REPORT OF J. P. STELLE. [33] 



I made some careful experiments with dry London purple, undiluted Avitli anything, 

 for the purpose of deciding whether or not it could be applied successfully and made 

 effectual in this condition. The implement employed in the ajiplications was the bel- 

 lows-and-box arrangement already mentioned in connection with pyrethrum. With 

 this I dusted double rows of cotton plants across a square acre, the worms upon them 

 being in strong force : 



No. 1, under side of leaves at the rate of two pounds of purple to the acre; No. 2, 

 same, at the rate of three pounds to the acre, and No. 3, thrown over the plants gen- 

 erally at the rate of two poinds to the acre. All the young worms still on the under 

 sides' of the leaves of Nos. I and 2 were promptly cleared off, but some large ones re- 

 mained for several days on the upper sides of the leaves, though they did not seem to 

 be feeding. The leaves were more or less scorched by the poison, especially on the 

 rows dusted at the rate of three pounds to the acre. But the rows dusted promis- 

 cuously at the rate of two pounds to the acre showed the best results — the worms were 

 all cleared off, while very little damage was done to the foliage. 



Of course a good deal of the scorching may be charged to the rudeness of the im- 

 plement with which the applications were made, it not distributing the powder with 

 entire regularity. But even so imperfect a test settles it, in my mind, that there is 

 really no need of diluting London purple with anything save air — a machine can be 

 invented that would apply it in this condition as successfully as in any other. My 

 idea of such a machine x^ictures something on the jdan of the revolving "fan" or 

 "blower" used by blacksmiths or fouudrymeu, with an attachment qualihed to feed 

 the dry x^urple in from a hopper only just so fast as needed. I think such a machine 

 can be gotten up easily and with very little complication in either its construction or 

 manner of working. 



With a view to testing whether or not the motlis of Aletia are killed by the appli- 

 cation of London jiiirple to the plants, I affixed two large dry-goods boxes each over 

 a small living cotton-plant, as in the yeast experiment. The plant in No. 1 was care- 

 fully sprayed on the under sides of the leaves with London purple in water at the 

 rate of three-fourths of a pound to forty gallons. Nothing was put upon the plant in 

 No. 2. Under each gauze-covered box, with the i)lants, were placed twelve lively 

 Aletia moths, taken from my breeding box, where they had been two days without 

 food. Next day found six moths dead in No. 1 and two dead in No. 2. And the next 

 day found three dead in No. 1, and none dead in No. 2. Replaced the dead moths with 

 living specimens, after having sprayed both plants promiscuously with the same mix- 

 ture as used at the beginning of the experiment. Next morning found four moths 

 dead in No. 1 and seven in No. 2. 



At the time of the season when the Boll Worm was most actively at work, I made 

 an experiment looking to a decision as to whether or not sprinkling the plants with 

 London purple had any bad effect upon that insect after it had ceased to feed upon 

 the leaves. Selecting several heavily-fruited plants, I spread dry London purple care- 

 fully over the bolls, applying it thinly with a camel's-hair pencil. It ijrotected every 

 boll. While a large per centum of the bolls on all the neighboring plants were af- 

 terwards bored into, not one to which I had applied the London purple was damaged 

 in the least . 



I applied London purple to many eggs of Aletia, spreading it thinly over them, dry, 

 with a camel's-hair pencil. I think it destroyed every egg so treated. 



PARIS GREEN. 



My experiments with this article were limited to a few applications made with the 

 poison suspended in water for the purpose of determining how small a quantity could 

 be made effectual as a destroyer of the Cotton Worm. The poison was obtained of a 

 dealer in Galveston, and was supposed to be as pui-e as any on the general market. It 

 gave entire satisfaction, mixed in the proportion of one pound of Paris green to forty 

 gallons of water, and thrown over the plants promiscuously with a force pump in finely 

 divided jets ; but less than one pound did not prove a decided success. This quantity 

 entirely cleared off' the worms, and did not seem to injure the plants in the least. I 

 added neither starch nor flour, but to one application I added common salt in the 

 proportion of two pounds to the forty gallons of water. The salt gave a greater speci- 

 fic gravity to the water, thus, as I thought, aiding in the suspension of the Paris 

 green. 



ARSENIC. 



The poison employed in these experiments was the common white arsenic (Acidum 

 arseniosum), costing, landed in Texas, from 3 to 4 cents per pound by the barrel. 



The first three tests were made with the poison in a dry state, applied undiluted to 

 the plants by means of the bellows dusting-implement already described. Each ex- 

 periment covered two rows of cotton running across a square acre, and well stocked 

 with worms in various stages of growth. 

 G3 CONG— AP ^3 



