334 
Journal of Agricultural Research 
Vol. VII, No. 7 
broad-leaved plantain. Other transfers were made during 1914, but it 
was not until the spring of 1915 that a large and definite migration to 
plantains was noted in the field. Winged specimens were then observed 
alighting in numbers and reproducing upon the underside of the leaves 
and on the long flower stems of the rib grass (PI. 23). Ross (8) reported 
that he was able to rear the species throughout the summer on apple. 
This the writers were unable to do even with a very few insects on a 
plant; all of the lines carried ultimately produced winged forms and 
migrated. It must be remembered also in this connection that the 
writers selected wingless and winged forms from each mother in order 
to obtain offspring. It is quite possible, however, that the lines carried 
by Ross had less of a tendency toward winged forms throughout than 
had those of the writers. Since the migration does not occur in any 
definite generation but is scattered throughout the apple life of the insect 
from the second generation onward, such a condition of affairs might 
easily occur. The following fact also is df importance here: The inter¬ 
mediates discovered by the writers remained upon apple and there 
reproduced, thus taking on the nature of the primary wingless forms. 
This would indicate that ultimately the species may become a permanent 
apple species like Aphis pomi , and the fact that Ross had carried it 
through the season upon apple would seem to show that this tendency is 
further advanced in the Ontario region where Ross conducted his experi¬ 
ments than in the Virginia region where the writers reared their insects. 
The fact that spring migrants occurred in every generation on apple 
in the writers' experiments from the third to the eighth caused this 
migration to spread over a long period of time, from May 20 to July 1 
at Vienna, Va. The pupae of the spring migrants very often do not 
feed but may be found under loose bark and in the crevices of the limbs 
and trunk. Many, however, remain within the curled leaves. In these 
places the winged form is produced and in a few days it migrates to 
the rib grass and settles upon the underside of the leaves and on the 
flower stems. Here it produces its young. Occasionally some winged 
forms reproduce upon the broad-leaved plantain, but at Vienna this is 
rare as compared to the large number that migrate to the rib grass. 
The fall migrants leave the plantains about 1 or 2 days after becoming 
adult, and fly to apple trees, where they settle upon the under surfaces 
of the leaves and commence feeding. Reproduction usually begins 
within 24 hours after the insect reaches the apple, though the migrants 
may feed for two or three days before producing young. 
When mature, the males leave the plantain, flying to apple. If the 
oviparous females are not fully mature when the males arrive, the 
latter settle down beside them and feed until such time as copulation 
can take place. 
Recently, since this paper was prepared, Brittain (12, p. 16, fig. 2) 
has reported his generation experiments on plantain. 
