40 tfATUBAL CONTROL OF WHITE FLIES IN FLORIDA. 
control, bat clue weight should be given to the authoritativeness of 
common reports. Otherwise the confusion which arises becomes a 
decided hindrance to progress. 
OLDER ESTIMATES OF THE NATURAL EFFICACY OF FUNGOUS PARASITES. 
In some respects the subject of the natural efficacy of the fungous 
parasites of white flies is the most important subject dealt with in this 
bulletin. Common reports concerning this matter are so frequently 
erroneous or misleading, as has just been explained, that in addition 
to the specific observations and records to be given under another 
heading it is considered advisable to present here quotations from 
previous publications showing the status of the fungous parasites at 
different periods since their discovery and the views expressed by 
various writers concerning their efficacy. 
In a publication previously referred to, submitted for publication 
in March, 1897, Dr. H. J. Webber makes the following statement i 1 
The writer believes it may safely be assumed that the spread of Aschersonia aleyrodis 
and the brown mealy wing fungus will ultimately materially check the ravages of the 
mealy wing (white fly) and sooty mold. 
According to the publication mentioned, Dr. Webber knew of two 
instances of apparently satisfactory control resulting from the red 
Aschersonia and one such instance resulting from the brown fungus. 
Owing to the comparatively brief period of his observations and to 
the checking of both the white fly and its parasitic fungi by the 
freezes of December, 1894, and February, 1895, the fact that the 
parasites did not maintain a uniform state of control apparently 
had not come under Dr. Webber's observation at the time of writ- 
ing the report from which the quotation is taken. However, as a 
prediction his statement was doubtless fully warranted by the 
circumstances. 
The next investigator to give attention to the matter of the efficacy 
of the fungous parasites was Prof. H. A. Gossard. After more than 
four years of more or less continuous investigations and observations, 
noting the fluctuations from year to year in the abundance of the 
insects and of the parasites, he arrived (1903) at the following 
conclusion : 2 
I repeat emphatically that while I have no word of condemnation for the man who 
with intelligence and skill directs nature's agencies so that he secures results from most 
insects equal to the best (and we have some such in Florida), I believe that white fly 
is an insect that should be fought by everybody by insecticides from the day it is dis- 
covered in a grove. I admit that there is no spray that will kill white fly and not at 
the same time inflict injury to the trees, but I am satisfied that the injury is far less 
than white fly causes, except during exceptional periods when fungous diseases are 
unusually active. Infested trees that are properly sprayed through many years and 
i Bui. 13, Div. Veg. Phys. and Path., U. S. Dept. Agr., p. 34, 1897. 
2 Bui. 67, Fla. Agr. Exp. Sta., p. 626, 1903. 
