98 BOARD OF AGRICULTURE. [Pub. Doc. 



of New England. Again, Paris green has a high specific 

 gravity, and requires constant stirring. An overdose will 

 clear the foliage from trees even quicker than the insects it 

 may be desired to destroy. 



At present prices for copper, Paris green retails at from 

 18 to 30 cents per pound, and a good article can hardly be 

 bought for less than 25 cents per pound. Paris green is ap- 

 plied at the rate of 1 pound to 100 or 150 gallons of water, 

 and should be used with double the amount of lime, to in- 

 sure a better distribution and to neutralize any uncombined 

 arsenic. With a strictly pure Paris green the addition of 

 lime is not necessary. 



Since the discovery of the value of arsenate of lead as an 

 insecticide by the chemist to the gypsy moth committee, it 

 has come into increasing use as a remedy for shade-tree in- 

 sects. Arsenate of lead is a white, flocculent poison, of 

 light, specific gravity, remains suspended in water, hence it 

 requires but little stirring, and adheres tenaciously to the 

 foliage for an entire season. While not as quick in its 

 effect on the insects as the two insecticides previously men- 

 tioned, this difficulty may be eliminated by increasing the 

 quantity used. Arsenate of lead also will not injure the 

 most delicate foliage, hence the extreme care and accuracy 

 necessary where London purple or Paris green is used are not 

 needed. Because of the general demand for this material, 

 several manufacturers are putting it on the market in paste 

 form, at a price ranging from 15 to 25 cents per pound, ac- 

 cording to the size of the package. These pastes carry from 

 50 to 68 per cent actual dry arsenate of lead, and are very 

 convenient for general use. In large spraying operations, 

 however, it is sometimes desired to make the arsenate of 

 lead from the ingredients, and where skilled labor is avail- 

 able this can be done with little difficulty. The materials 

 necessary are nitrate of lead and arsenate of soda of 96 per 

 cent purity. It is important to get a high-grade arsenate 

 of soda, as the low grades contain a considerable amount of 

 common salt, which will form chloride of lead, a substance 

 of no value as an insecticide, but which consumes the lead 

 salt. The formulae to be followed are given below : 



