PROGRESS EEPOET OX THE EUROPEAN CORN BORER 
65 
Table 19. — Susceptibility and extent of injury by Pyrausta rmbilalis to various 
field crops in experimental fields {New England, 1919 to 1922) 
Plant 
Millet ( Japanese). _. 
Millet (European)., 
Millet (Hungarian). 
Hemp 
Hegari 
Feterita 
Milo 
Kafir 
Broomcorn 
Barley 
Cotton i • 
Cowpea 
Sorgo 
Hop (common) 
Buckwheat 
Johnson grass 
Sudan grass 
Soy bean 
Peanut 
Egg clusters 
Per 
Total Total ' cent Total 
plants egg plants" plants 
exam- clusters bearing 1 exam 
ined found , egg ined 
clusters 
Larvae 
2.0 
0.0 
115 
142 
174 
282 
50 
210 
190 
50 
18 
21.2 
16.5 
14.8 
9.2 
8.5 
0.0 
11.4 
6.3 
22.0 
0.0 
250 
25 
441 
6.0 
12.0 
.6 
1.2 
200 
200 
200 
10 
84 
343 
420 
400 
450 
100 
656 
691 
450 
12 
200 
1.050 
50 
441 
114 
Total 
plants 
found 
tun 
Total 
plants 
con- 
taining 
Per 
cent 
plants 
con- 
neled larvae <^J| 
324 
29 
234 
5 
112 
240 
39 
10 
11 
27 
7 
18 
11 
17 
1 
10 
70 
56 
254 
8 
191 
1 
22 
52 
21 
3 
11 
12 
13.5 
8.5 
.5 
100.0 
83.3 
16.3 
60.4 
2.0 
42.4 
1.0 
3.4 
7. 5 
4.7 
25.0 
5. 5 
1.1 
10.0 
2.0 
2.6 
Total 
larvae 
found 
Aver- 
age 
larvae 
per 100 
plants 
38 
27- 
"l 
150 
218 
110 
444 
8 
314 
1 
23 
67 
28 
5 
11 
15 
19.0 
13.5 
.5 
500.0 
259.5 
32. 1 
105.7 
2.0 
69.8 
1.0 
3.5 
9.7 
6.2 
41.6 
5. 5 
1.4 
14.0 
2.3 
2.6 
1 Bolls developed on plants in one plat during 1921. A count of 200 green bolls showed that 9 per cent 
wer^e infested, one larva per boll. Plants killed by frost before bolls opened. 
The experiments detailed in Table 19 were conducted under con- 
ditions of severe infestation, and due allowance should be made for 
this fact when interpreting the susceptibility of the plants listed. 
It is significant, however, that many of these plants which have been 
recorded in foreign literature as hosts of P. hubilalis, notably hemp 
(fig. 30), hops, millet (fig. 31), cotton (fig. 32), and the grain 
sorghums (fig. 33), were also infested by the insect in Xew England. 
This development is only indicative, of course, of the susceptibility 
of these plants if grown commercially in areas where two generations 
of P. nub Hal is occur each vear. 
NEW YORK, PENNSYLVANIA, OHIO, AND MICHIGAN 
There has been but very little loss or infestation to date from the 
work of the European corn borer in vegetables, flowers, or field crops, 
except corn and broomcorn, in the infested areas of Xew York, Penn- 
sylvania, Ohio, and Michigan. During 1923 two fields of broom- 
corn, comprising a total of 12 acres, grown at Irving, X. Y., showed 
stalk infestations of 12.7 and 15.8 per cent, respectively. In western 
Xew York slight infestations have also been observed in commercial 
fields of soy beans, buckwheat, and potatoes, and in half-acre fields 
of European millet or proso, which was planted on two farms near 
Silver Creek, X. Y., to test its possible utility as a trap crop. Occas- 
ional infestations have also been observed in the stems and fruits 
of tomato. Occasional instances of infestation have also been ob- 
served in experimental plats of Japanese and European millet or 
proso, sorghum, rhubarb, kidney or wax beans, milo, soy beans, 
dahlias, and cosmos at Silver Creek, X. Y. 
25411°— 27 5 
