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 
eges 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 
larve 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 roUers. 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 
the air current onto the belts above. Thus, as the fruit is carried 
along by the belts, the hot air is blown over it. Such a machine 
arranged to deliver the fruit into a screened packing room (fig. 3) 
would insure the fruit against contamination before packing. 
