50 BULLETIN 1476, U. S. DEPARTMENT OF AGRICULTURE 
tion of 5.28 per cent, with an average of 1.75 larvae per infested 
-talk, or 9.2-4 larvae per 100 stalks. Maximums were recorded of 52 
per cent in stalk infestation of sweet corn and 33 per cent stalk infes- 
tation in dent field corn during 1924:. as compared to a maximum of 
17 per cent in 1923. 
DISTRIBUTION" OF GRAIN INJURY ON INFESTED EARS 
In making detailed counts of the grain injury on ears damaged by 
P. nuhUcdis. it was noted that while in general the greater proportion 
of this injury occurred to the kernels on the tip of the ear. the injury 
was also well distributed on the side and butt of the ear. In the 
majority of the lots of ears examined the total injury to the butt 
and side kernels nearly equaled, and sometimes exceeded, the injury 
suffered by the tip kernels, as will be seen in Tables 9 and 10. The 
ip is here considered to be the upper third of the ear. the side is 
considered to be the middle third, and the base the lower third. 
Table 9 shows the distribution of the grain injury on the infested 
ears of flint, dent, and sweet corn which have been previously men- 
tioned under Table 5. 
Table 9. — Distribution of grain injury caused by European corn borer on in- 
vested ears {three-year average from experimental plats) 
Distribution of grain injury 
Total Per cent on infested ears (per oenl - 
Type of corn ears ex- of ears 
amined infested 
Bun Side Tip 
Flint. 
Dent _ 
Sweet. 
Average. 
900 
1, 250 
5.500 
B6.7 
74.6 
57.1 
17. 5S 
19. 05 
13. 89 
29.67 
19.05 
22. 22 
52. 75 
61.90 
63.89 
15. 4S 
22. SO 
61.72 
1 These percentages do not refer to the total per cent of grain injury on the butt, side, and tip; they show 
only the relative proportions of injury to these three parts cf the ears. 
That the distribution of grain injury on the ears is influenced by 
'he severity of the infestation, was demonstrated during 1922 in the 
presence of a more severe infestation than during the preceding two 
years. Table 10 shows data on this point as taken from records 
of ear examinations in the 1922 experimental plats of flint, dent, 
sweet, and pop corn in New England. 
Table 10. — Distribution of grain injury caused by the European corn borer 
on infested ears from experimental plats of 19.22 
Distribution of grain injury 
Total Per cent on infested ears (per cent; ! 
Type of corn ears ex- of ears 
amined infested 
Butt Side Tip 
Flint 50 100 31.00 22.89 46.10 
Dent . . 100 100 20.79 30. SI 48.40 
Sweet 1.300 74 23.46 29.18 47.36 
Pop 50 100 24.34 2'IW 49.20 
Average 23.58 28.93 47.47 
' These percentages do not refer to the total per cent of grain injury on the butt, side, and tip; they show 
only tue relative proportions of injury to these thret pans of the ears. 
