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380 WHITE FLIES INJURIOUS TO CITRUS IN FLORIDA. 
the senior author of the present publication; camellia, reported by 
Dr. E. W. Berger. In the case of the last two plants mentioned 
the uncertainty as to their proper standing is on the possibility of 
the insect reaching maturity thereon and not on the identity of the 
infesting species. 
The present status of the plants which have heretofore been listed 
by entomologists as food plants of the citrus white fly is shown in 
the foregoing paragraphs. There are doubtless numerous additional 
introduced species and a few additional native species of plants occur- 
ring in the United States which serve or are capable of serving as 
food plants of the citrus white fly, but for the reasons connected with 
the identification of the insects, stated in the opening paragraph under 
the subject of food plants, reports of food plants other than those 
included in classes I and II should never be credited unless verified 
by or made by an entomologist. There are no important food plants 
occurring in the Gulf coast region omitted from this list, and future 
additions to the list probably will be of little significance economically 
as affecting the control of the pest. There is a widespread belief that 
many other common trees, shrubs, and vines in Florida are food plants 
of the citrus white fly, but the correctness or falsity of this belief 
can be readily ascertained in the case of the individual plants sus- 
pected by submitting specimens of the foliage and of the infesting 
insect to the Bureau of Entomology or to theState experiment station. 
There are three common causes for erroneous reports concerning 
citrus white-fly food plants. The first is the presence of sooty mold, 
on many plants, due to other honeydew-secreting insects, such as 
aphides, scale insects, and mealy bugs. The insects themselves are 
not seen in this case and the mistaken idea is due to ignorance of the 
fact that other insects than the citrus white fly excrete honeydew on 
which the same species of sooty mold fungus thrives. The second 
‘ause for erroneous reports in this respect is the misidentification of 
the insect concerned. The necessity for the identification of the in- 
festing insect by an entomologist has been discussed. The third 
cause is the frequent occurrence of the adult citrus white fly on the 
foliage of plants upon which it does not breed and upon which it sel- 
dom or never deposits ‘an egg. In the course of the present investi- 
gation by the Bureau of Entomology several trees and shrubs have 
been thoroughly tested as possible food plants by cage experiments, 
and observations have been made on these and other plants, showing 
that if it is possible for the citrus white fly to develop on one of them, 
it is, at the most, of too rare occurrence to be of any significance. 
Cage tests have been made with oak (Quercus brevifolia), Magnolia 
(Magnolia fetida), blackberry (Rubus spp.), Laurel cherry or mock 
olive (Prunus caroliniana), and cultivated figs (icus carica) and crape 
myrtle (Myrtus lagertremia). In each case a rearing cage (Pl. VII) 
