THE SHAKES-HEADED GRAIN LEAFHOPPEK. 
Osborn remarks that in Ohio " there are clearly two distinct genera- 
tions annually." In the Southern States, where there are more 
generations, these are not so clearly distinct, due to an overlapping 
of the three stages during the summer months. Because of this 
overlapping of the egg, nymphal, and adult stages it is very difficult 
to determine the exact number of generations from field observations. 
By the use of breeding cages it was possible to determine that there 
were six distinct generations for southern Arizona during 1914. 
The cage experiments checked up very closely with field observations. 
Thus the number of generations may vary from two to six. 
For southern Arizona the first spring generation extended over 
February, March, and April; the second, over May and the first half 
of June; the third, over the last half of June and July; the fourth, 
over August; the fifth, over September; and the sixth, over October 
and November, the adults of the sixth generation living over winter 
and ovipositing in February for the following spring generation. 
LENGTH OF EGG STAGE. 
The length of the egg stage in southern Arizona was found to vary 
from 3 to 35 days, depending upon the temperature, the average 
being 12 days. Table II gives the length of the egg stage, with the 
corresponding temperatures, and plainly shows that the length is 
materially shortened during the summer months. 
Table II. — Length of the egg stage of the sharp-headed grain leaf hopper, Tempe, 
Ariz., 19H- 
Average 
Number 
Date of 
Date of 
Length of 
mean 
tempera- 
ture during 
of eggs. 
tion. 
hatching. 
egg stage. 
egg stage. 
Days. 
°F. 
4 
Feb. 4 
Mar. 11 
35 
59.0 
16 
Feb. 13 
...do 
26 
61.7 
6 
Feb. 19 
Mar. 12 
21 
67.4 
6 
Mar. 5 
Mar. 20 
15 
65.9 
3 
Apr. 5 
Apr. 20 
15 
70.4 
5 
May 8 
May 16 
8 
74.3 
7 
May 11 
May 18 
7 
74.3 
8 
...do 
May 16 
5 
74.1 
10 
June 19 
June 28 
9 
85.0 
9 
July 29 
Aug. 1 
3 
93.0 
14 
Aug. 28 
Sept. 2 
15 
82.8 
20 
Oct. 1 
Oct. 5 
4 
71.0 
Av 
erage 
12.75 
SUMMARY, SHOWING CONDENSED AVERAGES. 
When 
The aver- 
length of 
age mean 
egg stage 
averaged— 
tempera- 
ture was — 
Days. 
°F. 
27. 3 
62.7 
15.0 
68.1 
8.0 
77.8 
4.2 
80.2 
