24S 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
Figure 7, which shows the total number of eggs found for each day 
during the six years, indicates the number of broods and the approxi¬ 
mate period that each brood was present. Similar curves drawn for 
each of the years resemble very closely the curve for the six years, 
except that there is some variation in the appearance of the broods 
with the different years due to environmental factors. There is a dis¬ 
tinct overlapping of the broods and the point of maximum emergence 
is not greatly emphasized for the first two broods. The first brood 
usually begins to emerge during the first week in June, and reaches its 
maximum about June 15. The second brood appears about July 4, 
and is at its maximum July 13. The third brood begins emerging 
about August 10, and the maximum is reached during the last days of 
the month, and the first days of September. As indicated by the chart, 
the first two broods are of relatively little importance as compared 
with the third brood, and in developing a system for the reduction 
of earworm injury to corn the problem becomes one of protecting it 
from this last brood. 
Silking 
The studies at this station in 1908 and 1909 emphasized the fact that 
the moths exhibited a decided preference for the silks for oviposition, 
and that a corn plant was in its most attractive stage during the period 
of silking. Other investigations also showed that a large per cent of 
the larvae entering the ear originated from eggs deposited on the silks. 
With these points in mind it became evident that in the development of 
many of the control measures it would be necessary to study the silk¬ 
ing of the corn plants with especial reference to oviposition, and the 
data presented emphasizes the importance of this point. The average 
period of silking for each variety with regard to date of planting is 
shown in Table IV, and this data is also graphically presented in 
Figure 1 with relation to the oviposition in the field. 
An examination of the table indicates that the date of silking is 
dependent on the variety rather than on the date of planting. Boone 
County White was the first variety to begin silking and to reach maxi¬ 
mum silking. Kansas Sunflower and Commercial White were a few 
days later, while Hildreth was the last variety to silk. There was 
relatively little difference in the period of silking of Boone County 
White, Kansas Sunflower, and Commercial White, while in the case 
of Hildreth the period was much shorter. Likewise the period between 
first silking and maximum silking is shorter in Hildreth than in the 
other varieties. 
It is also of interest to note that while the plantings were made at 
intervals of two weeks, the dates of silking show a difference of less 
