96 
BULLETIN 1476, U. S. DEPARTMENT OE AGRICULTURE 
stacked in the field, and from infested weeds or other plants growing 
near by. For this reason the percentage of the infested stubble 
(fig. 45) in certain fields sometimes exceeds the percentage of in- 
fested plants determined before cutting. During the late summer 
of 1921 counts were made of larval infestation in the stubble of 15 
fields of sweet and field corn in New England soon after the plants 
were cut. Field counts in these same fields previous to cutting 
showed that an average of 08.4 per cent of the stalks were infested. 
An examination of the stubble 
after cutting showed that 31.7 per 
cent contained living larvae. The 
stubble in these fields ranged from 
5 to 12 inches in height. 
In western New York an exam- 
ination of the stubble in 30 fields 
of dent and sweet corn during the 
period from August 8 to Novem- 
ber 11, 1923, showed that 6.63 per 
cent of the stubble was infested, 
containing on an average 7.78 lar- 
vae per 100 stubble. Field counts 
in these same fields previous to 
cutting demonstrated that an aver- 
age of 15.16 per cent of the stalks 
were infested, containing an aver- 
age of 19.75 larvae per 100 stalks. 
Comparing the average number of 
larvae left per 100 stubble with the 
average number of larvae per 100 
stalks, it will be noted that 39.39 
per cent of the total larval popula- 
tion was left in the stubble. In 
these 30 fields the stubble ranged 
from 2 to 18 inches high, with an 
average height of about 7 inches. 
A similar comparison between the 
larval population in the stalks and 
in the stubble of 36 dent and sweet 
cornfields in western New York 
during 1924 showed that 16.12 per 
cent of the total larval population 
was left in the stubble. In these 36 fields the stubble ranged from 2 
to 10 inches high, with an average height of about 6.2 inches. 
Examinations made of standing cornstalks in Ohio during the 
period from September 10 to November 3, 1924, showed a pronounced 
movement of the borers to the lower part of the stalks, as detailed 
in Table 30. 
base of corn stubble ; entrance bole just 
above 
