470 
Journal of Agricultural Research 
Vol. VII, No. n 
Viviparous females have been carried through the winter out of doors 
in breeding cages at La Fayette, Ind., and at Charlottesville, Va., and have 
been found on the small grains throughout the fall, in the winter, and 
again in the early spring, so they doubtless pass the winter both in the 
egg and as viviparous females in the Northern States. It is doubtful 
whether eggs and stem mothers normally occur much south of latitude 
35 0 unless it is in higher altitudes. 
The aphids remain on the leaves of wheat and other small grains until 
the heads are formed and then cluster around the tender kernels, sucking 
the rich sap. Just before harvest, when the plant tissues become hard 
and tough, all immature individuals become winged and migrate to some 
of the grasses, where they remain until volunteer grain and fall wheat 
put in their appearance. 
REARING CAGES 
The same type of shelter and rearing cages were used as those pre¬ 
viously described and figured by the writer (14). 
GENERATION SERIES 
The generation series were not started with stem mothers in any 
instance, as no eggs hatched until the spring of 1911. Since they had 
been carried through consecutive generation series for each of the three 
preceding years, it was thought unnecessary to continue longer. The 
series were started each year with the progeny of individuals that had 
survived the winter. In fact, they were started at the time the eggs 
of Toxoptera graminum began to hatch. It was found later that this 
was approximately the date of hatching for M. granarium. 
The usual method that has been followed in the past by the Office of Cereal 
and Forage Insect Investigations in the generation rearing was adopted for 
this species—that is, the first born from each first born and the last born 
from each last born were isolated and daily records made as far as possi¬ 
ble. Two partial generation series were carried through in 1907 and four 
complete ones in 1908 at Richmond, Ind.—that is, they were run either 
until the sexes appeared in the fall or until the work was interrupted by 
cold weather. Another generation series was carried through at La Fay¬ 
ette, Ind., in 1909 and one in 1915 at Charlottesville, Va. The writer 
thus has observations covering nearly 120 individuals. This is a com¬ 
paratively small number, but since the observations cover practically 
four years the data should prove reliable. 
Tables III and IV give in detail consecutive generations from one indi¬ 
vidual hatched March 27, 1908, at Richmond, Ind. 
