24 



Various arsenical coinpounds have proved to be the most satis- 

 factory internal poisons, those commonly used being London purple 

 and Paris green. To these should now be added a third, arsenate 

 of lead. 



London Purple. 



This substance ia a waste product in the manufacture of certain 

 dyes, and contains a more or less soluble form of arsenic. Against 

 leaf-feeding insects in general it is a very effective insecticide, but 

 should be used with care, especially on trees with tender leaves 

 (peach, plum, etc.), since burning of foliage often results from 

 an application of too great a strength. One pound of the poison 

 should be mixed with one hundred and fifty to two hundred gallons 

 of water and applied as a spray. It can be purchased at retail for 

 about fifteen cents per pound. 



Paris Green. 



Paris green has been and is the farmers' favorite munition of 

 war against the common insects of the first group. It retails at 

 about twenty-five cents per pound, and is too generally known to 

 need description. Professor Fernald of the Agricultural College 

 at Amherst estimates that $76,000 worth of this substance is used 

 annually in this State in combating the potato beetle. This poison 

 can be applied in a variety of ways, according to the habits of the 

 pest it is intended to desti'oy. A common and effectual way of 

 applying it to potato plants to destroy the potato beetle, and one 

 which I have often used with good success, is to enclose a quantity 

 of the dry poison in a small bag fastened at the end of a short rod 

 and with it lightly dust the plants by holding the bag over the potato 

 hills, at the same time striking the rod with a short stick held in the 

 other hand. Sometimes burning of the foliage results from this 

 treatment, and if used on a windy day there is presumably more 

 or less danger to the operator from poisoning. Another excellent 

 method for using the poison on low-growing plants consists in mix- 

 ing one pai't Paris green with thirty to fifty parts plaster, aslies, or, 

 perhaps best of all, wheat-middlings, applying the mixture to the 

 plants by means of a sieve early in the morning before the dew 

 has dried off. This forms a slight paste which causes the poison 

 to adhere to the foliage for a considerable period. Probably the 

 oldest and most common method of application to both plants and 

 trees is the mixture of Paris green suspended in water and applied 

 as a spray. This method, like the others, does not eliminate the 

 danger of burning the leaves when the mixture is too strong, but 

 to do the most effective work it is good policy to use the mixture 



