INSECTICIDES. 853 



PYRETnRUM. 



Pyrethrum or buhach is another valuable insect 

 destroyer. It contains a volatile oil that is supposed to 

 act upon the insects through their breathing organs. It 

 can be applied as a powder with a bellows, or in water 

 with a force pump or a syringe, using a teaspoonful to 

 a gallon. To be most effectual, it should be used in a 

 closed room, but even then the liquid application will 

 often succeed where the powder will fail. Care should 

 be taken to have a fresh supply, and if it is to be kept 

 any length of time, it should be placed in an air- 

 tight vessel. 



TOBACCO. 



For many insects, tobacco is an effective remedy. 

 If the houses are filled with smoke from burning tobacco 

 stems, the plant lice can be kept in check, provided they 

 have not too much of a start. As in other cases, pre- 

 vention is easier than cure, and if the houses are fumi- 

 gated once or twice a week, no aphides will appear. The 

 tobacco stems should be slightly dampened, and either 

 placed in fumigating cans, made of galvanized sheet 

 iron, with openings in the sides near the bottom to afford 

 a draft, or in piles upon the cement or dirt walk. Shav- 

 ings, paper, or better yet, a few live coals, may be used 

 for kindling the stems. Care should be taken that the 

 tobacco does not blaze. The amount of smoke that can 

 be used will vary with the plants, but if so thick that 

 one cannot see more than ten feet, it will generally 

 answer. A strong tobacco tea sprayed upon the plants 

 is also valuable as an insecticide, and in houses where 

 fumigation cannot be relied upon, the sprinkling of 

 tobacco dust or of tobacco stems about the plants will 

 assist in keeping the insects in check. The stems give 

 the house an untidy look and the dust is washed off 

 in syringing. 



