INJURING THE LEAVES. 159 



powder of the cigar factories. This should be used 

 freely as a mulch for low-growing plants, such as the 

 daisy ; and if blown upon infested plants, having first 

 sprayed them with water, by means of a powder- 

 bellows or Leggett's powder-gun, it will clear them 

 readily. In green-houses tobacco steins are com- 

 monly used to smoke the plants. A few live coals 

 are put upon a shovel, or into a metal bucket, and 

 refuse tobacco stems are laid upon them. The house 

 is then tightly closed and the smoke allowed to re- 

 main several hours. The greatest objection to this- 

 method is that tender plants are liable to be seriously 

 injured by an over-dose of the smoke. The tobacco- 

 may also be used in the form of a decoction, made 

 by pouring hot water on the stems, allowing it to 

 cool, and then drawing off the liquid. This may be 

 sprayed upon the plants, or, where not too large, the 

 plants may be dipped into the liquid. For window- 

 gardens this is perhaps as satisfactory a method as 

 can be suggested. 



The Red Spider. 



Tetranychus telarius. 

 Green-house plants are often seriously injured by 

 multitudes of very minute reddish mites that con- 

 gregate on the lower leaf surface, spinning a very 

 fine protective web, and sucking out the juices of the 

 plants through their infinitesimal beaks. These 

 little creatures are commonly called Red Spiders. 

 They are distantly related to ordinary spiders, and 



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