The European Corn Borer. 15 
mum of approximately 50 per cent. Under these conditions an aver- 
-age of 5 per cent of the ears have been found unmarketable. Dent 
corn under like conditions averages 18 per cent stalk infestation. 
In the eastern New York area the comparative infestation between 
sweet and field corn is the reverse of that found in the western area, 
although the difference is very slight. An average of 3 per cent more 
of the stalks were infested in dent than in sweet corn in this area, 
considering representative fields in making this statement. 
In this area sweet corn contains an average of slightly less than 6 
per cent of the stalks and 3 per cent of the ears infested, while dent 
and flint corn have an average 
infestation in the stalks amount- 
ing to 7 per cent and with only 
1 per cent of the ears containing 
the borer. 
The grain injury by the borer 
in New York has been slight. 
In the most heavily infested sec- 
tion of the western area, from 
3 to 5 per cent of the grain was 
damaged, with a few cases where 
the injury amounted to approxi- 
mately 16 per cent in sweet corn. 
In one of the worst infested 
fields of field corn the damage 
amounted to 3 per cent of the 
kernels destroyed. In the east- 
ern area an average of less than 
1 per cent of the ears of sweet 
corn were rendered unmarket- 
able by the borer and the dam- 
-age to field corn was slightly 
less. During the favorable sea- Sioa s i 
son of 1921, however, the grain Fic. 11.—European corn borer larva feeding 
injury in one case amounted Ase: Chek hee Siiehily 
to an average of 7 per cent 
damaged kernels and in sweet corn an average of 13 per cent 
was noted. 
PENNSYLVANIA, OHIO, AND MICHIGAN. 
At the present writing there has been no appreciable damage by 
the European corn borer in the newly infested cornfields of this 
section of the infested area, owing to the slight character of the 
infestation in these recently invaded regions. 
INDIRECT INJURY. 
The foregoing estimates of injury to the ears and grain refer only 
to the direct injury through the attack of the borer to the corn ear. 
In addition to this direct loss there is an indirect loss of grain in 
badly infested plants caused by the tunneling of the insect in the 
5781°—22 3 
