126 : LEAF-HOPPERS. 
weight from the triangle on plat I and the triangle on plat II 
was eighty-six pounds, or at the rate of 221 pounds per acre, 
34% in favor of the treated plat. 
“Our experiments seem to us to strengthen our previous 
opinion that by using this simple form of the hopper-dozer the 
yield of hay or pasture land may be increased from one-fourth 
to one-third at a cost not exceeding ten cents per acre, even if 
all help employed is hired. We would recommend the use of the 
simple flat dozer and advise that it be used in the spring just as 
soon as young hoppers appear, and then if either these or young 
grasshoppers appear numerous at time of hay cutting, that the 
treatment be repeated.” 
These insects have but few enemies, and, what is worse, 
they are becoming less and less in numbers. As Bruner feel- 
ingly remarks; ‘every insect has its natural enemies, either 
vertebrate or invertebrate. These natural enemies when left to 
themselves usually keep the insects that do the damage within 
certain limits, these limits being below the point of danger. 
When various unnatural conditions arise these enemies for some 
cause or other are not able to destroy the insects upon which they 
feed, and as a result these latter increase beyond the normal, 
when injury to the vegetation follows. Chief among these nat- 
ural enemies of grass insects in particular may be mentioned the 
various kinds of birds that naturally make their homes upon our 
prairies and on the bottom lands along our streams. Before 
civilized man came into the country and began his nefarious war- 
fare on the birds, there were seldom any reports of excessive in- 
crease among the grass-feeding insects. But when civilization 
pushed westward and encroached upon our broad prairies, these 
birds fell before the firelocks of civilized man. The insects being 
deprived of their natural checks to increase began multiplying, 
and in time became much more numerous than formerly, and the 
result was the devouring of grasses in much greater quantity 
than formerly. As the birds decreased, the insects naturally in- 
creased, and the gap has been growing wider and wider with 
each successive year. 
“The natural enemies of grass insects belonging to the bird 
class are first, prairie chickens, the sharp-tailed grouse, quail, 
meadow-larks, Bartramian sand-pipers, various other sand-pipers, 
