50 
Psyche 
[June 
But in Pheidole sita/rches the female is fecundated on the 
ground directly beneath the nuptial swarm and does not 
attempt to fly afterward. It is clear that in a single genera- 
tion this species is able to increase its range only by that 
distance over which the males form swarms away from 
their home nests. This limiting phenomenon may be more 
common in the Formicidae than previously realized. It 
will be recalled that ants generally have effected little 
dispersal to isolated oceanic islands. Polynesia, for in- 
stance, contains an extremely sparse endemic fauna, while 
the sharp diminution of the endemic Melanesian fauna 
from New Guinea eastward suggests that ants in this 
part of the world have relatively limited dispersal powers. 
Another line of evidence is that some ant species in 
Melanesia with flightless, ergatoid queens (e.g., Lepto- 
genys diminuta, L. foreli) have dispersed farther through 
the outer archipelagoes than most stocks with normal 
winged queens. Furthermore, some of the most widely 
distributed groups with winged queens (e.g., Colobopsis, 
Turneria) are arboricolous and could conceivably have 
been carried about as entire colonies in storm-blown twigs 
and branches. Further study may show that ants are 
generally limited in dispersal powers because of pecu- 
liarities in the organization of the nuptial flight similar 
to those described here for Pheidole sitarches. 
