for three colonies of Pheidole desertorum. 
Dates of nest movements are shown on the right. 
shading (Brian 1956, Carlson and Gentry 1973), or climatic ad- 
versity such as drought or frost (Brian 1952). A colony may also be 
forced to emigrate because of some biotic factor such as inter- and 
intra-specific competition (Holldobler 1976, Waloff and Blackith 
1962, Brian 1952, Brian et. al. 1965) and predation (Gentry 1974). 
The view that emigrations occur infrequently among most ants 
