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Psyche 
[Vol. 88 
EMIGRATION INTERVAL (DAYS) 
Figure 1 . Frequency of the time interval between emigrations for Pheidole hvatti. 
are totally organized by a substance secreted by the poison gland 
(Droual et al., in prep.)- The queen of both species moved inde- 
pendently in the emigrations although she was usually surrounded 
by a retinue consisting mostly of minor workers (workers of the 
genus Pheidole are dimorphic) who tugged her by the mandibles or 
antennae if she hesitated en route to the new nest. During June and 
the early part of July alates were frequently seen in the column also 
moving independently. However, on one occasion, during a P. 
desertorum emigration, workers were observed carrying some of the 
males. 
A number of phenomena related to these species’ high emigration 
frequencies were observed. One colony of each species (D-Jn20-1 
and H-Jnl9-2) performed what we call an aborted emigration. In 
these cases the colony was observed emigrating to a new nest but on 
the following night was found to be back at its old nest. One P. 
desertorum colony (D-Jn-25-1) appeared to perform two emigra- 
tions in one night. On August 17 the colony was observed emigrat- 
ing from nest 2 to nest 1 (see Fig. 6). However on the following night 
the colony was found at nest 3. On a number of occasions an 
