22 



CIRCULAR 6 3 5, U. S. DEPARTMENT OF AGRICULTURE 



SCREENING 



The doors, ventilators, and all other openings of the warehouse 

 should be effectively calked and screened to prevent the cigarette 

 beetle and the tobacco moth from moving into or dispersing from the 

 building. A screen satisfactory for this purpose is one containing 18 

 meshes per inch, made of wire 0.011 inch in diameter. It is desirable 

 to have two extra coatings of electrogalvanizing to enlarge the di- 

 ameter of the wire and to make the openings smaller. Because of 

 corrosion resulting from exposure, the galvanized steel wire will have 

 to be replaced about every 3 to 5 years. It is recommended that the 



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Figure IT. — Closed tobacco warehouse, which can be sealed and fumigated effectively 

 when outbreaks of the tobacco moth and the cigarette beetle occur. 



wire receive a coating of enamel at the time of manufacture to 

 prevent rust and thereby extend for several years the period of effec- 

 tiveness of the wire. 



The screening of open warehouses serves two main purposes, as 

 follows: (1) It materially reduces insect flight in and around storage 

 warehouses, and (2) it prevents insects from escaping when dust or 

 other insecticides are applied in the warehouse. 



Control in Closed Warehouses 



When the cigarette beetle and the tobacco moth appear in closed 

 warehouses, steps should be taken at once to reduce or eliminate the 

 infestation. The prompt use of control measures will prevent serious 

 outbreaks and avoid heavv losses. The control of these insects in 



