116 
Psyche 
[Vol. 88 
ALATES 
ALATE 
COCOONS 
WORKER 
COCOONS 
LARVAE 
EGGS 
i i i l l i i l l I i i i 
SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG 
( 13 ) ( 47 ) ( 42 ) ( 30 ) ( 25 ) ( 13 ) ( 28 ) ( 30 ) ( 72 ) ( 107 ) ( 32 ) ( 39 ) 
Figure 1. Seasonal changes in brood and alate composition in colonies of confusa 
and chalybaea, as measured by the proportion of colonies with various life stages. 
Maximum width (shown at either side of figure) indicates that 100% of colonies 
contain the particular stage. Because there were no obvious differences between species 
or between years, data covering both species over 3‘/2 seasons have been combined. 
Figures in parentheses refer to the number of colonies sampled in each month. Total 
sample size: 479 colonies. 
worker had eclosed) one queen was found ousted from the nest and 
almost dead. The colony (with one remaining queen) continued to 
develop until artificially terminated 15 months later. Subsequent 
spermathecal dissections and electrophoretic analysis using allo- 
zyme markers confirmed that both females were inseminated, and 
that both had contributed worker offspring to the incipient colony. 
Seasonal cycle in mature colonies 
There are consistent seasonal patterns in the occurrence of brood 
and alates in mature colonies of the impressa group. These seasonal 
patterns are essentially the same for both queenright and worker- 
reproductive colonies, except that alates in the latter are pre- 
