Field Studies of the Non-Social Wasps 393 
this had not a final plug directly over the opening. The 
vestige of cocoon-making was the same as in the speci- 
mens described above. Two weeks later the larvae were 
still quiet. The three uppermost ones emerged almost 
simultaneously, June 2 to 4, and the fourth, which lay in 
the bottom cell, was in all readiness to emerge when the 
twig was broken open on the latter date. 
The last twig, which was opened on March 30, con- 
tained a tunnel 8 inches deep, which also had been made 
by other Hymenoptera. This new tenant, O. conformis, 
had likewise not carried the bits of mud and 
cocoons of parasitic Diptera outside, but instead 
had packed this rubbish firmly in the bottom of the 
tunnel. This made a mass 11% inches deep, and at a 
point 2%4 inches above this she placed the floor of her 
first cell. The cells, five in number, were 34, %, 1, 9/16, 
and 9/16 inch in length, and a vacant chamber of only 
3/16 inch just under the plug at the mouth of the burrow, 
had either been intentionally left empty, or was too small 
to be used for a chamber. The floor and partitions were 
3/16, 1%, 1%, 3/16, 14, %4, and 1/16 inch thick, and were 
made in two portions or layers. The larvae were all 
naked, but in each cell was the usual vestige of cocoon- 
ing, the instinct of which had long since lapsed. Even 
on March 30 I could see the beautiful transitions in the 
development of this series of five young wasps, just at 
the point of change from larva to prepupa. In the low- 
est cell was a quiescent larva of a creamy yellow color. 
In the next cell above, the larva was going through slow 
contortions at intervals, and the constriction at the back 
of the head was apparent. In the cell above this, the 
third larva had assumed a very definite pupal form; in 
the fourth cell the pupal development was more ad- 
vanced, and in the fifth or upper cell, the development 
