Nov. 13,1916 
Rosy Apple Aphis 
323 
application of the name here appears to have been made by Sanderson 
(5, p. 189-191), who went rather fully into the history of the species. 
In some characters our rosy apple aphis does not fit the description 
given by Kaltenbach, and these characters cause the writers to believe 
that they are dealing with another insect. This belief is strengthened 
after examination of the European insects. Collections of A. sorbi from 
Sorbus, taken by Mr. J. F. Strauss in Germany, being from the same 
region and the same host as the original specimens, can with some cer¬ 
tainty be considered typical. Moreover, they fit very closely the original 
description of Kaltenbach., 
Although these specimens are in a general way very close indeed to 
the rosy apple aphis, a careful comparison shows that they represent a 
distinct species (PI. 22, C). In the wingless form the cornicles are con¬ 
siderably longer than are those of the rosy apple aphis, and the lateral 
tubercles are more prominent. The antennae, too, show a considerable 
difference, the length of IV, as compared with V, being much less in A. 
sorbi than in the rosy aphis. These characters are well illustrated in 
Table I. 
Table I. —Relative proportions of antennce and cornicles of wingless forms of Aphis 
sorbi and A. malifoliae 
Aphis sorbi . 
Aphis malifoliae. 
Segment 
m. 
Segment 
IV. 
Segment 
V. 
Segment 
VI. 
Cornicle. 
Segment 
III. 
Segment 
IV. 
Segment 
V. 
Segment 
VI. 
Cornicle. 
22 
15 
14 
8 ~24 
24 
28 
20 
14 
6. 5-27 
20 
24 
17 
16 
6. 5-22 
25 
28 
19-5 
14 
6. 5-28 
19 
26 
17 
14 
6- 5" 2 5 
23 
25 
21 
14 
6. 5-27 
20 
23 
16 
IS- 
7 ”23 
22 
30 
21 
IS 
6- 5-32 
20 
The winged forms of the two species, while very much alike in general 
appearance and color characters, can be separated quite easily by meas¬ 
urements of the antennal segments. The specimens of A. sorbi show 
the base of Segment VI considerably longer and the unguis considerably 
shorter than the same portions of Segment VI of the rosy aphis. The 
large number of sensoria on the antennae of the two species cause them 
to resemble each other very closely. 
Measurements of the antennae of six specimens chosen at random 
from the two species are given in Table II, together with the number 
of sensoria on the different segments. 
A glance at these data will show a fairly constant difference between 
the spring migrants of these two forms, and this structural difference is 
borne out by the writers' experiments. They have been unable to rear 
the rosy aphis on the host plant of the European A . sorbi . The European 
form they have been unable to test on apples on account of the lack of 
live material. 
