O FUMIGATION FOR THE CITRUS WHITE FLY. 
During the last few years certain nurserymen in Florida have made 
use of fumigation against the white fly with good success, treating:, 
for the most part, small-sized trees. Other parties have tested fumi- 
gation on trees of all sizes, but, for lack of adequate equipment or of 
a knowledge of the most economical methods of procedure and dosage 
requirements, have not continued. 
In January and February, 1907, the writer, aided by Mr. Stephen 
Strong, formerly horticultural commissioner of Los Angeles County, 
Cal., specially appointed in this Bureau as fumigation expert, and 
Mr. A. C. Morgan, special field agent, temporarily transferred from the 
cotton boll weevil investigations, conducted careful experiments in 
Orange County, Fla., in order that fumigation for the white fly might 
be placed upon a practical basis. Modern California methods as 
adapted to all sizes of trees were employed and the principal results 
are embodied in the present bulletin. 
In December, 1907, and January, February, and March, 1908, 
fumigation experiments were continued by the Bureau of Entomology 
on a larger scale, testing the conclusions drawn from the work of the 
previous winter and extending the investigation to cover the ground 
more thoroughly. In this work the writer was assisted throughout 
the season by Messrs. W. W. Yothers and E. A. Back, and during the 
month of January Mr. K. S. Woglum was also engaged in the work. 
Altogether nearly 4,000 trees have been fumigated in Florida in 
this experimental work, under the immediate supervision of the 
agents of the Bureau of Entomology. It is too early to include in 
this bulletin more than the general results of the past winter's experi- 
mental work, but the text has been made to conform to these 
results as far as worked out. 
There remain many details concerning the fumigation process which 
have demanded investigation, and at the present writing these are 
receiving attention by agents of this Bureau who are conducting an 
exhaustive study of the matter in California. The present bulletin 
aims to give the results of experiments in fumigation for the white fly 
and such information and recommendations as are of immediate 
value to those who may contemplate the adoption of fumigation as 
a practice, or who may desire first to secure a small equipment in order 
to become familiar with the methods of procedure. The directions 
given herein are believed to be sufficiently detailed to enable any 
orange grower to conduct fumigation, after a few preliminary tests, 
without the assistance of experienced hands. The recently discovered 
occurrence of the white fly in California increases the importance of 
definite information concerning the requirements as to dosage. 
A new system for the estimation of dosage is recommended herein, 
as it is believed that the usual method of judging concerning the dosage 
requirements for scale-insects can not give the uniformity of results 
which should be obtained inusing this remedy against the white fly. 
