82 



the trees will be less severe. Birches, however* were in many places 

 entirely defoliated by the middle of September. The destructive work 

 of these caterpillars was also considerably added to by a large aphid 

 (CaMtpterus mucidus) and by a green leaf -hopper (Mnpoasca smarag- 

 dula Fall). 



Mr. Washburn in discussing this paper stated that the locust 

 trouble was a very interesting one in Minnesota, and also a very 

 serious one. He stated that the farmers were very slow in using 1 

 poison bait, such as bran and horse droppings, because poultry roam 

 over the wheat fields, and in scratching over the poisoned droppings 

 would suffer. For this reason it was almost impossible to use the 

 poison bait in Minnesota. 



Mr. Alwood inquired if anyone had ever poisoned chickens with an 

 arsenite. 



Mr. Fletcher stated that he had been investigating this point for 

 some years, but had never heard of a single instance. 



Mr. Marlatt made the suggestion that ordinary white arsenate be 

 used instead of Paris green, the former being very much cheaper. 

 He said that Paris green is the most expensive of all arsenicals, cost- 

 ing 20 to 2.~> cents per pound, whereas arsenic could be purchased at a 

 few cents at the most. He said that the simple arsenite of copper was 

 as effective as Paris green, and could be purchased for about one- 

 half the cost of the latter. Difficulty was experienced, however, in 

 procuring the arsenite of copper in sufficient quantities to supply 

 the present demand; hence he thought Paris green (the aceto-arsenite) 

 would no doubt be largely used for some time to come. As relating 

 to this particular case, he was inclined to recommend simply poisoning 

 the bait material with white arsenic. He suggested that an enormous 

 quantity of poisoned material would be necessary to insure the destruc- 

 tion of the locusts in their widespread outbreaks. 



Mr. Fletcher explained that it was not necessary to cover an entire 

 field, but that the poison should be placed around the edges. With 

 regard to the use of arsenic as a substitute for Paris green he consid- 

 ered this very undesirable, from the great danger of poisoning from 

 its accidental or careless use. He thought arsenic resembled flour, 

 sugar, and some other household stuffs too much to allow of its gen- 

 eral prescription. The reason that he had continued to recommend 

 Paris green was that it is well known, and could not on account of its 

 warning color be mistaken for anything else. He would have no 

 hesitancy in using arsenic himself or advising its use by specialists, 

 but would not dare recommend it for everybody, and particularly if it 

 were likely to be kept about dwelling houses in the country, as a 

 result from having some of the poison left over. Fruit growers living 



