424 
Journal of Agricultural Research 
Vol. XXVI, No. 9 
INCREASE OF GRAPE LEAFHOPPERS 
In most of the grape-growing districts from Lake Michigan eastward, 
there has been a very marked increase of grape leafhoppers in the last 
few years, this probably being the effect of several mild winters in suc¬ 
cession. Vineyards in numerous localities in northern Ohio, which 
the writers' records show were practically uninfested in 1919, are now 
heavily infested. In several localities records of the infestation have been 
obtained each season since 1919. These records show that all species 
of grape leafhoppers have increased and that of the forms present Ery- 
throneura tricincta var. cymbium has increased most rapidly. 
CONTROL 
Control experiments against several of the species of grape leafhoppers 
occurring in northern Ohio vineyard districts have given results not 
significantly different from those reported by previous workers. Spray¬ 
ing is not effective against adults, but must be directed against the 
nymphs. A nicotine spray of strength 1 to 1,200 thoroughly applied 
to the under surface of the grape leaves when the first-hatched nymphs 
have nearly completed their growth has been recommended. Such a 
spray will reduce infestation sufficiently to permit normal development 
and ripening of fruit and wood. A spreader in the spray is desirable. 
Of the substances tested, lime caseinate, ground glue, ground gelatine, 
saponine, potash, fish-oil soap, and resin fish-oil soap have given best 
results on grape foliage. More frequently, however, nicotine is applied 
in combination sprays used against other grape insects and diseases. 
In this case resin fish-oil soap proved best, the others not covering or 
adhering to the grape clusters so readily. Combination sprays were best 
applied by the trailer method, using special care to cover the under 
surface of the grape leaves. Because of the slowness and expense of 
application and the difficulty of timing the combination spray advanta¬ 
geously, the nicotine spray alone (with spreader), or when desirable with 
Bordeaux mixture, was applied with a spray boom of the type described 
by DeLong (r). Results were as satisfactory as the average results 
obtained by trailer spraying and the expense much less. 
LITERATURE CITED 
( 1 ) DeLong, D. M. 
1922. THE BOOM NOZZLE SYSTEM AND THE TRACTION DUSTER AS FACTORS IN 
grape LEafhopper control. In Jour. Econ. Ent., v. 15, p. 87-90, 
I pi. 
(2) Fitch, Asa. 
1851. catalogue with references and descriptions of the insects col¬ 
lected AND ARRANGED FOR THE STATE CABINET OF NATURAL HISTORY. 
Reprint in Lintner, J. A., Ninth report on the injurious and other 
insects of the State of New York, for the year 1892, p. 383-413 (original 
pages 47-69; Erythroneura tricincta , original description, p. 63), 1893. 
(3) HartzELL, F. Z. 
1912. the grape lEafhopper and its control. N. Y. State Agr. Exp. 
Sta. Bui. 344, p. 29-43, 3 fig., 4 pl- 
(4) Johnson, Fred. 
1914. THE GRAPE LEAFHOPPER IN THE LAKE ERIE VALLEY. U. S. Dept. Agr. 
Bui. 19, 47 P-> *3 fig*» 3 pl- Bibliography, p. 43 ~ 47 - 
(5) Lawson, P. B. 
1920. the cicadELLidae of Kansas. Kans. Univ. Sci. Bui., v. 12, no. 1 
(Ent. no. 4), 376 p., 27 pl. 
(6) McATEE, W. L. 
1920. KEY TO THE NEARCTIC SPECIES AND VARIETIES OF ERYTHRONEURA. In 
Trans. Amer. Ent. Soc., v. 46, p. 267-322. 
