14 
NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 
important aids to the citrus white fly in regaining its normal abun- 
dance after it has been reduced by any cause. 
Grove No. 6 in Table II represents the general condition of trees 
in yards in Orlando aside from the groves 1 to 5. The important 
point shown by this is that whether the parasitic fungi were present 
or absent, the general condition in 1907 was practically the same 
throughout the city. 
The foregoing general observations led to a more detailed investi- 
gation of mortality from unexplained causes, and a large amount of 
data concerning the subject has accumulated. For the most part 
these data cover too great a range of conditions to be briefly sum- 
marized for this report. One series of observations, however, was 
made especially with a view to securing records under uniform con- 
ditions and sufficiently extensive to enable certain definite conclu- 
sions to be reached concerning this important subject. The data 
presented in Table II are based upon the examination of about 
275,000 insects found on 1,155 leaves. All but No. 6 represent 
citrus groves in Orange County selected on account ol the compara- 
tive abundance of fungous parasites, or because common reports 
placed a particularly high estimate on the effectiveness of the 
fungous parasites in them. In several cases it had been generally 
reported that the fungous parasites had brought the white fly into 
complete subjection. No. 6 includes a mixed lot of leaves from 
seven different points in the city of Orlando, representing town con- 
ditions. The first record was made by the senior author on October 
19, 1908, and the others were made by the junior author in Decem- 
ber, 1908. The leaves were 1908 growth, and mostly midsum- 
mer growth of that year. For convenience in the discussion the 
records in Table II are arranged in order of the percentage of unex- 
plained mortality. 
Table 
II.— St 
udy of 
causes 
of mortality of white flies near 
Orlando, Fla., in 1908. 
CO 
CD 
> 
>> 
i 
Leaf averages. 
Percentages of totals. 
CO 
3 
c3 
ft 
03 
CO 
Mfl . 
CD 
CD ~ 
— ' CD 
*$ 
a 
a 
3 
a, 
S 
o 
CO 
60 
§I« 
O >>c3 
CD CO 
a 
~T3 
6 
CD 
> 
o 
cd 
a 
3 
a co 
_ o 
e3 
O 
5-2 
^3 . 
M 
13 
X 
CD 

CO 
cd 
cu o 
CD 
a 
6 
CD 
Xi 
o 
CO 
T3 
cd 
<6 
PI 
2 
i 
E 
F-. c3 
X 
si 
O 
fc 
EH 
P 
H 
< 
P5 
^ 
W 
b 
EH 

CG 
1 
85 
8,813 
24.5 
24.5 
5.6 
49.1 
9.5 
0.05 
14.1 
0.0 
23.6 
23.6 
52.8 
2 
100 
6,541 
27.1 
34.0 
.7 
3.6 
.0 
41.2 
.0 
.0 
41.4 
52.0 
6.5 
3 
100 
10, 832 
1.7 
72.6 
2.0 
32.0 
.0 
1.6 
.0 
.0 
1.6 
67.0 
31.4 
4 
100 
13, 257 
19.2 
89.9 
3.4 
20.0 
4.0 
10.4 
.0 
.1 
14.5 
67.8 
17.6 
5 
100 
22, 922 
29.6 
157.2 
6.5 
35.9 
.38 
12.5 
.0 
.0 
12.9 
68.6 
18.5 
6 
85 
36, 841 
29.8 
306 
17.8 
80.6 
6.2 
.06 
.08 
.6 
6.9 
70.5 
22.6 
7 
100 
11, 944 
16.4 
91.8 
1.9 
9.3 
.4 
13.3 
.0 
.0 
13.7 
76.8 
9.5 
8 
100 
59, 728 
80.9 
469.5 
10. 4 
30.6 
12.5 
.05 
.03 
.9 
13.5 
78.7 
7.7 
9 
100 
28, 242 
43.9 
228.5 
1.7 
8.4 
5.8 
1.6 
7.9 
.2 
15.5 
80.9 
3.6 
10 
1C0 
46, 935 
84.2 
380.6 
2.8 
1.7 
10.1 
2.1 
5.2 
.5 
17.9 
81.1 
.95 
11 
100 
14, 702 
17.9 
119.2 
2.4 
7.5 
2.7 
9.4 
.0 
.1 
12.2 
81.1 
6.5 
12 
85 
19, 540 
9.7 
210.8 
1.1 
8.3 
.7 
2.1 
.6 
.9 
4.2 
91.7 
4.1 
Represented on leaves examined by empty pupa cases. 
