12 MISCELLANEOUS PUBLICATION 1348, U.S. DEPARTMENT OF AGRICULTURE 
grasshoppers. He clipped two quadrats at intervals 
of from 1 to 2 weeks at each station until August 
14th at which time the cages were removed, vege- 
tation inside was clipped, and the number of grass- 
hoppers per square meter was calculated. He deter- 
mined that the amount of dried vegetation de- 
stroyed averaged 41.0 g/m? and the average num- 
ber of grasshoppers in early June was 22.7 per 
square meter, indicating that each grasshopper at 
that time destroyed 1.806 g of vegetation in 2 
months. However, the actual amount consumed 
was 13.43 g/m’, only one-third of the total vegeta- 
tion destroyed. The effect of screening on the vege- 
tation was not measured. The author further calcu- 
lated that a 450-kg cow would require a minimum 
feeding requirement of 9 kg/day of dry range grass 
or 272,160 g/month. On the basis of 1.806 g of vege- 
tation being destroyed by one grasshopper in 2 
months (0.903 g/month), a population of 74 grass- 
hoppers per square meter over 1 hectare would 
destroy vegetation at the same rate as 2.5 cows per 
hectare. 
With lighter stands of vegetation requiring more 
hectares per cow, smaller numbers of grasshoppers 
per square meter would cause equivalent damage. 
Morton (1939) continued the above study, but in 
this later work one cage contained no grasshoppers 
and the other cage was infested with the same num- 
ber as were present per square meter on the out- 
side. This was changed to determine the effect of 
grasshopper cages on vegetation. He determined 
that, in Montana, cages increased grass growth 5.5 
percent and forb growth 77.5 percent, whereas 
grasshopper damage amounted to 44.3 percent to 
grass and 48.2 percent to forbs. The average num- 
ber of grasshoppers maintained in the cage was 
18.6, which varied from a high of 29 in June to 3 in 
September. In Wyoming, cages increased grass 
growth 13.9 percent and forb growth 41.4 percent, 
whereas grasshopper damage amounted to 59.2 
percent to grass and 46.5 percent to forbs. The 
average number of grasshoppers maintained in the 
cage was 14.4, which varied from a high of 26 in 
June to 2 in September. In 1938, favorable growing 
conditions existed at both locations, grasshopper 
populations were low and forage was undamaged. 
Hinkle (1938) also studied forage utilization by 
grasshoppers in Colorado with the use of cages. He 
determined that the greatest utilization occurred 
between August 8 and August 28; more than 50 
percent of buffalograss, Buchloe dactyloides Nutt. 
Engelm., western wheatgrass, and bluegrama 
were destroyed by native species. The period of 
peak grass production occurred during the time of 
greatest utilization. 
Pepper et al. (1951) also reported on grasshopper 
populations in two plant communities (western 
wheatgrass and needleandthread-western wheat- 
grass) in Montana. Part of each community was 
sprayed to control grasshoppers, and quadrats (122 
by 122 cm) were clipped in both sprayed and 
unsprayed areas. Areas were clipped on July 6 to 
14 right after spraying and twice at monthly inter- 
vals for a total of 87 quadrats in the sprayed area 
and 114 in the unsprayed area. Grasshopper popu- 
lations were measured by the cage method every 
third day. The following data were taken: 
Weight of grass clippings (period of test 2 months) 
(Expressed in kilograms per hectare air-dry 
weight) 
Grass- 
hoppers 1st 2d 3d Increase 
persquare clip clip clip or 
meter decrease 
Sprayed Area: 
Wheatgrass type <1 497 613 689 +192 
Needlegrass — 
wheatgrass type <1 743 900 783 + 40 
Unsprayed area: 
Wheatgrass type 8 586 370 303 —283 
Needlegrass — 
wheatgrass type 9 635 581 356 —279 
Total utilization by grasshoppers is the sum of 
the loss in weight on the unsprayed area plus the 
gain in weight on the sprayed area. This would 
amount to 469 kg/ha on the wheatgrass type and 
316 kg/ha on the needlegrass-wheatgrass type or an 
average of 369 kg/ha. If one were to assume that in 
the absence of grasshopper utilization this range 
would yield the weight of grass present on the date 
of the third clipping on the sprayed area, the 
amount of grass consumed by grasshoppers would 
amount to 55 percent of the total yield. The authors 
concluded that if grasshoppers were eliminated, 
grazing capacity would be increased by approxi- 
mately 50 percent. 
Anderson and Wright (1952) also compared net 
primary production on sprayed and unsprayed 
ranges in Montana by clipping vegetation. They 
found at one location that 52 percent of a dense 
stand of Agropyron smithii (western wheatgrass) 
