THE GRAPE LEAFHOPPEK IX THE LAKE ERIE VALLEY. 7 
presence or its injury to the foliage of the vines. During these 
periods serious injury to the vines or to the crop yield is confined to 
a few rows of vines adjacent to ravines, woodlots, or rough pasture 
lands. This limited amount of injury usually attracts little attention 
and no attempt is made by the vineyardist to hold the insect in check. 
Then a series of seasons favorable to its development may occur, 
and there appears to be a steady yearly increase in numbers and fur- 
ther encroachment into the infested vineyards. Finally it becomes 
so abundant and thoroughly disseminated throughout the vineyard 
Fig. 4.— Grape leaf in advanced stages of injury. Areas between veins have turned a reddish brown. 
(Original.) 
area, and its destruction is so obvious, that it attracts general atten- 
tion, and the so-called "outbreak" causes considerable alarm among 
the vineyardists. Such "outbreaks" have been recorded from many 
States, as is indicated in the quotation from Slingerland under the 
caption "Origin and distribution." The same author states that 
"outbreaks" have occurred at frequent intervals in various parts of 
the State of New York as follows: 
In Wyoming County in 1S60: in the Hudson Valley in 1865. 1867, 1882. 1887, and 
1897; on Crooked Lake in 1S80; in Jefferson County in 1SS7 and 1888; in central Xew 
York in 1895 and 1899; and in Chautauqua County in 1900 to 1904. 
