42 



THE AMERICAN ENTOMOLOGIST. 



every atom. Experiments which I made 

 with it in 1878 impressed me favorably 

 with this powder as an insecticide, and its 

 use on the Colorado potato-beetle by Pro- 

 fessors Budd and Bessey, of the Iowa 

 Agricultural College, proved highly satis- 

 factory. I was, therefore, quite anxious 

 to test its effect on the Cotton-Worm in the 

 field on a large scale, and in the winter of 

 1878-79 induced the manufacturers to send 

 a large quantity for this purpose to the 

 Department of Agriculture. The analysis* 

 made of it by Professor Collier, the chem- 

 ist of the Department, showed it to contain ; 



Per cent. 



Rose aniline 12.46 



Arsenic acid 43.65 



Lime 21.82 



Insoluble residue 14.57 



Iron oxide 1.16 



Water 2.27 



Loss 4.07 



100.00 

 Through the liberality of the manufac- 

 turers, Messrs. Hemingway & Co., a num- 

 ber of barrels of this powder were placed 

 at my disposal the past season and distri- 

 buted to various observers and agents in 

 Georgia, Alabama, and Texas. Early in 

 the spring Mr. A. R. Whitney, of Franklin 

 Grove, Illinois, found it to be a perfect 

 antidote to the canker-worms which had 

 not been prevented from ascending his 

 apple-trees, and the experiments of those 

 whom I had intrusted to make them on the 

 Cotton-Worm, as well as those made under 

 my own supervision, all showed that its 

 effects are fully equal to those of Paris 

 green. Like the latter it kills the worms 

 quickly and does not injure the plants, if 

 not applied in too great a quantity. 

 Farther, it also colors the ingredients so as 

 to prevent their being mistaken for harm- 

 less material. Finally, its cheap price 

 removes the temptation to adulterate the 

 poison, as every adulteration would prove 

 more expensive than the genuine article. 

 It is even superior to Paris green, as, 

 owing to its more finely-powdered condi- 

 tion, it can be more thoroughly mixed 

 with other ingredients and used in smaller 

 proportion. Experiments on a large scale 



* Ordinarily the Rose aniline has mixed with it a little 

 iilmic acid, and an increase of 2 percent, of arsenic acid. 



have been made with the dry application 

 at the rate of 2 lbs. to 18 lbs. of diluents, 

 also at the rates of i, i, i, and i lb. to 18 

 of the diluents. The last proved only 

 partially effectual, and in no case were the 

 plants injured or the leaves even burned. 

 In all but the last case the worms were 

 effectually killed, but as the mixture, at 

 the rate of i lb. was applied with greater, 

 care and regularity than is generally had 

 on a large scale, and also in very dry 

 weather, the proportion of i lb. to 18 of 

 the diluents is most to be recommended. 

 All higher proportions are simply waste of 

 the material. 



Like Paris green, it is not soluble,* but 

 is much easier kept suspended in water 

 than the former. If applied in this way 

 some care has to be taken in stirring it in 

 the water, as it has a tendency to form 

 lumps, owing to its finely-powdered con- 

 dition. Experiments on a large scale with 

 this material diluted in water gave the fol- 

 lowing results : When used in the same 

 proportion as Paris green, namely, i lb. of 

 the poison to about 40 gallons of water, 

 one experimenter reports that the leaves 

 were slightly crisped, while four others re- 

 port a perfect success, and no injury 

 whatever to the plant. Experiments by 

 myself and Mr. Schwarz showed that 

 when applied in the proportion mentioned 

 and thoroughly stirred up in the water the 

 leaves were partly crisped, though by no 

 means so much as by arsenic, even when 

 applied in weaker solution. When used 

 in smaller proportion, or at the rate of f or |^ 

 lb. to 40 gallons of water, it did not burn 

 the leaves and still proved effectual in de- 

 stroying the worms. Repeated experi- 

 ments on a smaller scale confirmed these 

 results obtained on large fields, and also 

 showed that the proportion may be still 

 farther reduced, and when applied with 1 

 great care and in very dry weather i lb. to T 

 40 gallons will kill. Still farther reduction 

 in the proportion of the powder used gave 

 negative results. I would, therefore, re- 

 commend the use of i lb. of this powder to 

 from 50 to 55 gallons of water as the pro- 



* The manufac 

 soluble if desired. 



-K.tT^f, T"""'?'^""''"'" '^^'^ '■«"<'<^'' about 1.3 per cent, of it 



