Feb. 21, 1916 
Green Apple Aphis 
983 
In the writers' experiments the feeding of this species caused very little 
leafcurl. In the field, however, it often induces considerable curling, 
and some writers have recorded the injury as being very severe. This 
injury appears to be produced mainly by the earlier generations. The 
writers have had under observation some old trees whose water sprouts 
were heavily infested from the middle of the summer to the close of the 
season. Very few of the leaves on these suckers showed any curling and 
these few were only slightly affected, being merely rolled over somewhat. 
Certainly the curling produced by this species (PI. LXXV, fig. 1) is never 
as severe as that caused by A. malifoliae . 
It is very interesting, in this connection, to note that in the spring 
we seldom found large, pure colonies of A . pomi occurring on the trees. 
In practically every instance there were some individuals of A . malifoliae 
present. Since a single half-grown stem mother of the latter species can 
cause very severe curling it seems probable that many of the records of 
this effect from the feeding of A. pomi should properly be referred to the 
rosy apple aphis. 
This species has been reported as attacking and injuring young fruit 
in some cases, and in severe infestations young aphides are often found 
clustered on the apples. A few experiments were performed along these 
lines, but the insects could not be induced to feed on the fruit in any 
instance, .even when all foliage was removed from the twig. It seems 
very probable, therefore, that such feeding is rather rare. 
The quality of the food has a very marked effect upon the size, color, 
and rapidity of growth of the insect (Table III). When furnished with 
tender succulent food throughout larval life, the adults are large, plump, 
and light green in color. On the other hand, if the food is poor in quality, 
the adults will be smaller, dark green, and the bodies will be much 
wrinkled. The insect will also require a considerably longer period to 
attain maturity on poor food. 
Table III. — Effect of food on rapidity of development and reproduction of Aphis pomi 
Poor food, insects small. 
Good food, insects large. 
Experiment 
No. 
Date born. 
1559 
1643 
1645 
1488 
1660 
1852 
Aug. s 
Aug. 14 
...do_ 
July 28 
Aug. 17 
Sept. 10 
Average 
Nymphal 
period. 
Number 
of young 
produced. 
Experiment 
No. 
Date born. 
Nymphal 
period. 
Number 
of young 
produced. 
Days. 
Days. 
IO 
15 
1617. 
Aug. 
13 
7 
IO to 12 
.8 
1687. 
Aug. 
19 
7 to 8 
28 
10 tO 12 
14 
1839 . 
Sept. 
I 
7 to 8 
20 
ii to 13 
44 
1754. 
Aug. 
21 
7 to 8 
25 
12 + 
1807. 
Aug. 
27 
7 to 8 
25 
12 tO 14 
T856. 
Sept. 
2 
8 to 9 
23 
II -5 
10.25 
7- 7 
24. 2 
