Gelechiidae 343 



to the outer flange by small bolts and winged nuts is a rigid wooden bar. 

 The cloth is fastened against this by the pressure of the bar against the 

 flange. The cloth then forms an enclosure with the front of the stack 

 within which the moths collect. 



The collecting tube extends several inches beyond each side of the 

 stack. One end is plugged with a cork and the other connects with a 

 tube extending through the cover of the moth trap. This trap consists 

 of a Royal electric hairdryer fastened permanently to the cover of a 

 gallon mayonnaise jar. The air intake opening of the dryer is connected 

 by a short right-angle tube to an aperture in the cover containing a 

 30-mesh copper screen to retain the moths in the jar. When the jar is 

 screwed onto the cap it completes an air suction circuit between the 

 hairdryer fan and the moth enclosure. 



The moths are collected in a few seconds by starting the fan and 

 shaking the cloth to dislodge the moths accumulated on it and on the 

 front of the stack. This is possible because the moths when suddenly 

 disturbed habitually drop down and slide through the slot at the bottom. 

 The air suction carries them into the jar without injury. Moths that 

 remain in the tube are pushed through with a bottle brush inserted 

 through the opposite end. 



In setting up a production unit it is necessary to use a pure culture of 

 Sitotroga. Contamination by other grain insects or by enemies of 

 Sitotroga, such as the mite Pediculoides ventricosus and the chalcid 

 Habrocytus cerealellae, must be avoided in order to insure continuous 

 and economical production. This may be accomplished by using clean 

 rooms and by sterilizing equipment and grain with carbon bisulfide in a 

 vacuum fumigator. The grain should not be inoculated with Sitotroga 

 until the fumigant has dissipated and the proper hygroscopic moisture 

 has been reached through holding the grain at 70% relative humidity 

 for several days. Then it should be well infested with a pure culture of 

 eggs. This may be done while the grain is in the sacks. If the units 

 are to be operated continuously they should be refilled with infested grain 

 that has produced one or more generations of moths. At a temperature 

 of 8o° to 85 ° F., the period from egg to adult is from 25 to 30 days. 



The "vertical bin" unit (illus. in Peterson, 1934) consists of a series 

 of narrow trays of 12 -mesh wire (24" x 12" x %") open at the top 

 and suspended in a row in a metal box about 30 inches square having 

 sides of 60-mesh copper screen. Six-inch holes in the top provide open- 

 ings for the moths to enter the traps placed above each hole. These 

 traps consist of coffee tins with inverted funnels soldered to the rims of 

 the screw tops. The percentage of moths collected through such 

 "geotropic" traps used with this type of unit is probably less than in the 

 suction trap used with the ''tilted bin" type. 



