440 Trans. Acad. Sci. of St. Louis 
covered spiders; no evidence of egg or larva could be 
found. The next three cells were likewise %4 inch in 
length, and contained cocoons of a light yellow color. 
The young wasp in the top cell was injured in opening 
the twig. The gallery of approximately 34 inch led to 
the orifice of the twig, which in this case was open. The 
partitions were very thin, 1/32 to 1/16 inch, and were 
made of mud. 
Another stem containing this wasp’s dainty nest was 
taken at Shaw’s Garden in January, 1920. It had a 
tunnel 44 inches long, which was not straight but fluc- 
tuated in even so tiny a space as the pith chamber of a 
stem %4 inch in diameter (fig. 664A). The width of the 
tunnel itself varied from 1% to 1/6 inch, and contained 
7 cells and 5 yellow, opaque cocoons 14 inch in length. 
There were very thin mud partitions between the cells 
and the pupal cases crowded against them. One cell in 
the middle was empty, but this contained a small dried 
mass which proved to be the remnant of a spider with 
hairy legs. Since it was found in the middle cell, this 
is sufficient proof that spiders are the prey of this 
species. 
The cocoons were not transparent, so on March 31 I 
opened one, the lowermost, to ascertain its condition, 
and found the larva having a slight constriction about 
the neck, showing that it was then transforming into 
a pupa. The one second from the top displayed the 
same condition. I dared not open more, but this indi- 
cated a tendency to simultaneous development, perhaps 
preparatory to simultaneous emergence. Above the 
topmost larva was an empty space of about an inch; 
then there was a thin mud partition, and above that a 
continuation of the open gallery for 34 inch to the ori- 
fice. One adult emerged from this nest on June 16. It 
