FLORIDA STATE HORTICULTURAL SOCIETY. 
91 
stage in a period varying from a little 
over four weeks to a period of thirty-five 
weeks, the maximum period being more 
than eight times longer than the min¬ 
imum period. The total periods from the 
deposition of the egg to the appearance 
of the adult in these two cases are 41 
and 256 days respectively. In other 
words, eggs of the White Fly deposited 
by the adult on July 15 may result in a 
few adult flies as early as Aug. 25, while 
some of the larvae will winter over and 
produce adults the following spring as 
late as the 20th of March. Our observa¬ 
tions show that the adult life under nor¬ 
mal outdoor conditions is about ten or 
twelve days, altho occasionally an indi¬ 
vidual may live for more than three 
weeks. Egg-laying usually begins within 
a few hours after the adult females reach 
maturity and continues usually at the rate 
of ten or 11 eggs per day throughout 
life. As near as we can estimate the av¬ 
erage number of eggs deposited by each 
adult female under normal conditions is 
in the vicinity of 100. In exceptional 
cases, however, individuals have been 
known to deposit more than twice this 
number. Previous to these investigations 
it has been generally considered that 
adults deposit twenty-five eggs or less and 
usually die in the course of three or four 
days. If this were correct the destruc¬ 
tion of adults would be of slight con¬ 
sequence even tho accomplished incidental 
to remedial work directed , primarily 
against the larvae and pupae. As it ap¬ 
pears from our studies, however, the de¬ 
struction of an adult even tho it has been 
depositing eggs for five days previously 
will probably prevent the deposition of up¬ 
wards of fifty eggs. This statement 
should not be considered as advocating 
the giving of particular attention to the 
destruction of adults; but only as show¬ 
ing the value of this when it can be ac¬ 
complished in connection with spraying. 
The foregoing facts concerning the life 
history of the White Fly are simply a 
brief resume of our records on some of 
the more important features. A bulletin 
will soon be prepared, giving full details 
of these studies and showing their prac¬ 
tical bearing on remedial work. 
NATURAL CONTROL. 
The subject of natural control is one 
of more than usual interest in the case 
of the insect under consideration. Its 
exposed condition, apparent vulnerability 
to attack by natural enemies, and the 
high degree of humidity in the citrus¬ 
growing regions of the Gulf states, favor¬ 
ing the effectiveness of fungus and bac¬ 
terial diseases, all give basis for the hope 
that complete control by natural enemies 
will be the eventual conclusion of the 
White Fly problem. 
So far the fungus diseases of the fly 
have been the most useful of the natural 
enemies; in certain favored sections of 
Florida, offering assistance to the orange 
growers amounting in a series of years 
to about one-third of a complete remedy. 
The important problem in this connection 
is to develop methods whereby thru arti¬ 
ficial means these fungus diseases can be 
relied upon to give satisfactory control. 
The experiments of the agents of the 
Bureau of Entomology, while extensive, 
and useful as adding to our understand¬ 
ing of the nature of these White Fly 
enemies, have not thus far contributed 
anything of value as a satisfactory 
method of this kind. The introduction 
into groves of these parasitic fungi is a 
comparatively simple operation under fa¬ 
vorable climatic conditions, and is to be 
