1931] Nest-Building Habits of Polistes rubiginosus 135 
swarming occurs much after the fashion of swarming of 
honey bees, with this difference; whereas the honey bee 
swarm seeks a new location in body, the swarm of Polistes 
wasps in the tropics breaks up into many smaller groups 
of few or many individuals, and these found the new 
homes. In the tropics where winter and hibernation do 
not occur, this is the method of dissemination. In the 
north, cold and hibernation interfere with this method, but 
we do see an adherence more or less complete (but in cer- 
tain species no less complete) to the habit of pleometrosis, 
after assembling on the old home site which, after all, is 
very similar to swarming. This may or may not be ves- 
tigial in character, for it is difficult to tell whether pleo- 
metrosis is ascending to higher socialization, or is in a ves- 
tigial condition. 
Thus we see that the occasional condition (more or less 
frequent according to the different species of Polistes) 
of more than one mother founding a colony has an anala- 
gous counterpart in the swarming of a sister species in 
the tropics. There seems to be but little difference between 
the psychological reactions of members of a colony when 
activities are cut short by the violent destruction of the 
nest in the tropics, or the violent curtailment of their 
activities in the north by the cold. In both cases, 
members of the colony disband and found new colonies 
with one, two or more queens present; however, in the 
tropics the founding of new colonies occurs immediately 
after adverse conditions occur, while in the north the 
founding of new colonies is interrupted by a period of 
hibernation in which the wasps are numb with cold. In 
any event, the long period of dormancy in the northern 
species apparently has not caused the wasps to forget 
how to behave like their tropical sisters when colonization 
occurs. Pleometrosis of Polistes in the tropics is due to 
the fact that with a twelve-month calendar, the colony 
splits up occasionally when it reaches great size, and one to 
many sister wasps go forth and found a new nest. But in the 
north where cold weather curtails the Polistes activities 
to only a fraction of a calendar year, pleometrosis undoubt- 
edly has its origin in the queen's remembering the home 
