of "bucklsrush patches or draws containing Jgoa or western wheatgrass» which 
had several times as many hoppers as did the grama grass. Uymphal popula- 
tions in the fields ranged from 25 to 300, with occasional concentrations 
of 1,000 to 5,000 per sqtiare yard. 
Adults appeared hy May 30 in the southern area (Wyoming, South 
Dakota, and ilehraska), hy June 15 from 5 to 35 percent were adult, and hy 
the first of July from *?5 to 95 percent were adult. Local flights were 
observed in'llehraska from June 14 to 21, One June 20 a major flight be- 
gan to develop on the large range area north of Miles City, Mont, From 
then on flights throughout the entire area at first increased in size and 
frequency and then continued throughout July and August and into September, 
The greatest sources of flights were the north half of the Black 
Hills, in 'Lawrence and Pennington Counties, S«.Dak#, west-central Nebraska, 
(made up of'Box Butte, Sioux, Morrill, and Scotts Bluff Counties), and 
southeastern Wyoming (composed of Niobrara, Goshen, Laramie, and Platte 
Counties), In the northern area the main sources of flight were the 
Missouri and Little Missotiri watershed in western North Dakota, including 
the bottom lands in the Bad Lands and along the river courses proper, 
and the 4, 000- square-mile range area in Garfield County north of Miles City, 
Flights from the Black Hills section were mostly toward the north- 
west; those , from western Nebraska and southeastem Wyoming were to the 
south and southwest into northwestern Kansas, northeastern Colorado, and 
the counties along the northeastern front of the mountains in Colorado, 
The main flights in western North Dakota and eastern Montana were west 
and northwest. They terminated in the north-central counties of Montana, 
Owing largely to emigration of the adults by flight, comparatively 
few eggs were laid in the main area in which the M, mexicanus infestation 
of 1939 developed, Mr, Gillett prepared a table showing the differences 
in his area between the average ratings resulting from the fall egg sur- 
veys of 1938 and 1939, 
Table 4.— Difference in average ratings in fall egg surveys. 1938 and 1959 
Area 
Average ratines in fall eee surveys 
1938 
1939 
Western Nebraska 
2.9 
2.1 
Western South Dakota 
2,8 
1.8 
Eastern Wyoming 
3.1 
1.9 
