Transaction’s Texas Academy of Science. 
41 
(9) Fresh grass-hopper, which I killed and threw on the nest- 
ing-ground, was picked np by a Microtiemtiex, as was also a dry 
Syrphid. 
(10) Dry yellow Mutillid. 
(11) Old Orthopterous pupa-case with dry dead pnpa inside. 
Of all the things which Microti emb ex feeds to her larvae, these last 
two things are the toughest. The Mutillid must have been a most 
indigestible morsel, for the skeleton is so tough that in the fresh 
state it is very hard to drive a strong pin through it. The Mutillid 
was broken in two and the halves were carried off separately. 
The above account gives one a very fair idea of the diet of larval 
Microti emb ex. It thus seems probable that the larval food consists 
mainly of insects, which the mother finds already dead and often 
dry. This is, moreover, borne out by the manner of the wasp’s hunt* 
ing, in which she differs decidedly from the solitary wasps and re* 
sembles markedly Polistes and Vespa. Bemtiex hunts her flies in 
a stormy fashion, flying around louder and faster than the prey 
she captures. Microti emb ex can be seen calmly flying through the 
woods much like a dragon fly, steadily maintaining a level of a foot 
from the ground. That she also attacks live insects is shown in 
that she attacks ants and in that her caterpillars are always limp 
and fresh. A fresh juicy caterpillar sandwiched in between a lot of 
old dry insects must indeed be a very welcome morsel for the grow- 
ing larva. 
It would thus seem that Microti emb ex, contenting herself with any 
insect she finds, has an advantage over Bemtiex, her nearest relative, 
and Monedula, both of which feed their larvae from day to day. But 
quantity alone does not bring the advantage. No doubt Bemtiex, 
knowing the habits of her prey, and having developed a skill in its 
capture (being a specialist in the art of fly-catching), can collect as 
much real nutritive substance as Microtiemtiex. Though more gen- 
eralized in the manner of procuring food, Microtiemtiex has devel- 
oped an improvement in her condition over Bemtiex tex. in that she 
closes her nest before leaving it, often smoothing it over with consid- 
erable care. In this way she is spared the inroads that commensal- 
istic larvae make into Bemtiex s store of food. 
In their semi-social habit Bemtiex (and this would apply to Mi- 
crotiemtiex) has been regarded as transitional between the truly soli- 
tary and the social wasps. Both genera are more solitary than social 
for their only social trait consists in a tolerance of each other’s pres- 
ence in the immediate neighborhood. Beyond an occasional quarrel 
or the stealing of each other’s flies the wasps preserve the peace of 
