I 76 Pyrethreum Roseum in Killing Insects. [March, 
EXPERIMENTS WITH PYRETHREUM ROSEUM IN 
KILLING INSECTS. 
BY W..L. CARPENTER, U.S.A. 
N the August number of the AMERICAN NATURALIST appeared 
an article on the carpet-beetle, by J. A. Lintner, in which the 
statement was made, as nearly as I can now remember, that 
“although he had never used Pyrethrum roseum as an insect 
exterminator, he had no doubt that it would prove unavailing if 
applied to the destruction of the Anthrenus? As it seemed 
unfair to condemn without a trial what is generally regarded as a 
useful insect poison, I resolved to test it experimentally; and now 
present the result of several trials with different orders of 
insects, 
The insects were placed under a tumbler, which was slightly 
raised to admit fresh air, and a small quantity of the Pyrethreum 
roseum, or Persian Insect Powder of commerce, introduced on the 
point of a pen-knife. The movements of the insects brought 
them in contact with the powder, which readily adhered to the 
body ; in attempting to remove it from their appendages a few 
particles would be carried to the mouth and thus incorporated in 
the juices of the stomach with fatal effect. 
A honey-bee became perfectly helpless in fifteen minutes, a 
mud-wasp in eight minutes, a small species of ant in five minutes ; 
a small species of Pyralide became helpless in twenty minutes ; 
the large Papilio asterias resisted the effects of the drug for over 
one hour, and upon being released seemed to recover, but died 
next day. A larva of one of the Woctuelite did not seem sus- 
ceptible, its jaws were repeatedly filled with the powder, which it 
invariably ejected by throwing out its juices; at the end of two 
hours it was still able to crawl feebly. A house-fly became help- 
less in ten minutes, a mosquito in fifteen minutes, a flea in three 
minutes, 
In experimenting upon the Coleoptera, an insect as nearly the 
size of the carpet-beetle as could be found was secured in Dia- 
brotica duodecim-punctata, an abundant species here. It was easily 
affected and became helpless in twelve minutes. A small pinch 
placed in the jaws of a large Carabus stopped locomotion in 
thirty minutes. The Hemiptera, owing to their peculiarly shaped 
mouths, were enabled to vigorously resist the baleful influence. — 
