42 
habit of growth (size of stalk) of the variety. In general, however, 
it may be conservatively estimated that in most of the infested fields 
the indirect loss at least equals and frequently exceeds the direct 
loss sustained by the feeding of the borers on the grain. The exit 
and entrance holes of the larvae in the ears and stalks also provide 
a means for the entrance of various rots and molds, as previously 
stated. 
The percentage of plants injured and the economic loss incurred 
have been greater as a rule in New England than in the other areas 
in the United States where the insect is present. 
EXTENT OF INJURY AND LOSS TO EARS, GRAIN, AND STALKS 
New England 
In order to obtain data relative to the direct injury and loss to 
ears, grain, and stalks in the New England area, a series of de- 
tailed examinations were made during 1920 in the plats of flint, 
dent, and sweet corn grown in the experimental fields at Medford, 
Saugus, and Cambridge, Mass. These examinations were repeated 
during 1921 and 1922 in plats grown at Medford and at Arlington. 
Each of these plats was approximately one-twentieth of an acre 
in size and consisted of 8 varieties of flint corn, 12 varieties of 
dent corn, and 13 varieties of sweet corn. Most of the varieties of 
flint and sweet corn used in these experiments are those commonly 
grown in New England, but the dent varieties are very seldom 
grown in the Boston area for grain. However, owing to the im- 
portance and widespread use of dent corn in many sections of the 
country, it was desired to ascertain the susceptibility of this type to 
attack by Pyrausta nubilalis, although only the earlier dent varieties 
will mature in the Boston area, even under favorable seasonal 
conditions. 
Table 5. — Extent of injury and loss caused by the European corn borer to ears, 
grain, and stalks of field and sweet com in experimental plats of the 
Neiv England area, 1920 to 1922 
Number of 
plats 
Ear examination 
Per cent 
of grain 
injured or 
destroyed 
on ears 
examined 
Stalk examination 
Locality (Massa- 
chusetts) 
1920 1921 
1922 
Number 
examined 
Per cent 
infested 
Number 
examined 
Per cent 
infested 
1920 
1921 
1922 
1920 
1921 
1922 
1920 
1921 
1922 
1920 
1921 
1922 
1920 1921 
1922 
Flint corn: 
Medford 
Saugus.. 
7 
4 
3 
1 
350 
200 
150 
550 
200 
250 
150 
150 
50 
50 
94.2 
75.2 
85.3 
84.2 
63.0 
62.3 
81.3 
66.7 
100 
100 
8.5 
10.0 
18.3 
2.5 
1.2 
2.5 
1.2 
.8 
3.0 
.6 
17.0 
28.7 
700 
400 
300 
1,100 
400 
500 
2,000 
1 . 000 
30C 
30C 
100 
100 
97. 98. 7 
99.0.... 
loo. oL— 
93. 6 96. 
95. 61 . 
100 
Cambridge _ 
3 
Dent corn: 
Medford 
Saugus... ... 
11 
4 
5 
3 
1 
100 
Cambridge 
'"lb 
1,300 
100.0 
Arlington. . 
1 
13 
100 
74 
.4 
11.7 
2.9 
1,200 
100 
1,300 
100 
Sweet corn: i 
Medford. .... 
Saugus. . . 
20 
10 
12 
2,000 
1,000 
1,200 
55.5 
52.0 
45.7 
34.2 
33.5 
( 2 ) 
( 2 ) 
Flint 
Dent 
Sweet 
Three-year averag 
Ear infestatioi 
Grain injury.. 
Stalk infestati 
e (per cent) : 
i .. 
86.7 
10.0 
98.4 
74.6 
3.14 
96.0 
57.1 
1.4 
2 33.9 
At roasting-ear stage of growth. 
■ 2 Complete counts not taken in 1921 and 1922. 
