April, ’20] McCOLLOCH: OVIPOSITION OF THE CORN EARWORM 
243 
cycle and towards the development of certain methods of control. 
Accordingly, during 1908 and 1909 general egg counts were made at 
irregular intervals in the field, and the results of these counts with rela¬ 
tion to the number of broods and to the time of planting corn have been 
discussed by Headlee. 1 These preliminary studies were of such signifi¬ 
cance that in 1913 further experiments were planned to determine 
more accurately the relation existing between oviposition and various 
phases of the life history and methods of control. 
These experiments were incorporated in “a time of planting experi¬ 
ment of corn” which has been in progress since 1909. Briefly, the 
major problems under consideration were to determine (1) the num¬ 
ber of broods in the field, (2) the part of the corn plant selected for 
oviposition, (3) the relation of oviposition to the time of planting 
corn, and (4) the relation of oviposition to the variety of corn. 
Experimental Methods 
Time of Planting Experiment 
In order to better understand the data presented in this paper, a 
brief discussion of the time of planting experiment is essential. This 
investigation has consisted of a series of five or six plots of corn planted 
at regular intervals beginning April 15. Four standard varieties of 
corn, namely, Boone County White, Commercial White, Kansas Sun¬ 
flower, and Hildreth, have been grown in each plot, each variety being 
planted in three 200-feet rows. Plantings were made on April 15, 
May 1, May 15, June 1, and June 15. In 1914 and 1915 a sixth plot was 
planted on July 1, but since corn seeded at this time seldom if ever 
matures, this plot was discontinued. Since 1913 this experiment has 
been conducted on the same area and the land has been handled in the 
same manner as is usually followed by the average farmer. The rows 
were forty inches apart and the hills thirty-six inches. Shortly after 
coming up, the corn was thinned to two plants in a hill. 
Method of Making Egg Counts 
The egg counts were made on the same plants throughout the entire 
season. A typical plant of each variety in each plot was selected when 
it was about six inches high, and was examined daily for eggs of the 
corn earworm. These plants were selected through the center of the 
plots and were in the middle row of each variety. 
Silking 
As earlier studies at this station and in other localities had shown 
that the earworm moths apparently preferred the silks of corn and 
* 
1 Headlee, T. J., Notes on the Corn Earworm. In Jour, of Econ. Ent., Vol. 3, No. 
2, pp. 149-157, 4 charts. 1910. 
