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Psyche 
[Vol. 87 
her newly-founded nest (4 cells) and confined in a small container 
with a few artificial cells (gelatin capsules) and no construction 
material. She laid her eggs directly in the artificial cells and continued 
to rear the larvae, the only time artificial cells were utilized without 
resorting to offspring transplant. 
Results and Discussion 
The adults solicit trophallactic exchanges just as soon as they find 
larvae within the artificial cells. The larvae were often pulled out of 
the cells and killed, usually because they had been damaged during 
transferring. A nest can be considered as adopted when all 
cannibalism has ceased, and at least one of the adults has begun to 
nourish the larvae normally with food placed in the cage. Some adults 
refused to return to the nest. 
A) Nests closely resembling natural nests 
A total of 21 nests, each formed of seven gelatin capsules, plus one 
of seven glass test-tubes (length 3 cm, filled with cotton to decrease 
their volume) (Fig. 1, 2) were affixed to the cages by wooden 
peduncles. Of 22 nests, 16 (73% including the glass “nest”) were 
adopted. The transparent walls allowed satisfactory observation of 
the adult-larva relationships and larval growth. 
The adults that adopted artificial nests did not substantially 
modify their behavior. 
The dominant female laid eggs without any difficulty in the 
artificial cells, placing as many as three in the larger capsules. Once 
the nest had been adopted, the cells were constantly licked, probably 
due to the lack of mouthing substance on the walls of the artificial 
cells. 
When furnished with paper, the wasps enlarged the artificial cells 
and contructed new ones, beginning in the dihedral angles formed by 
the walls of adjacent capsules. Additional cells were then constructed 
in contact with the natural rather than the artificial cells, with the 
result that the nest expanded in one direction—usually downward— 
in nests with horizontal cells (Fig. 1B). Cells with their axes oblique to 
those of the artificial cells, and not begun in the dihedral angles, were 
constructed without any peduncle near the mouth of one of the glass 
test-tubes (Fig. 2). The wasps continued to reinforce the artificial 
peduncle even though this was abnormally distant from the newly 
constructed cells. 
