THE CLOUDY- WINGED WHITE FLY: LIFE HISTORY AND HABITS. 97 
Table XXI. — Duration of pupal stage of cloudy-winged white fly. 
Speci- 
men 
No. 
Period of growth. 
Num- 
ber of 
days. 
Sum of 
effective 
tempera- 
ture. 
Speci- 
men 
No. 
Period of growth.. 
Num- 
ber of 
days. 
Sum of, 
effective 
tempera- 
ture. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
May 24- June 11 
May 26- June 14........ 
May 26- July 19 
May 26 
18 
19 
24 
694 
741 
2,107 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
Oct. 12-Mar. 27 
Oct. 31-Mar. 23 
Nov. 1-Mar. 25 
Nov. 14-May 29 
Nov. 20-May 4 
Nov. 23-Mar. 28 
Dec. 3-Mar. 27 
Dec. 3-Apr. 29 
Dec. 7-Mar. 28 
Dec. 11-Mar. 24 
167 
23 
145 
196 
165 
125 
114 
147 
111 
104 
3,500 
2,893 
2,920 
5,102 
4,318 
2,981 
2,702 
3,662 
2,681 
2,476 
July 16 i-Aug. 2 
July 18-Aug. 5 
Oct. 9-Oct. 26 
Oct. 9-Oct. 28 
Oct. 9-Oct. 30 
Oct. 9-Oct. 26 . . 
17 
18 
17 
18 
21 
17 
689 
714 
466 
519 
562 
466 
1 It is to be regretted that the falling of the leaf upon which Nos. 5 and 6 matured prevented gathering 
data on the maximum length of stage at this season of year. 
GROWTH, MOLTS, LOCOMOTION, AND FEEDING HABITS. 
Concerning growth, molts, locomotion, and feeding habits, there is 
little to add to that already stated in connection with the larvae and 
pupae of the citrus white fly. The two species are alike as regards 
the number of larval ins tars and in their crawling and sedentary 
habits. Their manner of feeding is similar also, with the exception 
that when crowded the larvae of the cloudy-winged white fly settle 
freely upon the upper surfaces of shaded leaves, where they frequently 
reach maturity. 
MORTALITY AMONG LARV.E AND PUP^E. 
Remarks relating to mortality among the larvae and pupae of the 
citrus white fly apply with greater force to the cloudy-winged white 
fly. This mortality appears to result from the same causes in the 
latter as in the former species. Life-history work has shown that 
mortality due to spring droughts and dropping from leaves is prac- 
tically the same for the two species, but that general mortality 
including "unexplained" mortality is about 3 per cent higher for 
A. nubifera. In this last respect, however, observations throughout 
groves where infestation is much heavier than on leaves used in the 
life-history work, and counts of forms on leaves infested with both 
species of fly, show that the comparative susceptibility to the influ- 
ences producing mortality of all kinds is often at least twenty times 
greater for A. nubifera. This greater susceptibility appears to be 
due not only to the more delicate structure of the larvae and pupae and 
their need of more room for development because of their larger size, 
but also to the adults' habit of crowding the new growth with eggs 
far beyond its capacity for maturing the larvae hatching therefrom. 
As may have been inferred already from statements upon the sub- 
ject of oviposition, it is this insatiable desire of the adults for feeding 
and ovipositing on new growth that is a most powerful factor lead- 
ing to the insect's control. While a large amount of data might here 
59131°— Bull. 92—12 7 
