FLORIDA ,STATE HORTICULTURAL SOCIETY. 
Q 
90 to 95 per cent, were killed. Preliminary 
chemical examination of Golddust showed that 
it consisted of about 25 per cent, of soap, 62 
per cent, of washing soda, and about 13 per cent, 
of water. One part of whale oil soap with three 
parts of washing soda gave practically the same 
result as Golddust, when each was used in the 
proportion of 1 pound to 4 gallons of water. One 
pound of whale oil soap to 9 gallons of water 
gave practically the same result as the whale oil 
soap and soda mixture, at about the same cost, 
which was a little less than half a cent per gal 
Ion. Whale oil soap is therefore a cheaper ma 
terial to use for spraying than Golddust. A mix¬ 
ture equally good as Golddust can foe made 
from whale oil soap and washing soda at about 
one-half the cost. 
Dr. E. A. Back. 
Mr. President, Ladies and Gentlemen : 
Dr. Back: I regret very much that 
the transfer of Mr. Yothers to other in- 
» 
vestigations makes it impossible for him 
to be with us this evening. I also regret 
that the shortness of time at my disposal 
since I knew that I was to take his place 
on the program, and press of work has 
made it impossible for me to prepare such 
a paper covering the various phases of 
the whitefly investigations undertaken by 
the federal government, as your program 
indicates. 
Since Dr. Morrill presented his paper 
before you two years ago, the investiga¬ 
tion of the life-history of the citrus and 
the cloudy-wing whiteflies, and their 
control by fumigation, spraying, and nat¬ 
ural agencies, such as fungi and possible 
bacteria, have been continued, and our 
results, aside from spraying, are now 
largely in manuscript form ready for pub¬ 
lication. I will, therefore, not dwell at 
length upon these but state briefly that 
we still believe that fumigation, when 
conducted under favorable conditions, is 
the best and cheapest method of controll¬ 
ing the fly; that control by fungi will very 
seldom prove satisfactory unless Florida 
weather conditions change very much? 
from those of the past five years; and that 
often a very large percentage of the death 
rate of either species is due more to pos¬ 
sible bacteria than to known fungi. There 
has accumulated evidence to sustain the 
belief that bacteria are even more valuable 
in controlling the fly than known fungi. 
It is difficult to explain in any other way 
the wholesale destruction of the fly in a 
grove where little or none of the known 
fungi exist. For a better term, Dr. Mor¬ 
rill and myself have used “unexplained 
mortality” in referring to this kind of 
death rate. 
At the present time, the agents of the 
Bureau of Entomology are giving special 
attention to insecticides and spraying. 
Spraying operations on a large scale are 
being carried on and gratifying results 
already have been obtained. A separate 
report on spraying will be issued at the 
completion of this work. 
Instead of a paper, I have decided to 
read certain extracts from our manu¬ 
script which give some of the results of 
our spraying work with fungi. While 
these are not in connected form, they will 
answer questions that are being asked us 
every day. After reading these, I will 
