14 



pest, and not merely a transient removal of it. If the insects are merely 

 kept agitated while in the fields this does not prevent them from pro- 

 ceeding to the outskirts and depositing their eggs in the waste places 

 heretofore mentioned, and thereby rendering the production of crops the 

 ensuing year equally uncertain, and even, with favoring conditions, ten- 

 fold more so. 



When I first visited the region infested, I learned of some efforts at 

 poisoning the larva) with arsenic and Paris green. These had been 

 tried merely as expffriments, and thus far had proved but partially suc- 

 cessful. The poisons in every instance had been applied in too large 

 quantities for the mixtures used, and resulted in the killing* of the vege- 

 tation over which they had been distributed. Where this was the 

 case, the hoppers escaped with little injury. These mineral poisons only 

 take effect when taken internally with the food, and when the vegeta- 

 tion has been killed the young locusts will not eat it, but hop away to seek 

 that which is fresh. Finding this to be the case, a series of experiments 

 was instituted in order to ascertain just what proportions of the poisons 

 were necessary in order to obtain the best results and not to kill the 

 vegetation. By inquiry it was learned that of the arsenic the follow- 

 ing solution had been used : to one barrrel (47.9 gallons) of water in 

 which two quarts of molasses had been stirred, 12 ounces of the poison 

 were added. The latter had first been boiled in a little water, with a 

 pound or more of carbonate of soda, for about an hour in order to dissolve 

 it. We therefore decided that the future experiments should be made 

 with less poison to the barrel of water, and accordingly a half pound 

 was substituted. This mixture also proved too strong for the vegeta- 

 tion. After continued experiments it was finally decided that from 4 

 to 5 ounces of the poison to the barrel of water gave by far the best 

 results, and did not injure the vegetation unless put on too thickly or 

 in too coarse a spray. Bright sunshiue during spraying appeared to 

 render the poison more injurious to the vegetation. A second spraying 

 over the same grounds also had the same effect as the stronger mixtures. 

 Light rains did not materially diminish the efficacy of the poisoning. 

 The results of arsenious poisoning are not immediate upon the hoppers, 

 but first show after about twenty-four hours, and prove fatal in about 

 thirty-six to forty hours. When the first examination was made after 

 the application [twenty-four hours afterwards) it was found that most 

 Of the larvse bad left the weeds and were found creeping and jumping 

 about in a rather sluggish manner upon the ground underneath. No 

 dead ones were to be found at this time. In examining the same local- 

 ity a day later, a great many dead were found, also many others that 

 were very sluggish, while but few really active ones were to be found. 

 On the morning of the third day I counted upon 1 square foot of sur- 

 face between fifty and sixty dead, and a few others were present that 

 must certainly have followed before the expiration of another twenty- 

 four hours. 



