﻿OF THE STATE ENTOMOLOGIST. 



1. Paris Green that has been four months in the soil no longer 

 remains as such, but has passed into some less soluble state, and is 

 unaffected by the ordinary solvents of the soil. 2. When applied in 

 small quantities, such as alone are necessary in destroying injurious 

 insects, it does not affect the health of the plant. 3. The power of the 

 soil to hold arsenious acids and arsenites in insoluble form will pre- 

 vent water from becoming poisoned, unless the Green is used in ex- 

 cess of any requirement as an insecticide. 



These experiments of Prof. Kedzie's accord, so far as they refer to 

 the influence ot Paris Green on man through the plants, with others 

 by Prof. McMurtrie of the Department of Agriculture, which showed 

 that even where the Green was applied to the soil in such quantities 

 as to cause the wilting or death of the plants, the most rigorous chem- 

 ical analysis could detect no trace of arsenic in the composition of the 

 plants themselves. They also fully bear out the opinions which I have 

 always held, and justify the advice which I have given. 



Before leaving this subject of remedies for the Colorado potato- 

 beetle, it may be well to say a few words about two other compounds 

 that have been strongly recommended and advertised as such. The 

 most notable of these is that advertised as " Potato Pest Poison," by 

 the Lodi Chemical Works of Lodi, N. J. It is put up in pound pack- 

 ages, which are sold at $[ each, with directions to dissolve four ounces 

 in two quarts of hot water, then pour into a barrel containing thirty 

 gallons of cold water, and use on the vines in as fine a spray as possi- 

 ble. Analysis shows it to be composed of one part pure salt and one 

 part of arsenic (arsenate of copper), and it has the general color and 

 appearance of common salt. Early in September, during quite hot 

 and dry weather, I had this poison tested in afield of late potatoes be- 

 longing to Mr. W. Hinterthur of Laclede, Mo., the field having been 

 badly infested during the Summer, but about half the vines having been 

 saved by pretty constant hand picking. These were at the time fairly 

 covered with the insect in the egg, larva, and beetle states. Five rows 

 were treated with the poison, both according to directions and by 

 finely sprinkling the dry powder over the vines. As soon as the pow- 

 der touched the larvic, they writhed and became restless, as with pain, 

 the powder dissolved and formed a translucent coating upon them, 

 and in about three hours they began to die. The beetles were not so 

 easily affected, though they too were in time killed by it. Used as di- 

 rected, it destroys, but hardly as efficiently as the ordinary Paris 

 Green mixture. A pound of Paris Green, costing much less than a 

 pound of the Lodi poison, will go nearly as far in protecting a field of 

 potatoes, and I cannot see a^y advantage to the farmer from the em- 



