PROGRESS REPORT ON THE EUROPEAN CORN BORER 
69 
Fig. 33. — Typical injury to he^ari l>v European corn borer. 
Woburn, Mass., September 29, 1921 
Table 20. — Percentage of weeds infested by Pyrausta nubilalis larvae (Neiv 
England, 1920-21) 
Plant name 
Num- 
ber 
fields 
or 
waste 
areas 
Total 
num- 
ber 
plants 
exam- 
ined 
Total 
Total 
Per 
Total 
num- 
ber 
larvae 
found 
Aver- 
num- 
num- 
cent 
age 
ber 
ber 
plants 
number 
found 
contain- 
contain- 
larvae 
tun- 
ing 
ing 
per 100 
neled 
larvae 
larvae 
plants 
168 
162 
95.3 
1,067 
627.6 
63 
50 
71.4 
95 
135.7 
228 
198 
48.1 
701 
170.6 
0) 
91 
44.3 
135 
65.8 
153 
136 
41.8 
175 
53.8 
48 
41 
35.6 
91 
79.1 
81 
40 
34.8 
123 
106.9 
66 
45 
34.6 
77 
59.2 
32 
17 
34.0 
26 
52.0 
88 
84 
32.3 
129 
49.6 
13 
9 
25.7 
9 
25.7 
189 
135 
21.2 
172 
27.0 
11 
9 
18.0 
17 
34.0 
5 
5 
6.3 
7 
8.8 
6 
6 
6.0 
6 
6.0 
8 
4 
5.3 
6 
8.0 
10 
3 
1.5 
3 
1.5 
Maxi- 
mum 
number 
larvae 
per 
plant 
Xanthium spp 
Chenopodium ambrosioides.-- 
Polygonum spp 
Ambrosia artemisiaefolia 
Echinochloa crus-galli 2 
Artemisia biennis 
Arctium minus 
Bidens frondosa 
Iva xanthifolia 
Rumex spp 
Erechtites hieracifolia 
Amaranthus retroflexus 
Lactuca scariola var. integrata 
Erigeron canadensis 
Chenopodium album 
Tanacetum vulgare 2 
Galinsoga sp__ 
170 
70 
411 
205 
325 
115 
115 
130 
50 
260 
35 
100 
75 
200 
1 Not possible to discriminate between tunnels of P. nubilalis and those of other borers present in same 
plant. 
2 Each stem counted as a separate plant. 
