i 
qe 
1. 7 
A 
g 
hi, 
ae" 
: { 
ce : 
i 
— ae 
ee 
Be AON et alte nina Ea ts 4 Sail 
28 BULLETIN 1335, U. S. DEPARTMENT OF AGRICULTURE 
time it is packed. If containers are not perfect, insects have little | 
difficulty in gaining access to the contents. Therefore preventive 
measures must be directed toward absolute exclusion of all insect 
pests from products from the time they are removed from the drier, 
through handling, curing, and storing, until they are placed in insect- 
free, insect-proof containers. 
Conveyors used to transfer products from the drier to the storage 
bins, as well as the storage bins, should be so constructed that they 
can be easily cleaned and steamed. The storage and packing room 
should be shut off from the rest of the plant, provided with every 
facility for the exclusion of insects, and adapted to fumigation by 
chemicals or heat. It should have no inaccessible corners or crevices 
where food materials might collect or insects breed unnoticed. No 
products, cartons, or phot materials should be brought into the 
storage and packing room without having been treated by heat 
or other means to insure their freedom from live insects. 
Products should be packed in the final containers or stored in 
insect-proof intermediate containers as soon as practicable after 
being dried. Products stored in bins for any length of time should 
be subjected to treatment with heat before being packed. If the 
products are being packed for immediate sale and if they have been 
stored with an unnecessarily low moisture content, this heat treat- 
ment may take the form of a short steam processing, which will 
kill all or nearly all live insect forms, and at the same time add a 
little water, thus making the product look fresher. 
REMEDIAL MEASURES 
Remedial measures should be applied whenever, in the opinion of 
the owner, the result warrants the cost. If prolonged storage is 
intended, the presence of a single insect is evidence that the insect 
problem should be watched closely. No treatment makes dried 
fruits immune to subsequent attack. 
The two generally recognized methods of control are fumigation 
and treatment with heat. At present fumigation of the dried fruit 
itself is in disfavor with the dried-fruit industry in California because 
of the fire hazard if carbon disulphide is used and because of the 
possible danger of gas absorption if hydrocyanic-acid gas is used. 
This whole problem is now under investigation in the Bureau of 
Entomology. The three most commonly used fumigants are hydro- 
cyanic-acid gas, carbon disulphide, and carbon tetrachloride. 
HYDROCYANIC-ACID GAS 
Hydrocyanic-acid gas, probably the most effective gas forfumigating 
dried-fruit establishments, packing rooms, etc., can not be depended 
upon for deep penetration. The fact, however, that it is lighter than 
air, nonexplosive, and noninflammable when used in ordinary fumiga- 
tion work, and will not injure the texture or color of the fruit, or affect 
the machinery, woodwork, etc., is very much in jts favor. Although 
dried fruits absorb this gas in varying quantities according to the 
method of packing, it is believed that the quantity absorbed does 
not affect the fruit as food forman (34). This subject is now under 
investigation. 
Methods for generating hydrocyanic-acid gas and the precautions 
necessary in using it are discussed in Department of Agriculture 
