THE HESSIAN FLY. 15 
Polygnotus minutus Lindm., which occurs in Russia, France, and 
HWngland, is in America represented by Polygnotus hiemalis Forbes 
(fig. 11), perhaps the most useful of any in this country. It is very 
minute, and Mr. Reeves has counted over 40 of the larve within a 
single flaxseed. It is black, with yellow feet, and the legs are dark 
brown, banded with yellow. The writer has again and again reared 
this in great numbers from fall wheat infested by the fly and wit- 
nessed the sudden check sustained by the pest the following spring. 
It is owing to this more than to any other influence that the Hessian 
fly is now being held in check in the spring-wheat regions of the 
Northwest, and it is probably due to a lack of this useful little insect, 
that the serious invasion of the Hessian fly during the year 1914 was 
primarily due. From all the information at present available the 
severe winter of 1912 and 1913 so greatly reduced its numbers as to 
relieve the Hessian fly from the enormous restraint that it was at 
that time exerting upon the pest. A vast amount of 
material was secured during the summer and autumn 
of 1914 from which this parasite could have been reared 
had it been present. From nowhere over the entire 
section of the country infested by the Hessian fly, 
excepting in the State of Pennsylvania, have we been 
able to rear the parasite, and it seems almost beyond 
doubt that the losses from attacks of the Hessian fly 
during 1914, and such as may occur during the year 
1915, will be due to the absence of this parasite in 
the wheat fields. The occurrence of the adult within 
the flaxseed of the Hessian fly is illustrated in figure 12. 
What appears to have been a most successful intro- 
Fia@, 12.— Adults 
duction of this beneficial insect was brought about 
some years ago in a shipment by Mr. EH. O. G. Kelly 
from the Wellington, Kans., laboratory, to Mr. George I, 
of Polygnotus 
which have de- 
veloped within 
the ‘‘ flaxseed’’ 
of the Hessian 
fly andareready 
to emerge. 
Greatly en- 
larged. (Auth- 
or’s illustra- 
tion.) 
Reeves in the State of Washington. Mr. Reeves 
liberated these parasites in fields badly affected by the 
Hessian fly. Up to that time he had not been able 
to secure this parasite in the State of Washington, 
whereas since the introduction of this insect from Kansas it has 
become not only very common, but in some cases abundant. 
Another parasite reared almost invariably in connection with the 
Hessian fly is Hupelmus allynii French. (Fig. 13, male; fig. 14, 
female.) While this is generally distributed over the country and 
seems to be associated with the Hessian fly, and was for a long time 
supposed to be parasitic thereon, it now seems possible that it may 
be a secondary parasite and therefore the reverse of beneficial. It 
may be said, however, in its defense that it is most certainly a very 
important parasite of some other grain insects, notably the jointworms 
