42 LEAFHOPPERS AFFECTING CEREALS, ETC. 
cally a negligible quantity, and that under the present methods of 
cultivation in the wheat-growing section of the Red River Valley 
these insects may be excluded from consideration. In permanent 
grasslands, however, the situation is quite different, as the author 
found, especially in fields that have been two or more years in tim- 
othy or other grasses, a considerable abundance of leafhoppers, 
especially of Deltocephalus inimicus and D. configuratus, with other 
species in less numbers. One of the most abundant infestations was 
noted in a field of brome-grass (see Pl. I, fig. 2) which had been 
planted for about five years and which was used at the time as a pas- 
ture. Alfalfa in this section showed little infestation. The prairie 
grasses showed a considerable abundance of the usual species. 
At Ada, Minn., an examination was made of a number of large wheat 
fields, and these were mostly free from jassids, as were also pasture 
lands which had recently been planted, but older pasture lands (see 
Pl. I, fig. 1) included considerable numbers of Deltocephalus inimicus 
and D. afinis. The wild grasses of this locality included the same 
species as were found at Fargo. 
At Bismarck, N. Dak., no wheat fields were studied, but a collec- 
tion of jassids upon the range grasses showed a very abundant occur- 
rence of the species of Deltocephalus, Athysanus, and Lonatura? In 
less numbers were species of Driatura, Chlorotettix, and Parabolo- 
cratus. 
At the substation of the North Dakota Experiment Station at Dick- 
inson the author found a considerable number of plats of oats, millet, 
wheat, alfalfa, etc., and while jassids occurred in small numbers in a 
number of these plats they were not abundant enough to cause any 
appreciable injury. In wheat Cicadula 6-notata occurred very spar- 
ingly, as alsoin oats and millet. A rather unusual occurrence was that 
of Philenus bilineatus Say in oats. This is an abundant species in the 
field grasses and probably had migrated from these into the oats field. 
Upon the wild prairie land (see Pl. ITT, fig. 2), which includes a mixed 
assemblage of the buffalo grass, wild-oats grass, etc., there was an 
abundance of different species of Deltocephalus with some other 
genera. The range grasses here are of special importance, as they 
are pastured to a large extent and are also mowed for hay. Wild 
oats, a most conspicuous element, is said not to be particularly trou- 
blesome, and even after the barbs are well formed it is cut and used as 
hay. In some localities farther east it is looked upon as a distinctly 
troublesome form. 
Near the Mammoth Hot Springs, Yellowstone Park, the writer 
secured a number of interesting species of Jassidz upon the annual 
grasses but a particularly interesting occurrence was noted in a small 
patch of cultivated grass kept under irrigation (see Pl. III, fig. 3). 
This patch, located very remotely from any other cultivated grasses 
and including timothy and clover and some bluegrass, was found 
