442 
Journal of Agricultural Research 
Vol. XXX, No. 5 
nessee are mostly loams or silt loams, 
which may be one reason why the in¬ 
sect is less injurious in this State. 
LIFE HISTORY 
Unlike some other species of plant 
lice, the strawberry root louse spends 
its entire life cycle upon the strawberry, 
migrating only to other strawberry 
fields. 
THE EGG 
The insect passes the winter in the 
egg stage upon the pedicels of the 
leaves (pi. l, c ), although eggs are 
sometimes laid on the underside of the 
leaves. In 1921, at Knoxville, Tenn., 
hatching began on February 15, and in 
1922 on February 22; hatching con¬ 
tinues for about a month. 
FIRST INSTAR (PL. 2, G) 
Color characters: Upon hatching the 
new-born nymphs are pale green in 
color, with legs, antennae, and cornicles 
whitish. After a few ho^rs the general 
coloration becomes greenish; head 
lighter, with two chitinized areas on 
either side of the median line; eyes 
reddish; antennae pale yellow, darker 
apically; tip of beak dusky; legs pale 
yellow; tarsi dusky; cornicles pale, 
darker at the tip. 
Morphological characters: Body rec¬ 
tangular, flattened; antennae and legs 
robust as compared with the rest of 
the body; antennae four-jointed, with 
a sensorium present at the distal end 
of the third joint and at the proximal 
end of the flagellum of the fourth joint; 
cornicles short, about as broad as long. 
Measurements: Length, 0.52 to 0.60 
mm.; width, 0.28 to 0.30 mm.; an¬ 
tennae, 0.26 mm. (pi. 3, J); segment 
No. 1, 0.03 mm.; segment No. 2, 0.03 
mm.; segment No. 3, 0.08 mm.; seg¬ 
ment No. 4, 0.12 mm.; cornicles (pi. 
3, K), length, 0.03 mm.; width, 
0.03 mm. 
SECOND INSTAR 
This stage does not differ in general 
coloration from that of the first stage. 
The body becomes ovate in form and 
the antennae five-segmented. The cor¬ 
nicles also become more elongate, being 
about twice as long as wide. 
Measurements: Length, 0.82 to 0.92 
mm.; width, 0.40 to 0.44 mm.; an¬ 
tennae, 0.31 mm; segment No. 1, 0.03 
mm.; segment No. 2, 0.03 mm.; seg¬ 
ment No. 3, 0.06 mm.; segment No. 4, 
0.04 mm.; segment No. 5, 0.15 mm.; 
cornicles, length, 0.05 mm. 
STEM-MOTHER 
After passing through five instars the 
stem-mother becomes mature in two to 
three weeks, depending upon the tem¬ 
perature. In 1921 stem-mothers were 
full grown as early as March 8. Upon 
maturity, often only a few hours after 
the last molt, they give birth to living 
young. In a study of the reproduc¬ 
tive capacity of the stem-mothers, it 
was found that they were capable of 
giving birth to an average of two 
young per day for a period of 20 to 28 
days. The highest number of young 
produced in one day was six. 
The intitial feeding of the young 
stem-mothers takes place where they 
hatch, but after a short time they find 
their way to the tenderest leaves just 
coming out of the crown. Here they 
insert their beaks and suck the sap. 
Color characters: The general color¬ 
ing of the stem-mother is bluish-green, 
head greenish, with anterior portion 
lighter. Eyes dark red; antennae 
with segments 1, 2, and basal portion 
of 3, pale yellow; remainder of seg¬ 
ments dark brown; beak yellowish, 
tip black, reaching to base of third pair 
of legs; legs yellowish; tarsi dusky; 
cornicles yellowish-brown, darker at 
tip; cauda yellowish brown, clothed 
with whitish hairs; posterior border of 
terminal abdominal segments, with a 
whitish pulverulent stripe; genital 
plate greenish-yellow; anal plate dark 
green. 
Morphological characters: Body 
ovate, tending to pear-shape; anten¬ 
nae six-jointed, with segments 3 and 4 
not differentiated; thorax with a pro- 
thoracic tubercle on each side; corni¬ 
cles tubular, tapering distally. 
Measurements: Length, 1.3 to 1.5 
mm.; width, 0.74 to 0.78 mm.; an¬ 
tennae, segment No. 1, 0.05 mm.; seg¬ 
ment No. 2, 0.04 mm.; segment No. 3, 
0.22 to 0.24 mm.; segment No. 4, 0; 
segment No. 5, 0.10 to 0.11 mm.; seg¬ 
ment No. 6, 0.06 to 0.18 to 0.20 mm.; 
cornicles, length, 0.19 to 0.21 mm. 
EXPLANATORY LEGEND FOR PLATE 1 
A. —Mother plant with 18 runners. Photograph made in midsummer from plot artificially infested with 
Aphis forbesi, showing vigorous condition 
B. —Oviparous females of Aphis forbesi clustered on young tender leaf 
C. —Egg of Aphis forbesi on pedicel of strawberry leaf 
D. —Mound built by Pheidole vinelandica around pedicel of strawberry leaf protecting Aphis forbesi 
E . —Paragus tibialis: Female, parasite on Aphis forbesi 
F. — Paragus tibialis: Pupa 
G. — Paragus tibialis: Larva 
