MONTANA INSECT PESTS 1945-1946 7 



and bait spreaders to treat 25,653 acres of railroad and highway 

 right of ways, ditch banks, and idle lands. This work was done in 

 an effort to control heavy 'hopper populations in these habitats 

 and prevent migration into cropland. In most counties farmer par- 

 ticipation was stimulated and excellent cooperation was received. 

 Approximately 4,172 acres, inaccessible to ground equipment, were 

 baited by airplane. At present this type of control is too expensive 

 to be practicable on a large-area basis. 



The estimated savings as a result of the control work were 

 nearly lYi million dollars, compared with approximately ••4 million 

 dollars damage (table I). One thousand seven hundred twenty- 

 eight farmers spread 2,237 tons of bait over 343,264 acres of land 

 (tables II and III). The approximate cost of conducting the pro- 

 gram was §216,753.34. Of this amount the State and counties con- 

 tributed $23,000. the farmers $65,096.14, and the Bureau of Ento- 

 mology and Plant Quarantine $128,657.20. It is estimated that for 

 every dollar spent in grasshopper control work, $16.35 were saved. 



1946 SEASON 



The 1945 egg survey indicated that a threatening infestation 

 was likely to occur in the eastern third of the State with severe 

 populations in the lower Yellowstone valley, extending from Miles 

 City to the North Dakota line in Richland County. Light to threat- 

 ening infestations were expected north of the Missouri River as 

 far west as Glacier County, and in Lake, Sanders, Flathead, and 

 Missoula counties. 



The light to threatening infestation expected north of the Mis- 

 souri River failed to develop. In the western part of the State, only 

 Lake and Flathead counties had infestations of economic import- 

 ance. The severe outbreak in the eastern counties extended much 

 farther south and covered a larger area than was anticipated. The 

 infestation as a whole covered a considerably smaller area, but 

 'hopper populations were more severe than the egg survev indicat- 

 ed. 



The counties having the most severe infestations were Big 

 Horn, Treasure, Rosebud, Custer, Powder River, and Prairie in 

 the east; Cascade, Pondera, Chouteau, Teton, Toole, and Glacier 

 in the Triangle area; and Lake and Flathead in the western part of 

 the State. 



The dominant species for the State were Melanoplus mexican- 

 us, M. dijferentialis, M. hivittatus, and M. femur-ruhrum, in the or- 

 der named. The distribution of these species was spotted with each 

 being dominant in one or more areas. There was a marked increase 

 of M. femur-ruhrum in the eastern part of the State. The impor- 

 tance of this species has been significant this season. 



