• TABLE OF CONTENTS
HIDE
 Copyright
 Title Page
 Board of control
 Table of Contents
 Injurious insects
 Mealybugs
 Whiteflies
 Aphids
 Rust mite
 Red spiders
 Florida flower thrips
 Large plant bugs
 Minor pests of the fruit
 Borers of trunk and limbs
 Bark and leaf scavengers
 Leaf eaters
 Other pests of young trees
 Allies of the citrus grower
 Trees that harbor citrus insec...
 Literature cited
 Index






Group Title: Bulletin - Florida Agricultural Experiment Station - 67
Title: Citrus insects and their control
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00024827/00001
 Material Information
Title: Citrus insects and their control
Series Title: Bulletin
Physical Description: 140 p. : ill. ; 23 cm.
Language: English
Creator: Watson, J. R ( Joseph Ralph ), 1874-1946
Berger, E. W ( Edward William ), b. 1869
Publisher: Cooperative extension work in agriculture and home economics
Place of Publication: Gainesville Fla
Publication Date: <1932>
 Subjects
Subject: Citrus -- Diseases and pests -- Florida   ( lcsh )
Citrus -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 133-135).
Statement of Responsibility: by J.R. Watson and E.W. Berger.
General Note: "June, 1932."
General Note: "A revision of Bulletin 183, Florida Agricultural Experiment Station".
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00024827
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: aleph - 002570636
oclc - 44791685
notis - AMT6949

Table of Contents
    Copyright
        Copyright
    Title Page
        Page 1
    Board of control
        Page 2
    Table of Contents
        Page 3
        Page 4
    Injurious insects
        Page 5
        Scale-insects
            Page 6
            Page 7
            Armored scales
                Page 8
                Purple scale
                    Page 9
                    Page 10
                    Page 11
                    Page 12
                    Natural checks
                        Page 13
                        Entomogenous fungi
                            Page 13
                            Page 14
                            Page 15
                        Predaceous insects
                            Page 16
                            Page 17
                            Page 18
                            Page 19
                            Page 20
                    Control
                        Page 21
                        Page 22
                Long scale
                    Page 23
                Florida red or round scale
                    Page 24
                    Page 25
            Minor armored scales
                Page 26
                California red scale
                    Page 26
                Dictyospermum scale
                    Page 27
                Rufous or West Indian scale
                    Page 27
                Camphor scale
                    Page 27
                San Jose scale
                    Page 28
                Chaff scale
                    Page 28
                    Page 29
                Citrus snow scale
                    Page 30
            Soft scales
                Page 30
                Soft brown or turtle back scale
                    Page 31
                Hemispherical scale
                    Page 32
                Black scale
                    Page 33
            Wax scales
                Page 33
                Florida wax scale
                    Page 33
                    Page 34
                Barnacle scale
                    Page 35
                Japanese or Mexican wax scale
                    Page 35
                Pyriform scale
                    Page 36
                Green shield scale
                    Page 37
            Entomogenous fungi of soft scales
                Page 37
                Page 38
    Mealybugs
        Page 39
        Common, or citrus, mealybug
            Page 40
            Page 41
            Page 42
        Long-tailed mealybug
            Page 43
        Cottony-cushion scale
            Page 43
            Page 44
            Vedalia or Australian ladybeetle
                Page 45
                Page 46
    Whiteflies
        Page 47
        Page 48
        Common, or citrus, whitefly
            Page 49
            Page 50
            Food plants
                Page 51
                Page 52
        Cloudy-winged whitefly
            Page 53
            Page 54
        Woolly whitefly
            Page 55
            Page 56
            Page 57
        Flocculent whitefly
            Page 58
        Florida, or guava, whitefly
            Page 58
        Bay whitefly
            Page 58
        Inconspicuous or sweet potato whitefly
            Page 58
        Mulberry whitefly
            Page 59
        Other whitefly
            Page 59
            Whitefly fungi
                Page 59
                Page 60
                Page 61
            Control of whiteflies and scale-insects
                Page 62
                Spraying
                    Page 63
                    Page 64
                    Page 65
                Fumigation
                    Page 66
                    Page 67
                By fungus parasites
                    Page 68
                    Page 69
                    Page 70
    Aphids
        Page 71
        The green citrus aphid
            Page 72
            Page 73
            Enemies
                Page 74
                Ladybeetles
                    Page 74
                    Page 75
                    Page 76
                    Page 77
                    Page 78
                Syrphus flies
                    Page 79
                Aphis-lions
                    Page 80
                Fungus diseases
                    Page 80
            Control
                Page 81
                Page 82
                Page 83
                Page 84
                Page 85
        The melon aphid
            Page 86
    Rust mite
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
        Page 92
    Red spiders
        Page 93
        Six-spotted mite
            Page 93
        Purple mite
            Page 94
    Florida flower thrips
        Page 94
        Page 95
        Page 96
        Page 97
        Page 98
    Large plant bugs
        Page 99
        Southern green stink-bug or pumpkin bug
            Page 99
            Page 100
            Page 101
            Page 102
            Page 103
            Page 104
        Other plant bugs
            Page 105
        Cotton stainer
            Page 106
    Minor pests of the fruit
        Page 107
        Orange tortricid
            Page 107
            Page 108
        Grasshoppers and katydids
            Page 109
        Bagworms
            Page 109
        Rodents
            Page 109
        Mediterranean fruit fly
            Page 109
            Page 110
        Morelos fruit fly
            Page 111
        Scavengers
            Page 111
    Borers of trunk and limbs
        Page 111
        Orange sawyer
            Page 111
        Shot-hole borers, or pin-head borers
            Page 112
        Tineid miner
            Page 112
    Bark and leaf scavengers
        Page 113
        Psocids
            Page 113
        Hymenorus obscurus
            Page 114
            Page 115
    Leaf eaters
        Page 114
        Orange dog
            Page 114
        Slug caterpillars
            Page 116
            Slug caterpillars
                Page 116
            saddle-back
                Page 117
            Hag moth
                Page 118
        Grasshoppers
            Page 118
            Page 119
        Katydids
            Page 120
        Citrus root weevil
            Page 121
        June bugs
            Page 122
        Prickly-ash beetle
            Page 122
        Striped cucumber beetle
            Page 122
    Other pests of young trees
        Page 123
        Sharp-shooter, or orange jassid
            Page 123
        Ants
            Page 124
        Termites, "white ants", or "wood lice"
            Page 125
            Page 126
            Page 127
        Salamanders and gophers
            Page 128
        Millipeds
            Page 129
    Allies of the citrus grower
        Page 130
        Birds
            Page 130
        Other vertebrates
            Page 131
        Predaceous bugs
            Page 131
        Wasps
            Page 131
        Parasitic flies
            Page 132
    Trees that harbor citrus insects
        Page 132
    Literature cited
        Page 133
        Page 134
        Page 135
    Index
        Page 136
        Page 137
        Page 138
        Page 139
        Page 140
Full Text





HISTORIC NOTE



The publications in this collection do
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
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






Bulletin 67 June, 1932
--------- -,
(A revision of Bulletin 183, Florida Agricultural
Experiment Station)


COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)


AGRICULTURAL EXTENSION SERVICE, UNIVERSITY OF FLORIDA
FLORIDA STATE COLLEGE FOR WOMEN
AND UNITED STATES DEPARTMENT OF AGRICULTURE
COOPERATING
WILMON NEWELL, Director






CITRUS INSECTS AND


THEIR CONTROL


By

J. R. WATSON, Entomologist,
Florida Agricultural Experiment Station

and

E. W. BERGER, Entomologist, State Plant Board of Florida






Bulletins will be sent free upon application to the
AGRICULTURAL EXTENSION SERVICE
GAINESVILLE, FLORIDA










BOARD OF CONTROL

P. K. YONGE, Chairman, Pensacola
A. H. BLENDING, Tampa
FRANK J. WIDEMAN, West Palm Beach
RAYMER F. MAGUIRE, Orlando
GEO. H. BALDWIN, Jacksonville
J. T. DIAMOND, Secretary, Tallahassee

STAFF, AGRICULTURAL EXTENSION SERVICE

JOHN J. TIGERT, M.A., LL.D., President of the University
WILMON NEWELL, D.Sc., Director
A. P. SPENCER, M.S., Vice-Director and County Agent Leader
J. FRANCIS COOPER, M.S.A., Editor
R. M. FULGHUM, B.S.A., Assistant Editor
E. F. STANTON, Supervisor, Egg-Laying Contest
RUBY NEWHALL, Secretary

COOPERATIVE AGRICULTURAL DEMONSTRATION WORK
W. T. NETTLES, B.S., District Agent
H. G. CLAYTON, M.S.A., District Agent, Organization and Outlook Specialist
J. LEE SMITH, District Agent and Agronomist
R. W. BLACKLOCK, A.B., Boys' Club Agent
HAMLIN L. BROWN, B.S., Dairyman
E. F. DEBUSK, B.S., Citrus Pathologist and Entomologist
N. R. MEHRHOF, M. AGR., Poultryman
WALTER J. SHEELY, B.S., Agent in Animal Husbandry1
J. E. TURLINGTON, PH.D., Agricultural Economist2
FRANK W. BRUMLEY, M.S.A., Agricultural Economist, Farm Management
W. R. BRIGGS, B.S.A., Assistant Agricultural Economist, Farm Management
D. E. TIMMONS, M.S.A., Agricultural Economist, Marketing
CARLYLE CARR, B.S., Specialist in Rodent Control1

COOPERATIVE HOME DEMONSTRATION WORK
FLAVIA GLEASON, State Agent
LUCY BELLE SETTLE, B.S., District Agent
RUBY MCDAVID, District Agent
MARY E. KEOWN, M.S., District Agent
VIRGINIA P. MOORE, Home Improvement Agent
ISABELLE S. THURSBY, B.S., Food and Marketing Agent
ANNA MAE SIKES, B.S., Nutritionist

NEGRO EXTENSION WORK
A. A. TURNER, Local District Agent
ROSA J. BALLARD, Local District Home Demonstration Agent

1In cooperation with U.S.D.A.
2Part-time.










CONTENTS
PAGE
INJURIOUS INSECTS -........~. ........ ..... 5
Scale-Insects ....... ..... ............. ...... 6
Armored Scales .......---.....--....-.-- ------.. -..... 8
Purple Scale .......-.. ......- --------------------------- 9
Natural checks ... ...--.. ......----------.........------. 13
Entomogenous Fungi ..----... -----..--......----... ..------ 13
Predaceous Insects ....-...... .....----------..-- .. --....- 16
Control .....---...-..---- ..-- .... ---------.. -- --. -- 21
Long Scale ...--....--......-.... ------- ----------.--- 23
Florida Red or Round Scale--....---... ---....... ---------- 24
Minor Armored Scales--...---.......------- ..-------..--.--..--- 26
California Red Scale ........----.....------------ -------- 26
Dictyospermum Scale .......... ........- -------------------. 27
Rufous or West Indian Scale---..----..--........ ------------ 27
Camphor Scale ..........---- ........-- --..-----------..-------. ----------- 27
San Jose Scale -...--.... -----------------.------------- 28
Chaff Scale ---------.............. ----.. ------ --------- 28
Citrus Snow Scale ----.... ........---- ------------------. 30
Soft Scales .......--........ .... ---------...------------ 30
Soft Brown or Turtle Back Scale .---. ---.----.~-..----.--.----. 31
Hemispherical Scale ....--............--------------------- 32
Black Scale ...-.......--..... ............- ------------ 33
Wax Scales ........----.- --------.---........- ---.------ 33
Florida Wax Scale .-----..........-.. ...-----. ----------- 33
Barnacle Scale ------............ .-----..--....---- ----- 35
Japanese or Mexican Wax Scale ----......------------------.- 35
Pyriform Scale ....................-----------.--------.- 36
Green Shield Scale ----.---.......-----.......... .---.--- 37
Entomogenous Fungi of Soft Scales ----...-.....-....-------.--- 37
MEALYBUGS .. --------....... ........ ......:-...-..... .......- 39
Common, or Citrus, Mealybug -..---.... -----.. ------------ 40
Long-Tailed Mealybug ....- --...... .----.......--...... ----- 43
Cottony-Cushion Scale ..........----------.------- ---...----.. 43
Vedalia or Australian Ladybeetle -----......------.-------... 45
WHITEFLIES .........----...............----------------------- 47
Common, or Citrus, Whitefly ----.------..........-- ------------.. 49
Food Plants ....------...............------- -----------. 51
Cloudy-Winged Whitefly ..------------............----- -------.. 53
Woolly Whitefly --............ ...-------------------------. 55
Flocculent Whitefly --------..................--.------------. 58
Florida, or Guava, Whitefly .--....---.... --- ..---------- -.....--. 58
Bay W hitefly ..-----............ ..........---- -... ........ 58
Inconspicuous, or Sweet Potato, Whitefly ....--- .........---- ..-------.. 58
Mulberry Whitefly ....----.....-......------.... --....---------. 59
Other Whiteflies ------.... .........--.......----- --.....- 59
Whitefly Fungi ...---.........---.....----.......--.......-... -59
Control of Whiteflies and Scale-Insects ............------------- 62
Spraying ......-... -....-......-.... .... -----------....--------- 63
Fumigation ............------- ..-----.....-......-- --- ...----- 66
By Fungus Parasites ....--..............---- .....-- ... .-- -------- 68
APHIDS .-................----.........--- ---- ----- ----... ---...... ----------... ....-.... 71
The Green Citrus Aphid---- --------- .... ..... .......----.......---- ....----. 72
Enemies -----....... .......- ...........---- .... ---........----......-- .... .--....- --- 74
Ladybeetles ......-- .....--- --....------..--.... ..........-...-.............----. 74
Syrphus Flies .............. .---.... .. -- .....- ... ..-- .... ...... 79
Aphis-Lions ...........-- ..........-----..... --------...... 80
Fungus Diseases .....-- --- --- ..... --------.. ----.--..-. 80
Control ..--...--- ---..... -........-. ...-- ......-- -....... 81
The Melon Aphid .....----------.--~. ..-- ..---- ...-- ...... 86













PAGE
RUST MITE ......... ...---------------------------..--- ------- 87
RED SPIDERS --..-.......----.... ..--. --------- ...------ ------------. 93
Six-Spotted Mite ..----.........-.....-------------.------ --- .... 93
Purple Mite ..-----....---... ... ------------------ ------- 94
FLORIDA FLOWER THRIPS -.....----------..~.~........ --.-- 94
LARGE PLANT BUGS ---....... ------.... -------.......-------... ---.-- ---- 99
Southern Green Stink-Bug or Pumpkin Bug--...........-------....... ------ 99
Other Plant Bugs --- --.. .............------------------.... 105
Cotton Stainer ------.... -----.... ... ...........------------ .------------ 106
MINOR PESTS OF THE FRUIT----..------..---------....... ---------- 107
Orange Tortricid .....---------------- ---......... .......... 107
Grasshoppers and Katydids ....--. ...-- .....-..-----------.----. 109
Bagworms .......-----------.. -------...... ---.... ....... --------------. ------------ 109
Rodents ...............-------. ....--------.. ... ------ -- 109
Mediterranean Fruit Fly ..-----. ...-.--.......------ -- ---. 109
Morelos Fruit Fly .......---------.........---------------- 111
Scavengers .---...-...-....--...--..----......----...------- 111
BORERS OF TRUNK AND LIMBS..---................ -----...---------- 111
Orange Sawyer ...........--------... .. ...- -----------.... 111
Shot-Hole Borers, or Pin-Head Borers ----- -...... ....------------- 112
Tineid Miner ..........---........ ............----- --- ..-- ....----. 112
BARK AND LEAF SCAVENGERS .---...... ..-- -.. ..- ---------... ........ 113
Psocids -...............-... -......-... ------..-- ......--------...- ... 113
Hymenorus Obscurus .-....-...... ....-------------......--- 114
LEAF EATERS ...----....--....-... -----..----------......----------- 114
Orange Dog .........----......-........ .-------- -------- 114
Slug Caterpillars ...--- ..---....--- ..... .. ----.-... -------- 116
Puss Moth -........- .. .....-------- ....--....-- -------116
Saddle-Back .-.... ---.............----. .---------------- 117
Hag Moth ...---... ----.........----.-------------- -- 118
Grasshoppers ..- -------.-.......--.---- ------.----.---- 118
Katydids ......-...........------.....---.....----....------..... ------..... 120
Citrus Root Weevil ..--....-.............------ ..-- --------.... 121
June Bugs ...-..-....-..-- -..---.----- .-----..... ...... ----- 122
Prickly-Ash Beetle ...-----........ .. ..........------- ------- 122
Striped Cucumber Beetle -....----- .~.- ... .. .. ---------------- 122
OTHER PESTS OF YOUNG TREES.............. ......------------------ 123
Sharp-Shooter, or Orange Jassid----...... --........-....-.... .-- 123
Ants .------------- ---------..................---....------- ------- 124
Termites, "White Ants", or "Wood Lice"......-----------.~.~. ...... 125
Salamanders and Gophers ..-...----... -------...... .. ---------. 128
Millipeds --...................---------------------------- 129
ALLIES OF THE CITRUS GROWER........... -----------------------..--- 130
Birds ... --------....................------... ---------- ---- 130
Other Vertebrates ....---.....................------------- 131
Predaceous Bugs .......-----........ ..... ....--------------. ---- 131
Wasps ........... .....................------------------........ ------------ 131
Parasitic Flies .---........... -----..........-...-.. ..-......------ -- 132
TREES THAT HARBOR CITRUS INSECTS ----............ ...--- .....------... 132
ACKNOWLEDGMENTS .-... ... ....------------- -------------------- 132
LITERATURE CITED --...-----.. --..~~.. ........--.. ------------- 133









CITRUS INSECTS AND THEIR CONTROL
By J. R. WATSON AND E. W. BERGER
The aim of this bulletin is to discuss briefly the most common
insects in the Florida citrus grove-the beneficial insects and
those of an indifferent relation, as well as those which injure
the tree-so that the grower may be enabled to recognize the
more common insects in his grove. No attempt has been made
to treat in full all insects to be found on an orange tree.
The writers have selected chiefly those insects which have been
the source of much correspondence with citrus growers. Neither
has any attempt been made to present an exhaustive account of
the more important pests, nor to repeat data that are easily ac-
cessible to the average grower through other publications. How-
ever, an occasional reference to such literature is included so
that the grower may readily find further detailed information.
In addition to the insects, red spiders, rust mites and other mites,
and other animal pests troublesome to citrus growers are in-
cluded in the discussions.
For studying the smaller forms and the early stages of a
majority of the insects, a good hand lens is necessary. A satis-
factory one, magnifying fifteen or sixteen diameters, can be
bought for three or four dollars. A glass of less power would
hardly be sufficient for the study of rust mites and many of the
eggs while a lens of higher power would present a field too small
to enable the observer to find again readily an object first located
with the unaided eye.

INJURIOUS INSECTS
Of the insects and mites treated in this bulletin there are but
six which should be classed as pests of primary importance,
against which the grower who would produce the maximum
amount of first-class fruit will find it necessary to use control
measures nearly every year. They are, in the order of their
importance:
(1) Purple scale
(2) Common, or citrus, whitefly
(3) Rust mite
(4) The green citrus aphid
(5) Florida red scale
(6) Cloudy-winged whitefly






6 Florida Cooperative Extension

There is, however, a larger number of pests which should be
watched, and against which the grower should take measures
during occasional years. They are, again approximately in the
order of their importance:
(7) Red spiders
(8) Thrips
(9) Long scale
(10) Mealybugs
(11) Pumpkin bugs and other plant bugs
(12) Cottony-cushion scale
(13) Citrus snow scale
(14) Orange dog
(15) Chaff scale
(16) Termites
(17) Ants
(18) Gophers and salamanders
In a third class may be placed those whose activities are harm-
ful, but which seldom become sufficiently abundant to make it
worth the grower's while to combat them. Such are:
Grasshoppers Florida wax scale
Katydids Barnacle scale
Sharpshooters Inconspicuous whitefly
Orange tortrix Bay whitefly
In addition to the foregoing insects which directly damage the
trees, there are many insects which damage the grove indirectly
either by giving aid and comfort to its enemies, as ants which
protect mealybugs, or by destroying beneficial insects, as do
certain parasites that live in ladybeetle larvae.

SCALE-INSECTS

The most serious insect pests of citrus in Florida are scale-
insects. They derive this name because of the fact that they
are usually flat and are closely applied to the surface of the
host plant like a scale. They are bugs and, therefore, sucking
insects, although very degenerate in structure. While most in-
sects go through four stages during their development (egg,
nymph or larva, pupa and adult) this is true of only the males of
scale-insects. The females virtually omit the last two stages. They
acquire mature sexual organs and reproduce while still retain-
ing the larval form. Even in the male the adult life is extreme-







Bulletin 67, Citrus Insects and Their Control 7

ly brief, lasting for but a day or two. As the adult males are
very small and inconspicuous, gnat-like creatures, the orange
grower seldom notices them. They have only two wings. Hav-
ing no mouth parts or digestive organs, they can take no food
during their adult life. Their only activities consist in finding
and fertilizing the females.
The scale-insects damage the trees chiefly by the withdrawal
of large quantities of sap. They also give off a sweet secretion
called honeydew and in this honeydew a fungus known as sooty
mold develops. Mealybugs and some of the soft scales, like the
turtle-back scale, produce this honeydew copiously.
Three Kinds of Scale-Insects:-The family of scale-insects
(Coccidae) may be divided into three groups, or sub-families,
according to the nature of the scale or covering of the insect.
In the first group the larva secretes two plates of a hard,
horny substance between which the insect lives, much as an
oyster in its shell, although not attached to the plates by muscles.
The lower plate next to the host plant is usually thin, delicate
and flat, but the upper one is more or less arched, thick and
rigid. The newly-hatched larva moves about for a few hours,
but at the end of one or two days inserts its beak into the host
and becomes anchored for life. Its beak, after being inserted
into the tissue of the host, grows extensively so that the insect
cannot withdraw it. If an attempt is made to pull it out by
force it usually breaks off; if successfully extracted it cannot
be reinserted. Insects of this group are called armored scales
(Diaspinae).
In the second group no separate detached scale is formed, but
the body wall itself is usually thickened and hardened by the
deposition of horny chitinous material. The scale in this case
is part of the animal like the "shell" of a turtle. In this group
the larva can usually move about until egg laying time, but it
moves very slowly. Insects of this group are called soft scales
(Coccinae) .
In the third group, mealybugs and their relatives (Dactylo-
pinae), no hard coating is formed but the body is usually cov-
ered with flaked wax which gives a mealy appearance. They usu-
ally retain their legs and are capable of moving about through-
out life.






8 Florida Cooperative Extension

Armored Scales
LIFE HISTORY
In the armored scale group the eggs are usually laid under
the scale of the female whose body contracts as they are laid.
Shortly after the last one is laid the shriveled female dies. The
eggs hatch under this protective covering which shelters them
not only from rain and cold but also from other insects which
might otherwise feed upon or parasitize them. It also protects
them from insecticides. Soon after hatching, the young, called
"crawlers", push their way out and wander about for a few
hours seeking a satisfactory place to attach themselves. Hav-
ing found it,, they insert their beaks composed of four slender
threads, and, if they are destined to become females, never
move about again. They at once begin to secrete threads of wax
which form a covering over the body. In two or three weeks
they have outgrown their larval skins and must molt. After
this molt the true permanent scale begins to form. Some weeks
later a second molt takes place. This time, however, the molted
skin is retained and incorporated with the new portion of the
scale where it is usually quite conspicuous. (Fig. 1.) It is situated
near the middle or the front end of the mature scale and often
differs a little in color from the remainder. At this point
in the life history a dif-
ference between the males
and females begins to be no-
P ticeable. The males grow no
more but molt again and pass
into the pupal stage from
which the adult two-winged
fly-like creatures emerge in
A B about a week.
Fig. 1.-A-Scale of female with exuviae The female is fertilized
central: a, first exuvia; b, second exuvia:
c, secretionary covering. B.-Scale of female shortly after the second molt
with exuviae terminal: d, first exuvia; e, sec-
ond exuvia; f, secretionary covering. (After and does not molt again, al-
Merrill and Chaffin, 16.*)
though she continues to in-
crease in size. As a result of this growth after the second molt,
the female scales are much larger than the males and live longer.
The males go through this molt at an age earlier by about a
week than the females. The third and fourth molts are then
passed quickly so that by the time the females are through with

*Figures after authors' names refer to Literature Cited, page 133.







Bulletin 67, Citrus Insects and Their Control 9

their second molt and are ready to breed, the males have become
winged adults and quickly find the females. The armored scales
produce very little honeydew.

PURPLE SCALE
Lepidosaphes beckii (Newm.)
The purple scale is the most destructive insect in Florida
citrus groves. The mature scale (Figs. 2 and 3) is shaped




























Fig. 2.-Purple scale on grapefruit, showing reaction to light. The clear spot in the
center was in contact with another fruit.

somewhat like an oyster shell. It is purplish-brown in color
and 1/8 inch in length. It is found on the twigs and fruit as
well as on the leaves. However, it is not abundant on the trunk
or larger branches except on young trees. On the leaves it col-
lects especially along the midribs and at the base, but occurs
on any part, on the upper as well as the lower surface.
-Like whiteflies and all other bugs, scale-insects are sucking






10 Florida Cooperative Extension

insects and withdraw large quantities of sap from the trees.
Although the effect of scattered individuals is not externally ap-
parent, they check the growth of the infested part and inter-
fere with its functions. If sufficiently abundant in one place
they will cause that portion of the leaf to turn yellow, and if
they continue to multiply the leaf will fall. These yellow spots
will often persist after the scales have been killed by natural
causes or by sprays and have fallen off. A heavily infested fruit
is small and slow to color.
Besides this direct injury the punctures of scale-insects af-
ford avenues of entry for certain fungus diseases of the fruit,
such as stem-end rot.
LIFE HISTORY
The eggs are laid under the scale of the mature female. They
hatch in from fifteen to twenty days. The young crawlers re-















Fig. 3.-Purple scale following woolly whitefly. (After Watson, 27.)
main under the shelter of the parent scale for a day or two and
then spend another day or two in crawling about looking for a
suitable place in which to affix themselves. These crawlers
show an aversion to strong light. If a crawler is placed on a
sheet of paper a part of which is, in the sunlight, the insect will
not usually crawl into the sunny part from the shade, but will
either turn back upon reaching it or crawl along the edge of the
shadow. On the other hand, if placed in a room near.a window,
but not in direct sunlight, the insect will travel toward the win-
dow. The crawlers avoid both deep shade and direct sunlight






Bulletin 67, Citrus Insects and Their Control 11

and seek an intermediate condition. If placed on a twig in total
darkness they will crawl to the top. Because of these reactions
to light the crawlers collect in shaded places, a favorite place
being under the calyx of the fruit. Two fruits touching or a
leaf resting against a fruit also produce conditions of shade
favorable to the insect. (Fig. 2.) Sooty mold slightly loose so
that the crawlers can get under it, forms favorable retreats,
as does also the wool of the woolly whitefly. (Fig. 3.) Prob-
ably for this reason scale-insects are usually more severe along
a road than in other parts of the grove. The dust particles
settling on the leaves provide the crawlers with the partial
shade and protection which is most favorable for their develop-
ment. An unusually favorable place for the development of the
scale crawlers is in the leaves curled by the green citrus aphid.
These curled leaves seem to supply the optimum degree of light
to the crawlers. The result is a heavy infestation of scales in
these curled leaves where they are very difficult to reach with
a spray solution.
The crawlers also have a definite reaction to gravity. In the
dark they will always climb up a branch-a reaction called neg-
ative geotropism, a movement opposite to the pull of the earth.
This leads the crawlers toward the tops of the branches where
they find suitable food. Their reactions to light, however, are
much stronger than those to gravity so that when the two come
into conflict the aversion to light will prevail.
Immediately after affixing themselves the young scales begin
to secrete waxy threads which soon thinly cover the body. When
about eighteen or twenty days old, in summer, the first molt
occurs and immediately afterward the insect begins to form the
true scale, which is reddish- or purplish-brown in color.
When the female is six or seven weeks old; in summer, the
second molt occurs. The scale covering the second-stage larva
is incorporated with the new scale; a habit characteristic of all
armored scales. In the purple scale most of the new material
is added on one side of the first scale which therefore comes to
occupy a position near the apex of the mature scale. (Fig. lB.)
The female begins to lay eggs when about two months old and
continues to lay for three or four weeks, averaging thirty or
forty eggs.
The entire life history extends over a period of about three
months, in summer. During cooler weather the growth and






12 Florida Cooperative Extension

development take place much more slowly, although in our cli-
mate probably seldom wholly cease.
BROODS
All stages may be found in one tree at almost any time of the
year, yet there are three periods when crawlers are more abund-
ant than at other times. They are in March or early April,
June or July, and September or October. Thus there are in the
main, three generations a year.
ASSOCIATION WITH WHITEFLIES
It has been commonly noted that a heavy infestation of white-
flies is likely to be followed by a marked increase in the amount
of purple scale present in a grove. Divers explanations have
been given to account for their association, a common one being
the weakened condition of the trees. While it is undoubtedly
true that a weakened tree cannot endure the attacks of as many
scales as a vigorous one, the weakened condition of the tree
obviously cannot be the cause of the multiplication of the scales.
The true explanation is to be found in the protection given to
crawlers and young scales by the sooty mold. As previously
stated the crawlers' aversion to strong light drives them to seek
the protection of sooty mold. When the mold is first formed it
adheres so closely to the leaf that the crawlers cannot get under
it; but in time it becomes sufficiently loosened to afford them a
retreat. Also, the sooty mold may form over the larvae after
they have anchored. The sooty mold partly protects the crawlers
and young larvae from some of their predators and parasites,
both insects and fungi. Extensive tabulations by the writer
have shown that the percentage of infestations with the para-
sitic fungi is less under the sooty mold than where the scales are
fully exposed.
In the case of the woolly whitefly, in addition to the sooty
mold, the wool itself and the honeydew with which it is usu-
ally entangled form an ideal refuge for the scales and an old
colony of this whitefly almost invariably shows a heavy infes-
tation of purple scale (27). (Fig. 3.)
DAMAGE
How seriously the purple scale damages trees by sucking the
sap is shown most clearly when the scales collect in groups on
a leaf, as under a colony of woolly whitefly. The part of the leaf
attacked turns yellow while the other parts remain green..







Bulletin 67, Citrus Insects and Their Control 13

These yellow areas often persist after the scales have matured
and fallen off. These spots may turn brown and finally become
holes in the leaf or they may be infected by fungi or become
the seat of gum exudations; some of the smooth, shining dark-
brown spots on leaves, commonly called "greasy spots" or
"black melanose," have their origin in attacks of scale-insects.
If too large an area of the leaf is attacked by scales the leaf
will fall.
The attacks of the scale on the twigs are attended by as seri-
ous consequences as on the leaves, a heavy infestation resulting
in the death of the twig.
On the fruit the results of the activities of scales are hardly
less marked. If the scales are abundant, the fruit is stunted,
ripening is delayed and the coloring is uneven. Vigorous scrub-
bing is necessary to remove the scales before packing the fruit.
Another serious consequence of the presence of scales on fruit
is that the punctures made in the rind afford avenues for the
entry of various fungi which cause decay, as previously stated.
The efforts of the crawlers to avoid strong light causes them to
collect under and around the calyx of the fruit. If scales are at
all abundant on the trees, there will always be found a heavy
infestation about and under the calyx, and often the entire
space is covered with a layer of scales several deep. Fawcett
(9) has shown that there is an intimate relation between the
numbers of scales in this situation and the development of stem-
end rot in the fruit.

NATURAL CHECKS
*ENTOMOGENOUS FUNGI
The most efficient parasites of the purple scale are entomog-
enous fungi. There are five species that are especially common
on this scale. Named in the order of their abundance they are
the red-headed scale-fungus, the white-headed scale-fungus, the
black scale-fungus, the pink scale-fungus and the cinnamon fun-
gus. As in the case of those species which parasitize the white-
flies, these fungi grow most abundantly during the rainy season.
Their development is not, however, so strictly limited to the sum-
mer season as is that of the whitefly-infecting species. They
*The scientific names of the fungi as revised by T. Petch (19) and as
given by H. S. Fawcett (11), or per letter to the writer have been adopted
in the text. The old names are given in footnotes.







Bulletin 67, Citrus Insects and Their Control 13

These yellow areas often persist after the scales have matured
and fallen off. These spots may turn brown and finally become
holes in the leaf or they may be infected by fungi or become
the seat of gum exudations; some of the smooth, shining dark-
brown spots on leaves, commonly called "greasy spots" or
"black melanose," have their origin in attacks of scale-insects.
If too large an area of the leaf is attacked by scales the leaf
will fall.
The attacks of the scale on the twigs are attended by as seri-
ous consequences as on the leaves, a heavy infestation resulting
in the death of the twig.
On the fruit the results of the activities of scales are hardly
less marked. If the scales are abundant, the fruit is stunted,
ripening is delayed and the coloring is uneven. Vigorous scrub-
bing is necessary to remove the scales before packing the fruit.
Another serious consequence of the presence of scales on fruit
is that the punctures made in the rind afford avenues for the
entry of various fungi which cause decay, as previously stated.
The efforts of the crawlers to avoid strong light causes them to
collect under and around the calyx of the fruit. If scales are at
all abundant on the trees, there will always be found a heavy
infestation about and under the calyx, and often the entire
space is covered with a layer of scales several deep. Fawcett
(9) has shown that there is an intimate relation between the
numbers of scales in this situation and the development of stem-
end rot in the fruit.

NATURAL CHECKS
*ENTOMOGENOUS FUNGI
The most efficient parasites of the purple scale are entomog-
enous fungi. There are five species that are especially common
on this scale. Named in the order of their abundance they are
the red-headed scale-fungus, the white-headed scale-fungus, the
black scale-fungus, the pink scale-fungus and the cinnamon fun-
gus. As in the case of those species which parasitize the white-
flies, these fungi grow most abundantly during the rainy season.
Their development is not, however, so strictly limited to the sum-
mer season as is that of the whitefly-infecting species. They
*The scientific names of the fungi as revised by T. Petch (19) and as
given by H. S. Fawcett (11), or per letter to the writer have been adopted
in the text. The old names are given in footnotes.







14 Florida Cooperative Extension

often grow well and do efficient work even in mid-winter but
only during a period of considerable humidity and warmth.
They do not thrive well during a very dry season.
PINK SCALE-FUNGUS (Nectria diploa B. & C.).-*This fun-
gus was discovered by Professor P. H. Rolfs at Winter Haven,
Florida, in December, 1912. It has since been found widely
distributed in Florida (and other countries) but not so gen-
erally, nor is it so common as the red-headed scale-fungus. To
the casual observer it is indistinguishable from the latter
fungus and Fig. 4 will serve here as an illustration of it. The
color of its heads, however, is pink rather
than red, and a pink or reddish border sur-
rounds the scales it has killed. It is espe-
cially effective on the Florida red scale. It
has undoubtedly been present a long time
in Florida and confused with the red-
headed scale-fungus. It has been found in-
fecting and killing the following scale-
insects in Florida: Florida red scale (Chry-
somphalus aonidum), mainly when on cit-
rus, but also on other hosts; obscure scale
or water oak scale (Chrysomphalus obscu-
rus), on water oak; gloomy scale or red
maple scale (Chrysomphalus tenebricosus),
on red or swamp maple; California red
i- scale (Chrysomphalus aurantii), on citrus;
Fig. 4. Red-headed scale-
fungus on purple sche purple scale (Lepidosaphes beckii), on
(on orange). The white
in the illustration is the citrus.
red color of the fungus.
Enlarged twice. (State RED-HEADED SCALE-FUNGUS (Sphaeros-
Plant Board.)
tilbe aurantiicola (B. et Br.) Petch).**-
This fungus is very effective against a number of scale-insects
and is widely distributed and common. Its reddish heads,
smaller than pinheads, grow out from the infected scales and
are easily visible. (Fig. 4.)
The following scale-insects have been found infected by this
fungus in Florida: Purple scale on citrus; San Jose scale (Aspi-
diotus perniciosus), mainly on trifoliate orange, peach, plum
and pear; long scale (Lepidosaphes gloverii), on citrus; ivy
scale (Aspidiotus hederae), mainly on chinaberry; chaff scale
(Parlatoria pergandii), mainly on citrus.
*Microcera fugikuroi Miy. et Sa.
**Sphaerostilbe coccophila Gul.






Bulletin 67, Citrus Insects and Their Control 15

According to records of the Entomology Department, State
Plant Board, and others (5), this fungus also
parasitizes Putnam's scale (Aspidiotus ancy-
lus), on pecan; latania scale (Aspidiotus la-
taniae), mainly on chinaberry, avocado and
loquat; English walnut scale (Aspidiotus jug-
lans-regiae), on pecan; Aspidiotus spinosus, on
Bauhinia; palmetto scale (Comstockiella sab-
alis), mainly on palmetto; lesser snow scale
(Hemichionaspis minor), mainly on hibiscus
and chinaberry; black thread scale (Ischnaspis
longirostris), mainly on palms; Parlatoria pro-
teus, mainly on palms; pine scale (Chionaspis
pinifoliae heterophylae), on pines.
WHITE-HEADED SCALE-FUNGUS (Podonectria
coccicola (E. and E.) Petch).*-(Figs. 5 and
6). It is apparently the first scale-fungus of
which there is any record in Florida and is Fig. 5.--White-headed
figured and described as a "bark fungus" by rus~e t s i-
H. G. Hubbard (14). ral saie. (Stat
Hubbard, however, failed to discover its Plant Bard.)
parasitic nature and believed it lived on dead
scales. The writers believe, furthermore, that
it was this fungus which saved the citrus
industry in the thirties of the last- century,
when the long scale had been introduced at
Mandarin and St. Augustine, and the trees
were killed back each year. It is reported that
even whiskey and aloes were tried but were use-
less in destroying the scale and reviving the
trees. But after some years the trees recov-
ered, from some then unknown cause, and it
is believed now that the cause was a friendly
fungus, wholly, or in part at least. Con-
tributing causes may have been insect ene-
mies of the scales, but as the insect enemies
now present are never so efficient, the pte-
Fig. 6.-White-head- sumption is that it was fungus.
ed sca le fungus.
Perfect stage. En- This fungus occurs nearly everywhere in
large twice. (State
Plant Board.) Florida, wherever there is long scale or pur-

*Ophinectria coccicola.






16 Florida Cooperative Extension

pie scale. It is an open question whether this fungus or the red-
headed scale-fungus is the most common. As its name indicates,
it appears as small whitish heads growing out from the scales
and but for its color would often pass for the last named fungus.
It has been found infecting and destroying the following
scales: Long scale, on citrus; purple scale, on citrus; chaff scale,
on citrus.
BLACK SCALE-FUNGUS (Myriangium duriae
Mont.).-This fungus is illustrated in Fig.
7. Its distribution apparently is more north-
erly than the other fungi, except the red-
headed scale-fungus. Specimens on San Jose
scale have been received from Virginia. This
fungus probably occurs everywhere in Flor-
ida. It has the appearance of black spatter
or black spots.
The insects killed by it are the following:
Purple scale, on citrus; long scale, on citrus;
chaff scale, on citrus; San Jose scale, mairily
on trifoliata, peach, plum and pear; Putnam's
scale, mainly on pecan; gloomy scale, on
maple; white peach scale (Diaspis penta-
Fig. 7. Black scale-
iungus. (By H. .~ gona), on mulberry and peach; English wal-
Bratley.) nut scale, on Ilex vomitoria and pecan; la-
tania scale, on holly and chinaberry; mining scale (Howardia
biclavis), on various trees and shrubs.
CINNAMON FUNGUS (Verticillium cinnamomeum Petch*).-
This fungus occasionally infects purple scale, long scale, chaff
scale, soft brown scale, as well as whitefly larvae. Since the pre-
ceding statement was made (June, 1926), the following addi-
tional scale-insects occasionally have been found infected by this
fungus: Palmetto scale, on palmetto; tea scale (Fiorinia theae),
on Camellia japonica; dictyospermum scale (Chrysomphalus
dictyospermi), on Asparagus plumosus; proteus scale (Parla-
toria proteus), on ophiopogon; pyriform scale (Pulvinaria pyri-
formis), on citrus and mango; and fern scale (Hemichionaspis
aspidistrae), on fern.
PREDACEOUS INSECTS
The purple scale is extensively preyed upon by other insects.
These predators are native insects that before the introduction
*V. heterocladum Penz.






Bulletin 67, Citrus Insects and Their Control 17

of the purple scale into Florida fed upon native scale-insects.
They have acquired a taste for the purple scale.
LADYBEETLES
Probably the most efficient predators which feed on scale-
insects are the ladybeetles. Of these the twice-stabbed lady-
beetle (Chiloco-

Muls.) (F i g.
8) is by far the
most important. .
It is very com-
mon in citrus
groves where it
f e e d s largely Fig. 8.-The twice-stabbed lady-beetle. Larva on left, pupa in
Center, and adult on right.
upon the crawl-
ers, and often on the young scales and eggs. It tears up the
females to get them. Like most of the ladybeetles this
one is nearly round in outline, almost hemispherical in shape.
It is shining coal-black in color with a large red spot on each
wing case, as if it had been stabbed and blood had oozed out;
S- hence its name. It is about a fifth of an inch
in diameter.
The young, like the larvae of all beetles, is an
S-- entirely different looking creature from the
adult. It is flattened in profile, broadly oval in
outline with the broader end in front. Like the
larvae of many ladybeetles (Fig. 8) it is cov-
S ered with spines. These are black and com-
pound; that is, the spines themselves are cov-
Sered with smaller spines. The body of the larva
is bluish-black. When ready to pupate, several
of the larvae often climb onto a dead twig and
attach themselves in a cluster to it. (Fig. 9.)
Ladybeetles do not crawl out of the larval skin
when they pupate but the skin splits length-
Fig. 9.-Pupal cases wise of the back, exposing the pupa within.
od he t6ce ta The life history of the beetle occupies about
Slightly enlarged. a month.
Another ladybeetle (Exochomus marginipennis children
Muls.), about an eighth of an inch long, occasionally is found in
citrus trees feeding chiefly on scale-insects, although it has been






18 Florida Cooperative Extension

seen eating whitefly larvae and aphids. The wing cases are
brown with two comma-shaped black dots near the tips. The
head and thorax and the abdomen beneath are black. The larva
is black and white. The original habitat of this species is mostly
oak trees where it feeds on native scales and aphids.
The two-spotted ladybeetle (Olla abdominalis var. sobrina
Csy.) (Fig. 46) is very similar in appearance to the twice-
stabbed and has about the same habits.
The blood-red ladybeetle (Fig. 47) and the convergent lady-
beetle (Fig. 45) also feed on scale-insects. However, their pref-
erence is for aphids and they will be described under that
heading.
DOWNY DARKLING BEETLE
Epitragodes tomentoaus (Lec.)
The downy darkling beetle (Fig. 10), a brown, oval beetle
which is about five-sixteenths of an inch long, is common in cit-
rus trees. Although not at all related to ladybeetles it, like them,
feeds largely on scale crawlers. It is very beneficial in control-
ling scale-insects as it feeds largely on the younger stages. Its
body is covered with very short gray hairs, hence the name.
Hubbard states that mulching the trees with
oak leaves will attract these insects to a grove.
LACEWING FLIES OR APHIS-LIONS
The larvae of lacewing flies are among the
important checks to the increase of scale-in-
sects and aphids. They are flat, spindle-shaped
larvae, grayish in color but marked with brown
or dull red. The front of the body ends in two
Fig sO .-EtLnt long, slender, sickle-shaped jaws on which the
ie( e a.tural). e insect impales its victims while it sucks their
(Adapted from body fluids. This is done through a tube
Hubbard.)
formed by the secondary jaw maxillaee) fitting
over a groove in the true jaws (mandibles). These larvae are
voracious, attacking insects much larger than themselves. In-
deed, they do not hesitate to jab their jaws into the skin on
the neck or the back of the hand of a person who happens to
brush them off a tree as he passes.. The bite, while quite sharp
and momentarily slightly painful, is not serious. These larvae
are particularly fond of aphids, and therefore are called aphis-







Bulletin 67, Citrus Insects and Their Control 19

lions. When full-grown, two weeks or sixteen days after hatch-
ing, they seek some sheltered place such as a curled leaf and
spin spherical glist-
ening white cocoons
about themselves.
(Fig. 11.) Here
they remain for a
week or ten days
and then the per-
fect insect emerges.
Dr. R. L. Miller has
noted (17) five
species of aphis-
lions feeding on
scale crawlers and Fig. 1.-Lacewing: Empty coons. Four times
aphids. The adults natural size.
of some (Chrysopa sp.) are green. The adults of the others
(Hemerobius sp.) are brown.
TRASH BUGS
One may often see an animated rubbish heap moving over the
surface of a leaf or the bark of a citrus tree. A close examina-
tion will reveal, projecting from the front end, a pair of jaws
similar to those of the aphis-lion. If the trash is removed one
finds a larva of an aphis-lion, but shorter and wider than most
of them. The trash is largely a collection of scalps; that is, the
dry skins of the victims of the larva.
There are two genera of lacewings common in citrus groves.
The adults of one genus are green (Chrysopa), those of the
other brown (Hemerobius). In both genera there are species
whose larvae are trash bugs and other species which do not
have the trash bug habit when young.
The aphis-lions are parasitized by minute wasp-like insects,
chalcids and ichneumons. These lay their eggs in the aphis-lions
and the grubs feed on the fatty tissues of the host. The aphis-
lion still has sufficient strength to spin its cocoon, but instead
of the lacewing the wasp-like parasite emerges. The larvae are
also parasitized by fungi and bacteria which produce, fatal
diseases.
THE GOLDEN-EYED LACEWING
(Chrysopa sp.)
The golden-eyed lacewing (Fig. 12) is a deep iridescent green
with eyes that shine like drops of liquid gold. The four delicate






20 Florida Cooperative Extension

gauzy wings when not in use are held up over the body like a
roof. The insect measures about 1/4 inches across the expanded
wings.
The eggs are laid on top of stiff stalks a half-inch long which
are placed in groups. These miniature
forests are a common sight on citrus
leaves. This arrangement protects the
eggs from the greedy aphis-lions that
will eat the eggs if they find them. After
hatching and crawling down its own stalk
the larva is not apt to find its way up
another.
Fig. 12.-Golden-eyed lace- PREDACEOUS MITES
wing. Twice atal ize. If a colony of scale-insects be observed
under a hand lens one will find many minute, soft-bodied 8-legged
animals running about among them. These are mites. They
belong to the spider class of animals rather than to the insects,
as shown by their eight legs. Insects never have more than six
true legs although many larvae such as caterpillars may have
a number of fleshy protuberances which act as legs. There are
several kinds of these mites. One of the most common is usu-
ally a pale flesh-color but varies from white to yellow. Another
is dark red.
Iany of these mites feed largely or entirely on the dry ma-
terial of dead scales. Others attack living scales although prob-
ably none of them are able to get at the growing insect under a
healthy permanent scale covering; but they devour the first-
stage young before the permanent scale is formed. As the scale-
insects reach maturity and a large number of eggs are laid, the
scale is apt to become loosened, allowing the mites to enter and
destroy the eggs. After spraying, the scales become loosened
and the mites are able to get at the dead, dying, or injured scales.
Their numbers always increase greatly after spraying. The
oil sprays undoubtedly kill all mites hit by the spray, but a
great many will be found untouched under dead scales or in
other sheltered places.
INTERNAL PARASITES
Upon close examination of a group of scales it will usually be
found that a certain proportion of them have a round, smooth-
cut hole in the top. These scales have been parasitized and the
round hole was cut by the adult parasite as it emerged from the






Bulletin 67, Citrus Insects and Their Control 21

dead scale. These parasites are minute four-winged creatures
belonging to the same order of insects as the wasps. They are
often spoken of as "wasp-like insects" and frequently as "wasps"
although they are much smaller than the true wasps and be-
long to different families. There are several families of these
wasp-like parasites.
In one family, the ichneumon flies, the body is usually quite
slender and wasp-like and the female is provided with long, stiff,
bristle-like appendages which project behind. These make up
the egg-laying organ or ovipositor and are sometimes many times
longer than the remainder of the insect.
In another family, Chalcids, the insects are generally smaller,
relatively short and thick, and have a shorter ovipositor than the
ichneumon flies.
The general habits of these families of insects are similar
and one account will do for all. The female lays one or more
eggs on the body of the scale-insects or in the scale's eggs either
by inserting her ovipositor under the scale or boring directly
through it. This egg hatches into a soft, whitish, footless, grub,
resembling that of a bee or wasp. The grub feeds at first on
only the body fluids or fatty portions of the host, avoiding the
vital organs. But finally the scale-insect is killed either as a
result of starvation due to the loss of its fat and body fluids, of
a direct attack on its vital organs, or of a poisoning by the larva.
The parasite after completing its growth goes into the pupal
stage and after a time makes its escape as a winged insect.
These internal parasites are an important check to the multi-
plication of scale-insects. There are many different species.
Most of them seem to be more common in winter than in sum-
mer, thus supplementing effectively the parasitic fungi.

CONTROL OF PURPLE SCALE
Ordinarily the control of purple scale and of whiteflies is but
a single problem and can be better discussed after we have
studied the life histories of the whiteflies.
In case of severe infestation it may be necessary to spray twice
in order to effect a control. An interval of a month in summer
or six weeks in winter should elapse between sprayings. This
will give all the eggs which, under the protection of the mature
females, escaped the first application, time to hatch; but it will
not give them time to mature and in turn lay eggs.






22 Florida Cooperative Extension

There are a few special cases where the measures which suffice
to control the whiteflies may not satisfactorily control the purple
scale. As examples of such conditions may be mentioned: (1)
During the first year following the setting of the trees; (2) when
a fungicide is used on the trees; (3) when there is little or no
whitefly in the grove; and (4) following a severe infestation of
the woolly whitefly or the citrus aphid.





























Fig. 13.-Increase of purple scale due to spraying the tree with bordeaux mixture: Top
row, sprayed fruit; bottom row, unsprayed fruit.

In a nursery row where the trees are set close together and
shade each other to a considerable extent, the entomogenous
fungi find sufficient humidity to multiply fairly well although
not as rapidly as in a grove of large trees. When these nursery
trees are transplanted into an open field and placed many feet
apart they are fully exposed to the drying effect of sun and wind
and the fungi do not thrive. As a result the scales are apt to mul-






Bulletin 67, Citrus Insects and Their Control 23

tiply rapidly. When nursery trees are transplanted into the
grove they should be defoliated and thoroughly scrubbed with a
strong soap solution. The State Plant Board requires this in the
case of trees sold by nurseries or moved from one property to
another. It should be done to all trees when transplanted into
the grove as it is very important that such trees be freed of
scale-insects. Young trees should be closely watched for scales
for a year or two. It will probably be found advantageous
to spray them at least three times a year. July will usually
be a desirable period in which to make the additional application.
When trees are sprayed with a fungicide to control either scab
or melanose fungi, the entomogenous fungi also are killed and
as a result the scales increase vastly (Fig. 13). Indeed it is -
possible to kill a citrus tree in the course of a year or so by
repeated sprayings with bordeaux. Such experiences afford the
most convincing proof of the importance of the entomogenous
fungi in controlling scale-insects. The application of bordeaux
to a tree should always be followed within two months by an ap-
plication of one of the oil emulsions, in order to forestall the in-
crease of the scales. At the beginning of the rainy season the en-
tomogenous fungi should be reintroduced.
In groves free from whitefly, spraying for purple scale should
be done immediately following the time when crawlers are most
abundant, which is usually from about the middle of April to
early May, mid-July and late October. The more important of
these dates corresponds quite closely with those which are pref-
erable for spraying to control whitefly. But, as explained under
whitefly, the April spraying should be postponed until the fruit
is an inch in diameter. This will usually defer the application
until May.
LONG SCALE
Lepidosaphes gloverii (Pack.)
Mixed with the purple scales may often be found other scales
which are almost identical in color and of about the same length,
but straighter and much narrower. These are the long scales.
(Fig. 14.) They are closely related to the purple scale to which
they bear such a marked resemblance that growers do not ordi-
narily distinguish between them.
According to Ashmead (1) this scale was introduced into
Florida about 1835 at Mandarin. By 1860, it had spread over
the orange districts and had become so destructive that it threat-






24 Florida Cooperative Extension

ened the existence of the citrus industry. Glover (12), in 1857,
stated that it was entirely free of parasites. This accounts for
its rapid multiplication. Later, parasites, both insects and fungi,
Appeared and were finally able to
control it better. Some of these para-
sites were probably introduced from
the original home of the scale,
thought to be southern China, and
native insects gradually developed a
taste for the long scale. As late as
1885 it was, according to Hubbard
(14), much more common than the
purple scale, although now it is much
less common.
Its life history, parasites and con-
trol are practically identical with
those of the purple scale. It is a little
more closely confined to the twigs and
Branches and less to the leaves and
fruit than the purple scale.

FLORIDA RED OR ROUND SCALE, OR
NAILRIEAD SCALE
Chrysomphalus aonidum (L.)
Scale for scale, the Florida red
scale is the most pernicious of our
citrus scale-insects. It does not do as
much aggregate damage as the pur-
ple scale because it is not as com-
mon, but when it does become abund-
ant it almost defoliates a tree. It is
less common in the northern part of
the. citrus belt, probably because it
is almost entirely confined to the
Fig. 14.-Long scale (Leidophes leaves and fruit and when these are
gloverii). enlarged 4 times, removed by a freeze it is almost ex-
(After Merrill and Chaffin.)
terminated.
This scale is dark reddish-brown in color, with a conspicuous
reddish-brown center, almost circular in outline (Fig. 15), and
about a twelfth of an inch in diameter when full-grown. The
center is formed by the cast-off first larval skin. This is






Bulletin 67, Citrus Insects and Their Control 25

nipple-shaped and varies in color from grayish to a reddish-
yellow brassy color. The surrounding part of the scale, that
which covers the second larval skin, is light reddish-brown, but
a little darker than the first larval skin. The scale of this insect
is very thick and heavy, much more so
than that of the purple scale.
The mature female under the scale is
bright yellow in color and the shape of
a wide short top.
The scale of the male is only about
one fourth as wide as that of the full-
grown female and a little lighter in
color. On one side, the posterior, there
is a grayish lobe. Its position and ap-
pearance gives the impression, at a su-
perficial glance, of a liquid which has
been pressed out from under the scale
and then hardened. The presence of
this lobe serves to distinguish readily Fig. 15.-Florida red scale
a male from a young female. Crsornalus anidu (L.)
The eggs are yellow in color and the
young crawlers bright yellow, the color of the mature female.
This scale seems to have been first noticed in Florida at Or-
lando in 1879 on a sour orange tree brought from Cuba in 1874.
LIFE HISTORY
The males complete their growth in about seven weeks, in
summer. The crawlers are at first oval.in form. They begin
to form their scales when less than a day old. By the second
day they cease to crawl and by the third day the scale has become
nearly circular in outline. The first molt occurs at the age of
about three weeks. The males complete their growth in about
seven weeks and soon afterward the females are fertilized.
Young are born* when the females are about ten weeks old and
continue to be produced for several weeks.
NATURAL CHECKS
The larvae, and especially the crawlers, are preyed upon by
ladybeetles and aphis-lions and the scale is preyed upon by the
same groups of insects as the purple scale.
Of the fungi which commonly parasitize the purple scale only
the pink scale-fungus is found at all common on this scale. At
times it becomes unusually effective.
*Eggs are produced which hatch at once or after a few hours.






26 Florida Cooperative Extension

CONTROL
The same oil emulsions which are used against the purple
scale are the best for this one also. However, because of the
thick and heavy scale which fits the leaf or fruit very closely
the mature females and the young under the scales are not easily
killed. Therefore, to control effectively a heavy infestation of
this scale two sprayings may be necessary. The second should be
applied from four to six weeks after the first. This will give the
females that were not killed by the first spraying time to mature
and die and their last young to emerge, but will not allow suf-
ficient time for a new generation to mature and begin to pro-
duce young.
Spraying with a 2% oil (i. e. twice the strength usually
recommended for purple scale and whitefly) has been recom-
mended for this scale. Trees sprayed with this strength of
oil should be thoroughly dormant.
Fumigation with hydrocyanic acid gas (see p. 66) has been
particularly effective in combatting this scale. The average
kill secured in groves under the senior author's observation has
been between 97 and 98%. The crawlers of this scale do not
have the tendency, so marked in the purple scale, to crawl under
other scales and into other protected situations. As a result
these scales are mostly found fully exposed on the surface of
the leaves (as often on the upper as on the lower surface) and
fruit where they receive the full effect of the gas. Hence the
percentage of kill is higher than in the case of the purple scale.
Lime-sulfur, 1-40, will kill the crawlers of this scale but not
the older stages.
In spraying fungus into a grove which has considerable
Florida red scale, the pink scale-fungus should be added to
the others if it can be obtained.
In addition to citrus, the Florida red scale infests many other
plants including the royal, coconut and many other palms, cam-
phor, magnolia, oleander, poinsettia, myrtle, and roses. In
spraying to control this scale any of these plants that may be
on the premises should also receive attention.

MINOR ARMORED SCALES
CALIFORNIA RED SCALE
Chrysomphalus aurantii (Mask.)
This scale, which is one of the worst pests with which the
California grower has to contend, is widely scattered over the






26 Florida Cooperative Extension

CONTROL
The same oil emulsions which are used against the purple
scale are the best for this one also. However, because of the
thick and heavy scale which fits the leaf or fruit very closely
the mature females and the young under the scales are not easily
killed. Therefore, to control effectively a heavy infestation of
this scale two sprayings may be necessary. The second should be
applied from four to six weeks after the first. This will give the
females that were not killed by the first spraying time to mature
and die and their last young to emerge, but will not allow suf-
ficient time for a new generation to mature and begin to pro-
duce young.
Spraying with a 2% oil (i. e. twice the strength usually
recommended for purple scale and whitefly) has been recom-
mended for this scale. Trees sprayed with this strength of
oil should be thoroughly dormant.
Fumigation with hydrocyanic acid gas (see p. 66) has been
particularly effective in combatting this scale. The average
kill secured in groves under the senior author's observation has
been between 97 and 98%. The crawlers of this scale do not
have the tendency, so marked in the purple scale, to crawl under
other scales and into other protected situations. As a result
these scales are mostly found fully exposed on the surface of
the leaves (as often on the upper as on the lower surface) and
fruit where they receive the full effect of the gas. Hence the
percentage of kill is higher than in the case of the purple scale.
Lime-sulfur, 1-40, will kill the crawlers of this scale but not
the older stages.
In spraying fungus into a grove which has considerable
Florida red scale, the pink scale-fungus should be added to
the others if it can be obtained.
In addition to citrus, the Florida red scale infests many other
plants including the royal, coconut and many other palms, cam-
phor, magnolia, oleander, poinsettia, myrtle, and roses. In
spraying to control this scale any of these plants that may be
on the premises should also receive attention.

MINOR ARMORED SCALES
CALIFORNIA RED SCALE
Chrysomphalus aurantii (Mask.)
This scale, which is one of the worst pests with which the
California grower has to contend, is widely scattered over the






Bulletin 67, Citrus Insects and Their Control 27

citrus growing sections of the world. It is well distributed in
Florida but in most sections has not been serious. In some
groves in Pinellas County it has given trouble.
This scale also is round but is much flatter in outline and
lighter in color than the Florida red scale. The first larval skin
is not nearly so prominent and the scale is not as thick. In color
it is more yellowish. The most marked differences and those
which afford the most certain means of identification are found
in the mature female under the scale. In this species the female
is red instead of yellow, and heart-shaped instead of top-shaped.
It is the color of the female through the semi-transparent scale
that gives this scale the name "red." The pink scale-fungus
sometimes attacks this scale. This may be the reason why it has
never become such a pest in Florida and in the more humid por-
tions of the West Indies as it has in California.
DICTYOSPERMUM SCALE
Chrysomphalus dictyospermi (Morg.)
The dictyospermum scale is intermediate in appearance be-
tween the California red scale and the Florida red scale. It is
generally distributed in Florida. Not much is known about
this scale on citrus here, but it does not seem likely to become
a serious pest. It attacks about 60 other plants in addition
to citrus. This scale will probably be found to be more easily
killed by the oil emulsions than is the Florida red scale.
This scale is a common and severe pest in the Mediterranean
region, and in South Africa is called the "Spanish Red Scale".
RUFOUS OR WEST INDIAN RED SCALE
Pseudaonidia (Selenaspidus) articulatus (Morg.)
The Rufous scale is, as far as known, found in the State
only at Key West and Miami, where it infests the lime and
other plants. It is flat, nearly circular, and pale brown in color.
Besides citrus it attacks oleander, Ficus, palms, and a number
of other plants. It is common throughout the West Indies.
CAMPHOR SCALE
Pseudaonidia duplex (Ckll.)
This scale is not at present known to be in Florida, but it
occurs in Louisiana and Alabama where it is a very severe
pest on satsumas. This scale is apparently a very difficult one
to control and it is to be hoped that its spread into Florida will
be long delayed. As its name indicates, it was first noticed
as a pest of camphor trees and was probably introduced into






Bulletin 67, Citrus Insects and Their Control 27

citrus growing sections of the world. It is well distributed in
Florida but in most sections has not been serious. In some
groves in Pinellas County it has given trouble.
This scale also is round but is much flatter in outline and
lighter in color than the Florida red scale. The first larval skin
is not nearly so prominent and the scale is not as thick. In color
it is more yellowish. The most marked differences and those
which afford the most certain means of identification are found
in the mature female under the scale. In this species the female
is red instead of yellow, and heart-shaped instead of top-shaped.
It is the color of the female through the semi-transparent scale
that gives this scale the name "red." The pink scale-fungus
sometimes attacks this scale. This may be the reason why it has
never become such a pest in Florida and in the more humid por-
tions of the West Indies as it has in California.
DICTYOSPERMUM SCALE
Chrysomphalus dictyospermi (Morg.)
The dictyospermum scale is intermediate in appearance be-
tween the California red scale and the Florida red scale. It is
generally distributed in Florida. Not much is known about
this scale on citrus here, but it does not seem likely to become
a serious pest. It attacks about 60 other plants in addition
to citrus. This scale will probably be found to be more easily
killed by the oil emulsions than is the Florida red scale.
This scale is a common and severe pest in the Mediterranean
region, and in South Africa is called the "Spanish Red Scale".
RUFOUS OR WEST INDIAN RED SCALE
Pseudaonidia (Selenaspidus) articulatus (Morg.)
The Rufous scale is, as far as known, found in the State
only at Key West and Miami, where it infests the lime and
other plants. It is flat, nearly circular, and pale brown in color.
Besides citrus it attacks oleander, Ficus, palms, and a number
of other plants. It is common throughout the West Indies.
CAMPHOR SCALE
Pseudaonidia duplex (Ckll.)
This scale is not at present known to be in Florida, but it
occurs in Louisiana and Alabama where it is a very severe
pest on satsumas. This scale is apparently a very difficult one
to control and it is to be hoped that its spread into Florida will
be long delayed. As its name indicates, it was first noticed
as a pest of camphor trees and was probably introduced into






Bulletin 67, Citrus Insects and Their Control 27

citrus growing sections of the world. It is well distributed in
Florida but in most sections has not been serious. In some
groves in Pinellas County it has given trouble.
This scale also is round but is much flatter in outline and
lighter in color than the Florida red scale. The first larval skin
is not nearly so prominent and the scale is not as thick. In color
it is more yellowish. The most marked differences and those
which afford the most certain means of identification are found
in the mature female under the scale. In this species the female
is red instead of yellow, and heart-shaped instead of top-shaped.
It is the color of the female through the semi-transparent scale
that gives this scale the name "red." The pink scale-fungus
sometimes attacks this scale. This may be the reason why it has
never become such a pest in Florida and in the more humid por-
tions of the West Indies as it has in California.
DICTYOSPERMUM SCALE
Chrysomphalus dictyospermi (Morg.)
The dictyospermum scale is intermediate in appearance be-
tween the California red scale and the Florida red scale. It is
generally distributed in Florida. Not much is known about
this scale on citrus here, but it does not seem likely to become
a serious pest. It attacks about 60 other plants in addition
to citrus. This scale will probably be found to be more easily
killed by the oil emulsions than is the Florida red scale.
This scale is a common and severe pest in the Mediterranean
region, and in South Africa is called the "Spanish Red Scale".
RUFOUS OR WEST INDIAN RED SCALE
Pseudaonidia (Selenaspidus) articulatus (Morg.)
The Rufous scale is, as far as known, found in the State
only at Key West and Miami, where it infests the lime and
other plants. It is flat, nearly circular, and pale brown in color.
Besides citrus it attacks oleander, Ficus, palms, and a number
of other plants. It is common throughout the West Indies.
CAMPHOR SCALE
Pseudaonidia duplex (Ckll.)
This scale is not at present known to be in Florida, but it
occurs in Louisiana and Alabama where it is a very severe
pest on satsumas. This scale is apparently a very difficult one
to control and it is to be hoped that its spread into Florida will
be long delayed. As its name indicates, it was first noticed
as a pest of camphor trees and was probably introduced into






28 Florida Cooperative Extension

this country from Japan. It resembles somewhat in shape
the purple scale but is smaller and darker in color. Thorough
sprayings with oil emulsions have been used to control this
scale, but the most successful method seems to be fumigation
with hydrocyanic acid gas.
SAN JOSE SCALE
Aspidiotus perniciosus Comst.
The San Jose scale, a pernicious pest of peaches, plums, pears,
and apples, attacks Poncirus (Citrus) trifoliata. It has been re-
ported as temporarily attacking young orange trees in groves
where orange trees are alternated with heavily infested peach
trees. This is a small scale, averaging only about half as wide
as the Florida red. It is gray in color and when only a few are
present they are easily overlooked. The first signs that the
grower is apt to notice are reddish or pinkish areas which de-
velop about each scale. When abundant they cover the bark and
give the whole tree their gray color.
The control of this scale on Poncirus trifoliata would be best
accomplished by spraying with the red-headed and the black
scale-fungi in the summer and at some time in the winter when
the bushes are dormant and leafless with commercial lime-sul-
phur solution, 1 part in about 9 of water, as is recommended for
peach trees when they become infested with this scale. For a
table of dilutions for different strengths of lime-sulphur see
page 92. A 2% oil emulsion applied during the winter is
fully as effective as the lime-sulphur solution.

CHAFF SCALE
Parlatoria pergandii Comst.
As the name indicates, chaff scales are those thin, gray, or
brownish-gray scales which often completely cover the branches
of a tree and overlap each other, giving the tree the appearance
of being covered with chaff. It is partial to the smaller branches
and the trunks of small trees, but when the infestation is heavy
it is often found on the leaves and especially the fruit as well
as on the larger branches and trunks of larger trees.
The scale of the female is irregularly circular in outline but is
usually bluntly pointed on one side. The first larval skin is
darker than the remainder of the scale and quite distinct from
it. It is oval in outline, has a prominent ridge down the middle,
and is placed nearer one edge of the scale, that is, it is not
central. This scale is a little smaller than the Florida red scale.






28 Florida Cooperative Extension

this country from Japan. It resembles somewhat in shape
the purple scale but is smaller and darker in color. Thorough
sprayings with oil emulsions have been used to control this
scale, but the most successful method seems to be fumigation
with hydrocyanic acid gas.
SAN JOSE SCALE
Aspidiotus perniciosus Comst.
The San Jose scale, a pernicious pest of peaches, plums, pears,
and apples, attacks Poncirus (Citrus) trifoliata. It has been re-
ported as temporarily attacking young orange trees in groves
where orange trees are alternated with heavily infested peach
trees. This is a small scale, averaging only about half as wide
as the Florida red. It is gray in color and when only a few are
present they are easily overlooked. The first signs that the
grower is apt to notice are reddish or pinkish areas which de-
velop about each scale. When abundant they cover the bark and
give the whole tree their gray color.
The control of this scale on Poncirus trifoliata would be best
accomplished by spraying with the red-headed and the black
scale-fungi in the summer and at some time in the winter when
the bushes are dormant and leafless with commercial lime-sul-
phur solution, 1 part in about 9 of water, as is recommended for
peach trees when they become infested with this scale. For a
table of dilutions for different strengths of lime-sulphur see
page 92. A 2% oil emulsion applied during the winter is
fully as effective as the lime-sulphur solution.

CHAFF SCALE
Parlatoria pergandii Comst.
As the name indicates, chaff scales are those thin, gray, or
brownish-gray scales which often completely cover the branches
of a tree and overlap each other, giving the tree the appearance
of being covered with chaff. It is partial to the smaller branches
and the trunks of small trees, but when the infestation is heavy
it is often found on the leaves and especially the fruit as well
as on the larger branches and trunks of larger trees.
The scale of the female is irregularly circular in outline but is
usually bluntly pointed on one side. The first larval skin is
darker than the remainder of the scale and quite distinct from
it. It is oval in outline, has a prominent ridge down the middle,
and is placed nearer one edge of the scale, that is, it is not
central. This scale is a little smaller than the Florida red scale.






Bulletin 67, Citrus Insects and Their Control 29

The adult female under the scale is dark purple, tinged with
yellow along the posterior margin. The young female is white.
The scale of the male is oblong and whitish in color. The first
larval skin is placed at one end and is about a third of the
length of the whole scale. It is greenish in color. The adult
male is purplish.
LIFE HISTORY
The female lays an average of about sixteen eggs. These are
large for the size of the female, hence the small number. The
crawlers wander about for a few hours and then come to rest.
They show the same aversion to strong light as those of the
purple scale. This frequently causes them to crawl under an
old scale or into the depressions or pits of the fruit and settle
there.
According to Hubbard, four generations are produced each
year. The crawlers of the first generation are especially abun-
dant in March or April and of the last in September or October,
but there is much overlapping and mixing of generations.
NATURAL CHECKS
In addition to the ladybeetles and other predaceous checks
on scale-insects in general, this species is attacked by a wasp-
like parasite which does very efficient work in keeping it under
control. The grub of the parasite eats first the eggs and then
the mature female herself. When mature the adult parasite
escapes through a hole in the scale.
The red-headed and the black scale-fungi attack this scale.
The latter does especially efficient work in controlling it.
CONTROL MEASURES
This scale is easily killed by the oil emulsions, or fish-oil
soap alone. The best seasons for spraying are toward the end
of the seasons of maximum abundance of crawlers, which are
April and October. In groves that are sprayed regularly for
whitefly in May and September the chaff scale will cause no
trouble. The only extra precautions that need be taken when
considerable of this scale is noticed in a grove are to make a
special effort to secure and spread the black scale-fungus, and at
spraying time to see that the insecticide covers the branches as
well as the leaves and fruit.
FOOD PLANTS
Among the most common host plants of this scale are, besides
citrus, camphor, many palms, Ficus, japonica, mango, and ole-






30 Florida Cooperative Extension

ander. These plants also when growing in an infested grove
should be sprayed.
CITRUS SNOW SCALE
Chionaspis citri Comst.
The citrus snow scale gets its name from the white color of the
male scales (Fig. 16). These, like those of the chaff scale, are
long and narrow. There is a prominent longitudinal ridge, and a
fainter one on each side. These three parallel ridges enable
the males of this species to be distinguished from those of the
chaff scale. The first larval skin is yellow-
S ish in color. Owing to the inconspicuous
color of the females it is the male scales
S that make a colony noticeable.
S The scale of the female is dark brown
with a lighter margin, a color that re-
sembles the bark of the trees so closely
that the scales are hard to detect. In shape
it resembles somewhat the purple scale but
is broader. It has a prominent longitudi-
nal ridge which, with the color and situ-
ation on the tree, readily distinguishes it
from the purple scale. The first larval
skin is brownish-yellow.
Like the chaff scale, this one, too, in-
fests chiefly the branches but shows a
preference for the larger branches and is
often found on the trunks. It may so
drain the bark of sap as to cause it to die
and split. It is not widely distributed in
Florida.
Control is the same as for the chaff
scale.
SOFT SCALES
sFige 16(Ch s itu Snor In this group of unarmoredd) soft
scales, no true scale covering, separate
from the body of the insect, is formed, but the skin or body wall
of the insect is hardened by a chitinous secretion which is either
incorporated into the skin itself or formed into a layer on top
of the skin. The female is not fastened permanently to the bark
of the tree, but is able to move about until the eggs begin to






30 Florida Cooperative Extension

ander. These plants also when growing in an infested grove
should be sprayed.
CITRUS SNOW SCALE
Chionaspis citri Comst.
The citrus snow scale gets its name from the white color of the
male scales (Fig. 16). These, like those of the chaff scale, are
long and narrow. There is a prominent longitudinal ridge, and a
fainter one on each side. These three parallel ridges enable
the males of this species to be distinguished from those of the
chaff scale. The first larval skin is yellow-
S ish in color. Owing to the inconspicuous
color of the females it is the male scales
S that make a colony noticeable.
S The scale of the female is dark brown
with a lighter margin, a color that re-
sembles the bark of the trees so closely
that the scales are hard to detect. In shape
it resembles somewhat the purple scale but
is broader. It has a prominent longitudi-
nal ridge which, with the color and situ-
ation on the tree, readily distinguishes it
from the purple scale. The first larval
skin is brownish-yellow.
Like the chaff scale, this one, too, in-
fests chiefly the branches but shows a
preference for the larger branches and is
often found on the trunks. It may so
drain the bark of sap as to cause it to die
and split. It is not widely distributed in
Florida.
Control is the same as for the chaff
scale.
SOFT SCALES
sFige 16(Ch s itu Snor In this group of unarmoredd) soft
scales, no true scale covering, separate
from the body of the insect, is formed, but the skin or body wall
of the insect is hardened by a chitinous secretion which is either
incorporated into the skin itself or formed into a layer on top
of the skin. The female is not fastened permanently to the bark
of the tree, but is able to move about until the eggs begin to






Bulletin 67, Citrus Insects and Their Control 31

form. At this time the legs are covered and made useless by the
swelling of the body as the eggs form and are more or less
fastened to the branch or leaf, etc.
LIFE HISTORY
There are no marked molts in these scale-insects but only a
steady growth. The eggs are laid down under the female or
retained in her body until they hatch. The crawlers are oval,
active, six-legged creatures, much like those of the armored
scales. Males, of the species found on citrus, are rarely seen.
These scales suck the sap from the tissues like the armored scales
do, but the beak never grows to be very long and the insect is
able to withdraw and insert it at will.
The scales of this group give off honeydew abundantly. In it
the sooty mold grows so that an infested plant soon becomes
blackened. This honeydew is greatly relished by ants which
are seen constantly about the
scales.
The soft scales seldom seri-
ously injure a mature tree,
but on nursery stock and on

turtle-back scale sometimes
causes some trouble. After
death these scales soon fall
off the trees instead of re-
maining for many months as
a crust which partly shuts off
the light and air as do the
armored scales.
They are easily controlled
by the oil emulsions.
SOFT BROWN OR
TURTLE-BACK SCALE
Coccus hesperidum (L.)
In this species and the next $
described, the wax is incor- Fig. 17.-Soft brown scale. Natural size.
porated with the skin which (After Comstock.)
becomes tough and parchment-like, resembling in appearance the
covering of the armored scales. (Fig. 17.) These scales are
larger than the armored scales and thicker.






32 Florida Cooperative Extension

The full-grown female of this scale is between an eighth and
a sixth of an inch long, oval in outline and dark brown in color.
It is much swollen in the center but flat at the margin. The
back is crossed by ridges which divide it into areas suggesting
the markings on the back of a turtle, hence the name. There
are three notches in the margin, a shallow one on each side and
a deeper one behind. The scale of the male is very small.
LIFE HISTORY
The eggs hatch inside of the mother scale. The crawlers are
yellow and nearly transparent so that the color of the bark shows
through them, making them inconspicuous. The skin is smooth
and shining. The margin of the body is extended outward as a
thin membrane which completely covers the six slender legs.
The young nymphs attack only the young growth, leaves and
twigs. Consequently this scale increases most rapidly during
the flushes of growth in the spring and early summer.
This scale is attacked by at least a half dozen different
species of wasp-like internal parasites which keep it under good
control. These parasitized scales turn jet black.
The Cuban Aschersonia (Aschersonia cubensis) (see page
37) has been observed as a very effective fungus parasite of
this scale in several places in south Florida.
The early stages are easily killed by the oil emulsions and in
groves regularly sprayed with them for whiteflies and purple
scale this scale will be controlled without any special attention.
In addition to citrus this scale attacks a large number of
plants. Those with smooth bark or leaves are especially attrac-
tive to it. Ivy, oleander and japonica are favorites. Bay, avo-
cado, guava, persimmon, and many species of palms are some-
times attacked.
HEMISPHERICAL SCALE
Saissetia hemisphaerica (Targ.)
The hemispherical scale is similar in size, color, and shape
to the soft brown; but its center is more swollen and the mar-
gin is narrower so that it is nearly hemispherical in profile,
hence the name. It averages about a seventh of an inch in length
and a trifle less in width. The height is about a twelfth of an
inch. The egg is about 1/150 of an inch in length and is yellow-
ish-white.
This scale infests guava, avocado, Asparagus plumosus, ja-
ponica, Ficus spp., ferns, peach, rose, palms, and many other







Bulletin 67, Citrus Insects and Their Control 33

plants. Natural and artificial control are the same as for the
soft brown scale.
BLACK SCALE
Saissetia oleae (Bern.)
The black scale (Fig. 18), the most destructive scale-insect
in southern California, is generally distributed in Florida. Here
it is more common on oleander than on citrus, which it rarely
attacks. Florida seems to be the only important citrus center of
the world which does not have consider- --
able trouble with this scale.
The adult female is from an eighth to a I
quarter of an inch long. It is black or
dark brown in color and nearly hemispher- :
ical in shape. The markings on the back
form a distinct letter "H". It gives off
honeydew in great abundance.
The female lays from 300 to 3,000 eggs
and averages 1,700. She lives for two
months after reaching maturity and lays
from 50 to 100 eggs a day.. They hatch
in from fifteen to twenty days. The young
prefer the leaves but migrate to the stems
before they are half grown. They grow
slowly, requiring from six to eight months
to reach maturity. Bul. 214 of the Cali-
fornia Station contains a full account of
this insect (21).
WAX SCALES
Ceroplastes spp. ... .
The wax scales are soft scales which se- Fig. 18.-Bck scale. (After
Wilson, 31.)
create a thick layer of white wax which
completely covers the body. This wax is soft and can be readily
scraped off. Underneath the wax the skin proper is soft and
delicate. These scales give off abundant honeydew. Even a mod-
erate infestation suffices to blacken thoroughly the host plant.
There are three of these wax scales which are likely to be
found on citrus in Florida, but only the Florida wax scale is
common.
FLORIDA WAX SCALE
Ceroplastes floridenais Comst.
The Florida wax scale (Fig. 19) when not stained by sooty
mold or other foreign matter is snow-white, often with a pink-

2







Bulletin 67, Citrus Insects and Their Control 33

plants. Natural and artificial control are the same as for the
soft brown scale.
BLACK SCALE
Saissetia oleae (Bern.)
The black scale (Fig. 18), the most destructive scale-insect
in southern California, is generally distributed in Florida. Here
it is more common on oleander than on citrus, which it rarely
attacks. Florida seems to be the only important citrus center of
the world which does not have consider- --
able trouble with this scale.
The adult female is from an eighth to a I
quarter of an inch long. It is black or
dark brown in color and nearly hemispher- :
ical in shape. The markings on the back
form a distinct letter "H". It gives off
honeydew in great abundance.
The female lays from 300 to 3,000 eggs
and averages 1,700. She lives for two
months after reaching maturity and lays
from 50 to 100 eggs a day.. They hatch
in from fifteen to twenty days. The young
prefer the leaves but migrate to the stems
before they are half grown. They grow
slowly, requiring from six to eight months
to reach maturity. Bul. 214 of the Cali-
fornia Station contains a full account of
this insect (21).
WAX SCALES
Ceroplastes spp. ... .
The wax scales are soft scales which se- Fig. 18.-Bck scale. (After
Wilson, 31.)
create a thick layer of white wax which
completely covers the body. This wax is soft and can be readily
scraped off. Underneath the wax the skin proper is soft and
delicate. These scales give off abundant honeydew. Even a mod-
erate infestation suffices to blacken thoroughly the host plant.
There are three of these wax scales which are likely to be
found on citrus in Florida, but only the Florida wax scale is
common.
FLORIDA WAX SCALE
Ceroplastes floridenais Comst.
The Florida wax scale (Fig. 19) when not stained by sooty
mold or other foreign matter is snow-white, often with a pink-

2







Bulletin 67, Citrus Insects and Their Control 33

plants. Natural and artificial control are the same as for the
soft brown scale.
BLACK SCALE
Saissetia oleae (Bern.)
The black scale (Fig. 18), the most destructive scale-insect
in southern California, is generally distributed in Florida. Here
it is more common on oleander than on citrus, which it rarely
attacks. Florida seems to be the only important citrus center of
the world which does not have consider- --
able trouble with this scale.
The adult female is from an eighth to a I
quarter of an inch long. It is black or
dark brown in color and nearly hemispher- :
ical in shape. The markings on the back
form a distinct letter "H". It gives off
honeydew in great abundance.
The female lays from 300 to 3,000 eggs
and averages 1,700. She lives for two
months after reaching maturity and lays
from 50 to 100 eggs a day.. They hatch
in from fifteen to twenty days. The young
prefer the leaves but migrate to the stems
before they are half grown. They grow
slowly, requiring from six to eight months
to reach maturity. Bul. 214 of the Cali-
fornia Station contains a full account of
this insect (21).
WAX SCALES
Ceroplastes spp. ... .
The wax scales are soft scales which se- Fig. 18.-Bck scale. (After
Wilson, 31.)
create a thick layer of white wax which
completely covers the body. This wax is soft and can be readily
scraped off. Underneath the wax the skin proper is soft and
delicate. These scales give off abundant honeydew. Even a mod-
erate infestation suffices to blacken thoroughly the host plant.
There are three of these wax scales which are likely to be
found on citrus in Florida, but only the Florida wax scale is
common.
FLORIDA WAX SCALE
Ceroplastes floridenais Comst.
The Florida wax scale (Fig. 19) when not stained by sooty
mold or other foreign matter is snow-white, often with a pink-

2







34 Florida Cooperative Extension

ish tint imparted to it by the red color of the insect beneath.
When seen against the deep green of the citrus leaf or stem it
is a beautiful object. However, its pure white wax, which is
very similar to the white wax of commerce, is commonly
stained with the sooty mold fungus which grows in the honey-
dew of the scale.
The full-grown female is an eighth of an inch or less in length,
oval in general outline but presents an angular appearance due
to the dome-shaped masses of wax on the back. (Fig. 19.) Of
these, there is one large rounded central dome surrounded by six
.-or eight lesser ones placed
in a circle about the margin
S of the scale and separated
from the central dome by a
depression.
r The eggs are dark red
:w a and about a hundredth of
an inch long. They aver-
age in number between 75
Sand 100 for each scale and
Share placed under the female
which shrinks as they ac-
cumulate. The pale brown
crawlers show a preference
for the leaves where they
collect especially along the
midrib on the under side.
The young larvae are star-
Fig. 19.-Florida wax scale. (After Wilson, 31.)
shaped and even more beau-
tiful than the adults. Three or four months are required for
growth and there are three principal broods or crawlers which
appear during April and May, July and August, and October
and November. The last is a smaller, less important brood.
NATURAL CHECKS
As the females mature and become heavy with eggs most of
them.are unable to cling to the smooth surface of the orange
leaf and fall to the ground and perish. A larger proportion
of those that settle on the twigs are able to hang on until ma-
turity. Because of this mortality the insect never becomes a
serious pest of orange or grapefruit trees. On the thick angular
stems of Poncirus trifoliata Raf., it can retain its hold much
better and sometimes becomes more of a pest. The native food







Bulletin 67, Citrus Insects and Their Control 35

plant of this insect is chiefly the gallberry (Ilex glabra) of the
flatwoods which is commonly blackened by the sooty mold grow-
ing in the honeydew given off by the insect. The mature females
do not fall off the gallberry.
HOST PLANTS
Besides citrus and gallberry, this scale attacks avocados,
feijoa, guavas, cherry laurel, sea grape, Ficus, loquat, mango
and many others. The writers have even seen it on sweet potato
vines.
CONTROL
The Florida wax scale is parasitized by several
wasp-like insects whose grubs live inside the
scale. The scale-eating caterpillar, Laetilia cocci-
divora Comst. (see mealybugs), sometimes de-
stroys this scale. This scale is also very effective-
ly parasitized by the turbinate fungus.
Should it become necessary to spray for this
scale the oil emulsions will probably be found per- .-
fectly satisfactory.
BARNACLE SCALE
Ceroplastes cirrivediformis Comst.
The Barnacle scale is closely related to the Flor-
ida wax, which it resembles in appearance and
life history. Its most conspicuous difference is in
its height which is about equal to its width. (Fig.
20.) The waxy coat is dirty-white in color mot-
tied with brown and is divided into distinct plates.
These plates give the scales a hard, limy appear- 1
ance, and the angular outline which it shares with
the Florida wax scale, suggests a barnacle in Fig e2.- ar-
appearance, hence the name. It is larger than the (Aft Wil-
son,
Florida wax scale, being a fifth of an inch long
and a sixth wide. It is a native scale, found throughout the
State, but nowhere is it abundant. Besides citrus it infests
guava and wild persimmon, quince, and Eupatorium sp.
Its life history is similar to that of the Florida wax scale.
The eggs are larger and darker. The crawlers are dark brown.
JAPANESE OR MEXICAN WAX SCALE
Ceroplastes ceriferus (Anderson)
The Japanese or Mexican wax scale has been found in a num-
ber of localities in Florida, growing on wild persimmon and







Bulletin 67, Citrus Insects and Their Control 35

plant of this insect is chiefly the gallberry (Ilex glabra) of the
flatwoods which is commonly blackened by the sooty mold grow-
ing in the honeydew given off by the insect. The mature females
do not fall off the gallberry.
HOST PLANTS
Besides citrus and gallberry, this scale attacks avocados,
feijoa, guavas, cherry laurel, sea grape, Ficus, loquat, mango
and many others. The writers have even seen it on sweet potato
vines.
CONTROL
The Florida wax scale is parasitized by several
wasp-like insects whose grubs live inside the
scale. The scale-eating caterpillar, Laetilia cocci-
divora Comst. (see mealybugs), sometimes de-
stroys this scale. This scale is also very effective-
ly parasitized by the turbinate fungus.
Should it become necessary to spray for this
scale the oil emulsions will probably be found per- .-
fectly satisfactory.
BARNACLE SCALE
Ceroplastes cirrivediformis Comst.
The Barnacle scale is closely related to the Flor-
ida wax, which it resembles in appearance and
life history. Its most conspicuous difference is in
its height which is about equal to its width. (Fig.
20.) The waxy coat is dirty-white in color mot-
tied with brown and is divided into distinct plates.
These plates give the scales a hard, limy appear- 1
ance, and the angular outline which it shares with
the Florida wax scale, suggests a barnacle in Fig e2.- ar-
appearance, hence the name. It is larger than the (Aft Wil-
son,
Florida wax scale, being a fifth of an inch long
and a sixth wide. It is a native scale, found throughout the
State, but nowhere is it abundant. Besides citrus it infests
guava and wild persimmon, quince, and Eupatorium sp.
Its life history is similar to that of the Florida wax scale.
The eggs are larger and darker. The crawlers are dark brown.
JAPANESE OR MEXICAN WAX SCALE
Ceroplastes ceriferus (Anderson)
The Japanese or Mexican wax scale has been found in a num-
ber of localities in Florida, growing on wild persimmon and







36 Florida Cooperative Extension

gumbo limbo. Citrus however, is one of its host plants and will
probably be found infested in Florida.
The wax of this species is not as symmetrically placed as in
the other species but forms a more irregular mass and has a
greasy appearance. The body of the insect is black or purplish-
brown and shows dimly through the wax.

PYRIFORM SCALE
Pulvinaria pyriformis (Ckll.)

The pyriform scale (Fig.
21) is found on many plants,
including citrus, guava,
mango, ivy, and many orna-
mentals. It frequently be-
comes very abundant on avo-
cados which it blackens
thoroughly with the sooty
mold which grows in its
honeydew.
As its name indicates, the
mature female is pear-
shaped, tapering to a point
in front. It is brown but
nearly surrounded by a white
cottony-looking wax. This
cotton is also formed under
the posterior part of the
scale and serves as a protec-
tion to the eggs which are
laid in it. The full-grown fe-
male varies from a twelfth
to a sixth of an inch in
length. The young are oval,
Fig. 21.-Pyrilorrm scale (Pulvinaria apyri-
formis) on guava leaf. greenish-yellow and without
any signs of cotton.
This scale is easily killed by contact insecticides, as the oil
emulsions, soap solution, kerosene emulsion, etc.
The Cuban aschersonia (Aschersonia cubensis) and Cephalo-
sporium lecanii have been frequently observed as very effective
fungus parasites of this scale.







Bulletin 67, Citrus Insects and Their Control 37

GREEN SHIELD SCALE
Pulvinaria psidii Mask.
In Florida the green shield scale, which has been in the State
20 or more years, has attacked chiefly the wild rubber tree, the
guava, the mango, the sea grape, and the avocado in about the
order named. Only occasionally has it been taken from cit-
rus in Florida, although it is said to be the worst pest citrus
has in southeastern Asia.
The adult female forms cotton even more abundantly than its






















Fig. 22.-Green shield scale (Pulvinaria psidii Mask.) on leaf of wild fig, or wild rubber
(Ficus areaa. After Wilson, 31. Enlarged twice.

related species, the pyriform scale. The mass finally becomes
many times larger than the scale proper, which is about the
size of the pyriform scale but more oval in outline, and lighter
in color. (Fig. 22.) It is greenish-brown. This scale is now
widely distributed in south Florida.

ENTOMOGENOUS FUNGI OF SOFT SCALES

A number of fungi do very effective work in parasitizing soft
scales. The following are the most important ones:
CUBAN ASCHERSONIA (Aschersonia cubensis Berk. and







Bulletin 67, Citrus Insects and Their Control 37

GREEN SHIELD SCALE
Pulvinaria psidii Mask.
In Florida the green shield scale, which has been in the State
20 or more years, has attacked chiefly the wild rubber tree, the
guava, the mango, the sea grape, and the avocado in about the
order named. Only occasionally has it been taken from cit-
rus in Florida, although it is said to be the worst pest citrus
has in southeastern Asia.
The adult female forms cotton even more abundantly than its






















Fig. 22.-Green shield scale (Pulvinaria psidii Mask.) on leaf of wild fig, or wild rubber
(Ficus areaa. After Wilson, 31. Enlarged twice.

related species, the pyriform scale. The mass finally becomes
many times larger than the scale proper, which is about the
size of the pyriform scale but more oval in outline, and lighter
in color. (Fig. 22.) It is greenish-brown. This scale is now
widely distributed in south Florida.

ENTOMOGENOUS FUNGI OF SOFT SCALES

A number of fungi do very effective work in parasitizing soft
scales. The following are the most important ones:
CUBAN ASCHERSONIA (Aschersonia cubensis Berk. and






38 Florida Cooperative Extension

Curt.).*-This fungus (Fig. 23) consists of buff, brown or red-
dish pustules 1/16 to nearly 1/4 inch in diameter. Frequently it
has been collected effectively destroying the liriodendron scale on
banana shrub at Gainesville. It appears to be widely distrib-
uted, however, and has been received from widely separated
localities in Florida. Also from Porto Rico and Cuba.
The chief importance of this fungus lies in the fact that it
has been received infecting and destroying several important
pests of the soft scale group. Pure cultures of this fungus were
first grown by the junior author in 1920, and are occasionally
available for distribution.
This fungus has been received on the following scales: Soft
brown scale (Coccus hesperidum), on citrus; liriodendron scale













Fig. 23.-Cuban Aschersonia on Pyriform Scale on guava leaf. Plant Board photo by
A. H. Beyer, courtesy of Experiment Station. Slightly reduced.

(Toumeyella liriodendri), on banana shrub and magnolia; tes-
sellated scale (Eucalymnatus tessellatus), on mango, cape jas-
hine and dahoon holly; pyriform scale (Pulvinaria pyriformis),
on guava, avocado, rhynchospermum, bottlebrush, red bay and
other plants-this scale rarely occurs on citrus in Florida; green
scale (Coccus viridis), on unknown plant from Cuba; Florida
wax scale (Ceroplastes floridensis), on fern; Lecanium nigro-
faciatum, on red bay.
TURBINATE FUNGUS (Aschersonia turbinata Berk.) **.-This
is the parasite that controls Florida wax scale. It produces one
or several short whitish stems that grow out from the mass of
fungus covering the scale. These stems approximate 1/16 of
*According to Petch (courtesy H. S. Fawcett, letter 1924) this has
perfect stage in Hypocrella epiphylla.
**According to Fawcett (1926) this has a perfect stage in Hypocrella
turbinata (Berk.) Petch.







Bulletin 67, Citrus Insects and Their Control 39

an inch in height and diameter and end in a shallow cavity con-
taining the red or near-red spores. It probably occurs wherever
the Florida wax scale is abundant on citrus and other plants.
It has also been received on the liriodendron scale, on banana
shrub.
CEPHALOSPORIUM FUNGUS (Cephalosporium lecanii Zimmer-
man).-This fungus may be recognized as a delicate powdery
halo-like growth of light color about the margins of soft scales,
several species of which are effectively parasitized and con-
trolled by it. The same type of growth may, furthermore,
cover the entire insect. It has been received from the West
Indies, and various localities in Florida. The importance of
this fungus lies mainly in its being an effective parasite of the
pyriform scale, which, while but a minor pest of citrus in Flor-
ida, is a severe pest on guavas, avocados and some other plants.
Other insects that occasionally infest citrus in Florida and on
which this fungus may occur are: Soft brown scale (Coccus
hesperidum (Linn.)) and the hemispherical scale (Saissetia
hemisphaerica (Targ.)). It has been reported on green scale
(Coccus viridis (Green)) on citrus in Ceylon (18) and received
from Cuba on the same scale infesting mistletoe.
This fungus has been received or reported from Florida or
elsewhere also on the following scales: Lecanium nigrofasci-
atum (Pergande) on bay; Coccus mangiferae (Green) on mango
in the Virgin Islands; Coccus acumina.tus (Sign.) on mango in
Barbados; liriodendron scale on magnolia and banana shrub;
tessellated scale (Eucalymnatus tessellatus (Sign.)) on palms
and some other plants; Toumeyella turgida on pine (Pinus
taeda) (Fawcett, 8).
This fungus can be readily grown artificially in pure cultures,
should a need for doing so arise.
MEALYBUGS
Mealybugs derive their name from the mass of mealy wax
with which they cover themselves and especially their eggs. The
females retain their legs and antennae throughout life and are
able to move about during at least most of their lives.
They are very destructive insects and where not controlled
by parasites and predators are capable of killing a tree. For-
tunately, in Florida they are usually controlled by those natural
checks. They give off large amounts of honeydew in which a
particularly heavy growth of sooty mold develops, blackening
the whole colony and all surrounding vegetation.






40 Florida Cooperative Extension

COMMON, OR CITRUS, MEALYBUGS
Pseudococcus citri (Risso.)
This mealybug is common over the entire State and is fre-
quently in evidence in a citrus grove, especially during the drier
portions of the year-spring and fall. It is likely to be
found on any part of the tree but mostly in sheltered places such
as the angle between the petiole of the leaf and the stem. On
the limbs and trunk it gets into the crevices of the bark.



























Fig. 24.-Citrus mealybug; infestation on grapefruit

Mealybugs often collect around the stem end of the fruit.
Frequently they get under the calyces where they are respon-
sible for the falling of much young fruit, particularly grape-
fruit. In this situation they are entirely hidden and only after
the fruit has dropped can one detect the presence of mealybugs
on the old calyx. A specially favored place is the sheltered nook
formed by two or more fruits in contact. This is more fre-
quently the case with grapefruit than with other citrus, conse-







Bulletin 67, Citrus Insects and Their Control 41

quently mealybugs are rather more troublesome to grapefruit.
Grapefruits become blackened with a particularly copious and
sticky honeydew which, with the sooty-
mo 1 d (Fig. 24) makes a vigorous
scrubbing necessary before they can
be packed.
The female grows to a length of from
one-tenth to a fourth of an inch. Her
color varies from white to light brown,
with brown legs and antennae. (Fig.
25.) The male is small, light colored, I
and has two long white threads of wax
Fig. 25.-A mealybug. (From
projecting backward. Farmers' Bul. 49.)
LIFE HISTORY
The female lays from 350 to 400 eggs in the mass of cotton
which she secretes. The eggs hatch in from eight to ten days
in summer, but twice this time is required in winter. The larvae
require from six to ten weeks to reach maturity. They are oval,
yellowish creatures. Their body fluids are also yellow as shown
when they are crushed.
PREDATORS
Mealybugs are eaten by several other insects which may
usually be depended on to control them fairly well. Among such
predators are the ladybeetles and their larvae, the larvae of
lacewing flies, trash bugs, and syrphus-fly larvae, and the
scale-eating caterpillar, Laetilia coccidivora. The latter is a dark
red caterpillar a half inch in length. It makes covered passage-
ways of silk among the scales on which it feeds. The adult is a
grayish-brown moth a third of an inch long. The caterpillars
make their appearance in March and April. The moths appear
in June. There is another brood in the fall.
Ants carry mealybugs from tree to tree and to some extent
interfere with the insects that would otherwise feed upon them.
During 1930 the Experiment Station imported from Cali-
fornia a species of ladybeetle, Cryptolaemus montrouzieri,
which came originally from Australia. This ladybeetle, often
called "Crypt", feeds especially on mealybugs. The Experiment
Station raised thousands of these beetles on mealybugs which
in turn were raised on the sprouts of potatoes and other plants.
These beetles were distributed widely over the State of Florida.
In the Experiment Station grove at Lake Alfred they were






42 Florida Cooperative Extension

found in the spring of 1932 showing that they can live through-
out the winter out-of-doors, at least during a mild winter, such
as the one of 1931-2. However, in California, where these are
used extensively to control mealybugs, it has been found advan-
tageous to raise them every year and liberate them in the groves.
This will probably be true in Florida. Even if they do live out-
of-doors all winter it will be advantageous to augment their
numbers in a grove with new liberations in the spring. At the
present time these beetles are being raised on a commercial
scale by one insectary in Florida and sold to growers.
MEALYBUG FUNGUS (Entomophthora fumosa Speare).-This
fungus was discovered in Florida in 1920 on the citrus mealy-
bug by Dr. A. T. Speare (24), at that time in the employ of the
Bureau of Plant Industry. It may become very effective during
the period of summer rains, but may allow the mealybugs to
increase inordinately during spring. However, it appears to be
always present on infestations of mealybugs whenever proper
weather conditions appear. It probably occurs wherever mealy-
bugs occur in Florida.
Mealybugs killed by this fungus appear "to be enveloped in
a dark slate-gray woolly covering", whence the specific name
fumosa (smoky). At other times some dead ones "appear jet
black, almost glistening" without the woolly covering.
In Florida, this fungus has been found infecting the citrus
mealybug (Pseudococcus citri). From Louisiana Dr. Speare re-
ceived it on the citrus mealybug, and also on a species of Phena-
coccus mealybug infesting hibiscus.
Methods for growing this fungus in artificial cultures in the
laboratory have not been discovered.
CONTROL
Careful spraying will reduce mealybug numbers. It is import-
ant to have good pressure to force liquid into corners and crev-
ices, and also to wash many of the insects from their support.
Washing them off the trees is so effective that spraying
with clear water is often sufficient to control them, yet it is
better to use an insecticide. One may use one of the oil emul-
sions which are recommended for whitefly, or fish-oil soap in
the proportion of 1 pound to from 4 to 6 gallons of water,
according to whether the water is soft or hard. Kerosene emul-
sion is fairly effective. To make this, dissolve 11/2 pounds of
soap in 3 gallons of hot water, add 3 gallons of kerosene and mix






Bulletin 67, Citrus Insects and Their Control 43

by means of a pump; then dilute to 50 gallons. If one has a
power spray outfit with a good agitator he may use a simple
mixture of oil and water, taking 5 gallons of kerosene to 50
gallons of water, and mixing thoroughly. However, unless one
has a good agitator he should not try this, as burning may result
from indifferent mixing. One of the best sprays, though some-
what expensive, is one pint of nicotine sulphate and a gallon of
an oxidized oil derivative in 100 gallons of water. A cheaper
spray is made by dissolving three pints of crude carbolic acid
and three pounds of fish-oil soap in 100 gallons of the spray.
Mealybugs are more abundant on some ornamentals than on
citrus. These, when grown about a citrus grove, may be a source
of infestation to the trees to which the bugs may be carried by
ants. If it is desired to grow these plants about the premises they
should be watched and treated when they become infested.
Among such plants are coleus, oleander, royal palm (roots),
and lantana. Mealybugs commonly infest seed potatoes which
are kept over summer for fall planting.

LONG-TAILED MEALYBUG
Pseudococcus longispinus (Targ.)
The long-tailed mealybug is much less common than the last
described, but is occasionally seen on citrus as well as on avo-
cado, mango, bamboo, oleander, coleus and croton. It is some-
what smaller than the common mealybug and is light yellow or
gray. The most prominent distinguishing characteristic is four
long threads of wax which project behind. The inner pair of
threads are especially long and conspicuous.
SThe work, life history, and control of the long-tailed mealybug
are the same as those of the common mealybug.
COTTONY-CUSHION SCALE
Icerya purchase Mask.
This notorious pest of citrus, whose native home is Australia,
was introduced into Florida from California in 1893. It was
carried to California in 1868 and a dozen years later had
reached the citrus sections where it was so injurious as to
threaten to wipe out the entire industry. In this emergency
an entomologist, Koebele, was sent to Australia to learn why
it was not so injurious there and, if a parasite or predator was
found, to try to bring it to California. As a result of Koebele's
researches, the Vedalia or Australian ladybeetle was found






Bulletin 67, Citrus Insects and Their Control 43

by means of a pump; then dilute to 50 gallons. If one has a
power spray outfit with a good agitator he may use a simple
mixture of oil and water, taking 5 gallons of kerosene to 50
gallons of water, and mixing thoroughly. However, unless one
has a good agitator he should not try this, as burning may result
from indifferent mixing. One of the best sprays, though some-
what expensive, is one pint of nicotine sulphate and a gallon of
an oxidized oil derivative in 100 gallons of water. A cheaper
spray is made by dissolving three pints of crude carbolic acid
and three pounds of fish-oil soap in 100 gallons of the spray.
Mealybugs are more abundant on some ornamentals than on
citrus. These, when grown about a citrus grove, may be a source
of infestation to the trees to which the bugs may be carried by
ants. If it is desired to grow these plants about the premises they
should be watched and treated when they become infested.
Among such plants are coleus, oleander, royal palm (roots),
and lantana. Mealybugs commonly infest seed potatoes which
are kept over summer for fall planting.

LONG-TAILED MEALYBUG
Pseudococcus longispinus (Targ.)
The long-tailed mealybug is much less common than the last
described, but is occasionally seen on citrus as well as on avo-
cado, mango, bamboo, oleander, coleus and croton. It is some-
what smaller than the common mealybug and is light yellow or
gray. The most prominent distinguishing characteristic is four
long threads of wax which project behind. The inner pair of
threads are especially long and conspicuous.
SThe work, life history, and control of the long-tailed mealybug
are the same as those of the common mealybug.
COTTONY-CUSHION SCALE
Icerya purchase Mask.
This notorious pest of citrus, whose native home is Australia,
was introduced into Florida from California in 1893. It was
carried to California in 1868 and a dozen years later had
reached the citrus sections where it was so injurious as to
threaten to wipe out the entire industry. In this emergency
an entomologist, Koebele, was sent to Australia to learn why
it was not so injurious there and, if a parasite or predator was
found, to try to bring it to California. As a result of Koebele's
researches, the Vedalia or Australian ladybeetle was found






44 Florida Cooperative Extension

preying on the scale and was introduced into California in
1889. It increased rapidly and soon had the scale under control.
While this mealybug has never been as
serious a menace here as in California it
caused much trouble until, through the ef-
forts of the Experiment Station, the Aus-
tralian ladybeetle was brought here also.
The experience in California was repeated
here. The Vedalia seldom exterminates the
scale from a grove but always keeps it
under at least fair control. Sometimes the
scale will increase for a time and become
quite conspicuous, but then the Vedalia
also increases and soon checks the scale.
For fifteen years the scale was confined
to the Pinellas Peninsula where it was first
introduced, but in 1912 it was found in
Tampa and from that commercial center
quickly spread to most of the citrus sections
of the State. It is now generally distrib-
uted throughout the State.
APPEARANCE
The cottony-cushion scale (Fig. 26) 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 posterior portion
of her body until she stands almost 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
lengthwise. Because of these longitudinal
u. 6.--arvbe of the ridges this scale is also called "the fluted
Australian ladybeetle or
Vdcottncushdion scathe scale." 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 mid-
rib. The young look much like those of the mealybug, but when
crushed they leave a red stain. Both young and old have the
mealybug 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 responsible for
the rapid spread of the insect. It is abundant also on wormwood,






Bulletin 67, Citrus Insects and Their Control 45

myrtle, mulberry, weeds and ornamentals. In the Annual Report
of the Florida Agricultural Experiment Station for 1915 (28),
is a longer list of host plants.
LIFE HISTORY
The time required for development varies from three to four
months or more, even in the summertime. There are about three
generations a year but no distinct broods. Like the mealybugs,
this scale increases most rapidly during the drier seasons of
the year but it is more apt to persist during the rainy season
than is the mealybug. Ants carry these insects from tree to
tree. A special effort should be made to control these pests in
a grove infested with cottony-cushion scale.
CONTROL
The cottony-cushion scale can be controlled by spraying. Ef-
ficient solutions are lime-sulphur and the oils which are used so
extensively against the whiteflies and purple scale. A lighter
oil is better, however, and at least one hts .been prepared and
placed on the market especially for use against this insect. As
in the case of mealybugs, high pressure is an important con-
sideration. On a few dooryard trees a frequent washing with a
strong soap solution may be effective.
VEDALIA OR AUSTRALIAN LADYBEETLE
The only permanent and satisfactory method of controlling
this scale in a large grove is by the introduction of the Vedalia
or Australian ladybeetle (Rodolia (Novius) cardinalis (Muls.))
(Fig. 27). This is much smaller than most native ladybeetles,
being only one-eighth inch long. It is of a cardinal-red color,
spotted and fringed with black. The larva
(Fig. 26) which also feeds on the scale, is
likewise red.
The female ladybeetle lays between 50 and
800 eggs. These are brick-red in color and are
most commonly laid on the cottony sack of the
female scales, but sometimes on the nearby
SFig. 27. Australian
branches. Each female lays up to 50 eggs per ladybeetle (Rodolia
cardinalis.) E n-
day. The eggs hatch in five or six days and larged drawing.
the young larvae at once begin to feed on the eggs of the scale.
As they grow larger they feed also on the scales, both old and
young. The larvae require about three weeks for growth arid






46 Florida Cooperative Extension

another week is spent in the pupal stage. These pupae are scat-
tered singly about among the scales and are found most fre-
quently on the leaves. (Fig. 28.)
It is to be noted that a generation of the Vedalia requires but
a month while that of the cottony-cushion scale requires at least
three. T h i s explains
the ability of the lady-
beetles to clean up an
infestation so quickly.
This is usually accom-
plished in three or four
months after the intro-
duction of the beetles.
SExcept for an occa-
sional citrus aphid, Ve-
dalia feeds only on cot-
tony-cushion scale or
turns cannibalistic, if
.the scale becomes
scarce. Therefore,
F-. when the supply of
Sm scales in a grove runs
A low, the Vedalia may
die out. After the dis-
appearance of the
beetles, the scale may
again multiply in the
grove. It may then be
Fig. 28.-Pupae of the Vedalia, or Australian ladybeetle. c. to reintro-
Twice natural size. necessary to reintro-
duce the Vedalia, al-
though experience in Florida has shown this to be seldom neces-
sary. As soon as the scale again becomes abundant, the beetles
almost invariably reappear, probably flying from adjoining
groves. Some observations of the senior writer show that the
Vedalia has found a colony of the cottony-cushion scale at least
two miles from the grove where the beetles hatched (28).
Colonies of the Vedalia are being supplied to the growers
for a dollar per colony by the Entomological Department of the
State Plant Board, Gainesville.
The native, twice-stabbed ladybeetle (Fig. 9) does good
work against this as well as other scales, but it cannot be de-
pended upon to control the scale as well as the Vedalia. Trash






Bulletin 67, Citrus Insects and Their Control 47

bugs and the scale-eating caterpillar also have been seen to feed
upon this scale.
COTTONY-CUSHION SCALE FUNGUS (Spicaria javanica Bally).*
-This fungus covers the infected scales with a delicate, gray-
ish-lavender, powdery growth. It probably is the same fungus
that H. A. Gossard observed destroying cottony-cushion scale
in Pinellas County in 1899 (13). Occasionally specimens of it
are received on the scale mentioned. According to Gossard, this
fungus may become very effective when weather conditions
(abundant warmth and moisture) are suitable. However, alone
it appears not to have been capable of effectively keeping the
cottony-cushion scale in check without the assistance of the
Vedalia.
Where or how this fungus holds over between outbreaks of
the scale in Florida is not known. In Ceylon it occurs on a wax
scale (Ceroplastes), on green scale (Coccus viridis), cottony-
cushion scale (Icerya purchase), the caterpillar of Euproctis
flava and on egg masses of another insect (Homona caffearis).
Bally described it on a beetle, Stephanoderes hampei, in Java.
It can be easily grown in pure cultures, on plugs of sweet
potato, should the need for doing so arise. For the present, how-
ever, the Vedalia effects an almost perfect control of the cot-
tony-cushion scale, so that this need has not appeared.
WHITEFLIES
Eight species of whiteflies have been found on citrus in
Florida. In the order of their abundance they are:
(1) The common, or citrus, whitefly, Dialeurodes citri
(Ash.)
(2) Cloudy-winged whitefly, D. citrifolii (Morg.)
(3) Woolly whitefly, Aleurothrixus howardi (Quaint.)
(4) Flocculent whitefly, A. floccosus (Mask.)
(5) Bay whitefly, Paraleyrodes perseae (Quaint.)
(6) Inconspicuous, or sweet-potato, whitefly,
Bemisia inconspicua (Quaint.)
(7) Mulberry whitefly, Tetraleurodes mori (Quaint.)
(8) Florida, or guava, whitefly, Trialeurodes floridensis
(Quaint.)
Whiteflies are sucking insects. Indeed, they are quite close-
ly related to scale-insects, and like them the young nymphall)
*Identified by Erdman West.






48 Florida Cooperative Extension

stages are flat scale-like creatures and (except the first stage,
which is an active "crawler") are immovably fastened to the
host. The most conspicuous difference is that instead of only the
males possessing wings and flying about as in scale-insects, both
sexes are winged and active. The presence of winged females en-
ables the insect to spread much more rapidly from tree to tree
and from grove to grove than can scale-insects and greatly in-
creases the difficulty of control.
LIFE HISTORY
The life history of all whiteflies is very similar and one dis-
cussion will answer for all, although the time spent in develop-
ment will vary with different species. As with all insects, there
are four stages in the
development of t h e
whitefly,-egg, larva
(or nymph), pupa,
and adult (or imago).
The whitefly egg is
nearly oval in outline,
and very small. It
is usually less than one
hundredth of an inch
long and about half as
Fig. 29.-Common (citrus) whitefly: Adults and eggs wide, barely visible to
on leaf. (After Gossard.) wide, barely visible to
the unaided eye. When
abundant the eggs give the citrus leaves an appearance of being
covered with a mealy dust. (Fig. 29.) The eggs are laid on
the under side of the leaves of the host plants to which they are
fastened by a short stalk. The eggs hatch in a few days into
pale yellow, flat "crawlers" which have six extremely short legs.
These nymphs crawl about for a few hours, but have a distinct
aversion to strong light, which keeps them on the lower side of
the leaves. Soon they insert their beaks into the tissue and begin
to suck the sap. After this the nymphs (Figs. 31 and 36) never
move again, but remain where they anchored themselves; oval,
exceedingly flat objects which lie closely pressed against the
surface of the leaf to which they hang by means of their sucking
mouth parts. They grow so rapidly that within a few days their
body walls become incapable of any longer accommodating the
insects. The skins are then cast off, moltedd." At this time the
legs and feelers are lost so that the second-stage nymph seems






Bulletin 67, Citrus Insects and Their Control 49

scarcely to resemble an insect, as commonly known. This process
is repeated twice.
The fourth stage nymph (Figs. 32 and 37) differs consider-
ably from these in other stages. It takes
much less food, is thicker, and the organs of
the adult whitefly begin to form. This stage
corresponds to the pupal stage of most insects
in which there is more difference between the
stages. After a more or less prolonged pupal
stage (the time spent in this stage depends ig. 30.- The Cal-
much upon the temperature) the pupal case for n i da whelty-
esat iancg ladybeetle
splits across the back and the adult insect (Di tnc
emerges. In this stage the insect differs drawing.
greatly from the nymph. It has the typi-
cal three parts of the usual insect body
-head, thorax, and abdomen-and is pro-
vided with two wings. These are covered
with mealy or dust-like scales which make
the wings look white, whence the name
whitefly. These insects are also known as
"mealy wings" in entomological literature,
a name never used by Florida growers. The
/ bodies of these insects are usually yellow
or orange. The sexes are very similar in
u t. 3.-cormmon (itus) appearance, although the male is a bit
w h i t e f ly: First-stage
nymph. (After Berger, 4.) smaller than the female.

COMMON, OR CITRUS, WHITEFLY
Dialeurodes citri (Ash.)
This is by far the most common of the whiteflies and the one
the grower has in mind when he speaks of "whitefly". Fif-
teen or twenty years ago it was our most destructive citrus in-
sect and still holds that distinction in the satsuma belt. Dur-
ing the past few years, however, it has undergone a striking
reduction in numbers in the peninsular part of the state. It
still, however, does an immense amount of damage. It injures
citrus trees in three ways:
(1) It withdraws immense quantities of sap from the trees.
This loss of sap is a serious drain on the trees, checking their
growth and that of the fruit. The fruits on badly infested trees
are always fewer and inferior in quality.






50 Florida Cooperative Extension

(2) The nymphs of whiteflies throw off from their alimen-
tary tract large quantities of a sweetish nectar-like substance
called honeydew. This falls on the leaves and fruit, and in this
honeydew grows a jet black fungus called "sooty mold."
Sooty mold blackens the entire tree including the fruit which
requires washing before it can be packed. Washing adds to the
expense of packing and introduces a new liability for loss of
fruit from scratches and inoculation with the spores of fungi
that cause decay. This blackening of the tree is the most
conspicuous sign of the presence of whitefly and the one that
most frequently engages the grower's attention. Indeed, many
growers judge of the presence of the whitefly in their trees solely
by the sooty mold. However, it is probable that this blackening
effect is really a much less
Serious matter than the loss
of sap.
S aSooty mold injures the
trees in another way; the
shade it produces cuts off
much of the light from the
leaves and thus interferes
with the production of
starch.
(3) The sooty mold is in-
directly responsible for an
increase in the amount of
purple and long scale. This
relation has been treated
Sunder purple scale.
LIFE HISTORY
Fig. 32.-Common, or citrus, whitefly: Fourth- The eggs (Fig. 33) of this
stage nymph. (After Berger, 4.)
species are pale yellow and
are scattered singly over the leaves, a marked preference being
shown for young leaves. Each female lays about a hundred eggs
in the course of her life of a week or ten days. Most of them
hatch in from ten to twelve days. The summer brood spends
about three weeks in the nymphal stages; the others a little
longer, up to five weeks. The spring and summer broods usu-
ally spend about two weeks in the pupal stage; the autumn
brood from four to ten months (Morrill and Back, 1911). There
are three main generations each year. In the latter part of the
summer these become much confused. The spring brood of







Bulletin 67, Citrus Insects and Their Control 51

adults is at its maximum, taking the average for the whole
State, in the latter part of March. They appear earlier in the
south than in the north. In addition, there may be a partial
brood in January or February in the extreme southern part of
the State. The summer brood is on the wing in June, and the
last and usually the largest brood the latter part of August or
early September. (Fig. 34.)

FOOD PLANTS OF COMMON, OR CITRUS, WHITEFLY
The common whitefly has been observed to mature on the fol-
lowing plants, arranged approximately in order of preference:

Preferred Less Severely Infested
Chinaberry and umbrella tree Laurel cherry
Citrus, all varieties and species Coffee
Tangerines Pomegranate
Satsumas Smilax sp.
Round oranges Wild olive (Osmanthus americanus)
Trifoliata Green ash
Kumquats Japonica (Camellia japonica)
Lemons Jessamine (Jasminum sp.)
Limes English ivy
Grapefruit Native persimmon
Cape jasmine (Gardenia) Water oak
Privet Trumpet flower (Tecoma radicans)
Prickly ash Ficus sp.
Japanese persimmons Scrub palmetto
Honeysuckle
Blackberry
Oleander
Viburnum nudum
Button bush (Cephalanthus occiden-
talis)
Boston ivy
Mexican orange (Choisya ternata)
Osage orange (Maclura aurantiaca)
Portugal cherry (Cerasus sp.)
Tree-of-Heaven (Ailanthus)

The wild and useless plants in the above list, particularly
those near the head, should be destroyed when growing near
groves. Of these the china and umbrella trees are particularly
important. The planting of these trees in citrus communities
should be prohibited by public sentiment and by law. It has
been estimated that a good-sized chinaberry tree will produce
on the average between 25,000,000 and 50,000,000 whiteflies
each season. From these trees the adults of the late summer
brood fly out to infest citrus trees when the maturing leaves of
the chinaberry are no longer attractive.






52 Florida Cooperative Extension

PARASITES AND PREDATORS
There are but few insects, and virtually no higher animals,
that feed upon this species. This is undoubtedly because it is an
imported insect which has left its enemies behind. In India,
which is probably the
native home of this
species, there are sev-
eral insects which prey
upon or parasitize it,
and an unsuccessful
attempt was once made
to introduce some of
them (32).
The twice stabbed
ladybeetle (described
under purple scale)
(Fig. 8) destroys some
crawlers and occasion-
ally an older larva, but
prefers other food, es-
Fig. 33.-Eggs of common (citrus) whitefly. Magnifie:. specially scale crawlers.
(After Berger, 4.) A tiny, dark brown
ladybeetle, Delphastus pusillus (Lec.) seems to be very fond of
the eggs, but for several reasons never becomes sufficiently
abundant to be of much practical benefit. A related species,
Delphastus catalinae (Fig. 30), an efficient enemy of another


l Ii i 1 i. i I I i i i i iI I I 1. ii i
I I I 1. I I II II T VT II II II.


S it i- I\ ft 1 1 1 1
I II II I I I I I ft I 1 1 I I I I
I I II II I I i I I II I I I
I I Ii It I .i LI _i Il :''II L I i
11 I 1 I I I I I II Ii I I I
SI .i II" 1 1 I I I I 11 I I I' I
I I I Ii IT I IIl, IIt' I 1I I\ 1
i If 1I--t i.L I I I /C I I I i -I I, i." i
L I I '1 I. I A. I I. AP _L '. I, '.lt 1I


Jan. Feb. Mar. ADr. May June July Aug. Sept. Oct. Nov. Dec.
-- Woolly whitefly. --- Common citrus whitefly. ..... Cloudy-winged whitefly.
Fig. 34.-Diagram showing relative date of emergence of adult whiteflies,
(From Bul. 126, 27.)






Bulletin 67, Citrus Insects and Their Control 53

whitefly in California, feeds greedily upon whitefly eggs, and
has been introduced into Florida by the Experiment Station.
CLOUDY-WINGED WHITEFLY
Dialeurodes citrifolii (Morgan)

The cloudy-winged whitefly is very similar to the common
whitefly; so similar indeed that for many years they were
considered as a single species. The junior author, then ento-
mologist to the Experiment Station, first separated the two spe-
cies (4). He named this insect Aleyrodes nubifera. The most
marked differences are in the egg, which is black in this species
(Fig. 35), and in the fact that this species is attacked by an-
other species of
fungus, the yellow
aschersonia, in ad-
dition to those
that attack the
common whitefly.
Black eggs or
the yellow fungus
on the leaves will
at once acquaint
the grower with
the presence of
the cloudy-winged
whitefly. In a
few localities and
in isolated groves
in the southern ig. 35.-Eggs of cloudy-winged whitefly. Magnified.
part of the State, (After Berger, 4.)
the cloudy-winged species only is found, but in most groves
where it occurs the common whitefly occurs with it. The
cloudy-winged species is less common in the northern part of
the citrus belt. Before the "big freeze" of 1894-95 this species
was common over the entire citrus belt, but as its food* in
Florida is confined mostly to citrus it was exterminated
throughout the northern part of the citrus belt by the entire
loss of the leaves from the trees in that region.

*Other hosts are Ficus nitida, one or two other species of rubber, and
yam vine, all very sensitive to frost.






54 Florida Cooperative Extension

DESCRIPTION
The egg is about the size and shape of those of citri, but is
black in color, and is covered with a network of ridges. (Fig.
35.) The females of this species show
an even greater fondness for new growth,
particularly watersprouts, than do those
of citri. The leaves of watersprouts are
often so thickly strewn with eggs as to be
distinctly blackened.
The nymphs (Figs. 36 and 37) closely
resemble those of citri but have a thinner
skin; so much thinner, in fact, that when
the adult emerges from the pupal case
the case collapses instead of maintaining
Fig. 36. Cloudy -winged its shape as does that of citri.
white fly: First-stage The adult, too, is similar but in the
nymph. (After Berger.)
middle of each wing there is a darkened
area which gives rise to the insect's name, cloudy-winged.
The wings are not held as high as in citri, and more of
the abdomen shows.
LIFE HISTORY
The life history re-
quires about two
weeks longer during
the summer than that
of citri, consequently
there is no. imperfect
winter brood as with
citri and the summer
broods lag behind
those of that species,
as shown in the dia-
gram (Fig. 34).
The maximum
flight of the spring
brood of adults oc-
curs in early April,
about three weeks
later than that of cit- Fig. 37.-Cloudy-winged whitefly: Fourth-stage nymph.
ri; the summer brood (After Berger, 4.)






Bulletin 67, Citrus Insects and Their Control 55

in the first half of July, a month later; and the last brood in
late October, about seven weeks after that of citri.
CONTROL

The same oil emulsions which are used against the common
(citrus) whitefly are used against the cloudy-winged also. The
only modification of the spraying procedure desirable is in the
time of applying the spray.
Whenever the two species are present, the common whitefly
is the more important and the cloudy-winged species becomes
of secondary importance. In this case spray at the time recom-
mended for the common species. Although not the most favor-
able time for the cloudy-winged species, spraying at that time
will virtually control it. In the few groves where the cloudy-
winged only is present, spraying should be delayed from three
to seven weeks; that is, spray in early May, August 1, and
November 1.
In groves in which the cloudy-winged species is abundant,
one can do a great deal toward effecting control by removing
the watersprouts at certain periods. These periods will be
when most of the eggs have been laid and but few adults have
emerged; in other words, when the fewest adults are about.
These periods will be in the middle of May, middle of August,
and some time in December, January or February.
In spraying the fungi where this species is present, the yel-
low aschersonia should be added to the others.
WOOLLY WHITEFLY
Aleurothrixus howardi (Quaintance)
The woolly whitefly was first observed infesting citrus in
Florida in 1909, when E. A. Back of the Bureau of Entomology,
U. S. D. A., discovered it in Tampa. It had been observed as
a pest of citrus in Cuba six years previously. It was thought
that the insect had been introduced from Cuba into Tampa;
however, Dr. A. L. Quaintance, a foremost authority on this group
of insects, states that it is identical with the whitefly which was
collected from the sea grape (Coccolobus) twenty-five years ago,
and is probably native to Florida. Yet the history of the insect
as a citrus pest in Florida shows plainly that it has spread from
the infestation in Tampa (27). It would seem most probable
then that, although it is a native insect which has long lived on
the sea grape, it has comparatively recently developed a strain






56 Florida Cooperative Extension

which has taken to citrus. From the fact that it was first dis-
covered as a citrus pest in the West Indies it seems probable
that this supposed citrus strain developed elsewhere and was
introduced into Florida about 1908. It is now spread over most
of the state.
For a few years after its introduction it threatened to be a
first class pest and in a few groves did a great deal of damage,
but it was quickly subdued by a little wasp-like parasite (Eret-
mocerus haldemani). (Fig. 38.)
The dense mat of wool (Fig. 39) which per-
sists for months on the leaves makes an excel-
S lent place in which the young of the purple
scale can hide, and much woolly whitefly in a
.--. grove has always been followed by a heavy in-
6( festation of purple scale. This is perhaps the
most serious phase of an infestation of woolly
/ \ whitefly.
Fig. S. Eretmoce- DESCRIPTION
rus haldemani:
Male. Greatly en- w y dfe
large. (From Bu. The woolly whitefly differs more from the
126.) two other species than they do from each other.
The name is derived from curled waxy filaments which complete-
ly cover the pupa and have the appearance of wool. The empty
pupal cases of this species are very persistent and remain on the
leaves for many months after the adults have emerged.
The eggs are brown in color, and curved in shape somewhat
like a short sausage. They are laid mostly in circles (Fig. 39).
This results from the habits of the female during egg laying.
She inserts her beak into the tissue of the leaf and, on that as a
pivot, rotates her body. The female does not choose the very
youngest and most tender leaves on which to lay eggs as do
those of the other species, but leaves more nearly mature, and
often lays on the leaf on which she herself was raised.
The first-stage nymphs are light green, with well defined legs
and antennae. The other stages are dark brown in color, black
if parasitized, and widely fringed with a corona of shining
white waxy plates. The nymphs give off honeydew copiously
and there is usually a drop clinging to them during their entire
life. In the third stage the woolly covering develops.
The adults are distinctly more yellow than those of the two
preceding species and do not hold their wings so high. They
are very sluggish, seldom taking to wing and then flying only






Bulletin 67, Citrus Insects and Their Control 57

short distances. On the other hand, they will cling tenaciously
to one's clothing and doubtless are thus carried long distances.
There are four distinct broods a year, with adults flying from
December to February, the last of May, the last of July, and the
first of September.
NATURAL CONTROL
Although both the red aschersonia and the brown fungus have
been found on this species, they are not nearly as efficient as
on the others. A species of Cladosporium does better, but the


















Fig. 39.-Leaf infested with woolly whitefly. (From Bul. 126.)
chief parasite is Eretmocerus haldemani. This insect lays its
eggs in the larvae of the whitefly. The grub of the parasite
feeds on the substance of the whitefly nymph and finally kills it.
The parasite pupates inside of its host which markedly swells
up, and about the time the adult whitefly should emerge the
wasp-like parasite comes out through a round hole that it cuts
in the top of the pupal case of the dead whitefly. These para-
sites are so abundant that they have invariably controlled in-
festations of this whitefly, and, usually before any serious harm
has been done.
ARTIFICIAL CONTROL
Should this insect become sufficiently abundant to threaten,
it may be controlled by the same oil sprays that are recommended
for use against the other species. It is imperative, however, that
the oil be applied before many of the larvae have reached the






58 Florida Cooperative Extension

third stage, as the dense mat of wool more or less smeared over
with honeydew, protects the third- and fourth-stage larvae from
the oil. The most favorable periods for spraying are late Feb-
ruary or early March, early June, the middle of August, and
about November 1. (Fig. 34.)
Minor Species
FLOCCULENT WHITEFLY
Aleurothrixus floccosus (Maskell)
Associated with the woolly whitefly, often on the same leaf, is
a closely related species, the flocculent whitefly, which can be
distinguished only by a microscopical examination.
FLORIDA, OR GUAVA, WHITEFLY
Trialeurodes floridensis (Quaint.)
The Florida whitefly which is often quite abundant on guavas
and avocados is rarely found on citrus. It resembles D. citri,
but the larva is smaller, somewhat thicker and more yellow
in color.
BAY WHITEFLY
Paraleyrodes perseae (Quaintance)
The bay whitefly resembles somewhat the woolly whitefly in
the larval stages so that one might easily confuse them. But
this species lacks the curly wool, although it has the straight
waxy plates. These plates break up when the adult emerges from
the pupal case, into short rods which are scattered about the slug-
gish winged insect which squats in the center, presenting an
appearance suggestive of a sitting hen surrounded by straw.
Instead of being curled and woolly these rods are nearly straight.
As its name suggests, this whitefly's native food plant is the red
bay (Tamala). It is a common sight in citrus groves but the
insects seldom become abundant. Only once has the senior au-
thor seen a grove that needed spraying for this species alone. It
is also found on the avocado.
Doubtless it would yield readily to the same oil sprays that
are used to control the other species.

INCONSPICUOUS, OR SWEET POTATO, WHITEFLY
Bemisia inconspicua (Quaintance)
The inconspicuous, or sweet-potato, whitefly is a common pest
of sweet potatoes in the southern part of the State and occa-
sionally gets on the citrus trees. It is markedly smaller in both
the larval and adult stages than the other whiteflies. Otherwise,






58 Florida Cooperative Extension

third stage, as the dense mat of wool more or less smeared over
with honeydew, protects the third- and fourth-stage larvae from
the oil. The most favorable periods for spraying are late Feb-
ruary or early March, early June, the middle of August, and
about November 1. (Fig. 34.)
Minor Species
FLOCCULENT WHITEFLY
Aleurothrixus floccosus (Maskell)
Associated with the woolly whitefly, often on the same leaf, is
a closely related species, the flocculent whitefly, which can be
distinguished only by a microscopical examination.
FLORIDA, OR GUAVA, WHITEFLY
Trialeurodes floridensis (Quaint.)
The Florida whitefly which is often quite abundant on guavas
and avocados is rarely found on citrus. It resembles D. citri,
but the larva is smaller, somewhat thicker and more yellow
in color.
BAY WHITEFLY
Paraleyrodes perseae (Quaintance)
The bay whitefly resembles somewhat the woolly whitefly in
the larval stages so that one might easily confuse them. But
this species lacks the curly wool, although it has the straight
waxy plates. These plates break up when the adult emerges from
the pupal case, into short rods which are scattered about the slug-
gish winged insect which squats in the center, presenting an
appearance suggestive of a sitting hen surrounded by straw.
Instead of being curled and woolly these rods are nearly straight.
As its name suggests, this whitefly's native food plant is the red
bay (Tamala). It is a common sight in citrus groves but the
insects seldom become abundant. Only once has the senior au-
thor seen a grove that needed spraying for this species alone. It
is also found on the avocado.
Doubtless it would yield readily to the same oil sprays that
are used to control the other species.

INCONSPICUOUS, OR SWEET POTATO, WHITEFLY
Bemisia inconspicua (Quaintance)
The inconspicuous, or sweet-potato, whitefly is a common pest
of sweet potatoes in the southern part of the State and occa-
sionally gets on the citrus trees. It is markedly smaller in both
the larval and adult stages than the other whiteflies. Otherwise,






58 Florida Cooperative Extension

third stage, as the dense mat of wool more or less smeared over
with honeydew, protects the third- and fourth-stage larvae from
the oil. The most favorable periods for spraying are late Feb-
ruary or early March, early June, the middle of August, and
about November 1. (Fig. 34.)
Minor Species
FLOCCULENT WHITEFLY
Aleurothrixus floccosus (Maskell)
Associated with the woolly whitefly, often on the same leaf, is
a closely related species, the flocculent whitefly, which can be
distinguished only by a microscopical examination.
FLORIDA, OR GUAVA, WHITEFLY
Trialeurodes floridensis (Quaint.)
The Florida whitefly which is often quite abundant on guavas
and avocados is rarely found on citrus. It resembles D. citri,
but the larva is smaller, somewhat thicker and more yellow
in color.
BAY WHITEFLY
Paraleyrodes perseae (Quaintance)
The bay whitefly resembles somewhat the woolly whitefly in
the larval stages so that one might easily confuse them. But
this species lacks the curly wool, although it has the straight
waxy plates. These plates break up when the adult emerges from
the pupal case, into short rods which are scattered about the slug-
gish winged insect which squats in the center, presenting an
appearance suggestive of a sitting hen surrounded by straw.
Instead of being curled and woolly these rods are nearly straight.
As its name suggests, this whitefly's native food plant is the red
bay (Tamala). It is a common sight in citrus groves but the
insects seldom become abundant. Only once has the senior au-
thor seen a grove that needed spraying for this species alone. It
is also found on the avocado.
Doubtless it would yield readily to the same oil sprays that
are used to control the other species.

INCONSPICUOUS, OR SWEET POTATO, WHITEFLY
Bemisia inconspicua (Quaintance)
The inconspicuous, or sweet-potato, whitefly is a common pest
of sweet potatoes in the southern part of the State and occa-
sionally gets on the citrus trees. It is markedly smaller in both
the larval and adult stages than the other whiteflies. Otherwise,






58 Florida Cooperative Extension

third stage, as the dense mat of wool more or less smeared over
with honeydew, protects the third- and fourth-stage larvae from
the oil. The most favorable periods for spraying are late Feb-
ruary or early March, early June, the middle of August, and
about November 1. (Fig. 34.)
Minor Species
FLOCCULENT WHITEFLY
Aleurothrixus floccosus (Maskell)
Associated with the woolly whitefly, often on the same leaf, is
a closely related species, the flocculent whitefly, which can be
distinguished only by a microscopical examination.
FLORIDA, OR GUAVA, WHITEFLY
Trialeurodes floridensis (Quaint.)
The Florida whitefly which is often quite abundant on guavas
and avocados is rarely found on citrus. It resembles D. citri,
but the larva is smaller, somewhat thicker and more yellow
in color.
BAY WHITEFLY
Paraleyrodes perseae (Quaintance)
The bay whitefly resembles somewhat the woolly whitefly in
the larval stages so that one might easily confuse them. But
this species lacks the curly wool, although it has the straight
waxy plates. These plates break up when the adult emerges from
the pupal case, into short rods which are scattered about the slug-
gish winged insect which squats in the center, presenting an
appearance suggestive of a sitting hen surrounded by straw.
Instead of being curled and woolly these rods are nearly straight.
As its name suggests, this whitefly's native food plant is the red
bay (Tamala). It is a common sight in citrus groves but the
insects seldom become abundant. Only once has the senior au-
thor seen a grove that needed spraying for this species alone. It
is also found on the avocado.
Doubtless it would yield readily to the same oil sprays that
are used to control the other species.

INCONSPICUOUS, OR SWEET POTATO, WHITEFLY
Bemisia inconspicua (Quaintance)
The inconspicuous, or sweet-potato, whitefly is a common pest
of sweet potatoes in the southern part of the State and occa-
sionally gets on the citrus trees. It is markedly smaller in both
the larval and adult stages than the other whiteflies. Otherwise,






Bulletin 67, Citrus Insects and Their Control 59

it resembles citri quite closely. It is parasitized by the red
aschersonia. It has never been sufficiently abundant to demand
control measures. Should it ever become so, doubtless it can be
controlled by the same oil emulsions recommended for other
whiteflies.
MULBERRY WHITEFLY
Tetraleurodes mori (Quaintance)
The larva of the mulberry whitefly is a small jet-black insect
with a wide fringe of white wax. It resembles the younger
stages of the woolly whitefly but is smaller, black, and never
develops the curly wool-like, waxy filaments. Although present on
a variety of trees, including the mulberry and persimmon, it
has never given any trouble to citrus growers in Florida. How-
ever, the same insect, or at the most a variety or strain of it,
is said to be a serious pest of oranges in Mexico.

OTHER WHITEFLIES (ALEYRODIDS)
There are five other species of whiteflies in other parts of
the world, that are more or less serious pests of citrus. One of
the most serious, the blackfly (Aleurocanthus woglumi Ashby),
is dangerously near Florida, it having been introduced a few
years ago into Cuba and the Bahamas. Like the two species
most troublesome to citrus in Florida, its native home is in
southeastern Asia. "Black" applies to both the larvae and the
adults. As the body of the adult is dark brown and the wings
are smoky with a white cross, the general impression to the un-
aided eye is bluish-black. Although stated by the Imperial
Entomologist of Jamaica and by entomologists in Panama to
yield to oil emulsions it is undoubtedly a dangerous insect and
the efforts of the State Plant Board to keep it out of Florida
should receive the hearty support of all citrus growers. Recent-
ly a parasite of the blackfly has been introduced into Cuba from
India and it is said to be doing effective work in controlling
this insect.
WHITEFLY FUNGI

RED ASCHERSONIA (Aschersonia aleyrodis Webber).--Also
known as the red whitefly-fungus. This fungus (Fig. 40) was
first studied in the early 90's by Dr. H. J. Webber, then of the
United States Department of Agriculture, about Crescent City,
Citra, Panasofkee, and other places, in Florida. It forms pink






Bulletin 67, Citrus Insects and Their Control 59

it resembles citri quite closely. It is parasitized by the red
aschersonia. It has never been sufficiently abundant to demand
control measures. Should it ever become so, doubtless it can be
controlled by the same oil emulsions recommended for other
whiteflies.
MULBERRY WHITEFLY
Tetraleurodes mori (Quaintance)
The larva of the mulberry whitefly is a small jet-black insect
with a wide fringe of white wax. It resembles the younger
stages of the woolly whitefly but is smaller, black, and never
develops the curly wool-like, waxy filaments. Although present on
a variety of trees, including the mulberry and persimmon, it
has never given any trouble to citrus growers in Florida. How-
ever, the same insect, or at the most a variety or strain of it,
is said to be a serious pest of oranges in Mexico.

OTHER WHITEFLIES (ALEYRODIDS)
There are five other species of whiteflies in other parts of
the world, that are more or less serious pests of citrus. One of
the most serious, the blackfly (Aleurocanthus woglumi Ashby),
is dangerously near Florida, it having been introduced a few
years ago into Cuba and the Bahamas. Like the two species
most troublesome to citrus in Florida, its native home is in
southeastern Asia. "Black" applies to both the larvae and the
adults. As the body of the adult is dark brown and the wings
are smoky with a white cross, the general impression to the un-
aided eye is bluish-black. Although stated by the Imperial
Entomologist of Jamaica and by entomologists in Panama to
yield to oil emulsions it is undoubtedly a dangerous insect and
the efforts of the State Plant Board to keep it out of Florida
should receive the hearty support of all citrus growers. Recent-
ly a parasite of the blackfly has been introduced into Cuba from
India and it is said to be doing effective work in controlling
this insect.
WHITEFLY FUNGI

RED ASCHERSONIA (Aschersonia aleyrodis Webber).--Also
known as the red whitefly-fungus. This fungus (Fig. 40) was
first studied in the early 90's by Dr. H. J. Webber, then of the
United States Department of Agriculture, about Crescent City,
Citra, Panasofkee, and other places, in Florida. It forms pink






Bulletin 67, Citrus Insects and Their Control 59

it resembles citri quite closely. It is parasitized by the red
aschersonia. It has never been sufficiently abundant to demand
control measures. Should it ever become so, doubtless it can be
controlled by the same oil emulsions recommended for other
whiteflies.
MULBERRY WHITEFLY
Tetraleurodes mori (Quaintance)
The larva of the mulberry whitefly is a small jet-black insect
with a wide fringe of white wax. It resembles the younger
stages of the woolly whitefly but is smaller, black, and never
develops the curly wool-like, waxy filaments. Although present on
a variety of trees, including the mulberry and persimmon, it
has never given any trouble to citrus growers in Florida. How-
ever, the same insect, or at the most a variety or strain of it,
is said to be a serious pest of oranges in Mexico.

OTHER WHITEFLIES (ALEYRODIDS)
There are five other species of whiteflies in other parts of
the world, that are more or less serious pests of citrus. One of
the most serious, the blackfly (Aleurocanthus woglumi Ashby),
is dangerously near Florida, it having been introduced a few
years ago into Cuba and the Bahamas. Like the two species
most troublesome to citrus in Florida, its native home is in
southeastern Asia. "Black" applies to both the larvae and the
adults. As the body of the adult is dark brown and the wings
are smoky with a white cross, the general impression to the un-
aided eye is bluish-black. Although stated by the Imperial
Entomologist of Jamaica and by entomologists in Panama to
yield to oil emulsions it is undoubtedly a dangerous insect and
the efforts of the State Plant Board to keep it out of Florida
should receive the hearty support of all citrus growers. Recent-
ly a parasite of the blackfly has been introduced into Cuba from
India and it is said to be doing effective work in controlling
this insect.
WHITEFLY FUNGI

RED ASCHERSONIA (Aschersonia aleyrodis Webber).--Also
known as the red whitefly-fungus. This fungus (Fig. 40) was
first studied in the early 90's by Dr. H. J. Webber, then of the
United States Department of Agriculture, about Crescent City,
Citra, Panasofkee, and other places, in Florida. It forms pink






60 Florida Cooperative Extension

and red pustules one eighth of an inch or less in diameter. The
color of the fungus is pink but the spore masses are red and give
it the red color. It is an important factor in the control of the
common whitefly (Dialeurodes citri), and cloudy-winged white-
fly (Dialeurodes citrifolii), both on citrus. The junior writer
has also observed it abundantly infecting a whitefly on sweet
potato, probably Bemisia inconspicua, Trialeurodes ruborum on
blackberry, Aleurodicus cardini on guava, and specimens of an
unknown black aleyrodid heavily infected by this fungus have
been received from Fort Myers, Florida. Other unidentified
aleyrodidae on dahoon holly and swamp bay in hammocks, and
Tetraleurodes mori on French mulberry, at times also become
infected with it. According to records kept by the Entomological
Department of the State Plant Board, this fungus is a useful
parasite of the blackfly (Aleurocanthus woglumi) in Cuba, Ja-
maica, and Costa Rica.















Fig. 40.-Red whitefly-fungus, or red aschersonia, showing roundish white areas
with black centers, the pink and red fungus pustules. Natural size. (Bul. 67.)

This is the first fungus that was grown in pure cultures by
the Plant Board, based on methods developed by .Dr. H. S. Faw-
cett while at the Florida Experiment Station (1906-1911).
YELLOW ASCHERSONIA (Aschersonia goldiana Sacc. et Ellis).*
-The yellow whitefly-fungus was discovered at Winter Park,
Florida, by P. H. Rolfs in 1906. It resembles the red aschersonia
(Fig. 40) in general appearance. The fungus growth, itself,
is cream-color or nearly white, but when this becomes covered

*A. flavo-citrina P. Henn.
\






Bulletin 67, Citrus Insects and Their Control 61

with masses of ripe yellowish spores the color becomes a kind
of yellow. It is, however, effective only against the cloudy-
Winged whitefly (Dialeurodes citrifolii) but is probably no more
effective against this species than the red aschersonia. Pure
cultures of this fungus are sometimes available.
BROWN WHITEFLY-FUNGUS (Aegerita webberi Fawcett).-
Figure 41 is an excellent illustration of this fungus. The fun-
gus was discovered in 1896 by Dr. H. J. Webber at Manatee,
Florida. It was only later (1910) given its scientific name by
Dr. H. S. Fawcett, who discovered its spores, thus enabling him
to classify it. It forms brown pustules about one eighth of an

















Fig. 41.-Brown whitefly-fungus. Natural size. Round black areas are the .

inch in diameter on the underside of the leaves of citrus in-
fected by either the common citrus whitefly (Dialeurodes citri)
or the cloudy-winged whitefly (Dialeurodes citrifolii). As this
fungus, when once established on a leaf, sends out fine threads
which grow from one infected whitefly larva to another until
every larva has been reached and killed, it is unusually effec-
tive. It also thrives later in the season after dry weather has
set in. This fact is probably due to its habit of growth just
explained. The fine fungal threads referred to also finally grow
around the edge of the leaf and eventually form a fine tissue-
like growth on the upper surface on which the brown spore-
bodies are formed. When the fungus is fruiting, or producing
spores, the leaves or parts of leaves, assume a cinnamon-brown
spores, the leaves or parts of leaves, assume a cinnamon-brown






62 Florida Cooperative Extension

color. While most of the spores are formed on top of the leaf,
some also are formed underneath. Unfortunately, methods for
growing this fungus in pure cultures have never been successful.
The records of the Entomological Department of the State
Plant Board also show this fungus as a useful parasite of the
blackfly (Aleurocanthus woglumi) in Cuba.
WHITE-FRINGE FUNGUS (Fusarium aleyrodis Petch).*-This
fungus was first noticed by P. H. Rolfs, in 1907, at Sutherland,
Florida. It has since then been found widely distributed through-
out the State. According to investigations made at the Experi-
ment Station, it is this fungus which is the cause of the so-
called "natural mortality" of whiteflies, when all but a few
whitefly larvae on a large majority of leaves die.
As its name indicates, the growth of this fungus outside of
the whitefly larvae is a white fringe, very delicate and easily
blown away, so that it is difficult to preserve. But it is a fairly
safe assumption that, whenever large numbers of whitefly lar-
vae die without evidence of another cause, it is the white-fringe
fungus that is present. It is found on both the common white-
fly and the cloudy-winged whitefly. As this fungus appears to
be so universally present, ready to destroy whitefly larvae
whenever favorable weather conditions arise, propagation of it
has not been undertaken, although it is easily grown in pure
cultures.
CINNAMON FUNGUS (Verticillium cinnamomeum Petch**).-
This occurs every now and then on citrus, infecting whitefly
larvae, chaff scale, soft brown scale, the purple scale and long
scale. It also infects these same and other similar insects on
other plants (page 16). In appearance its pustules are like the
brown fungus but with a powdery surface and cinnamon color.
It is widely distributed.
Pure cultures of this fungus were produced by Dr. H. S.
Fawcett in 1908, but as the fungus has not been considered of
the same importance as the several others, propagation of it
has not been undertaken commercially.
CONTROL OF WHITEFLIES AND SCALE-INSECTS
As stated under the heading of purple scale, the control of
whiteflies and scale-insects is a single problem; the control
measures are the same.
*Microcera sp. Fawcett.
**V. heterocladum Penz.







Bulletin 67, Citrus Insects and Their Control 63
SPRAYING
The common method of controlling whiteflies and purple
scale in Florida is to spray the trees with an oil emulsion.
Time to Spray.-As explained previously, there are three
broods of whiteflies. One is on the wing largely during the last
of August and first of September, another during the last of
March and the third in June. As whiteflies may fly several
miles, it is evident that a grove may be reinfested from neigh-
boring groves at each flight, necessitating control measures for
each brood. However, the summer brood, the adults of which are
on the wing in June, can usually be ignored as far as spraying is
concerned as the entomogenous fungi ordinarily will control it
very well. This leaves the fall and the spring brood to be dealt
with by insecticides. Ordinarily the average grove will need to
be sprayed for one or both of these broods in connection with
the control of purple scale. As stated before, the eggs of the
whitefly hatch in about a week. The younger the larvae the
more easily they are killed. Therefore it is important to spray
as soon as practically all the eggs have hatched. Another rea-
son for spraying early in the life history of the whitefly is to
avoid the drain on the trees resulting from the feeding of the
larvae. To spray the trees after the larvae have done much of
their damage would be somewhat like locking the barn after
the horse has been stolen. Although most of the fall brood of
whiteflies are usually on the wing during the last of August and
the first week in September, there are a good many slowly devel-
oping individuals that come straggling along during the early
part of September. So it is usually well along in September be-
fore the flight of the adults can be said to be over. This will vary
in different parts of the state and in the same grove from year
to year. The grower should watch the flight of the fall brood
of whiteflies and when they have practically all disappeared
he should mark down the date. He should then wait ten days
so that practically all the eggs will have hatched. The expira-
tion of this time will mark the most favorable time to spray for
whiteflies. This will bring the date to the last part of Septem-
ber ordinarily.
Moreover, it is difficult to spray a grove during the summer
rainy season when there is apt to be a shower two afternoons
out of three. The trees must be dry before they are sprayed.
If there is water standing on the leaves it will dilute the spray






64 Florida Cooperative Extension

solution and make it ineffective. Trees should not be sprayed
with this oil emulsion when the temperature is 900 or above,
particularly if the sun is shining brightly. Under these condi-
tions one is liable to get serious burning of the fruit. Sometime
then in late September or early October, conditions are usually
right for spraying with oil emulsions for whiteflies and scale-
insects and the spraying should be done promptly for the rea-
sons given above. Moreover, growers like to get this fall spray-
ing out of the way before the picking season opens. If the fruit
has much of a coating of sooty mold this spraying will help to
loosen it and aid in getting rid of it in the packing house.
One exception, however, must be made to early fall spraying.
In the case of early varieties such as satsumas, Parson Brown
oranges, etc., the fall spraying should be delayed until after
the fruit has been picked. As first pointed out by W. W. Others
(33), spraying with oil emulsions delays the ripening of the
fruit. In the case of the early varieties the price is usually so
much better early in the season that the grower cannot afford to
delay the ripening of his fruit except in the case of a very heavy
infestation.
As stated above, the spring brood of the common whitefly
is on the wing in late March. Again the growers should wait
until the brood has disappeared and ten additional days to al-
low the eggs to hatch. This would bring the spraying in April,
but it is not quite safe to spray when the fruit is too small. It
is, therefore, usually recommended that growers postpone this
spring spraying until the spring flush of growth has matured
and the trees have become partially dormant and the fruit has
reached the diameter of approximately an inch. This will bring
the spring spraying sometime in May.
Of course it will not always be necessary to apply both of
these sprayings to a grove. If the trees are free of scale-insects
or whiteflies there is nothing to be gained by the costly spray-
ing. However, a good clean-up spray, particularly in the early
fall, is much to be recommended, as trees thoroughly sprayed at
this time should remain reasonably free of insect pests through-
out the winter.
Under special conditions it may be desirable to apply the oil
emulsions at other times. Trees sprayed with bordeaux to con-
trol scab or melanose should usually be sprayed within two
months with an oil emulsion to counteract the increase of scale-
insects due to the killing of the entomogenous fungi by the bor-






Bulletin 67, Citrus Insects and Their Control 65

deaux. This is very important. If a grove becomes heavily in-
fested with scale-insects during the winter it should, of course,
be sprayed before the spring flush of growth makes spraying
unsafe.
Spraying Solutions.-The spray solutions which have been
most used are emulsions of lubricating oils. These are made by
thoroughly emulsifying a paraffin oil with soap and water.
There are two government formulae, both developed by W. W.
Others of the Bureau of Entomology, stationed at Orlando.
One does not need any heat and is called "cold mix". It is as
follows:
Fish-oil soap -........-.....--- .......-....-..........-.... 8 lbs. or 1 gallon
Lubricating oil, 24 or 28 Baume .................. 2 gallons
W ater ................-- ...---....- ----.. .... 1 gallon
For this emulsion, oils similar to the "Diamond Paraffin
Oil," "Atlantic Red" or the "Red Insecticide Oil" are used. The
following directions for making this emulsion are copied from
Others (35) :
"In preparing the stock mixture the soap should be put into a recep-
tacle of about 5 gallons' capacity and the oil should then be added very
slowly while the mixture is being vigorously stirred. It is important that
the oil be added in small quantities at first and also that the stirring be
sufficient to keep the oil and soap in the form of an emulsion after each
addition of oil. Thus at first about a pint of oil should be added to the
soap and the mixture stirred until no free oil appears. As the amount of
oil is increased it should always be stirred or mixed thoroughly before the
next addition is made. After the required amount of oil has been added
and after free oil has ceased to appear on top of the soap, the water is
slowly poured in, about a quart at a time. To determine whether the mix-
ture will form a perfect emulsion add a little of it to soft water, and if
no oil floats, the mixture is perfect and may be used for spraying. The
presence of floating oil indicates an imperfect mixture and results from
adding the oil too suddenly or from insufficient stirring. This condition
may be remedied by the addition of more soap, which is preferable to
throwing away the entire mixture.
"For spraying orange trees use 1 gallon of the stock mixture prepared
as just described to 50 gallons of water, or use the entire amount to make
200 gallons of spray material. This dilution contains approximately 1
per cent of oil, which is the maximum strength required for whiteflies
and the purple scale. For three-fourths of 1 per cent of oil add 1 gallon
of the stock mixture to 66 gallons of water, and to obtain one-half of 1
percent add 1 gallon of the stock mixture to 100 gallons of water.
"Many alterations may be made in the foregoing formula. The quan-
tity of soap will depend largely upon the time consumed in adding the oil
and the amount of stirring accompanying this process. The amount of
soap is lessened if the stirring is uniform and if ample time is taken in
the preparation. Petroleum fuel oil, or crude oil, and distillate, or gas
oil, may be used instead of the paraffin oil, but in these cases a mixture
of about twice the strength will be needed to kill the insects. The amount
of water is unimportant, since the emulsion should be perfect if either I
or 4 quarts be added. The only thing to be remembered is that the di-
luted spray should contain the required percentage of oil."

3






66 Florida Cooperative Extension

The dilution recommended above (1%) is sufficient when
chiefly whitefly is to be killed, but if purple scales and particu-
larly Florida red scales are very abundant Mr. Others recom-
mends 11/3 or 1 1/2% of oil. To make a 1 1/2% solution use
six quarts of the stock solution to 50 gallons of water.
The Boiled Formula.-The following formula is cheaper as it
requires less soap:
Soap .......-.. -.... -................--....- ..-- ...-...-- ...--........-- -- .....--.. 2 pounds
Lubricating oil ....--......~-- ..-...-- .. --..-- ......-. -- ............... -2 gallons
W ater --..................................... --....... ...........--- ........--- 1 gallon
This differs from the cold formula, with four times as much
soap, in that it was intended to be heated. It is heated to the
boiling point and emulsified by forcing it twice through a hand
pump. When ready to use, this new stock solution is to be di-
luted, as was the cold. Because of its cheapness this boiled
stock solution will probably find favor among growers who use
large quantities. When only a little is wanted, however, the
cold formula will often be preferred because it does not require
heating.
This formula can be made without heat, as was first shown
by Mr. Colin MacDonald of Grand Bay, Alabama. He emulsi-
fied it by forcing it through a pump several times.
The foregoing formulae require soft water. Hard water
must be softened before being used. Some hard waters may
be softened by carbonate of soda or caustic soda, others require
soap (2). Mr. Others (36) gives the following directions for
softening even the hardest waters from the deep wells of
Florida:
Add a pound of caustic soda to 1 quart of water. Stir for one minute,
then add 100 gallons of water. Dissolve 2 pounds of soap in 1 gallon of
water and add this to the 100 gallons. Then add the oil emulsion. When
spraying use no agitator.
There are several good proprietary insecticides very similar
to the above government formulae, i. e. made from the "red"
oils.
More recently there have been placed on the market emul-
sions made from the so-called "white-oils". They are, of course,
more expensive than the above oil emulsions originating from
less purified oils but are less liable to burn tender foliage.

FUMIGATION
Fumigation has been tried repeatedly in Florida but has never
made much headway with the growers, due to several objec-







Bulletin 67, Citrus Insects and Their Control 67

tions. The early methods could be used only at night and during
a comparatively few weeks during winter. In these early experi-
ments the hydrocyanic acid gas was generated first by the old
pot method in which sodium cyanide is dropped into a pot con-
taining dilute sulphuric acid under a tent; later by a cyana-
fumer in which the gas is generated in the same manner but in
a separate machine known as a "cyanafumer" outside of the
tent. The use of liquid hydrocyanic acid has also been tried in
Florida.
More recently a method of fumigating citrus trees has been
used which overcomes some of the above objections. This method
consists in dusting the trees with calcium cyanide dust. This
dust, when it comes in contact with moist air or soil, liberates
the hydrocyanic acid gas. This method of fumigating trees
seems to be safe over as wide a range of conditions of weather
as spraying. That is, it can be carried on during any time of
the year except during the rainy season and during the early
spring months when there is much new growth and young fruit
on the trees. The kills obtained by fumigation are appreciably
higher than those obtained by spraying. The cost is of course
greater as compared with a single spraying. Sometimes, how-
ever, the reduced number of fumigations necessary may, under
at least some conditions, compensate for the-greater cost of the
individual operation, particularly for scale-insects and especially
for the Florida red scale. Where the whiteflies are the chief
insects to be controlled, fumigation would not appear practical,
due to the fact that the trees would be reinfested by the flight
of the next brood of adults and fumigation would have to be re-
peated. At the time of the earlier experiments with fumigation
the common whitefly was of relatively greater importance than
it now is.
Fumigation, however, should be tried only by experienced
men. Inexperienced growers should hire it done by such men
rather than attempt to do it themselves. Furthermore, the
cost of the tents renders the method prohibitive if the small
grower has to provide his own tents. The dust ordinarily used
in fumigating trees is mixed with 15% of sulphur in order to
kill more effectively rust mites as well as scale-insects and
whiteflies.






68 Florida Cooperative Extension

CONTROL BY FUNGUS PARASITES
It is commonplace information to those who are conversant
with this subject that insects as well as large animals and man,
are subject to destruction by diseases. While bacteria are the
principal agents causing diseases in the higher animals, certain
parasitic fungi are generally the causative agents in insect
diseases. There are at least six fungus parasites known to in-
fect the whiteflies infesting citrus, and about as many more on
the scale-insects (3). On the whiteflies these are: Red ascher-
sonia, yellow aschersonia, brown whitefly-fungus, cinnamon
fungus, white-fringe fungus, and occasionally a species of Sporo-
trichum. All these fungi, except the species of Sporotrichum,
grow on, or infect, the larvae, or immature stages, of the white-
flies. Sporotrichum, a fungus similar to the chinchbug fungus,
infects the full-grown adult whiteflies. The fungi known to
infect and destroy citrus scale-insects are: The red-headed
scale-fungus, pink scale-fungus, white-headed scale-fungus, black
scale-fungus, Cuban aschersonia, turbinate aschersonia, cephalo-
sporium fungus, and cinnamon fungus.
Fungus growths consist of masses of exceedingly fine threads
that mass themselves in various ways: as fluffy, irregular
masses (molds), as cushions or pustules (the aschersonias and
brown whitefly-fungus), little stems with heads (red-headed
scale-fungus), as toadstools and mushrooms.
Fungi reproduce themselves by means of exceedingly small
bodies called spores. Those of the red aschersonia are so
small (and they vary in size) that from 13,000,000 to 52,000,000
of them could be arranged one layer thick on the surface of a
square inch.
When a spore (seed) of an insect-destroying (entomogenous)
fungus that has become lodged on or near its insect-host germi-
nates, it sends out one or several minute threads that penetrate
the body wall of the insect. Once inside the insect, these grow
and ramify into all its parts, gradually absorbing the substance
of the insect and transforming it into fungus. Sooner or later
the fungus begins to burst through some part of the insect's
skin, wholly or partly overgrowing the insect, and forming a
cushion, a pustule, or heads on short stems, and, in turn, pro-
duces spores (seeds). These fungi obtain their nourishment
only from the insects that they infect and not from the leaves
or other parts of the plant that the insects infest.







Bulletin 67, Citrus Insects and Their Control 69

Florida is indeed fortunate in that it has so many of these
parasites to assist in the control of its insect pests. Its moist cli-
mate and abundant rainfall, together with a high temperature,
during the period of summer rains, from about June through
September, account for this fact, as fungi require these condi-
tions in order to thrive. The importance of fungi in keeping
down scale-insects, for instance, can easily be demonstrated by
spraying a tree with fungicide, such as bordeaux mixture. This
destroys the fungi and the scales increase, a fact discovered in-
dependently by many citrus growers. Whenever it becomes nec-
essary to spray with bordeaux, and scale-insects or whiteflies
are present, this should, as a rule, be followed after some weeks
with an insecticide, as otherwise the scale-insects or whiteflies
may so increase as to seriously injure the trees.
In setting forth the merits of the fungi, the authors do not
wish to be understood as recommending them as a panacea, but
principally as an aid in the control of scale-insects and whiteflies.
The fungi do not thrive in all kinds of localities nor under all
conditions in which groves may be found. As previously indi-
cated, they thrive best during the period of summer rains.
Sometimes, however, favorable weather conditions prevail
earlier, as early as April, and the brown fungus thrives later in
fall than the others. The junior author also once observed an
unusual development of the red-headed scale-fungus during a
warm February (Gainesville, 1909). But while these excep-
tional instances occur, experience and observation all indicate
that the best results with fungus are in general obtained during
the period of summer rains. Neither do the fungi thrive in
groves and trees that are out of condition with perhaps only one
half to one third enough leaves upon them to conserve the mois-
ture. Young trees just set are poor candidates for fungus and
fungus should not be used on trees under three years old from
the time of transplanting. Unusually favorable weather condi-
tions may, of course, result in a fungus controlling either the
scale-insects or whiteflies in such trees, but as a more certain
proposition, we recommend spraying such trees with a spray
containing oil.
The grower should not wait until his trees are loaded with
either scale-insects or whiteflies before introducing fungus or
spraying with oil sprays, but should at all times know exactly
the insect condition of his trees, and use the treatment indicated
for the time and place. During the period of summer rains we







70 Florida Cooperative Extension

recommend the fungi, as spraying with insecticides may be
difficult and unsatisfactory at that time on account of frequent
showers.
Results from applying fungus are not immediate, but if the
application is successful some fungus will become visible in
three to six weeks, more generally in four weeks.
HOW TO INTRODUCE FUNGUS
Any of the insect-destroying fungi listed herein can be intro-
duced by simply spraying a mixture of their spores in water
into the trees infested with the insect or insects of which the
fungus is an enemy. For insects such as whiteflies that live on
the underside of leaves, the spray must be directed against that
side. A mixture of fungus spores (the seeds of a fungus) in
water is easily made by simply mixing, stirring and rubbing
some fungus material in water and straining through coarse
cheesecloth. Approximately 100 fungus pustules, cushions or
heads may be allowed to one gallon of water. Much more or
even less may be used depending on whether plenty or but
little fungus is available. Fungus materials collected from
trees may be used, but the pure cultures when available are to
be preferred as they are perfectly free from all other fungus
spores and diseases, which may not be true of fungus taken from
trees. Cultures of the red aschersonia, yellow aschersonia and
the Cuban aschersonia are obtainable from the Plant Board.
Fungus material of fungi not obtainable in pure cultures should
preferably be collected from deciduous trees (see under each
fungus) when it is wanted for use on citrus; or vice versa.
Directions for using pure cultures of fungus are sent with
each request.
Mixtures of fungus spores and water should not be allowed
to stand in brass or copper containers for more than a few
minutes. It is better to employ only vessels and spray pumps
having but little or no brass or copper in their construction, as
some copper may become dissolved and kill the spores of the
fungi if allowed to stand in contact too long.
Fungus may also be introduced by simply pinning or tying
fungus material collected from trees into other trees. Leaves
with whitefly-fungus should be pinned with the top of the
loose leaf against the bottom of the leaf on the tree. This places
the loose leaf in its natural position so that insects may crawl
over it and scatter the fungus spores.






Bulletin 67, Citrus Insects and Their Control 71

Scale-fungus material may also be used by cutting small
pieces of twigs and tying these onto the limbs and twigs of
the scale-infested trees. (Fig. 42.)
PURE CULTURES OF FUNGUS
Since 1915 the State Plant Board of Florida has been grow-
ing and supplying pure cultures of the red aschersonia, or red
whitefly-fungus, at cost of production. A few cultures of the
yellow aschersonia, the Cuban
aschersonia and the Cephalo-
sporium fungus are also some-
times available. A culture con- "
sists of the amount of fungus
that can be grown in a pint
wide-mouth bottle, and is suffi-
cient for an acre of trees. --
The Plant Board is still fur-
nishing these fungi at one dol-
lar per culture, with directions .
for using them. The red ascher-
sonia will infect both the com- -
mon whitefly and the cloudy-
winged whitefly. The yellow
aschersonia will thrive only on
the cloudy-winged whitefly. It
is urged that those who request
fungus send at least twenty or
thirty leaves collected at ran-
dom from their worst infested
trees for examination in order ig. 42.-A scale-fungus applied by tying
a piece of twig with fungus onto a scale-
to determine whether only one infested twig. (After Rolfs and Faw-
cett, 23.)
of these fungi is required or
whether the request may be filled with both kinds.
Address: "Entomological Department, State Plant Board,
Gainesville, Florida."
APHIDS
Four species of aphids or plant lice are commonly met with
on citrus in Florida. They are, in the order of their im-
portance:
(1) The green citrus aphid (Aphis spiraecola Patch).
(2) The melon aphid (Aphis gossypii Glover).






72 Florida Cooperative Extension

(3) The brown citrus aphid or grapefruit aphid (Toxop-
tera aurantiae (Fonsc.)).
(4) The green peach aphid or the common garden aphid
(Myzus persicae Sulz.). The last three are minor pests. But
during the spring of 1932 and those of 1924 and 1925, the green
citrus aphid was a pest of extremely great importance.
These aphids ordinarily can be distinguished by their color.
The green citrus aphid is of a quite uniform light green color,
almost identical with the color of the young tender citrus leaf;
the very young ones are a trifle paler. When the wing pads
begin to form the thorax turns first a light pink color and fin-
ally, as the wings develop, dark brown, almost black. However,
the abdomen usually remains green. The melon aphid is very
variable in color but the young stages are usually a light yellow-
ish-green, much lighter than the corresponding stages of the
green citrus aphid. The older stages are usually much darker,
a dark olive green, some of them having a slate-blue cast, vary-
ing to almost black. Toxoptera aurantiae is brownish or red-
dish brown, sometimes with a purplish hue. The garden aphid
is colored much like the green citrus aphid but is much smaller.
Often a colony of aphids will consist of two or three of these
species mixed.

THE GREEN CITRUS APHID
Aphis spiraecola Patch.

This aphid first attracted attention as a citrus pest during
the spring of 1923, although it was not until a year later that it
was distinguished from the melon aphid. However, its pres-
ence in certain groves in the Manatee section as early as the fall
of 1922 has been quite definitely established. There is no sure
record of its presence on citrus in Florida at an earlier date.
There are many records of earlier infestations of aphids, but
usually such expressions as "the aphids left the citrus and went
to watermelons" would indicate that the species involved was
the melon aphid.
The origin of the citrus aphid is a mystery. Its native plant
is undoubtedly shrubs of the genus Spirea, of which the bridal
wreath is the species most commonly planted in Florida. The
insect is undoubtedly closely related to the apple aphis of the
north (Aphis pomi) and Miss Patch, who described Aphis spi-
raecola, now regards it as identical with that species. As a cit-







Bulletin 67, Citrus Insects and Their Control 73

rus pest in Florida it was, when first discovered, confined to
the southwestern part of the state, the center of the infestation
being in the neighborhood of Tampa. From that center it
spread during the springs of 1924-25 to the entire citrus belt
of the peninsula. In the summer of 1925 Mr. Others found it
in one citrus section of California (37), where apparently it
























Fig. 43.-Foliage curled by the green citrus aphid. (After Beyer, 6.)

had been established for many years, and it has been found in
Honduras.
Besides spirea and citrus, it attacks the Japanese flowering
quince, haw apple, pear, the laurel cherry, and a considerable
number of herbs. Most of these are rather accidental hosts
and will be found infested only in heavily infested groves. The
sow thistle (Sonchus), fireweed (Erechthites), and Mexican Tea
(Chenqpodium ambrosioides) are apparently favorites.
LIFE HISTORY
During most of the year the insect breeds parthenogeneti-
cally and viviparously, that is the female is not fertilized by a






74 Florida Cooperative Extension

male and the young are brought forth alive. But as the cold of
the winter comes on, usually about the last of November, true
males and females are also produced. These differ markedly in
color from the parthenogenetic aphids in that they are a bright
straw yellow. These females lay eggs which in more northern
sections carry the species throughout the winter. In Florida
these eggs have never been observed to hatch, but invariably
shrivel up (A. N. Tissot). These sexual forms and eggs have
never been observed on citrus, only on spirea, the flowering
quince and other closely related shrubs.
The rate of breeding and growth depends very much upon the
temperature. They go through their life stages and breed most
rapidly during early May when it takes about six days for
them to complete their development. That is to say that six
days after birth an aphid usually begins to bring forth young.
The average rate at that season is five per day. As the weather
gets warmer not only the rate of growth but the number of
young produced per day diminishes. In June it takes eight days
to produce a generation and the average number of young pro-
duced is only two per day. This slowing up of breeding during
the summer time undoubtedly has much to do with the fact
of the insect's becoming less numerous at that season. As cool
weather approaches the growth also slows up until the average
length of a generation, the latter part of November, 1925, was
ten and a half days.

ENEMIES
In common with other aphids, the green citrus aphid is sub-
ject to the attacks of a large number of enemies which during
most of the year keep down their numbers, but have usually
been unable to do so in the spring when weather conditions are
favorable for the aphids.

LADYBEETLES
Among the most important enemies of the green citrus aphid
are ladybeetles. These feed on aphids during both the mature
and immature stages. The eggs are laid among colonies of
aphids. These hatch out in from four days to a week into small,
usually hairy, larvae. These usually consume between two and
three weeks in growth and then transform into a quiescent pupa
stage. They remain in this stage for about a week and then






74 Florida Cooperative Extension

male and the young are brought forth alive. But as the cold of
the winter comes on, usually about the last of November, true
males and females are also produced. These differ markedly in
color from the parthenogenetic aphids in that they are a bright
straw yellow. These females lay eggs which in more northern
sections carry the species throughout the winter. In Florida
these eggs have never been observed to hatch, but invariably
shrivel up (A. N. Tissot). These sexual forms and eggs have
never been observed on citrus, only on spirea, the flowering
quince and other closely related shrubs.
The rate of breeding and growth depends very much upon the
temperature. They go through their life stages and breed most
rapidly during early May when it takes about six days for
them to complete their development. That is to say that six
days after birth an aphid usually begins to bring forth young.
The average rate at that season is five per day. As the weather
gets warmer not only the rate of growth but the number of
young produced per day diminishes. In June it takes eight days
to produce a generation and the average number of young pro-
duced is only two per day. This slowing up of breeding during
the summer time undoubtedly has much to do with the fact
of the insect's becoming less numerous at that season. As cool
weather approaches the growth also slows up until the average
length of a generation, the latter part of November, 1925, was
ten and a half days.

ENEMIES
In common with other aphids, the green citrus aphid is sub-
ject to the attacks of a large number of enemies which during
most of the year keep down their numbers, but have usually
been unable to do so in the spring when weather conditions are
favorable for the aphids.

LADYBEETLES
Among the most important enemies of the green citrus aphid
are ladybeetles. These feed on aphids during both the mature
and immature stages. The eggs are laid among colonies of
aphids. These hatch out in from four days to a week into small,
usually hairy, larvae. These usually consume between two and
three weeks in growth and then transform into a quiescent pupa
stage. They remain in this stage for about a week and then






Bulletin 67, Citrus Insects and Their Control 75

the mature ladybeetles emerge. The time spent in the differ-
ent stages will vary with the different species of ladybeetles,
but the above will represent an average.

BLOOD-RED LADYBEETLE
Cycloneda sanguine immaculate (Fab.)
This (Fig.
44) is the most
important lady-
beetle feeding
on the green cit-
rus aphid. It d
is common
throughout the
entire year. An
adult of this
species will eat, Fig. 44.-Blood-red ladybeetle. Adult, left; pupa, center;
on an average,
sixty aphids per day, the larvae average about sixteen per day.
The larvae of these beetles are seriously attacked by a fungus
disease (Cladosporiuwr) and to a lesser extent by two hymenop-
terous parasites, Tetrastichus blephyri and HomolItylus ter-
minalis.
CONVERGENT LADYBEETLE
Hippodamia convergens Guer.
This (Fig. 45) is the second most important ladybeetle
which feeds on the green citrus aphid. In late spring it ap-
proaches in
abundance the
Sblood-red lady-
beetle, but
during the
winter and
early spring it
Sis not numer-
ous. It is pre-
Fig. 45.-Convergent ladybeetle. Larva, left; pupa, center; dominately a
adult, right.
southern spe-
cies which needs warm weather for its development. This lady-
beetle is more common on insects affecting truck crops.. It is
the most common ladybeetle in colonies of the melon aphid on





76 Florida Cooperative Extension

cucurbits, cotton, etc. It is also the common ladybeetle on ruta-
bagas and cabbages infested with the turnip louse and cabbage
louse and on peppers and other truck crops.
The egg stage lasts from three to four days and the larval
from thirteen to sixteen, the pupa stage from four to seven
days in April and May. There is also a preoviposition period
of about eight days, making the period from one generation
to another about a month. Early in the season these stages
take longer. Each female lays about four eggs a day.
As in the case of the blood-red ladybeetle, the chief check
on the multiplication of this ladybeetle is a disease, but a
different one. This disease appears to be caused by a bacterial
organism. It is very common and destructive.
A larva of this species eats from forty to seventy aphids
per day, while an adult eats nearly ninety.
TWO-SPOTTED LADYBEETLE
Olla abdominalis var. sobrina Csy.
Up to the middle of April this (Fig. 46) is the second most
abundant ladybeetle in colonies of the citrus aphid. After that
date, though it actually increases in numbers, it is forced into sec-
ond place by the rapid rise in numbers of the, convergent lady-
beetle. It appears to reach its maximum about May 1 and in
June becomes
ver y scarce.
In April it .
takes about F'
four days for o
the eggs to
hatch. The
larval stages
ccup y 2 3 Fig. 46.-Two-spotted ladybeetle. Larva, left; pupa, center;
days, the pu adult, right.
days, the pu-
pal, six days, and the preoviposition period about 11 days, mak-
ing the time from one generation to another about 44 days. A
larva of this species eats, on the average, about twenty aphids
per day. The larvae are very subject to a fungus disease
caused by a species of Cladosporium.
SCYMNUS TERMINATUS Say.
This little ladybeetle (Fig. 47) is the fourth most common
ladybeetle found feeding on the green citrus aphid. It seems to






Bulletin 67, Citrus Insects and Their Control 77

be preeminently a summer species and by the end of June is
the most common ladybeetle in the colonies of aphids. The lar-
vae of this ge-
nus are of strik-
ing appearance
because of a d
dense covering
of white hairs.
The y suggest r
mealybugs o r
trash bugs a t
first glance.
The larvae of
Fig. 47.-Scymrnus terminatus. Larva, left; pupa, center;
this species are adult, right.
heavily parasitized by a wasp-like parasite, Anisostylus similis.
Other ladybeetles found feeding on this aphid were Scymnus
brullei Muls; Scymnus collaris Melsh. (Fig. 48) ; Scymnus cre-
perus fraternus

Su as margini-
pennis children
Muls. (Fig. 49),
a little red lady-
bee t.e with
S-black spots on
Fig. 48.-Scynnus collaris ladybeetle. Larva, left; pupa, the wing cov-
center; adult, right. ers; Microwei-
sia coccidivora (Ashm.), a very small ladybeetle with the front
part of the wing covers red, the back part and the thorax black;
Stethorus utilis (Horn), the smallest of all the ladybeetles,
scarcely larger
than the head
of a pin, smooth
and shining .
black in color;
Ce r a tome- m
gilla fuscilabris
floridana
(Leng.), a spot- 14
t e d ladybeetle Fig. 49.-Ewochoms marginipennis children. Larva, left;
pupa, center; adult. right.






78 Fl6rida Cooperative Extension

occasionally found infesting colonies of the citrus aphid in low
places. The Australian ladybeetle is also found feeding on the
citrus aphid, but probably never completes its development there.
CHINESE LADYBEETLE
Leis conformis Boisd.
In June, 1925, the Experiment Station imported from Cali-
fornia a ladybeetle very much larger than any of the native
species. As this ladybeetle came originally from China it is re-
ferred to as the Chinese ladybeetle (Fig. 50). A larva of this
species eats an average of nearly 200 young aphids per day, and
an adult, an equal number.
This ladybeetle apparently has become established in at least
one grove in Florida. Here it has maintained itself for several
years and seems to have a very appreciable effect in keeping
down the citrus aphid in this grove. At least this grove has suf-
fered less from the citrus aphid than most other groves in
Florida. It has maintained itself for several months in other
groves, but in most groves into which it has been introduced
it seems to have died out.
Life History.-The eggs of this species hatch during warm
weather in three
days. During the
winter time the
average period is
Five days. The lar-
Svae require 11
S. days to 'mature.
hey remain in
Sa t h e pupa stage
five days. Thus
b it is seen that
during warm
weather their life
cycle occupies 23
days and during
the winter time
35 days. In addi-
2tion to the time
:' I spent in develop-
Fig. -Ckih.:e Isa. LIetliE. a, eggs, b, larva, e, pupa, d, adult.
ment there is a
preovip'6sition period of 30 days. A female lays on the average
about 71 eggs. ....







Bulletin 67, Citrus Insects and Their Control 79

SYRPHUS FLIES
Next to the ladybeetles, syrphus fly larvae are the most im-
portant insect predators on aphids. In almost any colony that
has been established for as much as a week, one or more of

yellow maggots
may be seen
crawling about
and impaling
aphids on its
sharp beak.
These insects
are more abund-
ant in the early
spring. S o m e
species seem to Fig. 51.-Syrphus fly, Baccha lugens. Left to right, adult,
pupa, larva.
disappear en -
tirely in May. Like the larvae of the ladybeetles, they are heav-
ily parasitized by both vegetable parasites (fungi and bacteria)
and insects. Three wasp-like parasites were bred out from the
syrphus flies during our studies of the citrus aphid in 1925.
The adults of these larvae are two-winged flies. (Fig. 51.)
These flies feed on the nectar and pollen of flowers and often
may be seen hovering about the flowers. They have the ability
to hover in front of a flower like a humming bird Without
alighting on it.
The eggs are
rather large for
the size of the
flies and glist-
ening white in
color. They are
laid among the
aphids where
they are con-
spicuous ob -
jects. Fig. 52.-Syrphus fly, Baccha clawata. Left to right, adult,
pupa, larva.
Syrphus wied-
manni Johnson (Syrphus americana Wied.:) This species of
syrphus fly larvae became very abundant as' early as the last:
of January, 1924. In 1925 the numbers began to disappear, iji







80 Florida Cooperative Extension

April and were entirely gone in May, and reappeared in Octo-
ber. One larva of this species ate 513 aphids in ten days. Two
others ate an average of 41 and 44 aphids per day. It is thus
seen that for their size syrphus fly larvae are voracious feeders.
Allographa obliqua (Say): This is another syrphus fly
which is very abundant in the early part of the season, Novem-
ber to January, and is found during every month of the year.
Baccha clavata Fab.: (Fig. 52.) This syrphus fly larva be-
comes particularly abundant late in the season, reaching its
maximum abundance in late May or early June and continues
to be found in colonies of aphids all summer. The larvae of
this species were much subject to a disease, apparently of bac-
terial origin.
APHIS-LIONS
Aphis-lions are also important checks on the multiplication
of aphids. Descriptions and illustrations of these insects will
be found under the heading of scale-insects, page 18.

FUNGUS DISEASES
Several fungus diseases are at times very destructive to
aphids. The most common of these is caused by the fungus
Empusa fresenii Now. Warm, humid weather extending over
several days is very apt to start an epidemic of this disease
which may in a day or two almost totally destroy the aphids.
In 1925 this disease thoroughly controlled the aphids about the
15th of April. In 1924 it was the middle of June before a gen-
eral epidemic occurred. The disease carried off many aphids at
other times and was a very important check on their multipli-
cation.
W. A. Kuntz, of the Plant Pathology Department, Florida Ex-
periment Station, who has given this fungus a close and exhaus-
tive study, thus describes the appearance of infested aphids (15) :
"First indication of the disease on the aphid attacking citrus is a slight
yellowish color over thorax and fore-abdomen with a grayish bloom. Ab-
domen very slightly swollen. (Newly molted aphids yellowish throughout.)
Hind legs somewhat raised from leaf or twig surface. Proboscis dark in
color. Elevation of abdomen becomes more evident. Death occurs. After
death yellow changes to, at first, a light brown and later to a ripe-olive
brown. The production of conidia is evident ten to eighteen hours after
death. These give to the surface of the diseased insect a tan to smoke-
colored appearance, glistening in the sunlight. Halo of spores may be
observed in moist calm weather on the leaf surface. With time the insect
becomes dark brown with tan areas, irregular, flattened and much smaller
in size." 0







80 Florida Cooperative Extension

April and were entirely gone in May, and reappeared in Octo-
ber. One larva of this species ate 513 aphids in ten days. Two
others ate an average of 41 and 44 aphids per day. It is thus
seen that for their size syrphus fly larvae are voracious feeders.
Allographa obliqua (Say): This is another syrphus fly
which is very abundant in the early part of the season, Novem-
ber to January, and is found during every month of the year.
Baccha clavata Fab.: (Fig. 52.) This syrphus fly larva be-
comes particularly abundant late in the season, reaching its
maximum abundance in late May or early June and continues
to be found in colonies of aphids all summer. The larvae of
this species were much subject to a disease, apparently of bac-
terial origin.
APHIS-LIONS
Aphis-lions are also important checks on the multiplication
of aphids. Descriptions and illustrations of these insects will
be found under the heading of scale-insects, page 18.

FUNGUS DISEASES
Several fungus diseases are at times very destructive to
aphids. The most common of these is caused by the fungus
Empusa fresenii Now. Warm, humid weather extending over
several days is very apt to start an epidemic of this disease
which may in a day or two almost totally destroy the aphids.
In 1925 this disease thoroughly controlled the aphids about the
15th of April. In 1924 it was the middle of June before a gen-
eral epidemic occurred. The disease carried off many aphids at
other times and was a very important check on their multipli-
cation.
W. A. Kuntz, of the Plant Pathology Department, Florida Ex-
periment Station, who has given this fungus a close and exhaus-
tive study, thus describes the appearance of infested aphids (15) :
"First indication of the disease on the aphid attacking citrus is a slight
yellowish color over thorax and fore-abdomen with a grayish bloom. Ab-
domen very slightly swollen. (Newly molted aphids yellowish throughout.)
Hind legs somewhat raised from leaf or twig surface. Proboscis dark in
color. Elevation of abdomen becomes more evident. Death occurs. After
death yellow changes to, at first, a light brown and later to a ripe-olive
brown. The production of conidia is evident ten to eighteen hours after
death. These give to the surface of the diseased insect a tan to smoke-
colored appearance, glistening in the sunlight. Halo of spores may be
observed in moist calm weather on the leaf surface. With time the insect
becomes dark brown with tan areas, irregular, flattened and much smaller
in size." 0







Bulletin 67, Citrus Insects and Their Control 81

THE EFFECT OF HEAVY RAINS
Heavy, dashing rains are very destructive to citrus aphids,
which are washed off the plants and pounded to death on the
ground. After heavy rains it often happens that the only live
aphids to be found are in the curled leaves where they were pro-
tected from the rain, whereas before the rain they had been
numerous on all tender parts of the plant.
CONTROL
By Cultural Methods.-As the citrus aphids can live only on
young succulent foliage, except the few that may be able to find
other host plants on which they may tide over the starvation
period, they must starve to death when there is not such foliage
on the trees. Fortunately, citrus trees naturally grow in flushes
of growth alternating with periods of relative dormancy. This
is particularly true of older, bearing trees. Younger trees, par-
ticularly some varieties like Temples, are prone to a more con-
stant growth and aphids are consequently more injurious to
such trees.
It should be the grower's aim to accentuate this natural
tendency of a citrus tree to grow in flushes, as it is very hard
on the aphids. The most important of the dormant periods is
that of the winter season. The most important factor in throw-
ing a tree into dormancy in the winter is undoubtedly cold and
next most important drouth. However, there are practices,
which are under the grower's control, which have a tendency to
make trees grow in the winter time. Heavy applications of ni-
trogen late in the fall may do this and should be avoided on
young trees. If trees need heavy applications of nitrogen in
the fall they should be put on in the early part, so that the trees
may make a good flush of growth and then go dormant in the
winter. On the other hand trees should'not be starved. Groves
in which the trees are starved are apt to be putting out a little
growth all the time instead of growing in flushes followed by
periods of dormancy. Cultivation late in the fall should be
avoided as it has a tendency to stimulate growth. Sometimes
spraying with an oil emulsion, particularly if many of the leaves
are caused to drop, may bring out new foliage. Fall spraying
of young trees should be applied not later than October. Sickly
trees which are apt to be putting out growth at unseasonable
times should be removed from the grove.




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