32 
BULLETIN" 1476, U. S. DEPARTMENT OF AGRICULTURE 
Borers entering the ear by way of the ear stem (fig. 9) usually 
cause injury similar to that inflicted by the larvae entering the ear 
directly. The tunneling in the ear stem, when severe, and occurring 
early- in the develop- 
ment of the ear, may 
interfere with its 
supply of nutriment. 
Furthermore, the ear 
stem is weakened by 
such injury and fre- 
quently breaks over 
(fig. 14) before the 
ear has completed its 
development. In in- 
stances where the in- 
jury to the ear stem 
is slight, or when 
such injury occurs 
after the ear is nearly 
mature, no appreci- 
able damage to the 
grain results, even 
though the ear breaks 
over. Many ears thus 
affected, however, fall 
to the ground long be- 
fore harvest and are 
subject to deteriora- 
tion by rots and other 
destructive agencies. 
When, as sometimes 
occurs, a large pro- 
portion of the ears 
have fallen to the 
ground (fig. 15), the 
expense of harvesting 
is increased. 
Injury to the ears, 
even where these 
remain attached to 
the plant, often is in- 
creased by the ingress 
of rots and molds as 
a result of the work 
of the borers, and 
aids in reducing even slightly infested ears to a soft decaying condi- 
tion, thus sometimes entirely destroying its food value. 
■» f$£ HI. 
*r*U* &^m »B"' j^^HwII^H 
K iM 
F ; ■' m m 
Bt H P 
SI ml 
H L| ; «| 
i&m % It m 
^B 111'' • * ' 
it' 
Il'i] 
'■{:' f 1 
. ■ 
■ Hfl 
Fig. 13. — Typical injury by the European corn borer to 
stalks and ears of sweet corn at roasting-ear stage. 
Pupae of the first generation are shown in position. 
One hundred per cent of the stalks and 99 per cent of 
the ears were infested in this field by the first genera- 
tion. Saugus, Mass., August 1, 1922 
