THE REt> SPIDER. 97 



The United States department of Agriculture has experi- 

 mented with fifteen remedies for Greenfly, and the most eifective 

 one is resin, dissolved in caustic soda. Its effect is said to be mark- 

 ed and immediate. The active principle of tobacco is offered in 

 commerce under the name oi nicotine and used as a spray by dis- 

 solving half a pint in three gallons of water. Resin, dissolved in 

 carbon oil, is recommended. Tobacco stems, steeped in water un- 

 til it is the color of coffee, and applyed as a spray is effective. A 

 teaspoonful of pyrethum, dissolved in two gallons of water, used 

 as a spray, will also exterminate the Greenfly. 



The formula for fumigating with hydrocyanic acid gas, is 

 ninety-eight per cent cyanide of potash, one half ounce, one ounce 

 of sulphuric acid, and three ounces of water for every 1500 cubic 

 feet of house space. The fumes should continue through the 

 night. This is one of the most powerful and deadly poisons known 

 to pharmacy and should be used with the greatest care. 



RED SPIDER {Tetranychus Telariiis.) 



The entomological history of this insect is 3^et to be written. 

 The broods hatch from eggs, and their rate of multiplication is 

 considered equal to that of the Greenfly. It spins a delicate webb 

 over the leaves, and subsists on the vital juices of the plant. A 

 dry atmosphere and fire heat favors the reproduction of this pest. 

 It is not confined alone to greenhouses, but the vegetable world is 

 its habitat, and the juices of most species of plants, its food. 



REMKDIES. 



Syringing with water has but a temporary effect. Maintain- 

 ing an atmosphere in the house of seventy-five degrees of hygro- 

 metric moisture is not inimicable to the health of plants and is 

 fatal to the Red Spider. Spraying with two ounces of Ivory soap 

 in two gallons of water will bring the Red Spider under control. 



Another remedy: Take four pounds of Chloride of Sodium 

 (common salt), to fifty gallons of water and use as a fine spray 

 is alleged to be an effective remedy. 



