Field Studies of the Non-Social Wasps 439 
been sealed stark empty. In some of the latter cases 
the sealing partitions were placed so that the cells were 
so small that a growing larva could not possibly have 
had room to develop anyway. In four cases death in 
the larval stage might be attributed to insufficient food, 
while 20 others died in the larval stage despite the fact 
that food remained untouched in their cells. The re- 
mainder, about 6 per cent, were parasitized by Melit- 
tobia, Anthrenus, a Dipteron and an Ichneumon. 
The species of the prey used by these wasps was de- 
termined in only three cells of one nest; the 18 spiders 
in them all proved to be Epeira donnciliarum [J. H. 
Emerton]. 
For interesting information on the feeding instincts, 
responses to light, shadows, hues and brightness, the 
reader is referred to a paper by Dr. C. H. Turner in 
the Journal of Animal Behavior, 2: 353-362. 1912. 
Trypoxylon plesium Roh, [S. A. Rohwer]. 
This Trypoxylon, a new species, makes beautiful little 
nests in hollows in twigs (fig. 65); the yellow cocoons all 
in a row of soft, neat cells present a scene which is cer- 
tainly worthy of the name of domestic art. The first I 
saw was in a sumac stem taken in the edge of St. Louis, 
April 1, 1920. There was a hollow 3% inches deep and 
9/16 inch in diameter. The nest itself, however, occu- 
pied only the upper 2% inches; why the little tenant 
did not utilize the rest of the tunnel which was all ready 
for it, I cannot see. There was a mud plug to serve as 
the floor of the first cell. The bottom cell, built on this, 
was 14 inch long, and it contained a dried mass which 
proved, by the aid of the microscope, to be four fungus- 
5 This species is described from material bred from these twigs by 
Mr. S. A. Rohwer in Proc. U. S. Nat. Museum 57: 229, 1920. 
