40 FUMIGATION FOR THE CITRUS WHITE FLY. 
the same as the surface area of such a figure, but rather the area of a 
circle with a diameter equal to the distance over the top of the tent 
from ground to ground. To a certain extent the folds in a tent when 
in position over a tree reduce this surface, but this is a factor of little 
consequence, as it i> present in all cases, and the portion of the tent 
folded so a- to prevent all leakage represents only a small percentage of 
the whole. For practical purposes, therefore, the leakage surface is 
calculated from the mathematical formula o.l416 multiplied by the 
square of the radius or 7tR 2 . The approximate height of the tented 
tree can be calculated from the following formula, in which C repre- 
sents the circumference of the tent at the base and O represents the 
distance over the top : H = - 9 + 9 —' 
The diameter is found by dividing the circumference by 3.141(3. 
The height and diameter having been obtained, the cubic contents of 
the regular figure mentioned can be calculated by the following for- 
mula : 7tll 2 I H — -5- )• The actual cubic inclosure of a tented tree will 
obviously always be more or less smaller than the regular figure to 
which this formula applies, although irregularities in shape will have 
a tendency to counteract one another. 
DOSAGE REQUIREMENTS FOR THE WHITE FLY. 
EXPERIMENTS WITH SHEET TEXT. 
Summary of results with regard to dosage. — In experiments to 
determine the dosage requirements for the white fly when using 
sheet tents, detailed records were made concerning each tree fumi- 
gated during the first season's work, including every factor which 
might influence the results. The main objects in view hi conducting 
the experiments were to determine the minimum dosage require- 
ments for destroying the white fly larvae and pupae, the rate of leakage 
of the gas through the cloth, the effect of moisture on efficiency of the 
treatment, the effect of the treatment upon the foliage under various 
conditions of moisture, the margin as to dosage between effective 
treatment for the insect and danger to the tree, and the effect of 
different proportions of water and acid. Observations on other 
points, such as effect of wind, sunlight, condition of foliage as 
affected by drought, etc., were made as opportunity afforded. All 
the experiments were conducted between January 12 and March 
1, 1907, inclusive, but observations as to results were continued for 
several weeks after the latter date. During this period practically 
" The results of the experimental work during the winter of L907 8 substantiate the 
conclusions derived from the work of the firsl season so far as the data up to this time 
completed show. 
