INDUSTRIAL FUMIGATION AGAINST INSECTS 



45 



RUGS AND TAPESTRIES 



Rugs and tapestries in storage can be protected by the same 

 methods and equipment that are recommended for the storage of 

 furs. Many firms, however, prefer to use naphthalene flakes or 

 paradichlorobenzene crystals in place of liquid fumigants. On ex- 

 posure to air at ordi- 

 nary room tempera- 

 tures, both these solid 

 fumigants give off a 

 heavy vapor, which 

 gradually permeates 

 the atmosphere of 

 the storage room. If 

 a saturated atmos- 

 phere of either of 

 these materials is 

 maintained in the 

 storage room, ade- 

 qu a te protection 

 from insects can be 

 obtained (fig. 38). 



At a temperature 

 of 77° F., 8 ounces 

 of paradichloroben- 

 zene or 0.64 ounce of 

 naphthalene is re- 

 quired to saturate 

 the atmosphere in 

 1,000 cubic feet of 

 space. Under ordi- 

 nary storage condi- 

 tions, however, it is 

 advisable to use an 

 excess of these f umi- 

 gants in order to 



counteract losses by absorption and leakage and to insure a con- 

 tinuously saturated atmosphere. 



A dosage of 1 pound of either flake naphthalene or paradichloro- 

 benzene to each 100 cubic feet of space will cause fabric pests to cease 

 feeding and to die after prolonged storage in tight rooms. 



When no attempt is made to hasten evaporation by the application 

 of heat, the vapors of naphthalene and paradichlorobenzene are not so 

 quickly toxic to insects as are the liquid fumigants. Their chief value 

 lies in the continuous protection that they afford. Since vapors are 

 evolved but slowly from the crystals, one application may last for 

 several months. 



Aside from having an irritating effect upon the eyes, the vapors of 

 naphthalene and paradichlorobenzene are apparently not injurious to 

 man unless inhaled in strong concentrations for an extended period. 



Paradichlorobenzene crystals can be purchased for from 16 to 60 

 cents per pound in small lots. Naphthalene flakes are quoted at 2y 2 

 to 10 cents per pound. 



Figure 37. — Exterior view of commercial fur-storage vault 

 equipped for fumigation with ethylene dichloride-carbon 

 tetrachloride mixture. Note storage drum at right, 

 pump at left, and pressure tank in center connected with 

 various fumigating vaults, not shown, by pipe lines on 

 wall. 



