CONTENTS. 



Page. 



Introduction 7 



Conditions favoring or necessary to good results 9 



Isolation of grove . . . : -' 9 



Concerted action 9 



Absence or elimination of food plants other than citrus 9 



Season of the year 10 



Meteorological elements 11 



Size of trees and regularity of setting 14 



Equipment 14 



Tents 14 



Poles and uprights 20 



Miscellaneous requirements 22 



Chemicals 25 



Degree of piuity required 25 



Handling, and necessity for protection from moisture 25 



Proportion of water and acid 25 



Procedure - 27 



Methods of handling tents 27 



Measiu'ing trees 30 



Method of generating the gas 35 



Work routine 36 



Estimation of time reciuired for fumigation of grove 38 



Methods of computing approximate dimensions and cul)ic conlenls 39 



Dosage requirements for the white fly 40 



Experiments with sheet tent 40 



Experiments with bell or hoop tent , 49 



Miscellaneous experiments and observations 50 



Appearance of larva? and pupse of the white fly when destroyed by fumiga- 

 tion ■- 50 



Density of the gas at various heights above the ground 51 



Effect of fumigation on the trees 51 



Suggestions for the fumigation of small trees , ^ 54 



In the grove 54 



In the nursery • 54 



Niusery stock for shipment 54 



Precautions 55 



Expense of fumigation 56 



For equipment 56 



For chemicals 58 



For labor 58 



Economy of treatment by fumigat ion 59 



Losses prevented 59 



Cost of fumigation compared with spraying 62 



Fumigation versus natural control 63 



Appendix 66 



Table of dosage for the citrus white fly 66 



Index 69 



5 



