70 
Psyche 
[Vol. 89 
At this point in the life cycle, the worker/ queen ratio is highest, as 
described above, yet colonies collected in the late spring are much 
smaller in size (approximately 50%). Therefore, colony reproduc- 
tion by budding may occur if one or more fecundated queens depart 
with a portion of the worker force. This hypothesis has previously 
been considered by Wheeler (1900) and Brown (1960), and is sup- 
ported by my data on colony growth, nest distribution, and nest 
structure. An additional feature of the nest distribution pattern sup- 
ports the hypothesis of limited dispersal. The most dense population 
of colonies occurred on the south side of an early stone wall (< 1 m 
high), although nest sites were abundant on both the north and 
south sides, and soil, vegetational, and exposure parameters ap- 
peared to be identical. Also, laboratory observations indicate that 
alate females may shed their wings before mating occurs. On several 
occasions newly eclosed females left the nest, shed their wings, and 
returned to the nest. Because mating occurs on the ground, such 
behavior does not exclude the possibility that these individuals 
could eventually become inseminated. These females may then 
return to the parent nest or may be adopted by a nearby colony. In 
several laboratory experiments queens were introduced into other 
queenright nests or orphaned colonies. In all cases they were 
accepted by both workers and queens. Similarly, workers could be 
transferred from one colony to another without aggression. There- 
fore, populations of A. pallipes appear to be unicolonial and secon- 
darily polygynous. Ecologically, the patchy distribution of this ant 
correlates with this type of population structure. 
2. Social organization 
The social ethogram. Social ethogram data were gathered from 
five colonies which were observed for a total of 73 hours, during 
which 6,500 individual acts were recorded. The behavioral catalog 
of a single colony of A. pallipes (2 queens, 18 workers, brood) that 
was studied for 25.7 hours is given in Table I. The total number of 
acts observed was 42 (95% confidence interval for catalog size [27, 
47]), and the sample coverage was 0.9992. Behaviors listed in the 
ethogram having a frequency of 0 were observed in other colonies 
and are included as part of the species repertory. The majority of 
activities are common to many ant species; those that are unusual 
will be discussed briefly. Antennal tipping is a behavior previously 
described in Zacryptocerus varians (Wilson, 1975) which occurred 
