Plants as Affected by Animal Parasites. 159 



Both Paris green and London purple, when perfectly 

 mixed with 150 parts, by weight, of land plaster, or an 

 equal bulk of any other cheap, harmless powder, are 

 satisfactory for destroying the potato beetle and many 

 other leaf-eating insects (307). 



288. Compounds of Arsenic are Deadly Poisons and 

 should always be handled with the greatest care. 



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. J 



Hellebore powder when used dry, may be diluted with 

 once or Jbwice 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 in- 

 sect 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 



* Veratrum album. f Nematus ribesii. J Pierls rapce. 



g "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. cineraicefolium. " Buhach " is the trade name 

 of a pure product prepared in California. 



