EXPERIMENTS ON THE COTTON WORM. 51 
pretty generally after they bad eaten it. The same is true of arsenite 
of potash dissolved in water. 
Some persons here employed London purple, and reported adversely 
on it.- They applied it while the rain was falling daily, and without 
any paste to give it adhesiveness to the leaves. 
I also used sulphate of zinc, 1 pound to 40 gallons of water; this 
killed 10 per cent, of the worms, but it is easily washed from the 
leaves, because of its ready solubility in water. 
PYRETHRini. 
I made experiments this season with this vegetable substance, which 
confirmed what had been said and written in regard to its remarkable 
insecticide properties; indeed, nothing that I have seen or handled is 
comparable to pyrethrum for quickly and safely destroying the worm-. 
I found that the powder suspended in water and sprayed on the plants 
is almost as effective as the carefully prepared and subsequently 
diluted alcoholic extract. 
I planted the seed you kindly sent me last spring, and have now some- 
healthy plants growing; these have not yet bloomed. I will report 
further in regard to them hereafter. 
I made infusions and decoctions of the following : 
1. Bpneset (Eupatorium perfoliatum), one ounceof dried leaves to a 
pint of water. 
2. Euonymus, one ounce of dried bark to a pint of water. 
3. Solanum nigrum, dried leaves, stems and berries, 2 ounces to a 
pint of water. 
4. Solatium aculeatissimum, as No. 3. 
5. Solarium pseudocapsicum, as 3 and 4. 
0. China berries {Nelia azederach), as 3, 4, and 5. 
7. Mock-orange fruit (Prunus caroliniana). 
8. White clover (Trifolium rcpens), 2 ounces to a pint of water. 
These preparations were carefully made, and as carefully applied. 
They exhibited no insecticide properties either by contact, like Pyre- 
thrum, or by consumption, like arsenic. 
I think it is not necessary for me to go into particulars in regard to 
the preparation and mode of application, except to say that I followed 
the usual methods, as prescribed in Parish's Pharmacy and other similar 
works, and employed a fountain-pump with line rose. 
Of the Solatium berries I made alcoholic extracts, and used these 
also, after diluting them first with ten volumes o\' water, ami after- 
wards with only live. These proved as valueless as the infusions and 
decoctions. 
I have the honor to be, very respectfully. &c, 
P. \V. JONES. 
Prof. 0. V. Riley, 
Entomologist^ United states Department of Agriculture. 
