9() WHITE FLIES INJURIOUS TO CITRUS IN FLORIDA. 
infested area is not generally infested, and the same precautions 
‘ . . . . . . 
should be observed within this area as outside of it to avoid unneces- 
sary spread of the pest. 
FOOD PLANTS. 
The cloudy-winged white fly is not known in Florida to breed 
upon any other food plant than citrus. It has recently been dis- 
covered infesting the rubber trees (/"icus nitida) growing in the green- 
houses in Audubon Park, New Orleans. Extensive examinations 
for possible food plants have been made by the authors and by 
Dr. Berger, and it is reasonably certain that no important food 
plant will be found 
in’ Florida  citrus- 
growing sections 
which will interfere 
with the control of 
this species. 
Examinations of 
prickly ash (Yan- 
thoxylum — clava-her- 
culis), the most com- 
mon representative 
of the family Ruta- 
cee to which the 
citrus belongs, indi- 
cate that this species 
of white fly never 
breeds on this plant, 
regardless of the con- 
dition of infestation of neighboring citrus trees. Reports of blacken- 
ing of the foliage of prickly ash by the white fly in sections where 
only the cloudy-winged white fly of the two herein treated occurs, 
are doubtless erroneous and probably based upon the blackening due 
to an aphis or to some other insect. In addition the following plants 
have been examined under favorable conditions to determine if sub- 
ject to attack by the cloudy-winged white fly, but so far without 
results: 

Fic. 13.—Map showing distribution of the cloudy-winged white fly 
(Aleyrodes nubifera) in Florida. (Original.) 
China trees and umbrella China trees, cape jessamine, privets, 
Japan and wild persimmons, oaks, wild cherry, guava, fig, grape, 
cherry laurel, blackberry, and magnolia. 
SPREAD. 
The dissemination of the cloudy-winged white fly is limited by the 
same factors which have been discussed as unfavorable to the sue- 
cessful establishment of the citrus white fly. Aside from these factors 
