922 
Journal of Agricultural Research 
Vol. V, No. 20 
THIRD GENERATION 
When the adults of the second generation had emerged, pairs were 
isolated as in previous experiments. 
Table VIII .—Record of egg deposition of second-generation female of a pair of the Colo¬ 
rado potato beetle, confined in rearing jar and fed upon potato foliage 1 
Date. 
Number of 
eggs laid. 
Number of 
eggs to a mass. 
1914. 
August 20. 
19 
19 
21. 
48 
48 
22. 
O 
0 
23 . 
45 
45 
Total. 
112 
1 Temperatures: Maximum, 96° F.; minimum, 46°; average, 70°. 
In the rearing experiments with the third generation the females of 
the second generation did not all oviposit. Four pairs began hiberna¬ 
tion after feeding for several days. One mass of eggs deposited on 
August 4 hatched on August 9, the larvae pupating on August 23 and the 
adults emerging on August 31. Another egg mass, which was deposited 
on August 21, hatched on August 26, and the larvae, becoming full-grown 
on September 14, entered the ground for pupation, the adults emerging 
on September 23. 
All of the beetles of this third generation were very active and fed 
voraciously on the foliage of the potato up to September 15. 
length of stages 
Table IX shows the maximum and minimum number of days covered 
by each of the immature stages in each of the three generations, as 
obtained from the foregoing rearing experiments. 
Table IX .—Maximum and minimum length (in days ) of immature stages of the Colorado 
potato beetle in each of the three generations 
Generation. 
Egg stage. 
Larval stage. 
Pupal stage. 
Total develop¬ 
mental period. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
First. 
7 
9 
15 
18 
IO 
IO 
3 ° 
37 
Second. 
6 
7 
16 
18 
6 
8 
32 
41 
Third. 
5 
5 
14 
19 
8 
9 
27 
35 
