70 
Mr. R. L. Webster carried thru the season successive generations 
derived from a single female that came from the egg March 23, and 
obtained (by breeding always from the first-born) as many as seven- 
teen generations, the young of the seventeenth brood issuing Septem- 
ber 21 to October 3. In the field, newly born young can be found as 
late as November 4, tho we can not name the generation to which they 
belong. His more important data may best be given in the form of a 
table. 
M. pisi 
Genera- 
tioD 
Birth 
Maturity 
Death 
Days to 
mature 
Days of 
life 
Number 
of young 
1 
Mar. 23 
Apr. 5 
May 12 
13 
50 
90 
2 
Apr. 5 
Apr. 25 
May 12 
20 
37 
87 
3 
Apr. 26 
May 8 
May 13 
12 
17 
25 
4 
May 8 
May 20 
June 16 
12 
39 
89 
5 
May 20 
May 31 
June 9 
11 
20 
49 
6 
June 1 
June 10 
June 20 
9 
19 
41 
7 
June 10 
June 19 
July 17 
9 
37 
37 
8 
June 19 
July 1 
July 17 
12 
28 
60 
9 
July 1 
July 10 
Aug. 2 
9 
32 
63 
10 
July 12 
July 22 
Aug. 3 
10 
22 
30 
11 
July 22 
Aug. 3 
Aug. 15 
12 
24 
44 
12 
Aug. 3 
Aug. 11 
Aug. 16 
8 
13 
34 
13 
Aug. 11 
Aug. 21 
Aug. 30 
10 
19 
16 
14 
Aug. 21 
Sept. 1 
Sept. 5 
11 
15 
8 
15 
Sept. 2 
Sept. 12 
Sept. 15 
10 
13 
10 
16 
Sept. 12 
Sept. 21 
Oct. 4 
9 
22 
53 
Ave 
11 
25.4 
46 
The averages are worth notice. A female begins to reproduce 
eleven days after birth, as a rule; this accounts for the large number 
of generations. The average number of young is not large for an in- 
sect, for insects as a whole average at least two or three hundred eggs 
per female. The average given in the table is confirmed by one based 
upon a large number of additional observations taken thruout the 
season. A female is, however, capable of producing as many as 147 
young, and many of the females at death have embryos of various 
stages in their bodies. 
The largest number of young produced in one day by one female 
is 13, and the average number 6, in our experience ; while the bearing- 
period of the female averages 12.1 days. In October and November the 
females bear but few young, but some of these females hibernate and 
produce more young the following year. 
Our breeding experiments, it should be said, were conducted in- 
doors, where the aphids were protected from every source of danger. 
Out-of-doors the mortality would probably not be so small. 
R. L. Webster's continuous^observations on the life history are a 
useful addition to our knowledge of the species. His results are cor- 
roborated by those of Mr. E. Q. Snider, who, while a student at the 
