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S UMMARY 
Probably the greatest change that took place in the relative abundance 
of species was that which happened to the Camnula pellucida and Melanoplus 
mexicanus populations in North Dakota, Minnesota, Wisconsin, and Michigan. 
C_. pellucida either equrled or exceeded M. mexicanus in 1934. In many places 
heavy infestations of C. pellucida hatched in June hut cold, foggy weather 
practically wiped out these outbreaks, reducing the numbers of this species 
almost to a minimum. M. mexicanus was also affected but not to the extent 
that C. pellucida was. M. mexicanus was dominant in about 10 States and 
C. pellucida in 4 out of the 18. 
Ageneotettix deorum was an important species in all the States east 
of the Continental Divide. It is widely distributed and abundant in small 
grains, field margins, legumes, and grasslands. Another important species 
was Encoptolophus costalis , which was numerous in Michigan, Wisconsin, 
Minnesota, and eastern North Dakota. Phlibo stroma quadrim aculatu m was 
prominent in the short-grass areas in pasture and on the range. Other 
important species of the range land in the short-grass areas were Cordillacris 
crenulata , which was dominant in Montana; Aulocara elliotti , Drepanoptcrna 
femora turn , Mestobre^r.a kiowa , and M. infantilis . Considerable damage was 
done to the rangeland and it was observed that under ordinary conditions 
of correct grazing native grasses will support populations of 7 or 8 per 
square yard without visible damage. When these increase to 15 per square 
yard the damage becomes severe, and at 20 or 30 the foliage is kept chewed 
to the crown, making the range unfit for pasturing. 
M. femur- rub rum was important and dominant in many places, reaching 
its greatest abundance in the legumes. It was the dominant species in 3 
States. M. bivittatus was of importance in 5 or 6 States, but the numbers 
of this species are still down. Both this and M. differential! s are building 
up again along the water courses of South Dakota and Nebraska. 
With increased moisture in the drought areas, M. bivittatus and 
M. differential is will have more succulent food and a chance to build up 
again. Increased moisture in Wisconsin and Michigan last summer caused tall 
weeds and grass to grow up in favorite egg-laying places of C_. pellucida , 
which are unfavorable conditions for this species. Therefore changes in 
weather also bring about changes in the optimum conditions for the develop- 
ment of certain species. 
