180 BUREAU OF PLANT QUARANTINE [April-June 
heater with open wiring was employed to bring up the temperature of the 
fumigation chamber during treatment and where a relatively high concentration 
of cyanide gas being generated from sulphuric acid and sodium cyanide came 
into direct contact witb such wiring. 
The commercial calcium cyanide prescribed in circular 337, in addition to 
being of the "slow-evolving type", has a content of 40 to 50 percent of pure 
calcium cyanide, and is of the so-called " granular type." 
VAPOR-HEAT TREATMENT FOR BULB FLIES 
It has been demonstrated by the Bureau of Entomology of this Department 
that the vapor-heat treatment properly applied will destroy all immature 
stages of the greater bulb fly, Mrrodon equestris. Based upon data furnished 
by that Bureau, the following method of treatment is authorized if desired in 
lieu of the hot-water treatment or fumigation for this bulb fly : 
Heating the bulbs contained in the tray in a chamber of approved design 
by means of conditioned air to a temperature of 110° F. at the approximate 
center of the bulb and holding them at that temperature for a period of 2 hours. 
The temperature to be determined by distance thermometers of an approved 
design in six or more locations in the treating chamber. 
The treating apparatus must be so constructed that the temperature of the 
bulbs is raised evenly to 110° F. with a variation of not more than 2° in the 
temperature in the air in different parts of the room at any time after it has 
been in operation 30 minutes. It must be equipped to maintain the temperature 
automatically after it reaches 110°, with a variation of not more than 1° from 
110° in the load throughout the treating period of 2 hours. The equipment 
must have sufficient capacity to heat a full load of bulbs from 60° to 110° in 
6 hours, and must be provided with facilities for maintaining the air circulated 
through the room saturated with water vapor without the presence of free 
water in the air. A heater, so that warm, dry air can be circulated through 
the load after the sterilization is completed, should be installed in the air 
conditioner. 
While the performance of equipment for applying this process and the dis- 
tance thermometers for determining the temperature will be carefully checked, 
and the equipment approved only after it is shown that it w T ill apply the 
treatment properly, the shippers will not be limited to any particular type. 
The general requirements for furnishing the proper conditions for this treat- 
ment are a source of steam at approximately 15 pounds pressure, an air 
conditioner, consisting of a blower of sufficient capacity, a conditioning cham- 
ber in which air. water, and steam can be mixed together to bring the air at 
the proper temperature to saturation, together with an automatic control 
for maintaining constant temperature. The blower must be of sufficient ca- 
pacity to force conditioned air at a temperature of 110° F. through the bulbs 
in large volume. At least four changes of air per minute through the treating 
chamber are necessary to provide the proper conditions for the treatment. 
The distance thermometers must be accurate to within one half degree 
Fahrenheit and of the type that will make possible reading the temperature 
of the bulbs in any part of the treating chamber within one half degree Fahren- 
heit without opening the chamber. The bulbs of these thermometers must 
be of such design that they may be inserted into the narcissus bulbs and so 
that the temperature at the approximate center of the bulb can be obtained. 
Distance thermometers calibrated for direct reading of the temperature in 
degrees Fahrenheit may be found easier to use than other types. Temperature 
readings should be made at 15-minute intervals and an accurate record of 
the temperatures maintained. 
Specifications for equipment which has successfully met these requirements, 
and information as to where the parts may be secured, will be furnished 
to State inspectors on request, and interested growers or dealers may secure 
sncl! information through them. Possible disappointment or loss through 
the purchase of equipment which might later prove ineffective may thus be 
avoided. 
TREATMENTS FOR EELWOBMS 
Hot-water treatment is to be supervised by the inspector. In case of insuffi- 
cient inspection personnel, an inspector may authorize the owner of the bulbs 
to proceed with treatment for limited periods in the inspector's absence, mak- 
