GRASSHOPPERS AND OTHER INJURIOUS INSECTS OF 1911 AND 1912. 27 



since grain is low enough and "springs" enough to suffer no damage from the 

 dragging of the dozer through the fields. At the same time there is not enough 

 of the vegetation to cover up the grasshoppers and allow the dozer to pass 

 over them without catching them as is the case later in the season. On the 

 other hand, in using the sodium arsenite, while the grain is young, and the 

 stems short, it spreads more uniformly on the vegetation. Also at that time 

 the hoppers feeding as they do in solid masses are affected in proportionately 

 greater numbers than later when scattered. The hoppers traveling more 

 slowly and more steadily than the adults must feed continuously on the poison- 

 zone and are more certain to eat enough poison to kill. The other advan- 

 tages in methods of applying poison early, from the fact that at that 

 time (and then only) can large fields be protected by spraying relatively 

 few acres about the borders, has already been treated. While any of the 

 methods described may be used later in the season it is evident that they can- 

 not be as effective at any other time than when the grasshoppers are very 

 young. Every week's delay after that time decreases the efficiency of any 

 method of killing. When one sees, as I have frequently seen, whole fields 

 totally destroyed by the hoppers, it must be admitted that there can be no work 

 on the farm more important in the month of May, than earnest and intelligent 

 work against this pest at a time when the work will be of most value. The 

 need of co-operation is of course imperative but co-operation depends largely 

 upon initiative and in every community there must be leaders who may take up 

 the work and by their efforts sow the seeds of a community spirit that may 

 result in general action against this common enemy. At the same time it must 

 be remembered that the greater part of the real damage done by the grass- 

 hoppers is early in the season and each one of the leaders who is applying the 

 various control methods is preventing a large part of the loss he would suffer 

 otherwise, even though the others in his community do not co-operate with 

 him. There is a real benefit to him, since the harm that may come later in the 

 season must be thus lessened. 



One of the principal objects of the summer's work is to plan if possible, a 

 method of control which would be at once more effective and more economical 

 than the use of the hopperdozer. With this in view, certain tests with poisons 

 were planned. It was found that Paris Green, either in dry or liquid form, was 

 not very satisfactory. Certain experiments with Arsenite of Sodium which 

 had been carried out by the Entomologist during the previous year seemed to 

 indicate that this poison was worthy of further trial. Reports upon the use of 

 this poison against locusts in S. Africa were also highly commendatory, so it 

 was determined to give some time to experiments with this compound. Most of 

 our tests were made in small enclosed plats measuring two and a half by four 

 feet, thus giving a definite area of ten square feet. Our first trials showed 

 that the poison was satisfactory as regards killing the insects, although we 

 were surprised to find that death did not occur until twenty-four to thirty-six 

 hours after feeding. We noted, however, that the poison took effect within a 

 few minutes and the grasshoppers ceased feeding, the hind legs became help- 

 less and the insect, although alive for a considerable time, gave every indication 

 of being very "sick." The first trials were made with a rather crude prepa- 

 ration of white arsenic and "sal-soda" boiled together but as this was found to 

 vary somewhat in effect, we tried the soluble salt. Commercial Arsenite of 

 Soda, which was found more effective, moi'e uniform and much cheaper than 

 the former. The formulae used in S. Africa were found to be too strong for 

 use here, since the grain or other vegetation was severely "bui'ned" by the solu- 

 tion. Gradually reducing the proportion of "Arsenite" it M'as found that the 

 most satisfactory solution was made by using four ounces of the "Arsenite" to 

 fifteen gallons of water. This gave a spray which killed the grasshoppers 

 without damage to the vegetation upon which it was placed. It is evident that 

 any excess of poison must be wasted. 



In the following table the solution in each case was made up of water, 15 

 gallons and molasses, 1 pint. The varying amounts of arsenite being shown 

 in the table: 



