154 
Psyche 
[September 
wasp to form straight sides on the inner walls of the cell. Con- 
versely, it is the lack of antennal contact along the outer margin of 
a peripheral cell which causes those walls to be rounded. 
Dominance interactions between females were never very ag- 
gressive. The highest ranking wasp on the nest invariably received 
food first from the returning forager. The higher ranking wasp 
generally held its body farther from the substrate than the sub- 
ordinate during the feeding (see Fig. i). The solicitor tilted its 
head to one side during the exchange and antennated the face of 
the donor. Occasionally, the solicitor, and especially the queen, held 
onto the donor and prevented her escape. 
Dominance interactions unrelated to food exchange were rare. 
In one of the few observed, the queen, apparently unprovoked, 
moved toward the third ranking individual and, holding her with 
her prothoracic legs, began to bite the subordinate about the man- 
dibles, eyes, neck, thorax and wings. The subordinate held her body 
very close to the nest. When she tried to back away, the queen 
held her and began biting more vigorously. When the attack ceased, 
the subordinate retreated to a position on top of the nest, while the 
queen returned to the face of the nest. 
When I disturbed the nest severely, the wasps showed typical 
threat behavior. At low intensities, the wasp faced the disturbance 
and raised and spread its wings. At higher intensities, the aroused 
individual buzzed its wings in short bursts. It was this action which 
seemed to arouse the nestmates. If the disturbance was very in- 
tense (as when I was marking the wasps) the females would fly 
off the nest and circle it a few feet away. After such intense dis- 
turbances, buzzing threat displays continued for up to io minutes. 
Foragers about to leave the nest held themselves erect on the 
nest, buzzed their wings loudly, paused for a moment, and then 
took off. A brief orientation flight generally followed. The re- 
turning foragers sometimes made a number of approaches before 
alighting on the nest. Occasionally the wasp landed on a rafter 
adjacent to the nest, groomed for a moment, and then took off and 
landed on the nest immediately. The queen herself made 5 of the 
29 foraging trips seen in this study. On the 29 trips, the foragers 
brought 25 loads of nectar, 3 loads of macerated greenish-gray prey, 
and 1 load of pulp. 
The returning forager fed the highest ranking resident first and 
then she and the solicitor fed the larvae (see Fig. 2). The wasps 
stuck their heads into the cells and then rapidly antennated the op- 
posite wall of the cell. The sound produced by the antennae striking 
