LEAF HOPPERS INJURIOUS TO CEREAL AND FORAGE CROPS 13 



to prevent access to the surface of the land. Such treatment, so far 

 as the mechanical features are concerned, would be entirely prac- 

 ticable. At the North Dakota Agricultural Experiment Station such 

 a broadcast sprayer is used for treatment of the fields to kill weeds, 

 and, if a contact insecticide were used, it would seem that very 

 effective results could be secured. 



THE MORE IMPORTANT SPECIES OF LEAF HOPPERS AFFECTING 

 GRAIN AND FORAGE CROPS 



THE YELLOW-HEADED LEAF HOPPER 



The yellow-headed leaf hopper, Draeculacephala reticulata Sign., 

 an extremely abundant species in the southern part of the United 

 States, has been noticed a number of times as destructive to wheat 

 or oats, but has never received any full discussion, and the details 

 of its life history are not known. It was described by Signoret 

 as Tettigonia reticulata in 1854 from specimens derived from Cuba 

 and without any statement concerning its importance. Later, in 

 1880, it was redescribed by Riley (24) and named by him Diedro- 

 cephala flameeps, and in connection with the description appears 

 the note : " Numerous specimens injuring wheat and oats in Texas 

 in 1876." There is a record of its destructive abundance in South 

 Carolina, and the records of the Bureau of Entomology include a 

 number of instances of its occurrence in wheat and other crops. 



DISTRIBUTION 



In Van Duzee's catalogue (28) the distribution of the species was 

 given in 1917 as covering Virginia, North Carolina, South Carolina, 

 Georgia, Florida, Alabama, Mississippi, Louisiana, Missouri, Ken- 

 tucky, Tennessee, Nebraska, Texas, Arizona, California, West Indies, 

 and Mexico, which gives it a considerable range. The one record of 

 its occurrence in Lincoln, Nebr., makes that the most northerly point 

 from which there are any indications of its presence, and so remote 

 from other recorded localities that it may be based on an exceptional 

 occurrence. If common there, it should be found at intermediate 

 points between this and Texas. It has been found in northern Okla- 

 homa, but careful collecting has failed to discover it in Kansas. The 

 other more northerly records are from Charlottesville, Va., Fulton, 

 Ky., and Mountain View, Mo. The writer found a similar form at 

 Yuma, Ariz., in wild grass, but this differs from the type in having 

 a triangular spot on the vertex. It appears, therefore, that there is 

 a northern limit for the species, and this limit is not determined by 

 any limitation of food plants, since the species feeds readily on 

 various plants, a number of which are common at points farther 

 north. 



PROBABLY AN INTRODUCED SPECIES 



With the evidence at hand it appears quite certain that this species 

 was introduced or migrated into the United States from a more 

 southerly habitat. Although 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 



