MONTANA INSECT PESTS, 1955-1956 5 



land vegetation by various grasshopper populations. It is hoped that 

 from such measurements it will be possible to predict the amount of 

 damage one would expect to a particular plant complex under various 

 conditions by any grasshopper species or combination of species 

 which may be present. Such information is extremely important in 

 determining the situations under which it is economically sound to 

 apply chemicals for the control of a rangeland grasshopper species. 



Most of the above research has been directed toward relating 

 grasshopper responses to the forces in their immediate surroundings. 

 However, it is now evident that unpredictable changes take place 

 within the grasshopper itself which make it impossible as yet to predict 

 the effect which a particular force such as weather, food-plants, 

 etc., will have on the future behavior of a particular population. 

 Therefore, future studies will of necessity include studies of the physi- 

 ology of the insect. From such studies, which will relate the behavior and 

 activities of the grasshopper to both its internal and external environ- 

 ment, it is hoped that it will be possible to predict from one year to 

 the next whether grasshoppers will increase or decrease in a given 

 area. 



It is believed that from the knowledge obtained from these investi- 

 gations a workable and economically feasible grasshopper control 

 policy involving either insecticides, land management, or both can be 

 attained. 



GENERAL FEEDERS 



GRASSHOPPERS (Orthoptera: Acrididae) 



1955 Season 



Melanoplus mexicanus mexiconus, the migratory grasshopper, 

 showed up in generally larger numbers this year, especially in the 

 central part of the state. Aulocara elliotti, the big-headed grasshopper, 

 was the most important range species with local damaging populations 

 in Fergus, Gallatin, Madison, and Broadwater counties. M. bivittatus, 

 the two-striped grasshopper, remained a problem in wheat field borders 

 in the north central part of the state. M. differentialis, the differential 

 grasshopper, occurred on corn in the eastern part of the state and 

 M . femur-rubrum, the red-legged grasshopper, caused some crop dam- 

 age in the lower Yellowstone Valley. Camnula pelhicida, the clear- 

 winged grasshopper, was a problem in the southwestern portion of 

 the state on range. Aeropedellus clavatus, a range species, did local 

 early damage to range in the central part of the state. Due to excellent 

 moisture conditions and the resultant high production of range forage, 

 eastern and central Montana ranges suffered little from grasshopper 

 depredations even though fairly large numbers of damaging species 

 were present locally. 



