114 
Psyche 
[Vol. 93 
transport (although adult transport of minor workers was observed 
at other times; see Table 1). Eggs were completely transferred early in 
both emigrations. The last immatures to be transferred were larvae, 
not because workers selected pupae over larvae, but because the 
clumped larvae were difficult to pull apart for transport. 
Only minor workers carried brood. Callow minors aided in pull- 
ing larvae and pupae free of piles of brood, but were clumsy at 
carrying larger immatures, which were quickly turned over to 
darker workers. Callows did, however, occasionally carry small lar- 
vae and eggs, taking egg clusters at a higher frequency than did 
other minors (p <0.01, Fisher’s exact probability test). Both replete 
and non-replete darkly pigmented minors transferred brood, and 
there were no significant differences between the frequency with 
which these subcastes carried different brood stages (for each brood 
stage p > 0.05). 
The queen emigrated soon after brood transfer began in the first 
emigration, and ten minutes before the start of brood transfer dur- 
ing the second emigration. She moved rapidly within a small en- 
tourage of minors, but no workers rode on her during her journey. 
Alarm and Defense: In three trials in which a small Solenopsis 
geminata worker with excised gaster was dropped into the brood 
area, most workers and the queen fled to adjacent nest chambers, 
with some minor workers carrying brood. Usually several major 
workers and a few minors stayed close to the intruder, mandibles 
open and facing the Solenopsis. Sometimes the ants attempted to 
bite the intruder. As described for Erebomyrma nevermanni (Wil- 
son, 1986), the proportion of major workers near the intruder was 
clearly higher than in the colony as a whole. The ants responded 
similarly to freshly crushed minor heads presented on applicator 
sticks, suggesting the head as a source of alarm pheromones. Majors 
were particularly attracted to crushed minor heads, approaching 
them with their antennae directed ahead and mandibles open. There 
was virtually no response to crushed thoraxes and gasters. 
Discussion 
The major workers of Oligomyrmex overbecki apparently func- 
tion primarily in colony defense and as repletes. The replete condi- 
tion is very poorly developed (the ants are “semi-replete” in the 
sense of Wilson, 1986). Major workers also participated to a limited 
