PRESS BULLETIN No. 298
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
COTTONY CUSHION SCALE
By J. R. WATSON
The cottony cushion scale receives its name from the fluted
white, cottony, egg-sac of the female. It is a native of Australia
from whence it was introduced into California in 1868. By 1880
it had spread into the orange sections of Southern California,
where it seriously threatened the entire industry. It was finally
conquered by introducing from Australia an enemy, a lady-beetle.
The insect was imported from California into Florida near
Clearwater in 1897. While it has never been as serious a menace
here as in California, it caused a great deal of damage until the
Australian lady-beetle was brought to Florida also.
Until found by the writer in Tampa in January 1912, it had
not been reported outside of Pinellas County. Since that time it
has been spreading rapidly, and is now found scatteringly over
Florida from Key West to Alachua County.
In view of the past history of the pest, it is urged that the
grower who finds it in his trees take energetic measures to con-
trol it. If unchecked, it is capable of killing the trees outright.
The cottony scale itself is brown and has somewhat the
appearance of a soft scale. When the egg-laying period arrives,
the female forms a large mass of cotton which elevates the pos-
terior portion of her body until she almost stands on her head.
This soft, cottony, cushion, in which the 500 to 800 eggs are laid,
may reach a length of nearly a half inch, and is ridged length-
ways. The adults are usually found on the bark of the trunk,
limbs, or twigs; but the young frequent the leaves, especially
along the sides of the midrib. The young look much like those of
the mealy bug, but when crushed they leave a red stain. Both
young and old have the mealy-bug habit of hiding in the crevices
and forks of twigs.
Besides citrus, the insects are partial to roses. The careless
shipping of cuttings about the State is probably partly respon-
sible for the rapid spread of the insect. It is abundant also on
wormwood, myrtle, mulberry, weeds and ornamentals. In the
Annual Report of the Florida Agricultural Experiment Station
October 26, 1918
for 1915, page LXXIV, there is a longer list of host plants. Any
one interested can obtain this report by addressing the Experi-
ment Station, Gainesville.
The cottony cushion scale can be controlled by spraying.
Efficient spray solutions are lime-sulphur and the oil emulsions.
For this insect it is best to use a lighter oil than commonly em-
ployed for the whitefly. At least one oil prepared especially for
the cottony cushion scale is on the market. As in the case of
mealy bugs, pressure is as important as the solution. To do
effective work one must have good pressure. On a few dooryard
trees, a frequent washing with a strong soap solution may be
The only permanent and satisfactory method of controlling
this scale in a large grove, is by the introduction of the Australian
lady-beetle (Vedalia). This is famous among entomologists as
the most successful case on record of combating an insect by the
importation of an enemy. It was imported into California in
1888 and quickly subdued the scale. In 1898 it was brought to
Clearwater, Florida, by the Experiment Station. It has lived
there ever since and has been introduced from there into other
localities in Florida.
Vedalia is much smaller than most of our native lady-beetles,
being only one-eighth inch long. It is of a cardinal-red color,
spotted and fringed with black. The larva; which also feeds on
the cottony cushion scale, is likewise red.
Vedalias are being supplied to the groves at the cost of
collection by the State Plant Board. If you find cottony cushion
scale in your grove and do not find Vedalia, write to Dr. E. W.
Berger of the State Plant Board, Gainesville, Fla.
Our native twice-stabbed lady-beetle does good work against
this as well as other scales, but it cannot be depended upon to
control the cottony cushion scale as well as the Vedalia does.
State Papers Please Copy.