Nov. 13,1916 
Rosy Apple Aphis 
341 
soon there is a large cluster of twisted leaves which is very conspicuous. 
In orchards composed of large trees these curled bunches are usually met 
with on the lower half of the trees and very often the small fruit §purs 
on the larger limbs in the body of the tree are affected. On very young 
trees, however, the feeding habits seem to differ in that the growing tips 
of the branches are attacked. This causes them, as they develop, to 
become twisted (Pi. 25, B), and as this growth hardens the limb is perma¬ 
nently deformed by being looped upon itself (Pi. 25, C). A branch will 
sometimes become looped several times, thus causing a much deformed 
tree unless the affected branches are cut out. In very young trees that 
are badly infested this is often a good portion of the tree. 
The insects may also be found feeding upon the fruit, and this they 
cause to be reduced in size, irregular in shape, and somewhat gnarled, 
or more or less pitted (PI. 25, A, D). In orchards composed of large 
trees this damage to the fruit is often a factor of considerable importance. 
As has already been stated, the normal summer host of the species 
appears to be rib grass. During the season of 1915, however, the insects 
were reared successfully on broad-leaved plantain {Plantago major) for 
a period of two months. No record of the generations was kept in this 
case and no transfers were made. The plant finally died. At that time 
a strong healthy colony was living upon it and apparently under normal 
conditions would have survived until fall. In several other experiments, 
however, much difficulty was experienced in procuring successful trans¬ 
fers from the apple to this species of plantain. Rib grass appears to be 
the host preferred. This is borne out by an examination of the occurrence 
of the insects in orchard regions. Observations were made over a large 
extent of orchard territory. Wherever the rosy aphis was found to be 
very abundant the narrow-leaved plantain was common in and about the 
orchards, the worst infested orchards being full of the growing plantain. 
The writers* observations upon the insects, both in the experiments and 
in the field, indicate that all parts of the rib grass are subject to attack. 
The insects appear to feed with equal readiness upon the leaves, the stem, 
and the flower stalks, and they may be found upon both sides of the 
leaves. The greater number of the insects, however, fed on the under 
surface of the leaves, especially along the veins. 
In the fall the migrants alight on the underside of the apple leaves, and 
when the oviparous females are produced these feed also upon the under¬ 
side of the leaves. The males, after migration from the plantains, often 
may be found feeding with immature oviparous forms. So far as the 
writers have been able to observe, these fall forms do not cause the leaves 
to curl and twist as do the spring forms. 
