PROGRESS REPORT ON THE EUROPEAN CORN BORER 
45 
corn appear to be about equally susceptible to infestation and in- 
jury, although the commercial injury to the ears and grain of sweet 
corn is limited to the development of the ear to the roasting-ear 
stage, unless grown for seed (fig. 23), and therefore does not serve as 
a real comparison of susceptibility with flint corn grown for grain. 
Table 6 gives data relative to the injury and loss to ears, grain, 
and stalks of flint field corn and sweet corn during the period 1920 
to 1922 in representative commercial fields in that portion of the 
New England area where the insect has become well established. 
All of the flint cornfields grown within this area are included. 
Since dent field corn is seldom grown commercially for grain in 
that part of the New England area now infested by the corn borer, 
there were no fields of this type available for examination. The 
sweet corn fields included herein were selected on the basis of per- 
sonal judgment of average conditions and not by the use of arith- 
metical methods. The injury and loss in certain small fields of 
sweet corn representing the maximum infestation (fig. 24) was 
greater than these figures indicate. No complete information is at 
hand relative to the clean-up measures employed in all of these fields 
during the preceding fall and spring, but judging from the usual 
practice in the section where these fields were located it is probable 
that all standing cornstalks were removed in the fall, and that the 
corn stubble, other crop refuse, and weeds were plowed under, either 
in the fall or spring. This type of field practice, however, usually 
results in leaving undisturbed large numbers of infested weeds along 
the field borders. 
Table 6. — Extent of injury and loss caused by the European corn borer to ears, 
grain, and stalks of field and sweet corn in the New England area, 1920 
to 1922 
Acreage of 
Ear examination 
Per cent of 
grain injured 
Stalk examination 
Locality (Massa- 
chusetts) 
fields exam- 
ined 
Number 
examined 
Per cent 
infested 
or destroyed 
on ears exam- 
ined 
Number 
examined 
Per cent 
infested 
1920 
1921 
1922 
1920 
1921 
1922 
1920 
1921 
1922 
1920 
1921 
1922 
1920 
1921 
1922 
1920 
1921 
1922 
Flint corn: 
Medford 
2.0 
4.0 
1.5 
3.5 
2.5 
3.5 
50 
50 
50 
50 
100 
100 
96.0 
24.0 
80.0 
58.0 
64.0 
44.0 
4.0 
.3 
10.4 
3.8 
3.1 
4.1 
200 
850 
300 
750 
5C0 
200 
98.0 
40.9 
100.0 
94.0 
Wakefield 
Arlington 
Stoneham 
Scituate. 
7.0 
1.0 
4.0 
"is 
6.0 
2.0 
i.y 
S."6" 
6 
50 
100 
50 
"166 
100 
100 
166 
"166 
300 
200 
400 
500 
70 
96 
66 
""72 
46 
39.0 
ioo.'o 
~37.~6 
57.6 
82.5 
42.5 
10.0 
1.5 
7.3 
2.2 
"§."§ 
.5 
1.9 
io.'o" 
..... 
.3 
3.9 
.4 
.02 
700 
200 
800 
"300 
500 
200 
"366 
"166 
300 
300 
300 
500 
60 
100 
78 
100.0 
Ioo.'o 
Sweet corn: * 
Arlington 
Watertown 
Medford 
Melrose 
88.0 
100.0 
"89 
98 
Ioo.'o 
7? 7 
Saugus. 
5.0 
4.25 
7.5 
100.0 
Winchester ... 
63 
Woburn ...1 
.... 
.... 
.... 
?a n 
Flint 
Sweet 
Three-year average (per cent) : 
Ear infestation ________ __ __ . .. 
71.9 
5.1 
76.6 
43.2 
Grain injury. ... 
1. 1 
Stalk infestation 
77.5 
1 At roasting-ear stage of growth. 
