64 



BULLETIN 737, U. S. DEPARTMENT OF AGRICULTURE. 



to insure perfect fitting of the door. The closet was fitted with 

 removable trays to insure easy and rapid handling of the cigars. 

 The trays have bottoms 'of one-half-inch wire screen. 



Fumigation is more effective when the temperature is high, and 

 it is not advisable to use carbon disulphid when the air temperature 

 is much below 70° F. To be fairly effective against all stages of 

 the beetle in tobacco, carbon disulphid should be used at a rate of 

 not less than 4 pounds to 1,000 cubic feet of space. When only 

 a small space is to be fumigated and the cost of the treatment is 

 consequently slight, the exact amount of the carbon disulphid used is 

 of no particular importance, even if the amount is very much in excess 

 of the dosage advised above. The period of exposure should be from 

 24 -to 48 hours. The results obtained in a number of experiments 

 with carbon disulphid are given in Table IX. The time of exposure 

 was 24 hours, except in experiments 5 and 11, in which the time 

 of exposure was 48 hours. 



Table IX. — Experiments with carbon disulphid in control of the tobacco beetle 

 (Lasioderma serricorne). Experiments at Clarlcsville, Taut., 1915. 



Exp. 

 Xo. 



Date. 



Dosage 

 (rate per 

 1,000 cu. 



ft.). 



1 

 2 



3 



1915. 

 Aug. 3 

 Aug. 4 

 Sept. 16 



Pounds. 

 1 

 1 

 2 



4 



Sept. 4 



2 



5 



Sept. 3 



3 



6 



Aug. 20 



3 



7 

 8 



Aug. 9 

 Sept. 1.8 



3 



4 



9 



Sept. 22 



4 



10 



Auk. 9 



5 



11 



Aug. 17 



5 



12 



Sept. 26 



10 



Stage of insect. 



Placement. 



Results. 



Larvae and adults 



Adults, larvae, and pupae 

 Larvae (87) 



Larvae (73) 



Larvae 



Adults, larvse, and pupae 



All stages.. 

 Larvae (22). 



All stages. 



All stages . 

 Eggs 



Eggs and larvae. 



In smoking tobacco 



do. . . : 



In pressed yeast cake. . . 



In wire cage, no protec- 



tion. 

 In plug tobacco 



In glass tubes with cloth 

 cover. 



do 



In cigars 



In smoking tobacco . 



In cigars and refuse 



i obacco. 

 About 50 on leaf tobacco. 



In cigars . 



Partially effective. 



3 days after treatment , 16 



alive, 71 dead. 

 All killed. 



2 days after treatment, 1 



alive, 26 dead. 

 All killed. 



Do. 

 2 days after treatment, 



all dead. 

 No live stages found 2 



days after treatment . 



Eggs did not hatch. 



Check eggs hatched 



normally. 

 All stages killed. 



Eggs did not hatch. 



Check eggs hatched 



normally. 

 Cigars kept for 6 months. 

 No signs of infestation. 



Fumigating with Oarron Tetrachlorid. 



Carbon tetrachlorid (CC1 4 ) has been used to a considerable extent 

 as a substitute for carl ion disulphid in fumigation. It is not as effi- 

 cient an insecticide as carbon disulphid, heavier dosages are required, 

 and the cost of treatment is greater. The substance is noninflamma- 

 ble, however, and owing to this property is convenient for use when 

 only a small space is to be fumigated where there might be danger 



