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. alhophaleratus 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. 



