PROGRESS REPORT ON THE EUROPEAN CORN BORER 
25 
appear upon the tender leaf blades surrounding the developing 
tassel. (Fig. 6.) Such injuries are caused by the feeding of the 
newly hatched larvae, and, while not economically important, this 
surface feeding affords a possible opportunity for attacking the 
larvae by insecticidal means. The midrib of the leaf blade some- 
times is entered and tunneled, more particularly by the smaller 
borers, in the same manner and with the same result as will be 
described later for the stalk. 
INJURY TO THE TASSEL 
The tassel buds and the immature branches and main stem of 
fed upon by the young borers 
the tassel are often entered and 
(fig. 6) even before the tassel 
appears above the unfolding leaf 
blades. Often several adjoining 
tassel buds are webbed together 
with particles of frass and silk 
by the small larvae. In this condi- 
tion the infested tassel is very 
conspicuous after it appears above 
the unfolding leaves. Frequently 
the injury to the immature tassel 
stem causes the breaking over of 
the tip of the tassel even before 
it begins to expand. 
As the tassel expands and the 
buds begin to open the larvae 
continue to tunnel within the 
branches and the main stem. This 
injury usually causes the tassel, 
or the infested portion thereof, to 
collapse and break over. Such 
broken tassels (fig. 7), with 
masses of frass at the breaks, are 
very conspicuous and often afford 
the most noticeable sign of the 
presence of the insect. It does 
not necessarily follow, however, 
that because none of the tassels 
are broken over in a suspected 
field the insect is not present, as 
plants sometimes are attacked only at points lower down than the 
tassel or at a late stage in their development when the tassel or its 
stem does not attract the larvae. 
Fig. 6. — Newly developed tassel of corn 
plant, showing injury by young larvae 
of the European corn borer. Note small 
gnawed areas on leaves at right caused 
by feeding of newly hatched larvae 
INJURY TO THE STALK 
Some of the newly hatched larvae, instead of tunneling within and 
feeding upon the tassel buds and tassel stems, habitually migrate 
to a point lower down on the same or near-by plants. Under these 
circumstances they commonly enter the plants at practically any 
point, but the favorite place of entrance is either between the leaf 
sheath and the stalk (fig. 8) or between the stalk and the base of the 
partly developed ear (fig. 9), providing the plant has advanced to 
that stage of growth. 
