INSECTS AND PREVENTIVES 



of weak tea may be used with good results. For 

 the destruction of the black louse, an insect apt 

 to infest the cucumbers in forcing-houses, the 

 removal of the first affected leaves is generally 

 practised. Tobacco fumigation seems ineffectual 

 in the case of this insect. 



The method of fumigation is, of course, not 

 applicable to out-door cultivation ; but is extensively 

 employed, and forms an efficient means of pre- 

 vention and relief, in all hot-houses. Vapour of 

 sulphur is regarded as a good means of controlling 

 powdery mildews. 



Fumigators offered in the market are made of 

 strong galvanized sheet iron, 20, 24, or 28 inches 

 high, of diameters 13, 14, and 16 inches; the 

 larger size containing one bushel, the others three- 

 fourths and one-half respectively. Each is sup- 

 plied with a firing-door and a perforated cover, 

 and with convenient handles for lifting and trans- 

 porting. 



In a house such as shown in photogravure facing, 

 which is 33 feet span, 15 feet high at the ridge, 

 and nearly 400 feet in length, containing about 

 130,000 cubic feet of interior space, I employ 

 four of the largest-sized ones. These require to 



[257] 



