36 FUMIGATION FOR THE CITRUS WHITE FLY. 



large box, and selected as needed to make up the proper dosage for 

 the trees as they are fumigated. It has been the writer's experi- 

 ence that the better plan is to weigh up the chemicals in the 

 field as fast as the dosage for the successive trees is determined. 

 Three times as many ounces of water (liquid measure) as of cyanid 

 is first poured into the jar. It is unnecessary to be exact in this 

 measurement, and a long-handled dipper of 16 ounces or 1 pint 

 capacity is preferable to the glass graduate. If, for example, 36 ounces 

 of water are required, two and one-fourth dipperfuls are poured into 

 the jar, dipping from the pail carried with the commissary tray. As 

 many ounces of acid as cyanid to be used is measured in the graduate, 

 being poured from one of the pitchers wdiich are carried in one end 

 of the commissary tray (Plate IV, fig. 1). 



Another member of the crew in the meantime arranges for the 

 proper dose of the cyanid and, with a lantern in hand when neces- 

 sary, raises the edge of the tent while the one who measures the acid 

 and water pours the acid into the jar containing the water, carries 

 the cyanid and generating jar under the tent (Plate VII, fig. 2), and at 

 arm's length empties in the cyanid. The jar should be placed about 

 halfway between the base of the tree and the edge of the tent. For 

 each 8 or 10 ounces of cyanid the generating jar should have a capacity 

 of 1 gallon. For very large seedling trees two 3-gallon, 4-gallon, or 

 even 5-gallon jars may sometimes be needed, while at other times one 

 3-gallon jar and one 2-gallon jar will be required for single trees, 

 although to avoid errors it is preferable to divide the dose evenly 

 between the jars when more than one are used. Wlien two jars are 

 used, they should be placed one on each side of the tree. The 

 operator holds his breath, as soon as the cyanid is dropped into the 

 generator, and as soon as he is outside the edge of the tent is dropped 

 into place, while the violent boihng of the chemicals, as the gas is 

 generated, can be distinctly heard for several minutes. The cyanid 

 should be added as soon as possible after adding the acid, for the 

 heat evolved by the acid and water at the time of mixing is neces- 

 sary for the rapid generation of the gas. The man who measures the 

 acid and generates the gas should have his hands protected by loose- 

 fitting rubber gloves and should avoid being too close to the jar 

 when pouring in the acid. He should never touch the tent while 

 wearing the gloves unless they have been thoroughly rinsed in water. 



WORK ROUTINE. 



The systematic arrangement of the details of the procedure is of 

 great importance in fumigation. The plans of work vary consider- 

 ably with different fumigators, but it is the purpose in all cases to fol- 

 low such work routine as will keep all hands constantly employed. 

 In California from two to six men are employed in each outfit accord- 



