364 BOARD OF AGRICULTURE. [Pub. Doc. 



1 . That it should kill quickly. 



2. That it should not burn the foliage or otherwise injure 

 the plant. 



3. That it should be cheap enough to be of practical 

 value. 



In addition to these requisites an insecticide of the first 

 class should be capable of remaining upon the foliage in an 

 effective condition for a considerable period of time. 



Various arsenical compounds have proved to be the most 

 satisfactory 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 is 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, espe- 

 cially 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 gen- 

 erally 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 he applied in 

 a variety of ways, according to the habits of the pest it is 

 intended to destroy. A common and effectual way of apply- 

 ing 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 



