2 BULLETIN 805, IT. S. DEPARTMENT OF AGRICULTURE. 



The destructiveness, habits, food plants, and life history of each 

 species are treated separately herein. A detailed account of the ex- 

 perimental work carried out for the control of these two species to- 

 gether with the most efficient remedy is included. 



The data on biology and control were obtained at West Chester, 

 Pa., during the seasons of 1915 and 1916, supplemented by field ob- 

 servations at several points in southeastern Pennsylvania, and western 

 Maryland. 



THE APPLE LEAFHOPPER, Empoasca mali (Le Baron). 



HISTORY. 



This species was originally described by Le Baron (1) in 1853 x 

 under the name Tettigonia mali, and it was recorded by him as in- 

 jurious to fruit trees in Illinois. In 1862 the genus Empoasca was 

 erected by Walsh (2) with a description of three new species, but no 

 mention was made of mali. Carlos Berg (3, p. 273), in 1879, described 

 a leafhopper from Argentina as Typlilocyba phytopMla, and this name 

 later was considered by Gillette to be a synonym of Empoasca mali. 

 In 1883 Forbes (4) sent specimens of a green apple leafhopper to Uhler 

 who determined them as belonging to the genus Empoa; subsequently 

 these insects were described by Forbes (5) as a new species, Empoa 

 albopicta. Woodworth (6) transferred Empoa albopicta Forbes 

 to the genus Empoasca in 1889 and called it Empoasca albopicta. 

 The first reference to this species under its correct name, 

 Empoasca mali, was made by Gillette (7) in 1890. Osborn (8) and 

 later Gibson (17) mentioned it as injurious to potatoes, and Gillette 

 (9), in 1898, gave the food plants and distribution. 



Frequent references to this insect have been made in American 

 entomological literature under the name of u the apple leafhopper" 

 and "the currant leafhopper," by Britton (12), Brues (13), and Gar- 

 man (16) among others. It has been often referred to as the most 

 injurious leafhopper, both to apple and to various field crops. Wash- 

 burn (15), in 1908, was the first writer to treat of this insect at any 

 length. He published a record of the seasonal history, food plants, 

 injury, and control of the apple leafhopper as a nursery pest in Min- 

 nesota. In 1910 R. L. Webster (18) made a detailed study of the 

 life history and control of this insect on apple nursery stock in Iowa. 

 In 1915 Webster (20) published an account of Empoasca mali, treating 

 it as a pest of potatoes. 



DISTRIBUTION. 



There are no records showing that the apple leafhopper occurs in 

 Europe. In America, outside of the United States, it has been re- 

 ported from Okanagan, British Columbia, from Nova Scotia, several 



1 Figures in parentheses refer to "Literature cited," p. 34. 



