FLORIDA STATE HORTICULTURAL SOCIETY 
hi 
ing during December and January, about 
May 15, July 20, 'October 10. 
The winter brood of adults is very va¬ 
riable in the date of its appearance, and 
much prolonged. The writer found 
adults abundant in December, 1912, in 
Tampa, as did Mr. S. S. Crossman in 
1909. Back found them flying in Jan¬ 
uary, 1910. This year the maximum num¬ 
ber of adults apparently appeared about 
February 1 in Tampa. It should not be 
inferred, however, that the adults are fly¬ 
ing during the whole of these two months. 
Much depends upon the weather. Dur¬ 
ing a cool spell they do not emerge. 
It is to be noticed that during the sum¬ 
mer there is a brood about every ten or 
eleven weeks. This period is one or two 
weeks shorter than that for A. citri. For 
those adults of the winter brood that issue 
in mid-December the time of development 
is about the same, but if emergence is de¬ 
layed until February 1, the time is length¬ 
ened to sixteen weeks. The time between 
February 1 and May 15 is again about 
fifteen weeks, while for the eggs laid 
earlier than February 1 the time is pro¬ 
longed. This shortening of the time nec¬ 
essary to mature a generation, as com¬ 
pared with A. citri, together with the 
ability to develop and emerge during the 
winter months, enables A. howardi to pro¬ 
duce one more generation than is the rule 
with A. citri, and always the case with 
A. nubifera. The October brood is nearly 
coincident with the fall brood of A. nubi¬ 
fera, otherwise the broods do not coincide 
with those of either A. citri or A. nubi¬ 
fera. 
Damage. As in the case of the other 
whiteflies, the damage that this species in¬ 
flicts upon its host plant is of a three-fold 
* 
nature: (1), the withdrawal of sap from 
the tree; (2), the excretion of honeydew 
and the consequent growth of the sooty 
mold which interferes with the proper 
functioning of the leaves and necessitates 
vigorous washing of the fruit; (3), in¬ 
crease in the numbers of the purple scale. 
2. It seems to be a less favorable me¬ 
dium for the growth of the ordinary sooty 
mold (Meliola camelliae) than is that of 
A. citri. There are, however, a number 
of other fungi which develop in it. One 
is a Meliola with much larger fruiting 
bodies than those of the common sooty 
mold. Another is of a dirty green color, 
suggesting the common green mold Peni- 
cillium. These and other fungi mat up 
an old colony of howardi and give it a 
particularly dirty appearance. 
3. The third aspect of the infestation, 
the rise of the purple scale, is usually the 
most serious feature in the case of A. 
howardi. This phenomenon has been fre¬ 
quently noted in the case of the other 
citrus whiteflies, and has received a va¬ 
riety of explanations. For instance, in 
the Year Book of U. S. Department of 
Agriculture for 1908, it is said to be “a 
secondary result of the weakening of the 
citrus trees by the whitefly A. citri,” the 
idea of the author of that statement being 
perhaps that the trees that have been weak¬ 
ened by the whitefly, although, perhaps, 
having no more scales per unit of surface 
than strong trees, are less able to carry the 
drain on their vitality; or, perhaps, that 
scales breed more rapidly on or seek out 
injured trees. But some investigations 
by the author show that leaves covered 
with loose-fitting sooty mold have, on 
the average, -twice as many scales per 
