SUMMARY AND CONCLUSIONS. 71 
There is a wide margin in wliich natural enemies of the white 
flies may act, apparently with great activity, but with no practical 
benefit to the infested trees. The deceptive appearances thus 
explained have proved a serious hindrance to progress in white-fly 
control. 
It is when several factors concerned in producing mortality among 
the insects are combined that the most satisfactory results are 
apparent. 
Aside from unexplained mortality, fungous diseases are the most 
important agents of natural control. The brown fungus (JEgerita 
webberi Fawcett) and the red Aschersonia (AscJiersonia aleyrodis 
Webber) are, in the order named, the most effective parasites of the 
citrus white fly. The yellow Aschersonia (AscJiersonia jlavo-citrina 
P. Henn.) is the most effective parasite of the cloudy- winged white 
fly. The cinnamon fungus (Verticillium Jieterocladum Penz.) and 
the Sporotrichum fungus (Sporotrichum sp.) are of comparatively 
little importance. The red-headed scale fungus (Sphserostilbe cocco- 
pJiila Tul.) is rarely parasitic upon white flies, while the white-fringe 
fungus (Microcera sp.) is with little doubt normally saprophytic. 
The fungous parasites thrive only under suitable weather condi- 
tions during a period of about three months each year; generally 
speaking the summer months in the case of the two Aschersonias 
and the fall months in the case of the brown fungus. 
Their efficacy in destroying white flies under natural conditions 
is dependent upon the abundance of the insects; a period of exces- 
sive abundance always precedes effective temporary control. 
Much damage has resulted in the past from ill-advised attempts 
to check the spread of white flies in newly-infested localities by 
means of fungous parasites. 
The control of destructive diseases affecting citrus trees and fruit 
has been interfered with by fungous diseases and much preventable 
loss thereby incurred. This interference is due to the fear that the 
fungicides recommended for the diseases referred to would, if applied 
to the trees, check the white-fly fungus parasites with injurious results. 
Under natural conditions, without artificial assistance in spreading, 
the fungi have ordinarily, in favored localities, controlled the white 
fly to the extent of about one-third of a complete remedy through a 
series of years. 
The most successful method so far devised for introducing the 
red and yellow Aschersonias into groves where they do not occur is 
the spore-spraying method, first successfully employed and recom- 
mended by Dr. E. W. Berger. For the introduction of the brown 
fungus the brushing or dipping and the rubbing methods first used 
by the authors are as successful as any yet discovered, but are not 
