66 
Journal of Agricultural Research voi.xxvn,No. i 
the corn earworm had deserted the ears to pupate. The injury, it will 
be observed, had increased considerably by the second date. On October 
31, 1921, practically all of the larvae of this species had left the ears, and 
those that remained were nearly all dead as a result of heavy frosts. 
The larvse of the European com borer, on the other hand, had continued 
feeding during this time, so that the damage that might be credited to 
this species was, by the last date, probably as great or greater than that 
done by the corn earworm. An actual count, like that of Table II, was 
not practicable, however, since it was not then possible to recognize the 
injury occasioned by each species. 
Tables I and II show in what parts of the ears the larvae of the two 
species were found and the damage that they had occasioned. For this 
purpose the ear has been divided into husk, peduncle, silk, cob, and grain. 
For the purpose of recording more accurately the exact region of injury 
to the grain with relation to the ear, the latter has been further divided 
into tip, middle, and butt; the “tip” being the upper third, the “middle” 
the middle third, and the “butt” the lower third of the ear. 
TablU I .—Infestation of field corn by the corn earworm, Heliothis obsoleta Fab., and 
the European corn borer , Pyrausta nubilalis Hbn., at Arlington , Mass., October 14, 
IQ2I 
(100 ears of Longfellow flint field com] 
Ear No. 
6.. 
7. • 
S.. 
9. . 
TO. . 
U . . 
12 . . 
*3- ■ 
14, . 
15- • 
16. . 
17. . 
15. . 
19. . 
20. . 
21. . 
22. . 
33. • 
24. . 
33- • 
* 6 . . 
27.. 
28. . 
29. • 
30. . 
31. . 
32- . 
33- • 
34- • 
35 - • 
j 6 . 
37. • 
38.. 
39 - • 
40. . 
41. . 
42. . 
43- • 
Number and location of larvae found. 
Corn earworm. 
v \ 
! w 
.*2 I 3 
S j « 
European com borer. 
1 I- 
1 i 
3 !• 
■ “i 
3 
1 1 2 
3 s 
S i « 
1 i- 
1 1. 
1 !■ 
I j. 
Part of ear infested 
or injured. 
^ , . ] 
Total grains on ear. 
Grains destroyed. 
j Peduncle. 
M 
VI 
w 
Silk. 
1 
1 
j 
N 
1 « 
Grain. 
1 
i 
! -+• 
I + 
+ 
i ~ 
i 0 
+ 
336 
20 
! + 
+ 
+ 
O 
0 
272 
0 
i + 
!.+ 
+ 
1 O 
4- 
264 
29 
j 0 
1 + 
+ 
° 
4- 
256 
0 
1 + 
! -f 
+ 
+ 
+ 
320 
39 
! 0 
! + 
+ ; 
1 + 
1 + 
240 
3 
i 0 
i 0 
+ 
! ° 
i 4- 
320 
14 
i + 
i 1 
1 *r 
-f 
O 
i + 
256 
30 
I 0 
j O 
+ ! 
O 
i + 
264 
19 
i 4- 
! + 
+ 
+ 
! 4 
416 
35 
O 
; + 
4* 
1 0 
296 
0 
» 1 
j ‘T | 
! + ! 
4* 
0 
i + 
240 
28 
; + j 
: + 1 
+ 
0 
4 
288 
66 
i O j 
i -U J 
+ 
0 
! 4 
384 
X9 
O j 
+ j 
+ 1 
C ! 
0 
240 
O 
O ! 
+ 
+ ! 
4- 1 
! 4 
256 
3* 
-H 1 
+ 1 
4- i 
-1- i 
4 
284 
37 
+ 1 
+ 1 
+ ; 
O | 
4- 
208 
47 
1 + ! 
+ i 
4- t 
0 ! 
4 | 
272 j 
35 
i + 
+ | 
4- i 
0 
0 : 
336 ! 
0 
+ 
+ 1 
0 | 
+ ! 
~i- ! 
224 i 
22 
0 
+ i 
4- ; 
0 ! 
4 : 
224 j 
48 
0 
+ j 
4* 1 
0 i 
4 
344 
18 
-+- i 
-r ; 
4- ; 
0 1 
4 ! 
264 { 
36 
i 0 j 
-f- ! 
■h i 
O ■ 
+ j 
272 ; 
15 
; ’r j 
4- ! 
0 ! 
4 ! 
344 i 
10 
j 0 i 
4- 1 
+ ■! 
-1- ; 
4 ; 
248 ! 
16 
_l~ [ 
4- ! 
4 - i 
4 ! 
240 i 
50 
1 + 1 
4* ! 
+ i 
4- : 
+ j 
0 c 
4 ; 
+ : 
224 ] 
224 i 
55 
53 
; + 
+ 1 
4- j 
4- 
4 1 
H j 
192 i 
14 
J 
+ i 
+ 
4- 
4 : 
208 j 
2 
1 O 
0 i 
+ | 
9 i 
4 | 
332 | 
16 
1 + 
4- ! 
4- : 
+ ! 
0 : 
320 i 
0 
: -4-' 
4- ! 
4- i 
0 
+ ! 
284 ! 
18 
: + 
-h ; 
t : 
4* 
4 ! 
344 
22 
. .u i 
4- i 
0 
4 
208 
34 
0 
-j- J 
4- i 
0 
4 i 
368 
20 
0 
-1. : 
4- i 
0 i 
4 ! 
280 
67 
1 4- 
-h • 
4- ■ 
+ \ 
+ | 
216 
24 
| 0 ! 
4-: 
4- i 
0 i 
4 1 
353 
15 
■ 0 1 
: 
4- j 
O : 
+ ! 
232 ! 
24 
- 4, 1 
*r 
4- ! 
4- i 
284 
5 
