159 
always fly away in the same direction, into the nearby jungle, to 
return presently carrying a green leaf-bit in her mandibles. | 
lost sight of her when she plunged into a vine-laden ravine. Some 
weeks later, however, | 
found in open country, 
a “Bancal” tree (Sarco- 
cephalus orientalis, Ru- 
biaceae) which supplied 
building material for 
some half dozen Zethus 
for a distance of per- 
haps 600 feet or more. 
The “Bancal” has large 
leathery leaves which re- 
main green for a consid- 
erable time and undoubt- 
edly have superior prop- 
erties as nest-building 
material. On one occa- 
sion I observed four 
wasps. gathering — their 
leaf-bits from this tree; 
the work is usually per- 
formed on the higher 
parts of this “Bancal,” 
Fig. 89. A four-cell nest of Z. cyanopterus, and many, of the leaves 
showing one emergence hole, < 3/4. show that they have been 
drawn on time and again 
(Fig. 90). it is evident from the figure that the leaf-bits, prob- 
ably largely on account of the toughness and thickness of the 
leaf itself, do not resemble the neat handiwork of the leaf- 
cutting bees. They are chewed along one or more of their edges, 
which makes them adhere the more firmly to the nest. 
Nest-building here, as compared with that process in most 
mud-using wasps, is, owing 
to the nature of the mate- 
rial, quite tedious. I did 
not observe the very first 
steps. The first work seems 
to be the thickening of the 
point of attachment by the 
application thereto of more 




Fig. 90. Sarcocephalus leaf from whieh 
or less masticated leaf-bits. portions have been bitten out by Z. 
Then the neck of the first cyanopterus for nest building, x 1/3. 
11 
