82 LEAFHOPPERS AFFECTING CEREALS, ETC. 
nymphs occurring July 16. While this record would indicate two 
generations each year, it indicates also the fact that an early mowing 
in May coinciding with the time at which the species occurs in the egg 
form in the stems of grasses would effectually control it. Other 
species of the genus, the egg deposition of which occurred at a different 
period, were not so completely exterminated as this one. The results 
in this case, however, would seem to show that mowing, at a time 
when the eggs occur on the plants, may be a very effectual method 
of reducing the numbers of this species, which has a definitely limited 
period of egg deposition. It would, of course, be open to the same 
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Fia. 17.—Map showing distribution of Deltocephalus affinis. (Original.) 
methods of destruction by hopperdozer, spraying, and burning as any 
of the other species. 
DELTOCEPHALUS AFFINIS Gillette and Ball. 
The species Deitocephalus affinis has been discussed under the names 
debilis and melscheimeri in earlier articles, but it is first mentioned as an 
economic species in a report of the Division of Entomology, United 
States Department of Agriculture, in 1890. It was an extremely abun- 
dant and apparently destructive species in Iowa during a number of 
years when it was observed in that State. It occurs in greatest abun- 
dance in bluegrass in lawns and upon pastures or meadows, showing a 
distinct preference for open and sunny situations rather than shaded 
locations. It was abundant in both wheat and grass at Sault Ste. 
Marie, June 23 and 24, 1910, mainly in the adult stage. 
DISTRIBUTION. 
It has a very extensive distribution (see fig. 17), having been 
reported under various names from the New England States and 
