Journal of Agricultural Research 
Vol.XXI, No. 6 
.26 
practically the same as that of Ditropinotus aurcoviridis (see p. 414-415). 
The process of oviposition usually requires several minutes. One female 
Eupelmus ally nil lived 52 days and oviposited over a period of 32 days. 
Four generations were reared in glass cell slides during the breeding 
season of 1918, starting with females that emerged from material col¬ 
lected the previous fall and kept under as nearly normal conditions as 
possible. 
CONCLUSIONS 
Judging from the observations recorded herewith and from the field 
observations of the season of 1919, it is quite clear why the parasites do 
not quickly gain complete control of the wheat jointworm. The writers 
have found that as the parasites become more abundant hyperparasitism 
increases greatly. Some of the parasites that are primary only, when 
present in small numbers, become both primary and secondary as they 
become more abundant. 
At the close of the season in 1919 at Warren ton, Va., Homo poms 
chalcidiphagus, a purely primary parasite, was very scarce indeed, while 
in 1916 it was one of the most important. This condition is undoubtedly 
due to other parasites existing upon it as secondaries. Eurytoma sp. 
was the most important parasite present at Warren ton in the fall of 
1919 and Ditropinotus aurcoviridis and Eupelmus allynii were turning 
their attention largely to this species, since Harmolita tritici was greatly 
in the minority. While Harmolita tritici has been greatly in the minority 
in the fall in proportion to the number of its parasites present, for several 
years at Warrenton, the percentage of jointworm-infested wheat plants 
has remained about constant from year to year. This is further evidence 
that hyperparasitism has been going on continuously. Therefore it 
would seem that the parasites can be relied upon for only partial and 
not complete control. 
