44 NATURAL CONTROL OF WHITE FLIES IK FLORIDA. 
condition in July, but in December the average number of dead 
larvae and pupae was found to be 61, live larvae and pupae 11.9, and 
pupa cases 5.1. This would indicate at least a slight blackening of 
the leaves by the end of the year, judging from the effects of a lighter 
infestation in the case of No. 4 as noted above. To a casual observer 
this fairly satisfactory condition might appear to have resulted from 
fungous diseases. As a matter of fact the fungous diseases had no 
appreciable effect. A fairly high average number matured per leaf 
in the spring of 1909, but very few eggs were deposited on the citrus 
trees. This appeared to be due to the emergence of the insects 
before the appearance of new growth on the citrus trees and as a 
consequence the attraction of the adult white flies to other food 
plants, persimmon and China trees, having new foliage. An examina- 
tion of a persimmon tree growing in the midst of the citrus trees on 
this property showed 8 times more larvae and pupae per leaf than on 
the leaves from surrounding citrus trees. If fungous diseases had been 
concerned in the reduction of the infestation of the citrus trees the 
July examination of the spring growth would have shown this. The 
examination of 100 leaves picked at random showed that an average 
of 0.37 white flies of the first generation had matured and that of 
this generation an average of 0.1 5 per leaf showed infection by fungous 
diseases. These, with a very small average of less than 1 per leaf 
dying from unexplained causes, represented the entire first generation 
as shown by the examination of the leaves. 
The July examination of No. 9 showed that an average of 0.2 white 
fly per leaf of the first generation had matured and that 0.46 per 
leaf was infected with fungous diseases. This low average of infec- 
tion could not have had any appreciable effect on the normal increase 
of the insects, and it is obvious that in this grove the comparative 
freedom of the foliage from blackening was not due to the fungous 
diseases. 
The very excellent condition as to white-fly infestation of grove 
No. 10 during the season of 1910 may be properly credited to the 
effective work of the fungous diseases after midsumer in 1909. The 
trees suffered so severely during 1909 from the excessive infestation 
that their unthrifty condition was noted at the time of the examina- 
tion in July, 1910. 
In No. 12 it was found, on July 1, that an average of 0.2 per leaf 
of the first generation had matured, while 0.74 forms of this generation 
showed fungous infection. As shown by Table II, the reduction in the 
number of the insects in this grove in 1908 was due almost entirely 
to an excessive rate of mortality from unexplained causes, fungous 
diseases being comparatively insignificant. As regards the cause for 
the failure of the live insects found in December, 1909, to multiply 
normally, No. 12 must be classed with No. 9. In both these cases 
the explanation is probably similar to that in the case of No. 8. 
