THE GEAPE LEAEHOPPEE IN THE LAKE EEIE VALLEY. 37 
able hibernating quarters. Hence too much should not be expected 
of this destruction of leaves and trash on a limited scale, since in the 
following spring the adults are likely to swarm back into the vine- 
yards from areas not included in the cleaning-up process. 
SPRAY TREATMENT. 
During recent years a great deal of attention has been given to 
combating this pest by means of liquid sprays. Owing to the agility 
of the winged adults, and also to the fact that their sloping wing 
covers protect their soft bodies from the killing action of spray 
liquids not sufficiently caustic to injure the foliage of the grapevines, 
it is a very difficult task to destroy many of them with liquid spray 
applications. This was demonstrated by Prof. Slingerland in his 
field experimental work in the vineyards of Chautauqua County, 
N. Y., during the outbreak of 1901-2. Since it frequently happens 
that during seasons of heavy infestation the hibernating adults 
appear on the new foliage in injurious numbers and cause consider- 
able alarm t among the vineyardists, he attempted to combat them by 
means of a kerosene and water spray. He found, however, that the 
margin between the percentage of oil necessary to kill the adults and 
the percentage that would seriously injure the grape foliage was so 
small that more injury to the vines was likely to occur than would 
offset the benefit derived from the number of flying adults that were 
killed by the process. 
Much greater success, however, was secured by him in spray appli- 
cations made against the nymphs by the use of whale-oil soap at 
a strength of 1 pound of the soap to 10 gallons of water. With 
this spray liquid he was able, by one thorough application when the 
majority of the nymphs were present on the foliage, to reduce their 
numbers to such an extent that those remaining caused no serious 
injury to the vines for the remainder of the season. 
In experiments with liquid sprays consisting of 1 pound of whale- 
oil soap to 15 gallons of water Mr. Quayle was able to destroy a very 
large percentage of the nymphs infesting grapevines in California. 
He was also able to obtain good results by the use of a spray consist- 
ing of 1 pound of resin to 15 gallons of water, using enough lye or 
potash completely to dissolve the resin. This required 1 pound of 
lye to about 8 pounds of resin. 
The chief objections to the use of whale-oil soap are the very 
offensive odor connected with its application and the fact that since 
the vines have to be thoroughly drenched with the spray in order to 
strike the underside of all of the leaves, the clusters of grapes are also 
necessarily drenched. This soapy liquid has a tendency to form in a 
drop on the lower part of each berry, and after the moisture has evap- 
orated a white stain remains which makes an undesirable discolora- 
