94 
WHITE FLIES INJURIOUS TO CITRUS IX FLORIDA. 
The duration of the egg stage, however, is in general slightly longer. 
As the bulk of the eggs hatch from 1 to 10 days later, a slightly higher 
number of degrees of accumulated effective temperature are neces- 
sary, and hatching is more evenly distributed though not always 
extending over a larger number of days. 
The process of hatching, proportion of eggs that hatch, and the 
effect of drying of leaves in hatching do not appreciably differ from 
what has been stated of A. citri; in hatching, however, the egg mem- 
branes split only about one-third the length of the egg from the tip 
and on one side only, and on account of the tougher chorion do not 
shrivel, but retain their original form. Frequently, after the larva 
has escaped, the membranes spring back into their original position, 
thus causing the eggs to appear unhatched; as a rule, however, this 
does not occur, and the opening made by the 
escaping larva does not close. While no adults 
have yet been reared from larvae hatching from 
infertile eggs, it has been proved that virgin 
females of the cloudy-winged white fly will 
deposit eggs and that these readily hatch and 
produce healthy larvae, and the evidence in 
case of the citrus and greenhouse white flies 
leaves no doubt that adults resulting from in- 
fertile eggs will prove to be of the male sex. 
The Larval and Pupal Stages, 
the larva. 
Fig. 15.— The cloudy-winged 
white fly: Ventral view of 
crawling larva of the first 
in star. Greatly enlarged. 
(Original.) 
The larva of the cloudy-winged white fly 
does not differ in general appearance from 
that of the citrus white fly except that it is 
a trifle larger. With the aid of the microscope 
the first instar may be separated from that 
of A. citri by the possession of 36 instead of 30 marginal bristles. 
No structural differences between the second and third instars of the 
two species have been discovered. Following is a more detailed 
comparative description: 
First larval instar (fig. 15).— Length, 0.29-0.32 mm. ; width, 0.19-0.22 mm. Similar 
to the corresponding instar of A. citri, but differing in being proportionately broader, 
in possessing 18 instead of 15 pairs of marginal bristles, and in developing soon after 
settling a marginal irregular wax fringe eventually equaling in width the length of 
the marginal spines. Relative length of marginal spines as follows: 
Pair 1 2 3 J_ _5_ 6 ? 7 8 ? 9 
Spaces 10.5' 7.5' 10.5' 8.5' 7. 0' 5.5' 6. 0' 5. 0' 6.0 
Pair 10 11 12 13 14 15 f 16 < 17 ^ 18 , 
Spaces 5. o' 5. 0' 5. 0* 5. 0' 5. 6. o 15. 5' 6. 5' 15. 5 
