96 
WHITE FLIES INJURIOUS TO CITRUS IN FLORIDA. 
DURATION OF INSTARS. 
Larval instars. — By comparing the data in Tables IX. and XX it 
will be found that the larva? of A. nubifera are slower in maturing 
than those of A. citri. While this difference is not so pronounced 
during the warmer months of the year, the total average number of 
days being 25.9 and 23.1, respectively, during the cooler months it is 
very striking, the total average number of days then being 56.7 for 
A. nubifera, as compared with 30.4 for A. citri. In other respects 
the statements made on the duration of the larval instars for A. citri 
apply to A. nubifera. 
Table XX. — Duration of larval instars of cloudy-winged white fly. 
Speci- 
men 
No. 
Period of growth. 
Number of days 
in — 
Sum of 
effec- 
tive 
tem- 
pera- 
ture. 
Speci- 
men 
No. 
Period of growth. 
Number of days 
in — 
Sum of 
effec- 
tive 
tem- 
pera- 
ture. 
In- 
star 
1. 
In- 
star 
2. 
In- 
star 
3. 
In- 
star 
1. 
In- 
star 
2. 
In- 
star 
3. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
June 26- July 19... 
June27-July 20... 
June 27- July 21... 
June 27- July 26... 
June27-July 19... 
June 27- July 21... 
June27-Julyl7... 
June 27- July 19... 
June27-July 20... 
do 
June 27- July 21... 
June 27- July 19... 
June 28-July 27... 
June 28-July 29... 
June 28-July 24... 
June 28-July — ... 
June 28-July 19... 
June 28-July 24... 
June 29- July 29... 
June 29- July 24... 
June 29- July 29... 
June 30- July 30... 
June 30-July 29... 
Sept. 30-Nov. 1... 
Sept. 30-Nov. 20.. 
Sept. 30-Nov. 30.. 
do 
9 
6 
8 
9 
9 
8 
7 
5 
7 
7 
7 
7 
14 
7 
11 
9 
6 
7 
6 
7 
8 
8 
12 
5 
8 
12 
14 
12 
8 
8 
8 
8 
6 
6 
6 
7 
7 
8 
6 
7 
6 
6 
6 
6 
8 
6 
8 
21 
6 
9 
15 
7 
8 
8 
7 
10 
16 
12 
15 
23 
10 
21 
13 
14 
8 
11 
10 
13 
6 
8 
7 
10 
10 
10 
11 
9 
7 
18 
7 
938 
942 
979 
1,179 
902 
, 979 
820 
902 
942 
942 
979 
902 
1,179 
1,260 
1,056 
33 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
49 
50 
51 
52 
53 
54 
55 
56 
57 
58 
59 
60 
Aver- 
age 
age. 
Sept. 30-Nov. 20.. 
Sept. 30-Nov. 23.. 
Sept. 30-Dec. 20.. 
Sept. 30-Dec. 3... 
Sept. 30-Nov. 23.. 
Sept. 30-Dec. 3... 
Sept. 30-Nov. 27.. 
do 
8 
11 
11 
8 
8 
11 
9 
8 
8 
9 
8 
8 
10 
7 
8 
9 
7 
8 
7 
11 
10 
10 
10 
10 
11 
11 
9 
66 
15 
12 
14 
19 
14 
12 
9 
14 
14 
11 
15 
14 
9 
9 
23 - 
10 
12 
9 
11 
18 
17 
16 
23 
15 
20 
20 
11 
died. 
28 
31 
46 
37 
32 
42 
40 
36 
42 
34 
48 
42 
47 
21 
26 
27 
27 
33 
28 
27 
35 
40 
28 
35 
33 
31 
18 
1,322 
1,401 
1,831 
1,670 
1,401 
1,670 
1,513 
1,513 
1,670 
1,513 
1,831 
1,670 
1,704 
1,060 
1,524 
1,235 
1,235 
1,332 
1,235 
1,414 
1,561 
1,662 
1,536 
1,510 
1,561 
1,561 
1,000 
Sept. 30-Dec. 3... 
Sept. 30-Nov. 23.. 
Sept. 30-Dec. 10.. 
Sept. 30-Dec. 3... 
Oct. 2-Dec. 7 
Oct. 2-Nov. 10.... 
Oct. 2-Nov. 30.... 
Oct. 2-Nov. 19.... 
do... 
9 
10 
9 
11 
14 
14 
10 
18 
28 
38 
33 
32 
17 
35 
40 
42 
861 
1,056 
1,222 
1,018 
1,222 
1,229 
1,188 
912 
1,322 
1,593 
1,593 
1,670 
963 
1,670 
1,593 
1,670 
Oct. 2-Nov. 23.... 
Oct. 2-Nov. 19.... 
Oct. 3-Nov. 27.... 
Oct. 3-Dec. 3 
Oct.3-Dec. 7 
Oct. 3-Dec. 2 
Oct. 3-Dec. 1 
Oct. 3-Dec. 3 
do 
Oct. 5-Nov. 11.... 
Oct. 5-Dec. 10.... 
) June 26- July 30... 
[Sept. 30-Dec. 10.. 
Sept. 30-Dec. 3... 
Sept. 30-Nov. 3... 
Sept. 30-Dec. 3... 
Sept. 30-Nov. 30.. 
Sept. 30-Dec. 3... 
8 
9.1 
7.8 
14.4 
10.1 
33.2 
1,031.7 
1,475.6 
Pupal instar. — That little difference exists between the .length of 
the pupal stages of the two species of white fly in question is shown 
by a comparison of the data in Tables X and XXI. The minimum 
length of the pupal stage (17 days) will average but a trifle above 
that of A. citri. But the maximum length is so dependent upon the 
seasonal history that a direct comparison is difficult; this subject, 
therefore, is more profitably discussed under the caption of seasonal 
history. What has been said in connection with the maturing of 
specimens of A. citri passing into the pupal stage at practically the 
same time is equally true of the cloudy-winged white fly, A. nubifera. 
