6 MONTANA EXPERIMENT STATION BULLETIN 526 



1956 Season 



In some areas, range-damaging species declined in numbers while 

 other areas showed definite increases. Again, the big-headed grass- 

 hopper was the most widespread and destructive. Grass removal by 

 this species occurred in harmful proportions in Yellowstone, Big Horn, 

 Jefferson, Broadwater, Madison, Sweet Grass, Stillwater, Fergus, 

 Golden Valley, Musselshell, Wheatland, and Judith Basin counties. 

 The clear-winged grasshopper has also shown up in greater numbers 

 this year in foothill areas in Fergus, Gallatin, Ravalli, Madison, and 

 Blaine counties. It has remained about the same in Beaverhead 

 County. The migratory grasshopper has generally increased in num- 

 bers in many areas and was much more common in the extreme 

 eastern part of the state and in local areas west of the mountains. 

 Aeropedellus clavatus, a rangeland species which has usuallly com- 

 pleted its life cycle by mid-July, showed up in generally larger numbers 

 in the central part of the state where it fed mostly on crested wheat 

 grass and related species. The Colorado grasshopper, a needle-and- 

 thread grass feeder, was also present in larger numbers generally. 



In general the most severe rangeland grasshopper problem seemed 

 to be centered in the central part of the state. Scarcity of forage 

 due to drought conditions aggravated the situation considerably, since 

 any forage that was available was doubly valuable under these con- 

 ditions. Any attempt at accurately predicting future population trends 

 is dependent on a complete knowledge of all the factors which affect 

 grasshopper numbers. Although many of these factors are as yet 

 unknown, past experience would indicate that the following may 

 happen: infestations in Beaverhead, Broadwater, parts of Jefferson 

 and Madison, and parts of Musselshell and Golden Valley counties 

 should subside somewhat; infestations in Stillwater. Yellowstone, and 

 Sweet Grass counties may remain the same. Potential infestations were 

 present in many areas over the state which could become serious if 

 favorable conditions prevail next year. 



OTHER IMPORTANT PESTS 



MORMON CRICKETS (Anabrus simplex) 



In 1955 Mormon cricket infestations occurred in Big Horn, Judith 

 Basin, and Meagher counties. In 1956 virtually the same areas were 

 infested. Local control programs were instituted in all of these 

 areas where farmers felt that crops were endangered. The large size 

 and banding habits of crickets make for rather exaggerated estimates 

 of their potential destructiveness. Since they feed on many plants, 

 but seem to prefer broad-leaved weeds, they should not be viewed 

 with too much alarm unless high populations or bands move into 

 small grains or other cultivated crops. 



