THE GEAPE LEAF-FOLDER. 5 
EXTENT AND CHARACTER OF THE INJURY. 
During most years in a few localities throughout its range of dis- 
tribution, this insect is quite abundant and the cause of important 
damage to the vine by the destruction of the foliage at a time when 
this is needed to ripen the fruit properly. During occasional years 
it may become excessively abundant and destructive, as has been 
the case in the environs of Washington, D. C, during the past three 
or four years. 
The grape leaf-folder gains its title through the injury inflicted by 
its larvae upon the foliage. In the experience of the writer, the 
direct injury is sustained by the foliage alone, although Mr. Fred 
Johnson has observed the larvae of the first brood eating the blos- 
soms and young fruit. 
The injury to the leaves is very characteristic and' may be easily 
recognized (PL I, e). As soon as the larva is large enough it folds 
the leaf, exposing the under surface, the edge being held in place by 
bands of silk" thread (PL II, a; PL III, a). It is within the protec- 
tion of this fold that the larva feeds, skeletonizing the leaf on the 
upper surface (PL III, b). 
When the larvae are numerous the injury to the vine becomes very 
conspicuous, even at a considerable distance, for the light color of 
the under surface of the folded leaves contrasts strongly with the 
dark green of the upper side presented normally, giving the vine a 
patchy appearance. Later in the season the skeletonized leaves dry 
up (PL II, d), exposing the fruit to the rays of the sun and, in case 
of a severe attack, rendering the fruit unmerchantable. The writer 
has observed such conditions in several vineyards in Fairfax County, 
Va. 
In a young vineyard at Herndon Heights, Va., consisting of sev- 
eral acres of Concords and Niagaras, four-fifths of the foliage was 
found to have been destroyed. In the immediate vicinity there was 
an abundance of badly infested " chicken" grapes (Vitis aestivalis), 
which doubtless served to supply the insects to the cultivated vines. 
The experience of a grower with the depredations of this pest at 
Riviera, Tex., is of interest and is presented in the following letter 
received by the Bureau of Entomology under date of January 15, 
1915: 
This insect was much more troublesome here last year than ever before. It appeared 
in force just as the grapes were beginning to color or ripen, and so thoroughly stripped 
off the leaves that the grapes could be used only for jelly, or sauce, by cooking them 
green. I saved most of mine by dusting the vines with Paris green and lime in the 
early morning while the dew was on the leaves and the wind was calm, but the few 
others here who raise grapes had no ripe ones to eat or sell. The clusters hanging 
below the leaves (and usually getting very little dew) caught very little of the poison. 
