326 
Journal of Agricultural Research 
Vol. VII, No. 7 
the number of lines carried. It is quite possible that lines from stem 
mothers taken in different localities or possibly different rearing condi¬ 
tions might have resulted in a higher percentage of summer winged forms. 
All molts and specimens in every generation in each line were mounted 
for study and these many forms gave an excellent opportunity for 
determination of variations. 
Technique. —The technique employed for the study of insects of this 
species was the same as that recorded in the writers' paper (n) on the 
green apple aphis. 
THE EGG 
DESCRIPTION 
Size 0.550 by 0.272 mm. The largest were 0.608 mm. long and the shortest 0.480 
mm. The width varied from 0.256 to 0.288 mm. The longest eggs were not neces¬ 
sarily the widest. In fact, this was seldom the case. 
The newly laid egg is light yellow in color, changing through greenish yellow and 
yellowish green to black in about four days. 
LOCATION ON TREE 
The eggs are laid mostly on the small twigs, under buds, or in crevices 
in the bark. They may, however, be laid on the small branches, or even 
occasionally on the large branches and trunk. They are seldom laid on 
the water sprouts, though- this also may occur. Usually oviparous 
females bom and reared on water sprouts lay their eggs at the base of 
such sprouts or on the trunk of the tree. 
The small plants used in the experiments were frequently potted with 
portions of the highest roots exposed. In such cases some oviparous 
females invariably laid eggs upon these exposed roots. 
HATCHING 
The eggs of this species commenced hatching, in 1914, about April 8, 
at the same time that the eggs of A. pomi began to hatch, and about 10 
days later than A . avenae . In 1915 hatching also commenced about 
April 8. Eggs of A. pomi commenced hatching on the same date. At 
this time the stem mothers of A. avenae were in the second instar. 
STEM MOTHER 
DESCRIPTION 
First instar. —Morphological characters. Antennal segments as follows: III, 0.12 
to0.144 mm., average 0.133 mm .; IV, (0.048 plus 0.12 mm.) to (0.064 plus 0.136mm.). 
Eyes with few facets. Cornicles short and thick, 0.088 to 0.096 mm., average 
0.089 mm. 
Color characters: Dark green; appendages and crown black. Insects covered after 
a short time with a mealy bloom. 
Second instar.— Morphological characters. Antennal segments as follows: III, 
0.112 to 0.114 mm., average 0.128 mm.; IV, 0.072 to 0.096 mm., average 0.081 mm.; 
V, (0.064 plus 0.136 mm.) to (0.072 plus 0.168 mm.), average (0.069 plus 0.150 mm.). 
