62 
Psyche 
[April 
tubes an initial cell was provided with an egg and several para- 
lyzed caterpillars and then abandoned. In both of these, eggs 
and caterpillars disappeared within a day, and the presence of 
ants in both leads me to believe that these depredators may have 
been guilty of the robbery. Whether the nests were abandoned 
by their builders before the incursions of these ants or whether 
the desertion was a result of their intrusion could not be deter- 
mined. The paralyzed caterpillars and the wasp egg would 
doubtless be attractive to these insects and it is not unlikely 
that the presence of a few worker ants in a nest would drive the 
owner away. 
Three nests of Ancistrocerus were infested by dipterous 
larvae. In one of these the eggs were very evidently deposited 
in the nest by the adult fly; the others may have been deposited 
on the caterpillars before they were brought to the nest. In all 
three nests the behavior of the fly larvae was the same — they 
devoured everything. After consuming the contents in one cell 
they broke through the mud partition and fed on the contents of 
the next and so on until the entire nest was destroyed. At- 
tempting to rear the adults for identification, I placed the pupae 
of these Diptera in glass tubes fitted with tight cotton plugs, 
thinking to prevent their escape. But the adults were evidently 
well provided with means for escaping from wasp’s nests, for on 
emerging they worked their ways through the cotton and were 
lost. 
An undetermined species of Chrysidid, which I shall men- 
tion elsewhere, was also associated with wasps of the genus 
Ancistrocerus observed during the summer of 1921. 
Summary and Conclusions. 
Observations on the three species of Eumenidae treated in 
this paper ( Ancistrocerus tardinotus Bequaert, A. capra de 
Saussure and A. albophaleratus de Saussure) bring out the fol- 
lowing facts concerning their biology. 
1. These species appear to nest usually in suitable cracks 
and crevices adapted to their needs. 
