138 IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



at another period of two weeks. As a result of this protection, at blos- 

 soming time Mr. Krebill had one of the finest pieces of second-growth 

 clover seen in the state during the summer. The accompanying illus- 

 trations show views taken in his meadow, also a view taken 

 the same day in a neighbor's field which had been unprotected. In 

 the latter case the clover heads were almost entirely gone. Much of 

 the clover was stripped to a stem and the meadow was being turned 

 under with a complete loss of seed or second crop of hay. 



Mr. Krebill had in all fourteen acres of clover, which yielded 

 sixty-five bushels and forty pounds of clover seed, an average of 

 about four and seven-tenths bushels per acre. The ten acres which 

 were best, netted over fifty-seven bushels or an average of five and 

 seven-tenths bushels per acre. This clover seed was sold at $19 per 

 bushel. As might be expected, Mr. Krebill is very enthusiastic over 

 the success of his control work and says that the hopper-dozer was 

 worth more than $1,000 to him. Other farmers have named amounts 

 equally large as representing the worth of the hopper-dozer to them. 



In many cases the use of the hopper-dozer did not get under way 

 until late in the season. Many suggestions were made that the de- 

 vice could be mounted on wheels after the clover had reached a good 

 height, but so far as our observations went all of the machines were 

 mounted on runners made of two by fours laid flat. Although this 

 mashed the clover down, it was found that it came up again, and if 

 the precaution was taken to run the hopper-dozer in the opposite 

 direction around the field from which the mowing machine would 

 be operated, no trouble was experienced in cutting the crop. Some 

 have tried hitching the hopper-dozer between two autos with good 

 success, the greater speed being especially valuable after a large 

 percentage of the grass-hoppers have their wings. 



Reports of taking one to two bushels of grass-hoppers to the acre 

 have been common. The question was frequently raised if the large 

 number of hoppers being caught could not be used for some practical 

 purpose. Accordingly grass-hopper catcher machines built after the 

 design first described by Dr. E. D. Ball in a bulletin of the Utah 

 Experiment Station and later shown in Circular Number 75 of the 

 University of Montana, were constructed and tried in several coun- 

 ties of the state. The machine captures the hoppers alive in a 

 screened cage, the device being operated by horses hitched at the 

 ends, the same as the hopper-dozer. The device has about the same 

 efficiency as the hopper-dozer and can be operated more easily on 

 hillv irround. but costs al)out twice as much to build. 



