105 
Life History, etc. — This aphid winters as an &gg in the vicinity 
of Urbana, and I have found as yet no evidence that the female hiber- 
nates. The course of the Hfe history differs but Httle from that of 
other aphids. The eggs produce viviparous females, and these con- 
stitute the successive generations up to the end of the season, when 
winged males and wingless oviparous females are brought forth vivip- 
arously. In this species, a large proportion — if not the majority — of 
the viviparous females are winged. 
Beginning with a viviparous female which issued from the egg 
March 27, Mr. R. L. Webster followed the successive generations 
thru the season and obtained a maximum of nineteen, the final genera- 
tion appearing October 18, in the insectary. The individuals of this 
generation were still very small on November 11, and disappeared 
thereafter. The more important of R. L. Webster's observations are 
given in the following table. 
c. 
trifolii 
Genera- 
Birth 
Maturity 
Death 
Days to 
Days of 
Number 
tion 
mature 
life 
of young 
1 
Mar. 27 
Apr. 20 
May 9 
24 
43 
36 
2 
Apr. 21 
May 3 
May 21 
12 
30 
21 
3 
May 6 
May 18 
May 26 
12 
20 
34 
4 
May 15 
May 30 
June 12 
15 
28 
25 
5 
May 30 
. June 7 
lune 19 
8 
20 
46 
6 
June 7 
June 15 
June 21 
8 
14 
25 
7 
. June 15 
June 22 
July 7 
7 
22 
55 
8 
fune 24 
July 3 
[uly 3 
9 
9 
13 
9 
July 3 
July 12 
July 18 
9 
15 
13 
10 
July 13 
July 18 
July 31 
5 
18 
34 
11 
July 19 
July 29 
Aug. 3 
10 
15 
23 
12 
July 29 
Aug. 5 
Aug. 22 
/ 
24 
70 
13 
Aug. 5 
Aug. 11 
Sept. 2 
6 
28 
75 
14 
Aug. 11 
Aug. 21 
Sept. 9 
10 
29 
60 
15 
Aug. 21 
Aug. 28 
Sept. 11 
7 
21 
36 
16 
Sept. 10 
Sept 18 
Sept. 28 
8 
18 
20 
17 
Sept 19 
Oct. 2 
Oct. 9 
13 
20 
6 
18 
Oct. 2 
Oct. 18 
? 
16 
40-f 
p 
19 
Oct. 18 
? 
? 
? 
24+ 
? 
Ave 
rages 
10 
22 
34.8 
The averages are made from the first seventeen generations. The 
number of young produced per day by one female ranges from none 
to thirteen, with an average of 3.7; and the bearing period of the 
female averages 12.1 days. 
Comparing this table with that for M. pisi (p. 70) slight differ- 
ences are apparent in the length of life and the period before maturity. 
These differences are of no weight, however, in view of the great 
variability of both species in both these respects. A few more obser- 
vations would have changed, one way or the other, these averages, which 
are so nearly alike. The averages show, rather, that M. pisi and C. 
