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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
During the six years that these investigations have been in progress, 
6,867 eggs (Table V) have been found on the plants under observation. 
Of these, 2,247 or 32.7 per cent were on the upper surface of the leaves, 
and 2,100 or 30.6 per cent on the silks. 
Table V— Summary Showing the Location of the Eggs on 128 Corn Plants Under Observa¬ 
tion at Manhattan, Kans., 1913-1918 
Year 
Leaf 
Upper 
surface 
Lower 
Silk 
Husk 
Tassel 
Stalk 
Total 
1913 
358 
57 
117 
30 
4 
219 
785 
1914 
1,413 
499 
1,556 
100 
449 
629 
4,646 
1915 
70 
7 
177 
11 
11 
54 
330 
1916 
48 
12 
12 
1 
22 
34 
129 
1917 
19 
4 
59 
6 
0 
4 
92 
1918 
339 
66 
179 
34 
124 
143 
885 
Total 
2,247 
645 
2,100 
182 
610 
1,083 
6,867 
Per cent of total 
32.7 
9.4 
30.6 
2.6 
8.9 
15.8 
100.0 
As indicated by the table, there is a marked variation in the number 
and location of the eggs in the different years, a condition influenced 
largely by the character of the year. An analysis of the data shows 
that the moths chose the silks, the upper surface of the leaves and the 
stalks for oviposition. Of these the silks were preferred, and during 
those years when the plants silked normally, the larger number of eggs 
were found on the silks. When silking was delayed or prevented, as 
in 1913, 1916, and 1918, by drouth and hot winds, the upper surface 
of the leaves and the stalks were selected in preference to the other 
parts. In considering the places selected for oviposition, it must be 
remembered that the plant under favorable conditions is in silk from 
four to eight days, while the other parts of the plant, especially the 
leaves and stalk, are available during the entire life of the plant. It is 
also of interest to note that a full grown plant has about twenty square 
feet of upper and lower leaf surface, and that eggs may be deposited on 
any part of the leaf. 
Relation of Oviposition to Date of Planting 
Since the amount of injury is obviously influenced by the number of 
eggs deposited on the plant, and especially on the ear and silks, a study 
of oviposition is necessary for the interpretation of the data secured in 
“a time of planting experiment.” The date of planting experiment at 
this station has been conducted primarily to determine the optimum 
time to plant corn to obtain the maximum yield and the minimum 
amount of corn earworm injury. In the present discussion, the rela¬ 
tion existing between date of planting and oviposition is considered, the 
relation between yield and injury being reserved for a future paper. 
As was shown in Tables II and III, there is a variation in the number 
and location of the eggs with regard to the different varieties planted at 
the same time, and this condition is true with relation to the varieties 
planted at different dates. A summary of the total number of eggs 
found on each variety for each date of planting is presented in Table 
