THE CITKUS WHITE FLY I SPREAD. 43 
Dr. E. W. Berger has reported having observed a coffee tree thor- 
oughly infested with as many eggs on its leaves as citrus leaves may 
have. This food plant is too rarely grown in the Gulf States in 
orange-growing regions to be of any importance economically as a 
white-fly food plant. 
OCCASIONALLY INFESTED FOOD PLANTS. 
The plants listed in Class II as a whole are of very little importance 
as regards their bearing on white-fly control. Banana shrub, cherry 
laurel, and cultivated pear might well be considered in a third class 
for rarely infested plants. Although not uncommon, their attraction 
for the citrus white fly is so slight as to make it safe to ignore them 
except in the matter of introducing the fly on them into noninfested 
districts. In unpublished notes Dr. Berger has recorded the wild 
olive as a food plant. He has observed the wild olive infested in com- 
paratively isolated places. The junior author has observed wild olive 
heavily infested in Charleston, S. C, and in several places in Orange 
County, Fla. The wild olive, being an evergreen, if neglected may 
prove to be of considerable importance as a food plant when growing 
in abundance near a fumigated grove or when citrus trees have been 
defoliated by cold. 
Dr. Berger has recorded pomegranate, allamanda, and smilax as 
food plants, and has verified Prof. Gossard's record of Viburnum 
nudum as a food plant of the citrus white fly. The positions of 
these plants as regards their attractiveness to the citrus white fly has 
not been fully determined, and further observations will perhaps 
show one or more of them to be of fully as high if not of higher rank in 
this respect than the persimmons. In general, however, like the coffee 
and lilac of Class I, they are not of sufficiently common occurrence in 
the Gulf coast citrus-growing regions to be of much economic impor- 
tance as citrus white-fly food plants. 
SPREAD IN THE UNITED STATES. 
There is seldom positive evidence in regard to the means by which 
the citrus white fly has become established in a previously non- 
infested grove or locality. Such direct observations, however, as it is 
possible to make, aided by strong circumstantial evidence, give us a 
sufficient knowledge of the methods of spread to show the advisa- 
bility of certain restrictive measures. 
Checks on Successful Establishments. 
Fortunately the chances are greatly against the successful estab- 
lishment of the citrus white fly in a previously uninfested locality, 
which is outside the limits affected by large numbers of migrating 
