says: "Our material of the parasites of P. nigrirostris was worked over 
and the more rarely occurring species of Microbracon were determined by 
C. F. W. Muesebeck as M. hyslopi Vier. and M. tychii Mues. The very 
small numbers of these species that have been reared from P. nigriros-— 
tris indicate that these are normally parasites of other insects * * * 
M. tenuiceps Mues. has been reared in such large numbers that there is 
no doubt that this is now the most important enemy of P. nigrirostris 
in this region. Bathyplectes exigua Grav. has been a close rival and 
in the early days of the occurrence of P. nigrirostris in the Pacific 
Northwest it was the most important parasite. Dibrachoides dynastes 
Forster, while now widely distributed in this region, normally takes on— 
ly a small toll of the host; however, our rearings indicate that this 
species, in some years, may be abundant in some localities." 
