ON THE DESTRUCTION OF NOXIOUS INSECTS BY MEANS OF THE 
PYRETHRUM. 
BY C. WILLEMOT. 
Of all substances hitherto proposed for the destruction of noxious insects, powders 
have been found the only ones that can be used to advantage, on account of their simple 
and easy method of application. All such powders, too, which have been employed, so 
far as known, are derived from the vegetable creation. It would occupy too great a 
space to enumerate here all the plants used in the form of powder for this purpose; it 
will suffice to mention some which have been more particularly under observation. 
Among these are the straight-leaved pepperwort ( Lepidium ruderale , Linn., and T/daspi 
rnderale, Desfon.), found growing in uncultivated places and among rubbish around Paris. 
This is used in Southern Dalmatia, in the form of powder, almost exclusively for the 
destruction of fleas. In some parts of Southern Russia, especially in the Crimea, a plant 
very common in France, Aristolochia Clematitis , Linn, (common birthwort), is used exclu¬ 
sively to destroy bugs. Sawdust of aromatic wood, particularly American cedar ( Ce- 
drela odorata, Linn.), is largely sold for the destruction of insects, and, according to some 
authorities, most of the powders sold in Paris for that purpose are composed of that sub¬ 
stance. But after using and experimenting with them we have been fully convinced 
that the object cannot thus be perfectly attained. Their action is feeble, or they merely 
stupefy for a time the insect, which soon recovers its strength and sensibility to do 
injury. 
The greater number of the plants which furnish the most satisfactory means for the 
destruction of insects are of the genus Pyrethrum. Many observers, considering the 
botanic resemblance (as well as similar properties of this genus) with kindred ones, as 
certain chamomiles, the Anthemis Cotida for instance, have pretended that such indi¬ 
genous plants (chamomiles) may specifically furnish a powder for destroying insects 
equal in every respect to the Pyrethrum. But accurate and detailed experiments by our¬ 
selves and other competent observers refute such assertion. All the efficacy of the 
Anthemis Cotida consists in rendering the insects insensible for a time instead of destroy¬ 
ing them. The inhabitants of the regions of Europe and Asia, near the Caucasian 
mountains, seem to have been the first to discover the properties of the Pyrethrum, and 
try on a large scale the powders obtained from these plants. The species employed 
differ according to the different localities. 
It is easy to comprehend that the inhabitants of the Caucasus choose for their use 
that kind which is most abundant in their own country. Thus in Armenia they prefer 
the red Pyrethrum (P. roseurn , Biebers.), commonly called “ lowizachek,” or flea plant. 
The Persian powder, which appears most extensively used, is almost wholly composed 
of the flesh-coloured Pyrethrum (P. carneum , Biebers.). Dr. Ch. Koch in his ‘Travels 
in the East’ gives very curious details respecting this precious species in the Caucasian 
regions. In the 4 Journal de la Societe Imperiale et Centrale d’Horticulture de la Seine,’ 
vol. iii., 1857, p. 750, also may be found an analysis of a note by Mr. Neumann, of 
Breslau, on the “Culture and Preparation of the Powder of the Pyrethrum carneum.” 
We may here remark, in passing, that in countries where the most frequent use has. 
been made of these powders of Pyrethrum , they have only been applied to the destruction 
of those insects which are troublesome in dwellings. Our object has been to select from 
the different plants the one which presents the greatest range of efficacy; and we have 
been more exacting in this than heretofore has been the case in seeking a plant of incon¬ 
testable efficacy for the destruction of insects, and which can be so applied, not only to 
vermin in the house, but also to those insects which every year commit such great ravages 
upon the cereals, fruit-trees, leguminous and ornamental plants, etc. A plant was de¬ 
sirable which can easily be acclimatized in France, the properties of which, in its wild 
state in its native regions, are neither destroyed nor weakened by cultivation, and which 
can be raised with but slight attention to its culture. We want, finally, a productive 
plant, to the end that the powder it furnishes may be sold at a very low price. Such a 
plant we are now fortunate enough to introduce for the public use. Its efficacy lias 
been fully proved by a great number of persons, as will be seen herealter; its acclimati¬ 
zation is very satisfactorily evinced ; its culture is most simple ; its properties are wholly 
retained; the production is very abundant; now nothing remains but its extensive pro- 
