88 
Journal of Agricultural Research 
Vol. XI, N0.3 
Table IV. — Lengths (in millimeters) of antennal segments and cornicles of fall migrant 
of Macrosiphum illinoisensis , with number of sensoria on antennal segments III , IV, 
and V 
Segment 
III. 
Number of 
sensoria on 
segment 
III. 
Segment 
IV. 
Number of 
sensoria on 
segment 
IV. 
Segment 
V. 
Number of 
sensoria on 
segment 
V. 
Segment VI. 
Cornicles. 
0. 304 
16 
O. 272 
13 
O. 224 
6 
O. 112+0. 32 ! 
0. 272 
•384 
28 
.304 
16 
.288 
8 
. 112+ • 35 2 
• 35 2 
•304 
17 
. 256 
18 
. 224 
7 
• ° 9 6 + • 336 
. 256 
MALE 
The males are produced a little later than the fall migrants, but can 
be found flying at the same time and may be taken on the viburnums 
in company with the fall migrants. Thus they are on the trees in many 
cases before the oviparous females are mature. They remain feeding 
upon the leaves until such time as copulation is possible. 
Fifth instar (adult). —General color a pale reddish brown, often, however, of a 
distinct greenish color. Appendages dusky; eyes black; wings hyaline with dusky 
veins and stigma. Antennae (Pi. 8, A) distinctly imbricated and segments III, IV, 
and V irregularly covered with very many small circular sensoria. Cornicles short, 
distinctly tapering and imbricated. Fore wing 2 mm. long; length from vertex to tip 
of cauda, 1.2 mm. Relative lengths of antennal segments and cornicles given in 
Table V. 
Table V. —Lengths (in millimeters) of antennal segments and cornicles of male of 
Macrosiphum illinoisensis , with number of sensoria on antennal segments III , IV, 
and V 
Segment 
III. 
Number of 
sensoria on 
segment 
III. 
Segment 
IV. 
Number of 
sensoria on 
segment 
IV. 
1 
Segment 
V. 
Number of 
sensoria on 
segment 
V. 
Segment VI. 
Cornicles. 
O. 336 
3 1 
0. 272 
29 
O. 224 
15 
O. 08+O. 32 
0. 176 
• 35 2 
30 
. 256 
27 
, 208 
15 
• 08+ . 336 
. 16 
.288 
38 
. 224 
35 
. 176 
19 
. 08+ . 336 
. 144 
.288 
35 
. 224 
28 
. 176 
17 
• 08+ . 352 
. 144 
OVIPAROUS FEMALE 
The oviparous female is a small, dark reddish aphis produced during 
the early part of October on the viburnum. It feeds upon the twigs and 
may be found until frost kills all the insects. Each oviparous female 
lays three to six eggs close about the buds or occasionally scattered 
along the twigs. 
First instar. —General color greenish brown, almost uniform, the appendages, 
however, a little darker. Antennae of four segments; segment III, 0.08 mm.; IV, 
0.032 plus 0.112 mm.; cornicles very small and tubercle-like. Length from vertex 
to tip of cauda, 0.48mm. 
Second instar.— General color more reddish than the first instar, otherwise 
similar. Antennae of four segments; segment III, 0.144 mm.; IV, 0.048 plus 0.16 
