1931] Nest-Building Habits of Polistes rubiginosus 137 
the house containing the three nests was destroyed by the 
new owner of the grounds, and an accident befell the fourth 
which was in the metal house. The latter, however, gave 
me the following notes before the occurrence of the acci- 
dent. 
This nest with seventeen queens was revisited on June 
19, after a nine-day absence. During this period, ten 
cells had been added to the nest, and instead of seventeen 
adults, only thirteen were on the nest. The others may 
have become easy prey to their enemies because of the con- 
spicuous paint spots which I had placed on their bodies. 
The nest was attached to the ceiling about ten inches from 
two small ventilator-slits in one side-wall; through these 
slits the wasps came and went. On hot days, one, two or 
three wasps were stationed at these ventilators; they vi- 
brated their wings rapidly for periods up to ten minutes. 
When the sun beat down upon the sheet-iron roof, it was 
indeed sweltering in there; hence I suppose this perform- 
ance was for the purpose of cooling the nest, much after 
the manner of the trumpeter bees which ventilate the nests 
of bumblebees, or honey-bees that do the same at the en- 
trance to the hive. 
It is hard to see how this would be accomplished with 
the nest ten inches away; I sometimes wonder if the same 
behavior on the nest instead of at the opening would not do 
more good, but doubtless the wasps’ judgment is better 
than mine in that. Their behavior agreed with that of 
other species of Hymenoptera which do their fanning at 
the hive entrance. 
The incoming queens carried water, and placed much of it 
in large globules in the cells with the eggs or young larvae. 
The lids of four sealed cells were thoroughly saturated 
with water, and another cell which had a concave instead 
of a convex cap had this cavity completely filled with water. 
This habit of spreading water on the outside of sealed cells 
was also noted for pallipes colonies elsewhere ; 6 this precau- 
tion may protect the pupae from drying up. These P. rubi- 
6 See article to appear in Ecology, 1931, entitled “Polistes Wasps 
and their us© of Water.” 
