THE YELLOW-HEADED LEAFHOPPER. 
55 
PROBABLY AN INTRODUCED SPECIES. 
With the evidence at hand it appears quite certain that this species 
was introduced into the United States from a more southerly habitat. 
While the species might possibly have been overlooked by early 
collectors, it is too conspicuous a species where it occurs for this to 
be probable. Moreover the records would seem to indicate an 
advance toward the north since its first appearance in our Southern 
States. Its original description from Cuba, 1854, precedes any 
record here, while the early records refer to such southern localities 
as Texas and South Carolina, a distribution still holding in 1894, 
when Van Duzee's catalogue was published. In 1900, as recorded 
Fig. 3.— Map showing distribution of Drzculaccphala reticulata in the United States. (Original.) 
by Prof. E. D. Ball after he had made an exhaustive examination of 
records and specimens, the species had not spread north of the Gulf 
States and South Carolina. Now, however, it is found north, in 
the Atlantic region to middle Virginia (1906) and in the Mississippi 
Valley to southern Kentucky (Fulton in 1905). (See fig. 3.) That 
it is restricted climatically is evidenced by the slow progress made 
and its limitation to the warmer zone, the line of its northward 
distribution agreeing very closely with that of the cattle tick. 
TREATMENT. 
While additional knowledge concerning the place of egg deposi- 
tion and development of nymphs and especially as to the number of 
generations during the year may furnish a better basis for the recom- 
mendation of measures for control, we may very safely conclude that 
the depredations on wheat and oats could be very materially lessened 
