398 Trans. Acad. Sci. of St. Louis 
From the foregoing evidence we may conclude, there- 
fore, that in this species the topmost individual matures 
before the lower ones, or the last egg deposited is the 
first to become adult. 
Odynerus leucomelas Sauss. [S. A. Rohwer]. 
A sumac stem taken at Clifton Terrace, Illinois, in No- 
vember, 1916, contained a hollow which was beautifully 
partitioned with mud plugs. One cell contained a pupa 
which developed into an adult O. leucomelas and emerged 
on April 12, 1917. A parasite, Epistenia osmiae Ashm., 
emerged on May 20, 1917. Fig. 51 shows the stem split 
open, with the mud partitions and the two filled cells; 
the lower one is the cocoon of the parasite. 
A second stem taken at the same place had nine cells, 
all likewise beautifully partitioned with mud; one cell 
contained a dried caterpillar, and others had living 
pupae, which gave forth two adults on April 14. One 
pupa was not encased in a real cocoon, but was thinly 
but completely covered with a transparent veil. That 
the cocoon making habit is waning and probably of no 
utility to the species is obvious when one finds cocoons 
started but not finished, and often the cocoon substance 
is dissipated on the walls of the cell. Another cell gave 
forth an adult euckoo-bee in June, identified as Chrysis 
(Tetrachrysis) sp. [S. A. Rohwer]. 
Odynerus foraminatus Sauss. [S. A. Rohwer]. 
The nest of this wasp was found in a large sumac twig, 
*4 inch in diameter, containing a burrow 14 inch wide, 
which afforded a roomy and protected nest. It was a 
tall stalk, in which the hollow went down to a consider- 
able depth. Only the top 514 inches of the cavity was 
used by this wasp, however; at that distance from the 
