CONTROL OF DRIED-FRUIT INSECTS IN" CALIFORNIA. 7 



of living insects or of any trace of them when the fruit was examined 

 four months later, January 14, 1912. 



That sulphur fumes are more or less effective in killing insects has 

 long been known, but in order to prove their efficiency the following 

 experiments were conducted: 



On September 4, 1911, 100 pounds of black figs, which were badly 

 infested by the dried-fruit beetle, were separated and sulphured in 

 the regular manner. Upon being removed from the sulphur box 

 they were immediately placed in cartons and sealed to prevent rein- 

 festation. They were examined January 14, 1912, and no insects or 

 evidence of recent work were observed. The sulphuring killed all 

 insects present in the figs at the time. 



An experiment to determine the effect of sulphur fumes upon the 

 eggs of insects was conducted at Sacramento during the summer of 

 1913. About 25 eggs of the Indian-meal moth, deposited on a dry 

 fig in a vial, were placed in the top of a sulphur box and given the 

 usual treatment. None of these eggs hatched, while the eggs kept 

 as checks hatched in due time. 



From the foregoing experiments it is evident that sulphuring the 

 fruit has a tendency to kill any insects infesting it. In case eggs or 

 larvae are well inside of the fruit, however, it is probable that they 

 would not be injured; and since the use of sulphur is not sanctioned 

 by the authorities, and the use of heat, either wet or dry, is so very 

 effective, the use of a belt heater is recommended. 



A BELT HEATER TO DESTROY INSECTS IN DRIED FRUIT. 



The belt heater is composed of a chamber in which is run a tier 

 of belts, each running in the opposite direction to the one above it. 

 These are so arranged that the fruit can be fed in at the top and will 

 travel on the top belt until it reaches the roller, when it will fall to 

 the belt below and be carried in the other direction, and so on down, 

 the last belt carrying the fruit out of the chamber. A heater, either 

 electric or steam, is arranged to maintain a temperature of 180° F., 

 and by adjusting the speed of the belts the time that the fruit remains 

 in the heater can be regulated. 



An experimental machine consists of six belts, 10 feet long and 5 



feet wide, running on 3-inch wooden rollers. The rollers are set on 



cold-rolled axles, turned by cast-iron sprockets connected by No. 25 



chain, which is so arranged that it reverses the direction of alternate 



rollers. To insure even heating an electric fan is so adjusted that 



the hot air is blown along the belts, and guides are arranged to direct 



tht air current onto the belts above. Thus, as the fruit is carried 



aloig by the belts, the hot air is blown over it. Such a machine 



arraiged to deliver the fruit into a screened packing room (fig. 3) 



wouk insure the fruit against contamination before packing. 



