THE POTATO TUBER MOTH. 
29 
1st Gen. 
Plot B. 
2nd Gen. 3rd Gen. 4th Gen. 
5th Gen 
Jan. Feb. 
Mar. 
Apr. May. 
June. July. Aug. Sept. Oct. 
Nov. Dec. 
The gradual emergence of adults from a generation the larvae of 
which all hatched on the same day may be shown from the examples 
which follow, one from midsummer and the other from midwinter. 
Table 8. — Emergence of adults of the potato tuber moth from two generations, the eggs 
of one hatching on July 7 and those of the other on December 8. 
Average mean temperature 72° F. 
Average mean temperature 51° F. 
1914 
1914 
July 7. Eggs hatched. 
Dec. 8. Eggs hatched. 
Aug. 1. 2 adults emerged. 
1915 
Mar. 7. 2 adults emerged. 
Aug. 3. 21 adults emerged. 
Mar. 9. 4 adults emerged. 
Aug. 5. 18 adults emerged. 
Mar. 10. 2 adults emerged. 
Aug. 6. 4 adults emerged. 
Mar. 11. 1 adult emerged. 
Aug. 8. 1 adult emerged. 
Mar. 12. 6 adults emerged. 
Aug. 10. 2 adults emerged. 
Mar. 13. 3 adults emerged. 
Aug. 11. adults emerged. 
Mar. 14. 3 adults emerged. 
Mar. 16. 1 adult emerged. 
Mar. 18. 4 adults emerged. 
Mar. 20. 1 adult emerged. 
Mar. 23. 1 adult emerged. 
Mar. 30. adults emerged. 
The records given above show plainly the difference in number of 
generations which may be caused by taking the first to emerge or the 
last to emerge in each lif e cycle. If the first eggs deposited by the 
11 first to emerge/' and the last eggs deposited by the "last to emerge" 
are taken for the second generations, the difference will be increased 
to such a degree that almost a month will elapse between the time 
of starting the two generations. 
Taking generations throughout the year gives the following periods 
(Table 9). The records are for 1914, and were made at Pasadena, Cal. 
Table 9. — Variation in life cycle of the potato tuber moth. 
Month started. 
Eggs 
laid. 
Adults emerging. 
Greatest 
number 
emerg- 
ing. 
Length 
First. 
Last. 
of life 
cycle. 
1914. 
January 
Jan. 4 
Feb. 11 
Mar. 18 
Apr. 15 
May 16 
June 14 
July 13 
Aug. 17 
Sept. 14 
Oct. 14 
Nov. 7 
Dec. 12 
Apr. 6 
Apr. 25 
May 18 
June 9 
July 4 
July 24 
Aug. 15 
Sept. 19 
Oct. 29 
Dec. 24 
Feb. 7 
Mar. 19 
Apr. 30 
May 13 
May 31 
June 20 
July 16 
Aug. 3 
Aug. 23 
Sept. 27 
Nov. 10 
Jan. 14 
Feb. 22 
Apr. 10 
Apr. 10 
Apr. 29 
May 21 
June 12 
July 7 
July 27 
Aug. 17 
Sept. 22 
Nov. 1 
Dec. 31 
Jan. 13 
Mar. 25 
Days. 
91 
73 
61 
55 
49 
40 
33 
33 
45 
71 
92 
97 
February 
March 
April 
May 
June 
July 
August 
September 
1913. 
October 
November 
December 
