249 
April ’20] McCOLLOCH: OVIPOSITION OF THE CORN EARWORM 
Table IV—Average Period of Silking for Each Variety in Each Date of Planting Plot, 
Manhattan, Kans., 1913-1918 
Dates of silking 
Period between 
Period of first and maxi- 
silking, mum silking, 
Variety 
Planted 
Began 
Maximum 
End 
days 
days 
-Boone 
April 
15 
7-12 
7-26 
8-18 
37 
14 
County 
May 
1 
7-17 
7-31 
8-24 
38 
14 
White 
May 
15 
7-23 
8-4 
8-31 
39 
12 
June 
1 
8- 2 
8-14 
9- 3 
32 
12 
June 
15 
8-14 
8-27 
10- 3 
50 
13 
Commercial 
April 
15 
7-18 
7-30 
8-24 
37 
12 
White 
May 
1 
7-21 
8- 2 
8-28 
38 
12 
May 
15 
7-27 
8- 8 
9- 5 
40 
12 
June 
1 
8- 2 
8-17 
9- 8 
34 
12 
June 
15 
8-18 
9- 3 
10-10 
53 
16 
Kansas 
April 
15 
7-13 
7-28 
8-19 
37 
15 
Sunflower 
May 
1 
7-21 
8- 1 
8-26 
36 
11 
May 
15 
7-26 
8- 6 
9- 3 
39 
11 
June 
1 
8- 4 
8-15 
9-19 
33 
11 
June 
15 
8-18 
9- 2 
10-10 
53 
15 
Hildreth 
April 
15 
7-20 
7-31 
8-22 
33 
11 
May 
1 
7-24 
8- 3 
8-27 
34 
10 
May 
15 
7-29 
8-10 
9- 3 
38 
12 
June 
1 
8-10 
8-21 
9- 8 
29 
11 
June 
15 
8-22 
9- 5 
10-11 
50 
14 
than a week between the plantings of April 15 and May 1, and May 1 
and May 15. In the later plantings, however, the interval between 
silking approximates the difference between dates of planting. It is 
also worthy of notice that the period of silking for all varieties is much 
longer in the planting of June 15, and that the shortest period occurs in 
the planting of June 1. In the first three plots there seems to be a 
tendency for the period of silking to be prolonged with the delay in 
planting. 
The present studies indicate that silking is influenced by a number of 
factors such as climatic conditions and pollination. Under favorable 
conditions a plant usually remains in silk from four to eight days. 
During years of low rainfall and hot winds, fewer silks are produced 
and many of the silks that do appear are destroyed within one or two 
days by the hot winds. Pollination is often prevented, delayed or 
incompleted and the silk may continue to grow to an unusual length 
and remain green for a much longer time. An examination of the 
daily records shows that during the period the plants under observa¬ 
tion were silking, the majority of the eggs were found on the silks, and 
any factor that influenced silking had its influence on the number and 
location of the eggs. 
Location of Eggs 
A knowledge of the parts of the plant selected by the moths for ovi- 
position is important in developing certain measures of control. This 
is especially true in working out a spraying program, a time of planting 
experiment, or in a study of varieties of corn with relation to their 
resistance to corn earworm injury. 
