1932] SERVICE AND REGULATORY ANNOUNCEMENTS 73 
Treatments for Bulb Flies 
If an infestation of greater bulb flies alone (that is, without eel worms) was 
disclosed during either the field or storage inspections, the bulbs, as a condition 
for the issuance of permits, must either be fumigated with calcium cyanide or 
with sodium cyanide or given the hot-water treatment as prescribed below. 
Fumigation with calcium cyanide. — Sixteen ounces 4 of calcium cyanide (slow- 
evolving type) are used to each 100 cubic feet of space, and the bulbs are exposed 
for four hours at a temperature of 60° F. or more in an air-tight chamber. 
Construction of fumigation chamber. — The fumigation chamber, if of wood, must 
have walls of double thickness, each thickness made of tongued and grooved 
material free from knots, and with a lining of tar paper or asphalt paper between 
the walls. The inside must be painted, preferably with aluminum paint, or given 
a coat of paraffin or aluminum foil. The door (which may consist of the entire 
side of the fumigation chamber) is to be constructed in the manner of a refrigerator 
door, closing against at least two offsets with weather stripping or padding. 
Ordinary hinges are unsatisfactory; all edges of the door should be forced against 
the seat by a lever or screw clamp. Fumigation chambers up to approximately 
500 cubic feet may be approved. Fans are required in ail fun igators over 150 
cubic feet in capacity. In fun igators of the larger sizes, fans of the blower type 
may be necessary in order to secure complete distribution of the gas. 
Provision is made for inserting cyanide by sliding in a flat pan extending the full 
length of the fu irrigator. The cyanide can advantageously be placed on papers 
covering the floor of the pan, and the residue gathered up with the papers at the 
conclusion of fumigation. Two separate pans may be used in the case of large 
fu irrigators. A special opening is made in the fumigation chamber for the 
insertion of the pan after the main door is closed. 
Fumigation chambers, if of metal, such as galvanized iron, must have all joints 
soldered, and must be constructed without a door or other opening in the side or 
top. Provision must be made for sealing such chambers around the base after 
lowering over the bulbs. Such chambers are raised and lowered by a block and 
tackle over the pile of trays of bulbs to be fumigated. The trays must be sup- 
ported above the ground in such way that the operator can slide a pan containing 
the cyanide under the trays of bulbs at the time the fumigation chamber is being 
lowered. 
Fumigators should not be built in closed buildings on account of the danger 
of accumulation of gas in the building, but may be maintained under cover in 
open storage sheds if desired. 
Some means should be provided for opening the fumigator from the outside, 
other than the main entrance door, in order to air the chamber after each fumiga- 
tion. The preferable method of exhausting the gas is the use of an exhaust fan, 
built into the wall of the fumigation chamber. The cover of the exhaust opening 
must, like the door, be so fitted as to be air-tight. 
_ The fumigator must be tested at least once each season and must be completely 
air-tight before fumigation is authorized. Leakage may be tested either by 
burning a piece of rubber (such as part of an inner tube about 1 foot long) in a 
pan or by pouring formaldehyde over potassium permanganate in a dish. In 
either case the container is to be raised above the floor to avoid danger of fire. 
If the rubber is used, leaks may be discovered by smoke issuing from the cracks. 
In the case of formaldehyde any odor of gas around the fumigator indicates 
leakage. The proportions for the formaldehyde test are: 12 ounces potassium 
permanganate crystals and 1 pint 40 per cent formaldehyde to 1,000 5 cubic feet. 
Methods. — Cyanide compounds and the gases they release are very poisonous, 
and if carelessly used jeopardize human life. Every precaution to avoid danger 
must be employed. 
The amount of calcium cyanide must be carefully calculated for the individual 
chamber concerned. Care must be taken to be sure that all cyanide used is fresh 
the same season and is prevented from losing its strength/ It should not be 
bought in large containers, as when exposed to the air even for a few minutes 
during removal of successive charges, the remainder loses its strength. 
Avoid delay in weighing out separate charges. The amount needed for a full 
charge of the box concerned should be determined and a measure should be 
prepared which will contain the exact full amount required for the charge. This 
can be done by cutting off a small can at the right height. 
* This is a change from the dosage formerly used. 
5 Corrected from the mimeographed edition of this circular. 
