EXPERIMENTS ON THE COTTON-WORM. 51 
pretty generally after they had 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 zine, 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. 
PYRETHRUM. 
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 tou pyrethrum for quickly and safely destroying the worms. 
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. Boneset (Lupatorium perfoliatum), one ounce of dried leaves to & 
pint of water. 
2. Huonymus, one ounce of dried bark to a pint of water. 
3. Solanum nigrum, dried leaves, stems and berries, 2 ounces to a 
pint df water. 
4, Solanum aculeatissimum, as No, 3. 
5. Solanum pseudocapsicum, as 3 and 4. 
6. China berries (Melia azederach), as 3, 4, 5. 
7. Mock-orange fruit (Prunus caroliniana). 
8. White clover (Trifolium repens), two 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 particularg 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 fine rose. 
Of the Solanum berries I made alcoholic extracts, and used these 
also, after diluting them first with ten volumes of water, and after- 
wards with only five. These proved as valueless as the effusions and 
decoctions. 
I have the honor to be, very respectfully, &e., 
R. W. JONES. 
Prof. C. V. RILEY, 
Entomologist, United States Department of Agriculture. 
