160 
cell is begun; the wasp, working from two near points (Fig. 
92) on this thickened base, applies leaf-bits, more or less 
on edge, thereto, securing each near the base of and on the 
inner side of its neighbor in a shingling manner. In _ this 
way anarc is soon formed, which, with the addition of more leaf- 
bits, becomes a collar. Sooner or 
later the upper edge of this collar 
is strengthened and made more 
smooth by the chewing up of tts 
components into a greenish pulp. 
Shingling from the lower part of 
this collar now proceeds, the wasp 
applying the leaf-bits from the in- 
side and working downwards. Thus Fig. 92. The beginning of a cell 
the shingling is done in a different of 2. cyanopterus; semi-dia- 
: grammatic. On the upper side 
is shown the foundation thick- 

Fig. 91. Egg ening of well-masticated leaf- 
of Z. cya- bits; at either end of this 
nopterus. twig-girdling ring the leaf-bits 
Slightly are shingled so as to form a 
enlarged. ring, the cell-opening and from 
which leaf-bits are shingled ver- 
direction from that on the collar, tically and downwards to com- 
and the bottom of the cell is com- peste CaN gsimudier pity, Sa 
pelted) last} Several layers: are: > * 
put on, and smaller portions of leaf are applied as an interior 
finish, and these being vigorously chewed up form a compara- 
tively smooth surface. The cell (Fig. 93) has now an interior 
depth of about 30-32 millimeters, with a mouth of 8 mm. in width 
and 12.5 mm. below the middle. This, the first cell, probably 
requires the longest time of all to construct. About five days 
of variable and rather cool January weather were required by 
a Zethus in making the fourth cell 
of her nest. | 
Hardly is the cell completed 
when an egg is deposited therein. 
Unlike Eumenes, Odynerus, Rhyg- 
chium and most other Eumenidae 
whose eggs are suspended from the 
ceiling of their cells by a filament, 
but as in Synagris, that of Zethus 
is laid unattached to the bottom of 
the cell, so that if the latter be un- 
Fig. 93. The first cell of a Z. duly inclined the egg will tumble 
cyanopterus nest, X 3/4. out, The ego (Fig, 91) as creamy 

