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 it 

 may not be desirable to use a deadly poison, such as 

 the imported currant worm,t and the cabbage cater- 

 pillar.} 



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 iised 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, (PersiaA 

 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 volatile, 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 



* Veratrum album. t Nematus reheeii. t Pieria rapoe, 



§ "Persian Insect powder" Is made from the flowers of Pyrethrum 

 roseum and P. carneum ; "Dalmatian Insect powder" and "Buhach" 

 are made from those of P. clneraioefolium. "Buhach" Is the trade 

 name of a pure product prepared in California. 



