344 Psyche [Vol. 94 
Figure 1 . The abscissa shows number of days since ants in a particular activity 
were marked. The ordinate is the ratio of numbers of marked ants observed to total 
numbers of ants marked in the colonies under observation on that day (see text for 
explanation). 
Discussion 
The main result of this study is to extend the known lower limits 
on how long a Pogonomyrme x worker can live. The results show 
that in P. barbatus and P. rugosus, exterior workers can clearly live 
longer than 14 days after marking. 
Figure 1 suggests that activities may be ranked as follows in the 
order of decreasing longevity: nest maintenance, foraging, and 
patrolling. Other results indicate that at a given time in a mature P. 
barbatus, there are three distinct groups of workers: one group of 
individuals that do nest maintenance, one that does foraging, and 
one that does both midden work and patrolling (Gordon, in prep.; 
also Gordon, 1984 for P. badius). Marked patrollers may disappear 
the most quickly because they lead the most dangerous lives; it is the 
patrollers that respond most actively to intrusions by other 
workers, and the numbers of patrollers increase when artificial dis- 
turbances are created (Gordon 1987). Patrollers as defined here 
probably correspond to the “first defenders” described by Porter & 
Jorgensen (1981) to be longer-lived than foragers. The latter 
authors elicited defenders by experimental perturbations, while in 
the present study patrollers were observed in undisturbed colonies. 
