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not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
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site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
IwA wadt Mt&
OF FLORIDA CITRUS
JAMES E. BROGDON
FRED P. LAWRENCE
TOP-Russeting of oranges (1/2 natural size) caused by
citrus rust mites.
BOTTOM-Citrus rust mites, Phyllicoptruta oleivora
(Ashm.), magnified 15 times. These mites are so small that
they are difficult to recognize under a 10-power magnifying
glass. They are lemon-yellow and wedge-shaped. (See
further discussion of rust mites under photographs on back
of this circular.)
Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
This public document was promulgated at an annual
cost of $842.00 or $.084 cents per copy by the Uni-
versity of Florida Institute of Food and Agricultural
Sciences to help citrus growers become better ac-
quainted with citrus insects and mites and their in-
juries. Some beneficial ladybeetles and several fungi
are illustrated and discussed.
(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
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.
TOP.-Upper surface of leaf showing early six-spotted
CENTER.-Injury to underside of leaf. (Mites and eggs
in circle magnified 36 times.)
BOTTOM.-Upper surface of leaf showing severe six-
spotted mite injury. (Leaves are 1/2 natural size.)
Six-spotted mite, Eotetranychus sexmaculatus (Riley), is
about 1/50-inch long, pale grayish-yellow in color, and lays
a round, yellowish-white egg. It usually has four or six
dark spots arranged in two rows on the body. With a 10-
power magnifying glass, the spots are barely visible on the
adult mites and few or none can be seen on the young.
Mites and eggs are found in colonies, often covered with a
webbing, and located only on the under surface of the
leaf. Feeding causes yellow or chlorotic areas, usually along
the veins, and results in leaf drop. These mites are usually
most numerous March through May, but may build up in
January and February after a cold December. Although
grapefruit varieties are preferred, they can be found on other
types of citrus. Inspections should be made with a mag-
nifying glass, although the yellow spotting of the leaves can
be seen with the naked eye.
,f ro I
(SCALES IN CIRCLES ARE MAGNIFIED 6 TIMES)
TOP.-Glover (long) scale, Lepidosaphes gloverii (Pack.),
and (BOTTOM) purple scale, Lepidosaphes beckii (Newm.),
are very similar in appearance and habits, but Glover scale
is longer and narrower. These scales feed on leaves, fruit
and wood, and are often overlooked because they are found
primarily on the inside of the tree and on the wood. They
like shady areas such as the under surface of leaves and
collect especially along the midrib and at the base. Resi-
dues of any type encourage heavier infestations. Yellow,
chlorotic areas on the leaf result in defoliation and subse-
quent twig death. Infestations on the fruit, particularly
near the stem end, cause fruit loss, as well as green spots
which can not be removed in the coloring room. Inspections.
of groves should be made at intervals, particularly prior to
post-bloom and summer spray periods.
The female purple scale lays grayish-colored eggs in a
sac-like enclosure under her armor, while Glover scale eggs
are pink in color and found in two rows. Crawlers of both
scales are oval and have an off-white color with a posterior
brown tip. Peaks of young stages occur in March-April,
June-July and September-October.
Cd, 0 Ii
(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, partic-
ularly 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
female is nearly circular, hemispherical, dark-brown to al-
most 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 para-
sitized 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
(SCALS INCIRCLS AR MAGIFID6TMS
TOP.-lc clecmlx Ssei pp h dl
TOP LEFT (enlarged 10 times).-Cloudy-winged white-flies,
Dialeurodes citrifolia (Morg.), with immatures and eggs.
The eggs, which are commonly laid on young leaves, are
yellow when first laid but soon turn dark. The surface of
the egg is netted with ridges. The flat transparent larvae
(young) settle on the under surface of the leaves. The
citrus whitefly, Dialeurodes citri (Ashm.), and the woolly
whitefly, Aleurothrixus floccosus (Mask.), are also common
on citrus. There are others of lesser importance. Peak
broods of whiteflies usually occur about March-April, June-
July and September-October.
TOP RIGHT.-Sooty mold fungus, Capnodium citri Berk.
and Desm., develops primarily on the sweet, syrupy ex-
cretions (honeydew) of immature whiteflies, but to a lesser
extent on the honeydew of aphids, mealybugs, and certain
soft scales. Control of these insects will prevent the
development of this fungus.
BOTTOM.-Red Aschersonia (left), Aschersonia aleyrodis
Webber, and brown whitefly fungus (right), Aegerita webberi
Faw., are beneficial fungi that kill immature whiteflies. The
latter is often mistaken for Florida red scale. (Both one-half
( ., ..
LEFT CENTER AND TOP.-Aphids (magnified 10 times)
and aphid injury to young growth. Aphids, or plant lice, are
particularly injurious to young trees. The green citrus or
spirea aphid, Aphis spiraecola Patch., is the most common.
Others including cotton or melon aphid, Aphis gossypii
Glover, black citrus aphid, Toxoptera aurantii (Fonsc.), and
green peach aphid, Myzus persicae (Sulz.) are found at
times. Ants feed on a sweet, syrupy excretion (honeydew)
of aphids and may move them around, aiding in their spread.
Aphids injure young tender growth in the spring, especially on
temples and tangerines, causing leaves to curl. Inspect for
these insects at frequent intervals when new growth starts,
especially during the spring months.
TOP RIGHT.-Cottony-cushion scale, Icerya purchase
Mask. (about twice natural size), is most damaging to young
trees. It is usually kept under control on citrus by the
vedalia or Australian ladybeetle, Rodolia cardinalis (Muls.),
shown feeding on the scale. The large illustration of the
vedalia ladybeetle is magnified 6 times.
BOTTOM ROW (all magnified 5 times).-Left to right:
Twice-stabbed ladybeetle, Chilocorus stigma (Say); lady-
beetle larva; covergent ladybeetle, Hippodamia convergens
Guer.; blood-red ladybeetle, Cycloneda sanguine (L.). Lady-
beetle adults and larvae feed on many citrus pests, in-
cluding scales, aphids and mites.
RUST MITES AND EGGS MAGNIFIED ABOUT 20 TO 25 TIMES
Citrus rust mites, Phyllocoptruta oleivora
(Ashm.), are so small (about 1/200-inch long)
that they cannot be recognized with the unaided
eye. Under a 10-power magnifying glass they
appear as lemon-yellow, wedge-shaped objects,
but distinct features cannot be seen. Rust mites
can be seen more easily on green leaves and
fruits than on ripe fruits. A heavily-infested leaf
appears to be fuzzy or dusty. Eggs of whiteflies
are often mistaken for rust mites. The life cycle
requires only about a week in summer, which ac-
counts for the rapid build-up often noted.
Rust mites infest leaves, fruit and tender green
shoots, causing russeted or rusty-colored fruit.
Heavily-infested leaves lose their gloss and dark-
green color and may drop prematurely. Heavy
infestations may develop on the leaves just be-
fore bloom and cause severe injury to young
fruits soon after they are set. Rust mites seem to
prefer exposed locations and are numerous in
the tops of trees. They are more numerous on
fruit from spring until late summer. Inspect the
fruits and underside of leaves with a magnify-
Melanose, a fungus disease, causes blemishes
on citrus fruit often confused with russeting or
rust mite injury. Lesions caused by the melanose
fungus are blacker, more rounded and raised,
RUST MITE AND EGGS GREATLY MAGNIFIED
and have a rough or sandpapery feel. Scab,
another fungus disease, causes spots that are
usually rougher, larger, more irregular and
lighter in color than rust mite injury.
Citrus mealybug, Planococcus citri (Risso), lays
its eggs in a mass of cotton which it secretes.
Mealybugs are often confused with cottony-
cushion scale. They also excrete large amounts
of honeydew in which sooty mold fungus (see
other side of circular) develops. They may get
into crevices in the bark on the limbs and trunk
and in such sheltered places as the angle be-
tween the petiole of the leaf and stem. Mealy-
bugs often collect around the stem end and
under the button (calyx) of the fruit (especially
grapefruit) and cause fruit drop. Another favor-
ite place for mealybugs is the sheltered area
formed by clusters of two or more fruits, partic-
ularly grapefruit. Controls should be applied
before mealybugs have settled under the fruit
MEALYBUGS (NATURAL SIZE) ON FRUIT
MEALYBUGS MAGNIFIED APPROXIMATELY 5 TIMES
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 Flor-
ida 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
specially important on tangerines and early var-
ieties 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
lengthwise roof-like ridge. They are very dif-
ficult 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 pre-
senting 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.
FLORIDA WAX SCALE (MAGNIFIED 5 TIMES)
The orange dog, Papilio cresphontes Cram., is
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 1 /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 or-
ange dog can push out a fold of skin back of the
head which forms two long, red, horn-like pro-
jections. This organ gives off a strong, disagree-
able odor which repels natural enemies. The
adult is a beautiful large, yellow and black but-
The broad-winged katydid, Microcentrum
rhombifolium (Sauss.), lays its eggs along the
margin of the leaf and there are several gen-
erations a year. Other kinds of katydids occur
in citrus groves, but only the broad-winged katy-
did is of any economic importance. They some-
times feed on the rind of growing oranges, caus-
ing large, smooth sunken areas to develop on
the fruit. Occassonally they cause severe de-
foliation of young trees.
Grasshoppers (several species) may be found
in citrus groves, causing injury to fruit and foli-
age. Eggs are laid in the ground and, after
hatching, young nymphs may migrate to the
cover crop and trees in the grove. Injury is most
important on young trees. In some instances
they have completely defoliated newly set trees.
The eastern lubber grasshopper, Romalea micro-
ptera (Beauv.), produces one generation per year
BROAD-WINGED KATYDID (TOP)
AND LUBBER GRASSHOPPER (BOTTOM)
and may be found during spring and summer
in groves adjacent to low,marshy land.
True bugs of several kinds, including stink
bugs and leaf-footed plant bugs, puncture the
fruit rind, often causing premature color break
EGGS OF THE BROAD-WINGED KATYDID
and drop. They may cause considerable dam-
age to all varieties of citrus but injury is most
common on tangerines and early and midseason
oranges. These insects move to mature or nearly
mature fruit from host plants in or near the grove,
particularly when the cover crop is chopped or
is beginning to dry up or harden. Pods of legu-
minous cover crops, such as beggarweed and
crotalaria, as well as the citron melon, are at-
tractive to these pests and often induce heavy
Fuller's rose beetle, Pantomorus cervinus
(Boh.), gray-brown in color and 1/4- to 1/3-inch
in length, and the citrus root weevil, Pachnaeus
litus (Germar), blue-green in color and 1/2- to
3/4-inch in length, may occur in sufficient num-
bers to cause severe injury to both roots and foli-
age of all varieties of citrus. Injury from these
pests has been noted most commonly along the
Florida east coast. Growers should familiarize
themselves with these insects and the injury
symptoms of both the larval and the adult stages.
Injury by the larval stage is by far more ser-
ious than injury by the adult stage. The legless
white larvae of both species eat canal-like chan-
nels in the roots. This injury is usually more
prevalent on the underside of the lateral roots,
although where high populations occur many
primary roots may be girdled near the main
trunk root. Adult injury to leaves typically ap-
pears as notches cut out along the leaf margin.
Injury is usually more prevalent on the lower 6
feet of trees and on leaves of sprouts near the
main trunk. Adults also feed on small fruit dur-
ing and shortly after bloom.
Ants (several species) are found in citrus
groves. Some may cause injury to newly-budded
trees in the nursery; others are a nuisance to
pickers. Ants may damage the trees indirectly
by protecting and caring for scale insects, aphids
and especially mealybugs. Ants carry them from
place to place and feed on the excreted honey-
Termites sometimes damage citrus trees, espe-
cially young trees banked for cold protection. If
banking soil contains cellulose material, such as
roots, chips and paper bags, termites may attack
this material and later injure young trees.
The pink scavenger caterpillar, Sathrobrota
rileyi (WIsm.), is a small caterpillar with a deep
wine-red abdomen, brownish head and black
mouth parts. It has a dark brown area just be-
hind the head. The pink scavenger worm feeds
primarily on dead insects and decaying areas of
fruit, but also may feed on the rind of sound
fruit, causing a lowering of. grade. They may
be present during heavy infestations of mealy-
bugs, and are sometimes numerous on fruit with
heavy infestations of scales.
(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 examined first.
* 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 1OX 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
* 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 infestation reaches 15 to 20 percent.
Since new pesticides are constantly being in-
troduced, no attempt is made here to list specific
recommendations of insecticides and miticides.
Commercial growers should refer to the Current
Citrus Spray and Dust Schedule, while growers of
dooryard citrus may refer to Cooperative Ex-
tension Service Circular 139-H, Control of Insects
and Diseases of Dooryard Citrus Trees. These
circulars may be obtained from your County Ex-
tension Agent or by writing to the Cooperative
Extension Service, University of Florida, Gaines-
Appreciation is expressed to Marion Ruff Sheehan for
the color illustrations, to Milledge Murphey, M. W. Tyler,
the Citrus Experiment Station and USDA for the photo-
graphs, to workers of the College of Agriculture, Citrus Ex-
periment Station and Cooperative Extension Service for
helpful suggestions used in the preparation of this circular.
Helpful information was taken from Agricultural 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)
Cooperative Extenson Service, IFAS, University of Florida
and United States Department of Agriculture, Cooperatng
Joe N Busby, Dean