20 
BULLETIN 100, U. S. DEPARTMENT OF AGRICULTURE. 
to the size of the body. When on the lower surface of the leaflet it has 
the habit of resting with the head directed straight toward the 
peduncle of the leaflet. In July and August, in which months this 
insect is most abundant, as many as 400 individuals may be found on 
one leaflet, 5 per cent of which will be resting on the upper side. At 
this time it is much sought after by ants, which feed on the liquid 
excreted by it. A large red and black species, determined by Mr. 
Theodore Pergande as Formica obscuriventris Mayr, is a very common 
attendant. Formica subsericea Say also attends it. The sweet excre- 
tions of the aphis attract many flies of the families Muscidae, Anthom- 
yiida?, Oscinidse, and Syrphidse, many large bees including the 
honeybee, wasps of the family Pompihdae, and parasitic wasps of the 
f amilies Ichneumonidse and Braconidse, and numerous smaller forms 
of insect life. The author first observed this aphis on July 20, 1911, 
at San Jose, Cal. 
LIFE HISTORY AND TECHNICAL DESCRIPTIONS. 
The Viviparous or Asexual Forms. 
The stem-mothers hatch as soon as the buds start to swell, about 
the 1st of April. These develop into winged aphides and pass their 
life cycle in from 25 to 30 days, according to temperature and the 
amount of food supply. The viviparous aphis passes through four 
molts, becoming winged after the final one. Table ATI indicates the 
life cycle of 38 individuals of the summer generations. 
Table YII. — Life-cycle of viviparous females of Monellia caryae, summer generations, 
San Jose. Cal, 1912. 
No. of indi- 
vidual. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
'■ 
16 
n 
18 
19 
Gener- 
ation. 
Date of 
deposi- 
tion. 
Date of 
acquiring 
wings. 
Life 
cycle. 
Days. 
II 
Apr. 22 
Mar 12 
20 
II 
22 
12 
20 
II 
22 
12 
20 
II 
Mav 1 
20 
19 
II 
1 
22 
21 
II 
1 
23 
22 
II 
1 
23 
22 
III 
13 
29 
16 
III 
13 
29 
16 
III 
13 
29 
16 
III 
13 
29 
16 
III 
13 
29 
16 
III 
13 
30 
17 
III 
13 
30 
17 
III 
13 
30 
17 
III 
13 
30 
17 
III 
13 
30 
17 
V 
June 22 
Julv 4 
12 
V 
22 
7 
15 
No. of indi- 
vidual. 
Gener- 
ation. 
Date of 
deposi- 
tion. 
Date of 
reaching 
maturity. 
Life 
cycle. 
Days. 
V 
June 22 
Julv 7 
15 
V 
23 
i 
14 
V 
23 
7 
14 
V 
24 
7 
13 ■■ 
V 
24 
7 
13 i 
V 
24 
7 
13 
V 
24 
8 
14 
v 
24 
8 
14 
V 
24 
8 
14 
V 
25 
8 
13 
V 
25 
8 
13 
V 
25 
8 
13 
A" 
25 
8 
13 
V 
25 
9 
14 
V 
27 
10 
13 
V 
27 
10 
13 
V 
27 
10 
13 
Y 
27 
10 
13 
VI 
Julv 13 
Aug. 1 
19 
Thus, the second generation requires 20 days, the third 16 or 17, 
and the fifth 15, in which to complete the fife cycle. Records of the 
fourth generation were not obtained owing to premature death of all 
