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Copyright 2005, Board of Trustees, University
PRESS BULLETIN 212
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
THE CUBAN OR WOOLLY WHITEFLY
By J. R. Watson
A few years ago there was brought to Tampa and Miami a Cuban
whitefly. From Tampa it has spread west to St. Petersburg, south to Arcadia
and Fort Myers, and east to Winter Haven. Until lately no cases of heavy
infestation have occurred. A wasp-like parasite has killed a large percent-
age of the larvae. Investigations in Cuba showed that the woolly whitefly
was not a severe pest there. These facts led us to hope that it would not
become a severe pest in Florida; but lately it has developed to such an
extent as to assume somewhat alarming proportions, and a warning notice
to growers is needed. In the area above-mentioned this whitefly is becoming
more abundant, and in one grove in Lakeland it is doing more damage than
the common citrus whitefly ever did.
SFrom the common whitefly (Aleurodes citri) and the cloudy-winged
whitefly (A. nubifera) this one (A. howardi) is easily distinguished by the
woolly or cottony growth which entirely covers the larvae, except when very
young, and makes them quite conspicuous. This woolly covering may reach
a thickness of an eighth of an inch or more. The larvae give off abundant
honeydew which is not thrown away from them as thoroughly as with A.
citri, but collects in shining drops in the wool, making the under side of
the leaf appear as if coated with frost or snow.
There is a- fourth species of whitefly in the State which is frequently
confused with the woolly whitefly. This (Paraleyrodes perseae) may be
called the bay or waxy whitefly. Its larva is furnished with short rods
of wax which, when broken and scattered over the surface of the leaves,
make it resemble somewhat the woolly whitefly, but on a closer inspection
the two may be easily distinguished. The wax rods of the bay whitefly are
short and nearly straight, forming a thin coating of no appreciable thickness.
The "wool" of the woolly whitefly is curled and long enough to form a cushion
or mat. The bay whitefly is a native species, common in most groves, but
The larva of the woolly whitefly, when divested of its woolly coat,
measures less than tlh larva of the citrus whitefly as far as length and
breadth are concerned, but is distinctly thicker. It is yellowish brown.
The adult is smaller, more yellow, and is distinctly more sluggish than
the citrus whitefly, not taking wing unless the leaf is jarred. While laying
eggs, the female anchors herself by her sucking mouth-parts and rotates
about the anchorage as a pivot, depositing the eggs moslty in circles about
an eighth of an inch in diameter.
The food preferences of this species for different varieties of citrus are
apparently the reverse of those of the citrus whitefly in that grape fruit
seems to be its first choice and oranges second, while tangerines come
last. The woolly whitefly has been found on no food plant other than
Eradication and Control
In many of the towns in the infested territory there are as yet only
small colonies on dooryard trees. Many of these colonies it should be
possible, to stamp out by prompt action. The groups of larvae are so
conspicuous that it would not be an arduous task to pick off all the infested
leaves from the trees, and thus destroy the colony. Indeed, the writer ap-
parently did so eradicate a small colony in a grove near Tampa. A little
time spent now may save a great deal of trouble later on. While we have
had little experience in spraying for this pest, it would seem that one of
the miscible oils or whale-oil soap, if applied while the larvae are young,
should be effective; but the older larvae are so protected by the collection
of honeydew that it is difficult to reach them with a spray. The larvae are
now in the most favorable condition for spraying.
Although the red Aschersonia has been found on this species, both in
Florida and in Cuba, it is much less effective.than with the citrus whitefly
and cannot be depended upon for control.
As we are anxious to keep a record of the distribution of the woolly white-
fly the Entomologist requests the growers to send him specimens of leaves
that are suspected of harboring this insect. To prevent the possibility of
spreading the pest, the leaves should be inclosed in a tight bottle or box
with a few drops of alcohol, chloroform, ether, or gasoline, and left for an
hour or so, after which they may be taken out and safely mailed in a letter.
State papers please copy.