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JOURNAL OF ECONOMIC ENTOMOLOGY 
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NOTES ON THREE SPECIES OF APPLE LEAF-HOPPERS 
By Frank H. Lathrop, Assistant Entomologist , Oregon Agricultural Experiment 
Station 
While connected with the New York (Geneva) Agricultural Experi¬ 
ment Station the writer had opportunity to make observations on the 
life-histories and habits of three important leaf-hoppers attacking apple. 
The three species of leaf-hoppers, Empoasca mali LeBaron, Empoasca 
unicolor Gillette, and Empoa rosce Linnaeus, which are discussed in this 
paper, are quite similar in general appearance. Especially is this true 
of the two species of Empoasca and the nymphs of all three species. 
Distinguishing Characteristics 
The nymph of Empoa rosce may be distinguished by its white color, 
as well as by the contour of the anterior margin of the vertex. The 
f Fig. 5. Heads of leaf-hopper nymphs, showing comparative structures and sizes; 
a, Empoa rosce , b, Empoasca mali, c , Empoasca unicolor. 
nymphs of both the other species are green, and by this character may 
be separated from the preceding form with little difficulty. The two 
Empoasca nymphs are very closely similar, and are very easily con¬ 
fused. The nymph of Empoasca unicolor differs most distinctly from 
that of E. mali in the contour of the anterior margin of the vertex and 
there is also a difference in the coloration of the two species. 
The adult of Empoa rosce , like the nymph, is recognized by its white 
