8 



Pyrethrum. — This insecticide is a vegetable powder 

 obtained by grinding the flo^yers of two species of plants 

 belonging to the genus pyrethrum. It is also known as 

 buhach, persian insect powder, dalmatian insect powder 

 and insect powder. Its power to destroy life resides in a 

 volatile oil, which acts on the nervous system of the insect, 

 and which is readily lost on exposure to the atmosphere — 

 hence the difficulty often experienced in procuring it suffi- 

 ciently fresh and of the desired strength. It is harmless to 

 man and the higher animals, and kills insect life only by 

 contact. 



It may be used dry or with water, or in fumes by burn- 

 ing. When used dry the powder may be applied pure or 

 diluted with several times its own bullv of flour, road-dust, 

 sifted ashes, etc. In the former case it should be used very 

 sparingly and in the latter more freely. It may be dusted 

 from a muslin bag or used in one of the many manufactured 

 blowers. The powder is more eftectual when applied in the 

 dry way and in the earl}^ morning, when the dew is still on 

 and the insects are numb and damp. If used in the wet 

 way one ounce should be put in three gallons of water. In 

 order to get the full strength the powder should be wet up 

 and allowed to stand twenty-four hours, or else prepared as 

 a decoction in boiling water. 



This remedy is especially useful in destroying many soft- 

 bodied insects that are not protected by hairs, as the larvae 

 (worms) of many of the butterflies and moths, plant lice, 

 house flies, mosquitoes, cucumber beetles, etc. 



Hellebore. — This insecticide is obtained from the pow- 

 dered leaves, flowers and roots of Veratrum alba or American 

 white hellebore. It is a vegetable poison, but much less 

 dangerous than the mineral arsenical poison ; and kills both 

 by contact and by being eaten. When applied dry, this 

 powder may be diluted with five to ten parts of flour and 

 dusted on the plants through a muslin bag. As a rule, this 

 poison should l)e applied in the evening, because many of 

 the saw-fly larva? feed mostly during the night ; and second, 

 because the powder loses its strength very mucli more rapidly 

 in the daytime. It is used in the wet way mixed with water 

 in the proportion of one ounce to a gallon or six quarts and 



