12 MONTANA EXPERIMENT STATION BULLETIN 474 



The percentage ground cover for the needle-and-thread west- 

 ern wheatgrass community is given below. 



NEEDLE-AND-THREAD WESTERN WHEATGRASS TYPE 



Percentage of Ground Cover 

 Name of Species Sprayed Area Unsprayed Area 



Agropyron smithii 1.7 1.0 



Aristida longiseta 0.2 



Bouteloua gracilis 1.7 1.2 



Brovius japonicus 0.3 3.5 



Koeleria cristata 1.9 



Poa secunda 0.3 0.3 



Stipa comata 7.0 7.6 



Stipa viridula 1.2 1.5 



Carex spp. 0.3 1.5 



Artemesia jrigida 1.5 1.3 



Artemesia tridentata 0.6 



CirsiuTn undulatuvi 0.3 0.2 



Malvastrum coccineum 0.7 



Opuntia polyacantha 1.0 



Phlox hoodii 0.1 



Tragopogon pratensis 0.3 



Total Density 14.3 22.9 



In order to obtain a measure of grasshopper utilization, the 

 grasses in plots four square feet in area were clipped in the two 

 community types in both the sprayed and unsprayed areas. The 

 first plots were clipped from July 6-14, immediately after the 

 spraying operation; and two successive clippings at monthly in- 

 tervals were made in the same area in which the first clippings 

 v/ere made. The plots were laid out at 10 foot intervals in the 

 first clipping and subsequent clip plots were located adjacent to 

 those clipped the first time. The weights of grasses obtained are 

 expressed in pounds per acre air dry weight. A total of 87 plots 

 were clipped in the sprayed area, and 114 plots in the unsprayed 

 area. Grasshopper populations were m.easured by the cage method 

 approximately every third day in the areas of study. The average 

 population over the two months clipping period is given in the 

 following table: 



