166 Principles of Plant Culture. 



289. Hellebore (hel'-le-bore) Powder, i. e., the 

 ground root of white hellebore,* is a far less virulent 

 poison than the arsenic compounds. It is therefore 

 useful in destroying a class of insects against which a 

 deadly poison cannot wisely be used, as the imported 

 currant worm,f and the cabbage caterpillar. $ 



Hellebore powder when used dry, may be diluted 

 with once or twice its bulk of flour, which causes it to 

 adhere better to the foliage than if used alone. When 

 applied with water, a heaping teaspoonful or more may 

 be added to three gallons. The dry powder is very 

 light and should only be used in a still atmosphere. 



A decoction made by boiling the root of white helle- 

 bore in water is said to possess insecticide properties 

 similar to those of the powder. 



290. Pyrethrum (py-re'-thrum) Powder, (Persian 

 insect powder, Dalmatian insect powder, Buhach) is 

 the pulverized flowers of certain species of Pyrethrum. 



Pyrethrum powder is not poisonous to the higher ani- 

 mals, but the oil that pervades it is destructive to many 

 insects. As the oil is extremely vo^tile, pyrethrum is 

 better adapted for use under glass or with plants other- 

 wise inclosed. It is not injurious to foliage or flowers. 

 Fresh and pure pyrethrum powder may be diluted half 

 or more in bulk with any other light, cheap, harmless 

 powder, but the mixture should stand a day or two be- 

 fore use, to enable the diluent to absorb the oil. The 



* Veralrum album. f Nematus rtbeM. % Pieris rapce 



? "Persian insect powder" is made from the flowers of Pyre- 

 thrum roseum and P. carneum; "Dalmatian insect powder" and 

 "Buhach" are made from those of P. cineraioefolium. "Buhach" 

 is the trade name of a pure product prepared in California. 



