REPORT OF THE STATE ENTOMOLOGIST 1901 fal & 
cular hole in the side has produced a parasite and not a fly. 
Sometimes fully nine tenths of the Hessian flies are destroyed 
by parasites and occasion- 
ally entomologists have ex- 
perienced difficulty in breed- 
ing any adult flies from 
infested wheat stems _ be- 
cause the parasites were so Vi (ES \ +— 
Vi — '\ 
numerous. f | a | \ 
e K aay; q 
The above notes give some aa 
idea of the importance of 
these little creatures. One Fig. 2 Merisus destructor (after Riley) 
ef the most efficient of these parasites is known as Merisus 
destructor Say, a minute four winged fly which is repre- 
sented in the accompanying illustration. It occurs not only 
Fig.3 Boeotomus subap- Fig.4 Platygaster herrickii Pack. (after Riley) 
terus (after Riley) 
throughout the American territory affected by the Hessian fly 
but it is known in England and Europe. 
Another parasite which ranks next in economic importance to 
the preceding is known as Boeotomus subapterus. It 
-is frequently wingless as seen in fig. 8. The proportion of 
winged to wingless individuals is said to vary at different sea- 
sons of the year. In Missouri this species has been bred from 
infested wheat stalks more commonly than the preceding. 
imtaey easter “herrie¢kiiPack., represented” in the 
accompanying figure, is another common parasite of this grain 
pest. % 
