Field Studies of the Non-Social Wasps 381 
in failing to oviposit, I do not know; among the fungus- 
grown prey we did not find eggs or young, but these 
might have been obliterated by the growth. Another 
item of interest is the fact that going upward we find 
the number of aphids in each cell increases; but this 
might have been due to nothing more than accident. 
Another family group of this sub-species was found in 
a sassafras twig in St. Louis in the winter of 1919-20. 
The hollow in the twig was quite narrow, and although it 
contained three insects, there were no cocoons, partitions 
nor debris to indicate what their past history had been. 
One adult emerged on ‘April 15, and the other two were 
mature, black and almost ready to emerge on that date 
when the twig was split open. 
Tue Fiy-Carcuer, Hypocrabro stirpicolus Pack 
[S. A. Rohwer]. 
In a thirteen-inch elder stem taken at St. Louis in Feb- 
ruary, 1919, were several cells of H. stirpicolus. They 
were distributed along eight inches of the tunnel, and the 
top four and one-half inches was hollow and empty. The 
stem was opened, covered with strips of mica, placed in a 
milk bottle in an upright position, as it had been in 
nature, 
On March 18, one adult emerged from a cocoon. It was 
not from the top cocoon, as one might expect, but the 
bottom one. The wasp worked its way upward, and at 
the end of the second day had progressed about one inch, 
kicking the loose pith behind it in the crowded quarters. 
The third day it must have spent in resting, for at the 
end of this day it had advanced only %4 inch. It was not 
observed for two days, but at the end of that period it 
was evident that it had traversed 54 inches; the little in- 
Sect must have worked hard indeed. This effort ex- 
