CONTROL OF INSECTS ATTACKING STORED TOBACCO 



21 



1. All electrical equipment of an electrically operated dusting machine, includ- 

 ing motor, switches, and attachment plug, should be of the type approved for 

 dust-laden atmospheres, and the frame of the dusting machine and discharge 

 nozzle should be effectively grounded to prevent static electricity accumulation. 

 Fan blades of the blower should be constructed of a nonferrous metal. 



2. During dusting operations all electrical equipment other than that directly 

 connected to the dusting machine should be disconnected and no open flames 

 or other sources of ignition should be allowed in the building. 



3. No internal-combustion engine furnishing power for an insecticide duster 

 should be used or stored inside any principal building or additions thereto. 



Wind movement in excess of 5 to 7 miles per hour seriously inter- 

 feres with dusting in open warehouses, both by hindering the proper 

 distribution of the insecticide and by carrying it outside; there- 



FlGURE 16. 



-The power duster and operating crew applying pyrethrum powder to a 

 section of an open warehouse. 



fore, applications should be made when conditions are as calm as 

 possible. Rainy weather does not interfere provided the dust is not 

 allowed to get wet. Pyrethrum powder is eifective only against adult 

 tobacco moths, and for this reason applications should be made when 

 moths are present in the storages. Suction-light-trap catches serve 

 as a satisfactory gage of moth abundance. Operation of the traps 

 should start in April, the time depending on the temperature, and 

 the dust should be applied weekly as long as the average catch of 

 tobacco moths per trap exceeds about 25 per week. 



The use of pyrethrum powder in open warehouses has the following 

 objectionable features: (1) After a season of dusting a coating of the 

 pyrethrum powder covers the containers of tobacco, and this residue is 

 undesirable, and (2) the rate of reduction in population is slow, 

 permitting considerable damage each year in open warehouses. 

 Efforts are being made to develop a more satisfactory control measure. 



