22 
BULLETIN 124, U. S. DEPARTMENT OF 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 pupae of Eurymus were made by the writer in August, 
Fig. 10. — Pt-eromalus eurymi, a parasite of pupse 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 pupa? of the alfalfa caterpillar by Pteromalus eurymi. 
Date. 
Pupa? 
collected. 
Infested 
with 
Ptero- 
malus. 
Per cent 
infested. 
1912._ 
65 
39 
11 
154 
26 
17 
82 
40 
Aug. 14 
43+ 
Aug. 19 
63+ 
Aug. 26 
53 
Total and average 
269 
132 
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 Eiver Valley as was the case the year before. Just why this 
was so, it is hard to say, The extremely cold weather during the 
