INHABITANTS OF AN OLD STUMP. 45 



nests, but we were successful witli only one of them. We had 

 taken the eggs on July eleventh, and on the following day one 

 of them hatched. By this time many of the aphides had dried 

 up and were turning yellowish. On July fifteenth there were 

 only two or three green ones left, all the rest being brown or 

 black, but the larva continued to eat contentedly. On the 

 twenty-first the aphides were all dry and the larva now ate only 

 the inside, leaving the shell. On the twenty-sixth it spun a 

 light yellow cocoon within which it remained until September 

 second. On that day there came forth not a wasp at all, but a 

 brilliant green Chrysis fly (Omaliis corrusccuis) which we had 

 often seen in close attendance upon Diodontus americanus. The 

 egg of the wasp would probably have been laid after the nest 

 was fully provisioned, but since the fly had the start the wasp 

 larva would have had small chance of finding a sufficient food 

 supply. 



The only notes that w^e find concerning this genus are one in 

 Mr. Ashmead's paper which says that Stigmus argcntifrons 

 provisions its nest with aphides, and one in Westwood stating 

 that Mr. Kennedy discovered the cells of Stigmus troglodyies 

 in hollow straws of a thatch, the cells being filled with minute 

 insects, v/hich appeared to be the larvas of a Thrips, as many as 

 fifty being found in one cell.* 



^Modern Classification of Insects, Vol II., p. 195. 



