4 CIRCULAR 356, U. S. DEPT. OF AGRICULTURE 



from which hangs an electric light, and it serves to increase the flow 

 of air through the barrel, and also to reflect the light, thereby in- 

 creasing the effectiveness of the trap. 



The barrel is made of galvanized iron, is cylindrical in shape, and 

 the dimensions are 12 inches in length and 13 inches in diameter. 

 A steel bracket or crossbar, to which is attached a Ko-horsepower 

 motor, is riveted inside the barrel. The motor is connected to two 

 12-inch fan blades and is placed in the barrel so as to locate the fan 

 centrally. The motor is of the closed type to prevent it from becom- 

 ing clogged with dust or insects and is especially designed for continu- 

 ous duty. It is operated on a double socket attached to the light, 

 and the fan blades draw a current of air past the light on the flange 

 through the barrel of the trap. 



The cone, which is constructed of 20-mesh steel or copper screen 

 wire, is attached to the rear end of the barrel, and it terminates in a 

 small opening which accommodates a quart glass fruit jar. The rim 

 of the jar top is soldered to the neck of the cone so that the jar can 

 be screwed to the trap. The screen cone reduces materially the 

 quantity of air that passes through the barrel, but sufficient suction is 

 produced to draw the beetles into the trap. When the insects get 

 beyond the fan blades, the current of air is so strong that none can 

 escape while the motor is running. 



The trap is suspended from the ceiling of tobacco warehouses, 

 where it will not interfere with the regular operations. Usually once a 

 week the traps were examined and the beetles removed from the glass 

 jars. 



The cost of constructing a suction light trap, including all materials 

 and labor, is approximately $20 (based on 1934 prices in Virginia and 

 North Carolina). The motor and fan blades, complete and ready 

 for installation, were priced in 1934 at from $9 to $11 each in lots 

 of 10 or more. The block tin, galvanized iron, screen wire, and glass 

 jars varied in price according to the quantity purchased. The trap 

 may be constructed by local tinsmiths from a blueprint or a model. 



MOST EFFECTIVE LIGHT FOR USE WITH THE TRAP 



The light that has been found most satisfactory for use with the 

 trap is a 50-watt "mill-type" bulb, constructed for rough service. 

 These lamps were designed especially for use where there is consider- 

 able vibration, and will give longer service than the ordinary type of 

 bulb. Experiments in 1933 indicated that lights of greater intensity 

 than 60 watts repelled the beetles, and that catches were also smaller 

 when lamps of less intensity than 40 watts were used. It is reported 

 in unpublished notes from the Dried Fruit Insect Laboratory, Fresno, 

 Calif., that blue neon light proved most attractive to the raisin moth 

 (Ephestia figulilella Greg.) in field experiments. This type of light 

 is now being tested. 



METHOD OF DETERMINING THE CATCH 



The trapped insects were brought into the laboratory periodically, 

 usually every 2 weeks, and killed with chloroform. They were then 

 run through a 14-mesh screen to remove the moths and other miscel- 

 laneous insects, the cigarette beetles passing through the screen with 

 practically no foreign matter attached. At first the beetles were 

 weighed to obtain a figure representing the approximate number 



