1983] 
Calahi, TranieUo, and Werner — Pheidole 
397 
We excluded from analysis behaviors with frequencies < 1% of all 
behaviors performed by that physical caste; for P. hortensis that 
gives a possible frequency per behavior of about 25, or five occur- 
rences per age class, under the null hypothesis. 
Associations between age class and behavior were assessed by a 
relative performance measure (RPM). We calculated the probability 
that ants of a particular age class will perform a given behavior, and 
divided those ratios by the highest such probability for that behav- 
ior. Thus 
X = frequency of behaviorj performance by ants of age classj, 
y = frequency of all behaviors by age classj, 
z = highest such frequency for that behaviorj, and RPM = (x ^ y) 
7 . 
Finally, any attempt at an ergonomic assessment requires that 
one distinguish between task and non-task behaviors. We use the 
terms as follows. “Behavior” means a logical unit like grooming, 
made up of one or more physical acts, such as drawing the tibial 
comb over the antennae. “Task” is used in the sense of Oster and 
Wilson (1978) to denote a set of acts which achieve some purpose of 
the colony. Thus there are task and non-task behaviors, and though 
all tasks are behaviors, not all behaviors are tasks. 
Results 
1. Completeness of Repertory. 
The repertory of each physical caste separately and of the species as 
a whole was judged complete, based on statistical comparison with a 
lognormal Poisson distribution (Bulmer 1974, Fagen and Goldman 
1977). For minors, the observed repertory size is 25 behaviors, and 
the estimated size is 26, with a 95% confidence interval of [23, 
29]. For majors, six behaviors were observed, and six estimated, 
with a 95% confidence interval of [5, 7]. For P. hortensis the 
observed repertory includes 31 behaviors, with 33 estimated, and a 
95% confidence interval of [30, 36]. 
2. Division of labor by physical castes. 
Comparison of the behavioral repertories of the two physical 
castes shows that there is, with the exception of trophallaxis, no 
overlap in task performance (Table 1). Of the tasks carried out. 
