April, '11] WEBSTER: wheat-head army-worm 181 



Distribution 



Although the species was first noticed by European wTiters, it is 

 not known to occur outside of America. To the north the moth has 

 been taken from Nova Scotia to Alberta, to the east in Delaware and 

 New Jersey, to the west at Glenwood Springs, Col. (Barnes), and 

 southern Arizona (Barnes). According to Sir George F. Hampson 

 the species occurs at Mexico City, Mexico; Coquimbo and Mulchen, 

 •Chili; and Florenzia, Argentine. Buenos Ayres, Argentine, was given 

 as the source of Hiibner's type. 



Natural Enemies 



Dipterous parasites. Three tachinids were reared from the larvae. 

 Two of these, Winthemia quadripustulata Fabr., and Euphorocera 

 claripennis Macq., are common species, and have been reared from 

 many other hosts. The first species was by far the more numerous. 

 It was very abundant in the summer of 1910, but was not found at 

 all that fall. The third species, Metachceta helymus Walker, was more 

 rare. It was reared in the fall only. The determinations are by Mr. 

 D. W. Coquillett. 



Besides these three Riley recorded another tachinid as parasitic 

 on the wheat-head army-worm. This is Frontina frenchii Will. 



Hymenopterous parasites. In the summer of 1910 an egg parasite 

 wa.s found, which has never been recorded. Mr. A. A. Girault tells 

 me that this is a new^ species, and he has given it the manuscript name 

 of Pentarthron retorridus. It was first seen August 23 by the writer, 

 when a single specimen was observed ovipositing in eggs of the wheat- 

 head army-worm. Afterwards it was reared abundantly, emerging 

 August 30 to September 14. 



The hymenopterous parasites of the larvae were less numerous than 

 the tachinid parasites. Of these, Microgaster auripes Prov. (H. L. 

 Viereck determination) was the most common. 



Another parasite, somewhat less common, was a species of Micro- 

 pUtis, which Mr. Viereck says is new. This parasite affected the 

 younger stages of the larvae only. A secondary parasite was reared 

 from one of the Microplitis cocoons, a new species of Mesochorus, 

 according to Mr. Viereck. 



One specimen of Paniscus geminatus Say (Rohwer determination) 

 was reared in 1910. 



My father, F. M. Webster, writes me that Apanteles Iceviceps has 

 been reared from this host in New Mexico by Mr. C. N. Ainslie. 



Riley had previously recorded two species from this host, which 



