PROGRESS EEPOET ON THE EUROPEAN CORN BORER 
57 
Rhubarb 
Ehubarb has been infested to a greater extent than any other 
vegetable or garden crop excepting sweet corn. The large leaves of 
this plant are particularly attractive to the adults as a place for 
concealment and subsequent deposition of eggs. Later the larvae 
infest the leafstalks and veins of the leaves. In two fields where 
detailed examinations were made during June, 1922, an average of 
2.5 egg clusters per plant were found on the leaves, with occasional 
egg clusters on the lea f stalks. The majority of the fields in the 
Boston area contained from 5 to 40 per cent of infested stalks during 
1921 and 1922. In fields representing maximum infestation as high 
as 75 per cent of the stalks were infested. Most of the severe injury 
occurred after the close of the commercial season for harvesting 
rhubarb, and the growth of the injured plants did not appear to be 
seriously affected by it. The necessity of discarding infested stalks 
in preparation for market caused appreciable loss in fields severely 
infested early in the season. 
Beets 
The extent of infestation in beets was very nearly equal to that 
mentioned for rhubarb. Most of the injury to beets was confined 
to the leafstalks (fig. 26), although during 1922, when the increase of 
infestation in this vegetable was most marked, a considerable number 
of the beet roots, amounting in some instances to 5 per cent of the 
total in the worst infested fields, were found to contain the borer. 
Except in instances where several of the leafstalks were entered by 
the borer, the injury did not appear seriously to interfere with the 
growth of the plant. The fact that the injured leafstalks must 
be removed in preparing for market as bunched beets, affected the 
appearance and consequently the price of the product from fields 
where a high percentage of the plants were affected. Table 16 gives 
results of examinations in average beet fields of the. Boston area 
taken on various dates distributed throughout the season when the 
plants were ready for market. 
Table 16. — Extent of injury and infestation by the European 
New England area, 1922 
com borer in 
beets, 
Field 
Locality (Massachusetts) 
Date 
exam- 
ined 
(1922) 
Num- 
ber 
of 
plants 
Plants show- 
ing injury 
Plants con- 
taining larvae 
Larvae per in- 
fested plant 
No. 
Num- 
ber 
Per 
cent 
Num- 
ber 
Per 
cent 
Aver- 
age 
Maxi- 
mum 
h 
Arlington... ._. ... 
Sept. 20 
June 30 
July 11 
--do 
July 10 
July 13 
Oct. 4 
July 17 
Oct. 5 
July 17 
Sept. 30 
July 12 
Sept. 28 
July 11 
100 
600 
100 
200 
100 
100 
100 
100 
100 
500 
200 
100 
100 
100 
10 
35 
39 
64 
10 
25 
61 
9 
71 
126 

48 
59 
34 
10.0 
5.8 
39.0 
32.0 
10.0 
25.0 
61.0 
9.0 
71.0 
25.2 
0.0 
48.0 
59.0 
34.0 
8 
23 
31 
49 
8 
18 
57 
8 
66 
113 

41 
59 
27 
8.0 
3.8 
31.0 
24.5 
8.0 
18.0 
57.0 
8.0 
66.0 
22.6 
0.0 
41.0 
59.0 
27.0 
1.00 
1.00 
1.32 
1.59 
1.12 
1.00 
1.98 
1.25 
2.95 
1.24 
0.00 
1.53 
1.79 
1.96 
12 
Do 
1 
3 
8 
2 
1 
13 
Medford 
14 
15 
Do... 
Do.-_ 
16 
Saugus _ . _ 
7 
Do..- 
18 
Somerville.. 
9 
Do----_- 
14 
110 
Watertown. 
11 
Do----_ 

112 
Winchester 
13 
Woburn . 
6 
114 
Do... 
Total 
' 
2,500 
591 
~~~23.~6~ 
508 
Average- _. 
20.3 
1.69 
i 
1 Infestation chiefly by first generation. 
