88 FUMIGATION FOR THE CITRUS WHITE FLY. 
He notes on the scratch pad the first reading and paces around the 
tent, noting on the pad the reading on the opposite end of the selected 
line. Upon reaching the starting point the distance over and the 
circumference — as, for example, 38-44 — are noted at once upon the 
diagram (fig. 3, D; figs. 4, 5). The dosage table is referred to and the 
amount of cyanid to be given is noted in the diagram below the figures 
noting the dimensions. The foreman or the man who determines 
the amount of chemicals then assists in measuring and introducing 
the chemicals, or if two other men are available for this work he pro- 
ceeds to the next tree and determines the dosage as before. 
The supply of water and chemicals for the set of tents is moved 
ahead as fast as the generating of the gas is started under each tree. 
The assistant, when working on the second set of trees, picks up the 
generating jars beneath the first trees recently fumigated and midway 
between the rows scoops out a hole with his foot or with a spade ana 
buries the contents of the jar. The foreman should never trust anr 
responsible part of the operation to an assistant whom he does not 
know to be reliable. He should thoroughly systematize the work so 
that no unnecessary hands will be employed while at the same time 
his entire outfit of tents will be utilized to the best advantage. 
ESTIMATION OF TIME REQUIRED FOR FUMIGATION OF GROVE. 
When two men can conveniently shift the tents, they can eoV;»'..a 
tree, take the measurements, and generate the gas without difficulty 
in about five minutes when not hampered by irregularities in 'the 
location of trees. This means that two men should be able to ha' idle 
9 or 10 tents in forty-five minutes with the methods herein recom- 
mended. Allowing fifteen minutes each hour for rest and restock- 
ing of the commissary tray with chemicals, two men begiming 
at 4 p. m. could fumigate about 75 trees by midnight. Tkrep men 
in the same time could easily fumigate 100 or 115 trees somewhat 
larger in size, or at the rate of 13 or 14 tents every hour. Four or five 
men should be able to fumigate each hour from 20 to 25 trees as large 
as can conveniently be covered by means of changing poles. When 
uprights are used a crew of six men, or possibly in some casesas many 
as eight, can work to best advantage. Such a crew shouLl handle 
from 10 to 15 tents 50 feet in diameter, or larger, every hour, including 
time for rest and restocking cart or tray with the chemicals 
With three men attending to determining the dosage andgenerating 
the gas and two men shifting t he tents, the trees being 1- to 15 feet 
high, the author with other agents of the Bureau in experimental 
work on one occasion fumigated 19 trees in thirty-live (oinutes. In 
one night a crew of six men have fumigated 221 budded/trees varying 
from 12 to 16 feet in height. In this case certain irregularities in 
the plan of setting the grove prevented a much better record. 
