1981] 
Ward— Rhytidoponera impressa. II 
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(March, 1977) the colony consisted of 1 queen, 1 worker, 1 worker 
^cocoon, 1 larva and several eggs. 
The following spring, in the morning and early afternoon of 1 
October 1977 another large mating swarm of chalybaea occurred on 
the University of Sydney campus. As before, this consisted mostly 
of male alates, concentrated into more or less discrete clusters 
around several nest entrances. Large clusters were situated at Sites 
A and C (Figure 3), at exactly the same places observed in 1976. No 
matings were directly observed, but a timid worker which was being 
mobbed by males was later found to be inseminated. Workers were 
generally very aggressive towards males, but the latter persisted in 
attempts to mate. Once again, samples of alates were collected from 
various sites, of which 97.0% (195) were males and 3.0% (6) were 
females. These figures are not significantly different from those of 
1976. 
On October 12, 1978 small swarms (20-30 individuals) of 
Rhytidoponera chalybaea males were observed at Site C and at 
several other locations on campus (but not Site A). At 10:15 a.m. 
males were mostly at nest entrances, apparently in the process of 
emerging. One alate female was observed; this individual emerged 
from a nest entrance, and flew off into open sky, ascending rapidly. 
Similar behavior was observed in males. By 1 1:30 a.m. many males 
appeared to be flying into the area, congregations had formed 
outside nest entrances, and males made repeated attempts to mate 
with workers. 
On the afternoon of the same day two chalybaea queens (one 
alate, one partially dealate) were seen floundering on the sidewalk in 
a heavily built-up section of downtown Sydney. Both were unin- 
seminated. This suggests that alate females may disperse a con- 
siderable distance before mating. 
Colonly Structure and Life Cycle 
In most populations of confusa, chalybaea, and impressa, queen- 
right and worker-reproductive colonies coexist, in intermediate 
proportions. Despite the likely disparity between mating sites of 
winged queens and workers, genetic data from electrophoretic 
studies (Ward, 1978, 1980) reveal no indication of extensive 
inbreeding or assortative mating with respect to colony type. This is 
consistent with the observation that brood development and alate 
production proceed at similar rates in the two colony types, and that 
