xvi THE GYPSY MOTH. 



the tree the issue of not more than two females. Almost daily I 

 went to that tree, and found fresh specimens that I had overlooked 

 the day before. Yet in the Smithsonian grounds I have absolutely 

 stopped similar injury on larger trees in a few minutes by spraying. 

 It would have been no use, in my judgment, to have attempted to 

 eradicate them by hand picking. Suppose you have somebody 

 climb a tree and gather twelve batches of eggs, but he fails to get 

 the thirteenth. It will cost no more to spray a tree for the thirteen 

 batches than it will for the one. 



Professor Shaler. AYhen I came here I was strongly in favor 

 of offering a reward for the eggs, but I admit I am shaken now. 



Mr. ScuDDER. I don't think you can get sufficient force to spray 

 the trees thoroughly in the time allowed. 



Professor Shaler. I think we shall have to ask the Agricultural 

 College to lend us say eighty or a hundred of their young men for 

 this work. 



Mr. Sessions. There are many people living in the neighbor- 

 hood of this spraying who claim that it was of no sort of value. 

 Do any of these gentlemen believe that? 



Professor Riley. I think the reasons that have been given ex- 

 plain why they had that experience. It was simply due to the 

 impurity of the Paris green and the imperfect manner of applying 

 it. You will always have more or less of failure until you put this 

 matter into the hands of men who can give their whole time to it 

 during that period. Only those men should be employed who 

 have ability and experience ; and one man, particularly, should be 

 engaged to superintend the whole work, and as many other com- 

 petent pei'sons as possible. 



A tree fifty feet high is very easily sprayed. If the caterpillars 

 could not be killed by spraying, it would be better to cut the trees 

 down over the whole of the Middlesex Fells. It pays better to 

 make one grand effort than to fritter your energies away over a 

 number of years, and then fail. The Board in control of the 

 work should control everything. If Paris green is used, it should 

 all be issued by the Board, after being tested. 



Professor Shaler. I should like to ask your opinion, gentle- 

 men, whether any considerable risk to health is to be apprehended 

 from this large use of arsenic in the country. Is there any risk of 

 poisoning the water or of poisoning animals or men ? 



Mr. Appleton. The committee on public health is having an 

 extended hearing on the use of arsenicals. 



Professor Riley. If the spraying is copious and careless, 

 which is unnecessary, there is danger of stock feeding upon grass 

 which has been so impregnated, but there is no necessity for that. 



