around the latter’s jumping-off place, but she could not locate her 
prey. 
Some of the more highly specialized Eumeninae have habits in 
common with their social brethren, i. e., feeding their young from 
day to day and abiding by their nests during the night. This 
applies to Zethus (Calligaster ), some Zethusculus and. Synagris. 
Odynerus tropicalis H. de Saussure of Africa feeds her young 
from day to day (Bequaert, 1918). This latter habit occurs also 
in other solitary wasps of entirely different groups ( Bembecidae 
and Sphecidae), but I do not regard it here as a development 
towards social life. 
Rhygchium atrum Saussure. 
Length 20 mm.; thick-set; black; antennae and most of wings, 
orange. 
This is a tame household insect and in a sense therefore rather 
a nuisance. But inasmuch as it seems to prey wholly on the 
larvae of certain moths of the leaf-roller type (Pyr alidina), this 
fact should counterbalance any annoyance it may occasion. 
While some species of this genus fashion neat cells of clay, 
the handiwork of atrum is rather crude and consists solely 1 
partitioning off a pre-existing cavity with plugs of mud. The 
mother Rhygchium was a frequent visitor to the chemistry lab- 
oratory and insectary at the College of Agriculture, where she 
sometimes attracted unfriendly notice by plugging up Bunsen 
burners and other apparatus with mud. In dwellings she makes 
a specialty of nesting in the bamboo furniture, and as this is 
often shifted about, the poor insect is then at a loss where to 
stuff the heavy caterpillar she is carrying and which she may 
perforce exhibit to the unappreciative household while assembled 
at the noon meal. 
One of these insects made her nest in a reclining bamboo 
chair; she scarcely objected to my presence in this chair, but that 
afternoon brought in seven caterpillars. Other nests were found 
in shallow rung holes, the wasp coiling up her slender prey within 
them. 
The empty cells of the leaf-bit nests of Zethus (Calligaster) 
are not infrequently appropriated by Rhygchium, w stores them 
and seals them up with mud. In another case, a large empty 
mud nest of Eumenes fulvipennis, lying on a shelf in the insec- 
tary, was utilized by a couple of Rhygchium; the empty cells 
were close together, and so there was quite a skirmish whenever 
the two mothers met. Then they faced one another in hostile 
attitude and made snaps at their mandibles. 
