22 



BULLETIN 124, U. S. DEPARTMENT OP AGRICULTURE. 



reared this parasite, it was believed to be the first rearing record. 

 During the following summer the parasites were so numerous that 

 it was hard to understand why they had not been discovered before. 

 Collections of pupse of Eurymus were made by the writer in August, 



Pig. 10. — Pteromalus eurymi, a parasite of pnpre of the alfalfa caterpillar : Adult. Greatly 



enlarged. (Original.) 



1912, and showed that 49 per cent were parasitized by this species. 

 The record follows : 



Table IV. — Parasitism of pupw of the alfalfa caterpillar oy Pteromalus eurymi. 



Pupee 

 collected 



Infested 



with 

 Ptero- 

 malus. 



Per cent 

 infested. 



1912. 



Aug. 5 



Aug. 14 



Aug. 19 



Aug. 26 



Total and average 



65 



39 



11 



154 



40 



43+ 

 63+ 

 53 



49 



This insect thus seems to be exerting a larger influence than any 

 other parasite toward the control of the alfalfa caterpillar. 



In 1913 Mr. T. Scott Wilson did not find it nearly so numerous in 

 the Salt River Valley as was the case the year before, Just why this 

 was so, it is hard to say, The extremely cold weather during the 



