THE GRAPE 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 fohage 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 Washmgton, D. C, during the past three 

 or four years. 



The grape leaf-folder gains its title through the injury inflicted by 

 its larvje upon the fohage. In the experience of the writer, the 

 direct injury is sustained by the fohage alone, although Mr. Fred 

 Johnson has observed the larvae of the first brood eating the blos- 

 soms and yoiuig 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, exposmg the under surface, the edge being held in place by 

 bands of sdk thread (PI. II, a; PI. Ill, a). It is within the protec- 

 tion of this fold that the larva feeds, skeletonizing the leaf on the 

 upper sm-face (PI. Ill, h). 



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 (PI. 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 fohage 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, 

 1-915: 



This insect waa much more troublesome here last year than ever before. It appeared 

 in force ju.st as the grapes were beginning to color or ripen, and so thoroughly stripped 

 oflf 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 ancl the wind was calm, but the few 

 others here who raise grapes had no ripe ones to eat or sfill. The clusters hanging 

 below the leaves (and usually getting very little dew) caught very little of the poison. 



