lOF FLORIDA CITRUS
OF FLORIDA CITRUS
JAMES E. BROGDON
FRED P. LAWRENCE
This circular is designed to help citrus
growers become better acquainted with
citrus insects and mites and their injuries.
Some beneficial ladybeetles and several
fungi are illustrated and discussed.
TOP-Russeting of oranges natural size caused by
citrus rust mites.
BOTTOM-Citrus rust mites, lt optruta oleivora
(Ashm.), magnified 15 times. These mites are so small that
they are difficult to recognize under a 10-porer magnifying
glass. They are lemon-yellow and w e-shaped. (See
further discussion of rust mam u lsAfiotographs on back
of this circular.)
FLORIDA AGRICULTURAL EXTENSION SERVICE
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
UNIVERSITY OF FLORIDA, GAINESVILLE
(MITES AND EGGS IN CIRCLES ARE MAGNIFIED 36 TIMES)
TOP.-Texas citrus mite, Eutetranychus banks (McG),
showing eggs, young, and adult female and male. The
adult female, about 1/60-inch long, has a shiny body
without conspicuous hairs. The color varies from tan to
brownish-green with dark brown to greenish spots or bars
near the lateral margins. The adult male, which has
longer legs than the female, has a somewhat triangular-
shaped body smaller than the female. The female lays flat,
disc-like eggs along the midrib and near the lateral margins
of the leaves. The eggs vary in color from light yellow
when laid to tan and green as they mature, turning to
reddish brown just before hatching. Newly-hatched mites
are light yellow to tan with pale legs. Populations of mites
are much heavier on the upper leaf surface. Injury to
leaves is caused by mites sucking out the juices which
may give the leaf a scratched or etched appearance as
shown above. Injury may result in collapse of leaf cells
and leaf drop, particularly during fall and winter. The
mites are most numerous May through July, but most
injurious October through February because of dry weather
and less vigorous tree condition.
BOTTOM-Citrus red mite (purple mite), Panonychus
citri (McG.), showing eggs, young, and adult female and
male. The adult female is about 1/50 inch long, rose to
deep purple in color with prominent light-colored hairs,
and lays a round, reddish-colored egg. Both eggs and mites
occur mostly on the upper leaf surface, but also are
found on the under surface and on green twigs. Eggs
laid on leaves are most abundant along the midrib and
petiole. The life cycle is short and there may be 12 to 15
generations per year. The mites are most numerous May
through July, but most injurious October through February
because of dry weather and less vigorous tree condition.
Leaf injury is similar to that of the Texas citrus mite.
(SCALES IN CIRCLES ARE MAGNIFIED 6 TIMES)
TOP.-Florida red scale, Chrysomphalus aonidum (L.),
and (BOTTOM) yellow scale, Aonidiella citrina (Coq.),
feed on leaves and fruit, preferring exposed surfaces. Their
feeding results in yellow areas on leaves and fruit which
may often be followed by heavy leaf and fruit drop. The
denuded branches may be killed the following fall and
winter. Inspections of groves should be made at intervals,
particularly from May through October.
The adult female Florida red scale is circular in outline,
about 1/12-inch in diameter, and dark reddish-brown in
color, with a conspicuous lighter-colored center. She lays
bright yellow eggs under her armor that produce bright,
lemon-yellow, oval-shaped crawlers. There are usually four
generations per year.
Yellow scale can be distinguished from Florida red
scale by the lighter color of its armor and the shape of
the scale body. The adult female is circular, yellow to
light orange in color and noticeably flatter than other
armored scales on citrus in Florida. The body, which
can be seen through the semi-transparent armor, is lemon-
yellow and kidney-shaped. No eggs are found, as the
females give birth to living young.
(SCALES IN CIRCLES ARE MAGNIFIED 6 TIMES)
TOP.-Black scale, Sassetia oleae (Bern.), as an adult
female is nearly circular, hemispherical, dark-brown to
almost black, with two lateral ridges and a longitudinal
ridge forming a pattern on the back resembling the letter
"H". She lays approximately 2,000 eggs in a cavity under
her body. The eggs are oval and pink in color changing
to reddish-orange before hatching. The light brown, flat,
oval crawlers travel about considerably before settling on
twigs or leaves and to some extent on fruit. Later the
young move from leaves or fruit to small twigs, particularly
stems that hold fruit. There are two or three generations
a year. Black scales excrete large quantities of honeydew.
BOTTOM.-Brown soft scale, Coccus hesperidum L., is
oval and flat, and light brown in color. No eggs are laid;
pale yellow crawlers are born alive. Young female and
male scales are similar in shape and color, but smaller
than adult females. These scales infest young twigs and
often gather along the midrib of the leaf. They are highly
parasitized by tiny wasp-like insects and rarely become
abundant except on young trees, either in newly-planted
groves or in a nursery, where ants feed on the honeydew
and drive away the parasites. Brown soft scales excrete
large amounts of honeydew.
CHAFF SCALE CITRUS SNOW SCALE
Chaff scale, Parlatoria pergandii Comst., forms
a light brown nearly round armor which is slightly
smaller than that of a mature female Florida red
scale. The eggs and crawlers are purple. This scale
infests leaves, wood and fruit where it causes green
spots which lower the grade. It is especially im-
portant on tangerines and early varieties of oranges
that must be degreened. Heavy infestations are
most likely to develop during late summer and
through the winter.
Citrus snow scale, Unaspis citri (Comst.), gets
its name from the white color of male scales.
Female scales are brown to blackish with a length-
wise, roof-like ridge. They are very difficult to see
against the tree bark. Scales are largely confined
to the trunk, limbs and twigs.
Florida wax scale, Ceroplastes floridensis
Comst., is a soft scale that is white to pinkish-
white when not stained by sooty mold or other
foreign matter. The adult female is 1/8-inch or
less in length, oval in general outline but present-
ing an angular appearance due to dome-shaped
masses of wax on the back. The pale-brown
crawlers collect on the lower leaf surface along
the midrib. Young larvae are star-shaped. This
scale is highly parasitized.
The orange dog, Papilio cresphontes Cram., is
FLORIDA WAX SCALE (MAGNIFIED 5 TIMES)
often a pest of citrus trees. Two or three may
defoliate a young tree in a few days. They are
most important on young trees and nursery stock.
The caterpillar is dark brown with light yellow
patches, growing to a length of 11/2 to 2 inches.
The front part of the body is enlarged and when
not feeding the caterpillar pulls the head back into
these large segments and causes the whole front
part of the body to resemble, somewhat, the head
of a dog-hence the name. The orange dog cel
push out a fold of skin back of the head which
forms two long, red, horn-like projections. This
organ gives off a strong, disagreeable odor which
repels natural enemies. The adult is a beautiful
large, yellow and black butterfly.
The broad-winged katydid, Microcentrum rhom-
bifolium (Sauss.), lays its eggs along the margin
of the leaf and there are several generations a
year. Other kinds of katydids occur in citrus
groves, but only the broad-winged kaydid is of
any economic importance. They sometimes feed
on the rind of growing oranges, causing large,
smooth sunken areas to develop on the fruit. Occa-
a lowering of grade. They may be present during
heavy infestations of mealybugs, and are sometimes
numerous on fruit with heavy infestations of
(LEFT TO RIGHT), BROWN STINK BUG, LEAF-FOOTED PLANT
BUG, AND BIG-LEGGED PLANT BUG
THREE TYPES OF HAND LENS USEFUL IN MAKING SCALE
AND MITE SURVEYS.
Suggestions on How to Inspect
A Citrus Grove for Mites
Some growers make periodic inspections for rust
mite, citrus red mite (purple mite) and Texas citrus
mite and apply the recommended materials only
when needed. When properly done, this procedure
is more economical and gives better control than
when miticides are applied by the calendar. Mites
often build up in certain areas of a grove. These
areas should be learned by the inspector and ex-
Travel through the grove to cover all parts of
the block. Some people use a figure "8", others
a "Z" pattern.
* Inspect at least 20 trees in a block (10 to 20
acres). Examine leaves and fruit from the north
side of the first tree, alternating the east, south
and west sides of succeeding trees.
* With a 10X lens, examine 5 full grown leaves
from terminals in the outer canopy of each tree
inspected. Examine one lens field on each surface
of each of these leaves for rust mite. Examine
entire surfaces of each leaf for citrus red mite
and Texas citrus mite. From spring to late
summer when the fruit is green, examine a
lens field on both the sunny and shady sides of
5 fruit for rust mite.
* If one or more mites are found on a leaf or fruit
it is counted as infested. Fifteen infested leaves
or fruit in 100 inspected indicates a 15 percent
* Records for rust mite should be tabulated
separately from citrus red mite and Texas citrus
mite. Such records should be maintained through
each growing season.
* In general, damage is likely to occur soon after
a mite infestation reaches 20 percent. Control
measures should be started when the mite in-
festation reaches 15 to 20 percent.
Since new pesticides are constantly being intro- i
duced, no attempt is made here to list specific
recommendations of insecticides and miticides.
Commercial growers should refer to the Better
Fruit Program Spray and Dust Schedule, while
growers of dooryard citrus may refer to Agricul-
tural Extension Service Circular 139B, Control .
of Insects and Diseases of Dooryard Citrus Trees.
These circulars may be obtained from your County (
Agricultural Agent or by writing to the Agricul-
tural Extension Service, University of Florida,
Appreciation is expressed to Marion Ruff Sheehan foi
the color illustrations, to Milledge Murphey, M. W. Tyler,
the Citrus Experiment Station and USDA for the phot
graphs, to workers of the College of Agriculture, Citi
Experiment Station and Agricultural Extension Service for
helpful suggestions used in the preparation of this c'
cular. Helpful information was taken from Agricultur.
Experiment Station Bulletin 591, Insects and Mites
Found on Florida Citrus; Bulletin 640, Mites Associated
With Citrus in Florida; and Florida Guide to Citrus
Insects. Diseases and Nutritional Disorders in Color.
(Originally Printed June 1955)
COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Agricultural Extension Service, University of Florida
United States Department of Agriculture, Cooperating
M. O. Watkins, Director