28 grasshoppers and other injurious insects of 1911 and 1912. 



Strength Effect on Grain Effect on Hoppers 



2 oz. Arsenite No effect shown 45 dead; 4 "sick" 



4 oz. " No effect shown 49 dead; 5 alive 



6 oz. " Tips of leaves burned 64 dead; 4 "sick"; 5 alive 



8 oz. " Grain burned badly 51 dead; 5 alive 



A stronp:er formula gave the following results. 



5 lbs. Arsenite 



1 qt. molasses Grain killed 206 dead; 11 alive 



50 gals, water 



In the S. African experiments, the arsenical spray was found most ef- 

 fective when sweetened with treacle or molasses, hence we added molasses to 

 our solution with very good results. Indeed we found the molasses valuable 

 in more ways than one, since aside from rendering the solution more attrac- 

 tive to the grasshoppers, it serves to hold the poison on the plant. After once 

 drying upon the plant the molasses is not readily washed off even by heavy 

 rains and merely softens to sticky masses which drying again still hold the in- 

 cluded poison. 



Our working formulae may be given as follows (the formula is expressed 

 in three different quantities for more ready use in sprayers of various sizes). 



FOR WHEAT, OATS, BARLEY, RYE OR FLAX. 



Arsenite of Sodium 4 ounces 1 lb. 3 lbs. 



Water 15 gallons 60 gals. 180 gals. 



Molasses 1 pint 2 qts. IV^ gals. 



The Sodium Arsenite, which is a whitish powder, should be added to the 

 water in small amounts and thoroughly dissolved before the molasses is stirred 

 in. 



This solution may be applied by any sprayer which is intended to use 

 liquid poisons. Certain features, however, tend toward economy in operation 

 as well as toward most effective results. We have found the best results when 

 using spray at the rate of about fifty gallons to the acre. It is evident there- 

 fore that with small sprayers of fifty gallons, capacity or less there must al- 

 ways be a considerable item of waste of time from the frequent filling required. 

 Another point is that the area passed over should be thoroughly covered and to 

 do this the cones of spi-ay must meet at the base, i. e., the nozzles must be so 

 arranged that the whole strip may be covered. This is imjDOSsible or at least 

 impracticable with most types of the so-called "Potato Sprayer" since in most 

 of these the nozzles are arranged to spray the rows and usually leave the space 

 between unsprayed. 



Our field tests were conducted with large sprayers having a tank capacity 

 of 165 gallons working by compi'essed air and having extension bars permit- 

 ting us to spray a .strip twenty-three feet wide at a time. On the extension 

 bars were fifteen nozzles so placed as to thoroughly cover the strip. With such 

 machines and an ordinary thresher tank wagon for hauling water we have been 

 able to cover fields of eighty acres in one day. 



After our preliminary tests in the test plats previously mentioned we be- 

 gan a series of tests upon a large scale by spraying fields of from twenty to 

 eighty acres of various crops which we found to be badly infested with grass- 

 hoppers. The result shown in one or two representative fields may be of in- 

 terest. On June 24th, Mr. Tanquary sprayed a field of 22 acres of wheat near 

 Beltrami, using the formula given above. Two days later this field was care- 

 fully examined and counts made to determine the number of dead hoppers. 

 In order to secure an idea as to the whole field these counts were made in 

 several widely separated parts of the field. The number of dead hoppers found 

 ranged from .30 to nearly 200 in spots ten feet square. To estimate the total 

 number in the field the following plan was used. After several trials to secure 

 uniformity it was determined by count that with the relative proportion of 

 nymphs and adults present it took 370 grasshoppers to make one pint. Aver- 

 aging results from the various spots counted it was found that the average 

 for the field was 2 1-2 bushels of dead grasshoppers per acre of over fifty 

 bushels to the whole field as a result of one treatment. 



