377 



vho claimed 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 explain why they had 

 that experience. It was simply due to the impurity of the Paris green and the im- 

 perfect 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 dur- 

 ing that period. Only those men should be employed who have ability and experi- 

 ence, and one man, particularly, should be engaged to superintend the whole work, 

 and as many other competent persons as possible. 



A tree 50 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 Middle- 

 sex 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 con- 

 trol 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, gentlemen, whether any con- 

 siderable 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. The spraying should be of such a character that there 

 would be comparatively little falling from the tree or shrub sprayed. 



Professor Shaler. Have you known any cases of poisoning in persons employed in 

 spraying ? 



Professor Riley. No, I have seen none, but I have known of cases where negroes 

 would sit on the back of a mule with spraying pumps, going through cotton fields, 

 and carelessly allow the water to fall on them. I have known them to become sore 

 in the groin, but never knew of a fatal case. 



Mr. Appletox. The spraying is washed off by the first rain of course ? 



Professor Riley. It should not be. The whole tree is enshroudert in a vapor 

 which is all-sufficient, and which is more effective than a more copious spraying. 



Professor Shaler. Is there any particular form of engine which will give that form 

 of spraying ? 



Professor Riley. There are various spraying devices in use, depending largely on 

 the height of the vegetation. If you want to throw to any great height without the 

 use of ladders, you need a spraying device that will throw a strong jet. In almost 

 all cases you can use the cyclone nozzle in its Vermorel modification. 



Mr. ScL'DDER. I should like to say, before going, that it does not seem to me likely 

 that the thing will be exterminated, but that it can be held in check for many years. 

 The reason why I don't think it can be exterminated is because we have not got 

 enough persons used to looking for the caterpillars, to examine the trees and say for 

 certain that there are none there. I do think, however, that it can beheld in check. 



The Mayor of Arlington said they had had very little trouble with it in his 

 neighborhood. The sentiment of the people there was in favor of the continuation 

 of the work. 



The Mayor of Malden. We went through and marked every tree that was in- 

 fested and then went through again and sprayed them. The trees were not so infested 

 as to be particularly noticeable. 



The Mayor of Melrose. The selectmen did not believe there were any Gypsy 

 Moths in their town. As far as he knew, the people were not disturbed by their 

 presence. They would be glad, however, to have the inspectors go through the town 

 and look for it, and would gladly second their efforts. 



Professor Shaler. I think it would be a tax of probably more than $100,000 annually 

 if not checked. 



