Field Studies of the Non-Social Wasps 383 
the broken pith was then all below them, they were really 
free, having no barriers between them and freedom. In 
the drift of loose pith, more than an inch deep beneath 
them, one still remained hidden from view, but working 
its way upward. In the four inches below this were five 
adults, four of which were working at the pith, and one 
with the wings not yet spread. Two of the five were facing 
downward, one of which was diligently attacking the 
pith and making a good progress toward the bottom. Of 
course in this case the bottom was open so it could even- 
tually gain its freedom. In nature, however, this travel- 
ing downward would certainly lead to its death-trap. 
Precautions were made to see that none of the twigs were 
So placed as to put the cocoons upside down, and this 
must have been an individual variation. This, of course, 
goes against Fabre’s idea of the effect of gravity upon 
emergence, 
The evidence from this nest indicates that emergence 
in this species does not occur in order of primogeniture, 
nor in the inverse order, but that emergence does prob- 
ably occur simultaneously; twelve out of the thirteen 
cocoons gave forth their young within two days. 
A third sumac twig containing Hypocrabro was found 
on April 1, 1920. The stem was cut off too short, but 
the portion brought home began at the bottom with a 
plug one-half inch in thickness. Above this the next 7% 
inch contained three cocoons; the partitions between 
these were so thin that they had been knocked down by 
the feeding larvae. Next came a partition which was 
38/16 inch thick and one more cell, the last, which was 3g 
inch in length and contained a larva. The seven-inch 
tunnel above this had some interesting features. For 
2% inches it was filled with packing; in the lower 34 inch 
of this, the packing was of the finely bitten and closely 
