102 WHITE FLIES INJURIOUS TO CITRUS IN FLORIDA. 
corresponding to that of A. citri, the statements made regarding the 
number of annual generations of A. citri is true of A. nubifera when 
the additional statement is made that the height of the various 
emergence periods occurs usually about two or four weeks later than 
the corresponding periods for A. citri. The emergence of adults 
brings about the same complications in broods and generations 
described for A. citri, resulting from variation in length of life cycle, 
and the double-brooded character of each generation is also to be 
found in the life history of A. nubifera. Of eggs laid August 23, 
1907, 1.5 per cent produced adults between October 1 and 15 and 63.2 
per cent between October 16 and 31; of the remaining pup wintering 
over, 34.6 per cent emerged between March 16 and 30 and 0.7 per cent 
between Aprilland15. From eggs laid September 4, 1907, 24 per cent 
of the adults emerged between October 16 and 31, 2.8 per cent between 
November 1 and 15, 71.8 per cent between March 16 and 30, and 1.4 per 
cent between Aprilland15. From eggs laid September 18, 1908, 81.6 
per cent of the adults emerged between March 16 and 30, 4.1 per cent 
between April 1 and 15, 10.2 per cent between April 16 and 30, and 
4.1 per cent between May 1 and 15. From eggs deposited March 29, 
1909, 44.5 per cent emerged between June 1 and 15, no further records 
being kept. 
It might be inferred from the slower development of A. nubifera 
that it would pass through a less number of annual generations than 
A. citri. This, however, is not true, inasmuch as its slower develop- 
ment is offset by its seasonal history—it remaining active later inv 
fall and early winter. 

SEASONAL FLUCTUATIONS IN THE NUMBER OF ADULTS OR SO-CALLED ‘‘Broops.”’ 
Because the generations of the cloudy-winged white fly are of the 
same general double-brooded character as those of the citrus white 
fly, and are subject to the same unexplainable variation in the 
length of the life cycle, the seasonal history of A. nubifera is not 
unlike that of A. citr? in nearly all essential features. In fact, the 
same three periods of general emergence of adults occur as with A. 
citri, but with the difference that the adults of each so-called “‘ brood” 
reach their numerical maximum usually from two to four weeks 
later than the corresponding broods of A. citri. In figure 19 are 
given curves representing the abundance of adults of A. citrt and A. 
nubifera at Orlando during 1909. As a result of this striking differ- 
ence in the seasonal history of these two species, previous observa- 
tions on this subject are considerably confused and should be disre- 
garded unless one is positive of the species under consideration at the 
time. As with A. citri, no one definite statement can be made to 
cover the exact time when the emergence of various broods will begin. 
Emergence is strongly influenced by local weather conditions. While 
the curve in figure 19 represents the condition in one Orlando grove 
