• TABLE OF CONTENTS
HIDE
 Front Cover
 Front Matter
 Table of Contents
 Introduction
 Allies of the citrus grower
 Trees that harbor citrus insec...
 Publications concerning citrus...
 Index






Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 148
Title: Insects of a citrus grove
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00026691/00001
 Material Information
Title: Insects of a citrus grove
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: p. 165-267 : ill. ; 23 cm.
Language: English
Creator: Watson, J. R ( Joseph Ralph ), 1874-1946
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1918
 Subjects
Subject: Citrus -- Diseases and pests -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 263.
Statement of Responsibility: by J.R. Watson.
General Note: Cover title.
General Note: Includes index.
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00026691
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000922768
oclc - 18162276
notis - AEN3277

Table of Contents
    Front Cover
        Page 165
    Front Matter
        Page 166
    Table of Contents
        Page 167
        Page 168
    Introduction
        Page 169
        Injurious insects
            Page 169
        Whiteflies
            Page 170
            Page 171
            Page 172
            Page 173
            Page 174
            Page 175
            Page 176
            Page 177
            Page 178
            Page 179
            Page 180
            Page 181
            Page 182
            Page 183
            Page 184
        Scale insects
            Page 185
            Page 186
            Page 187
            Page 188
            Page 189
            Page 190
            Page 191
            Page 192
            Page 193
            Page 194
            Page 195
            Page 196
            Page 197
            Page 198
            Page 199
            Page 200
            Page 201
            Page 202
            Page 203
            Page 204
            Page 205
            Page 206
            Page 207
            Page 208
            Page 209
            Page 210
            Page 211
            Page 212
            Page 213
            Page 214
            Page 215
            Page 216
            Page 217
            Page 218
            Page 219
        Rust mite
            Page 220
            Page 221
            Page 222
            Page 223
            Page 224
        Red spiders
            Page 225
        Florida flower thrips
            Page 226
            Page 227
            Page 228
            Page 229
            Page 230
        Large plant-bugs
            Page 231
            Page 232
            Page 233
            Page 234
            Page 235
        Minor pests of the fruit
            Page 236
            Page 237
            Page 238
            Page 239
        Scavengers
            Page 240
        Morelas fruit fly
            Page 240
        Citrus root-weevil
            Page 240
        Borers of trunks and limbs
            Page 241
        Bark and leaf scavengers
            Page 242
        Minor pests of young trees
            Page 243
            Page 244
            Page 245
            Page 246
            Page 247
            Page 248
            Page 249
            Page 250
            Page 251
            Page 252
            Page 253
            Page 254
            Page 255
            Page 256
            Page 257
            Page 258
    Allies of the citrus grower
        Page 259
        Birds
            Page 260
        Other vertebrates, predaceous bugs, wasps, and parasitic flies
            Page 261
    Trees that harbor citrus insects
        Page 262
    Publications concerning citrus insects in Florida
        Page 263
    Index
        Page 264
        Page 265
        Page 266
        Page 267
Full Text

Bulletin 148


UNIVERSITY OF FLORIDA

Agricultural Experiment Station





INSECTS OF A CITRUS GROVE

By J. R. WATSON


Fig. 74.-Orange dog butterfly (Papilio cresphontes). Natural size


Bulletins will be sent free upon application to Experiment Station,
GAINESVILLE, FLORIDA


June, 1918.












BOARD OF CONTROL
JOE L. EARMAN, Chairman, Jacksonville, Fla.
E. L. WARTMANN, Citra, Fla.
T. B. KING, Arcadia, Fla.
J. B. HODGES, Lake City, Fla.
J. T. DIAMOND, Milton, Fla.
BRYAN MACK, Secretary, Tallahassee, Fla.
J. G. KELLUM, Auditor, Tallahassee, Fla.

STATION STAFF
P. H. ROLFS, M. S., Director
J. M. SCOTT, B. S., Vice-Director and Animal Industrialist
B. F. FLOYD, A. M., Plant Physiologist
S. E. COLLISION, M. S., Chemist
J. R. WATSON, A. M., Entomologist
H. E. STEVENS, M. S., Plant Pathologist
E. G. SHAW, Secretary
J. MATZ, B. S., Laboratory Assistant in Plant Pathology
T. VAN HYNING, Librarian
C. D. SHERBAKOFF, Ph. D., Associate Plant Pathologist
R. NEWHALL, Mailing Clerk
F. G. BENDING, Stenographer
O. W. WEAVER, B. S., Agricultural Editor
A. M. SMITH, B. S., Assistant Chemist
M. NOTHNAGEL, Ph. D., Assistant Plant Physiologist
J. B. THOMPSON, B. S., Forage Crop Specialist
G. C. OBERHOLTZER, Farm Foreman
G. UMLAUF, Gardener
H. L. DOZIER, M. S., Assistant to Entomologist
K. H. GRAHAM, Auditor and Bookkeeper









CONTENTS
PAGE
INTRODUCTION ................. ....... ................................... 169
INJURIOUS INSECTS ....... ................ ........... ............... 169
W hiteflies, life history .......... -........................ ................. ........ 170
Common Citrus Whitefly, life history, parasites and predators, con-
trol, a spraying schedule ........................................................... ... 172
Cloudy-winged Whitefly, description, life history, control.................. 178
Woolly Whitefly, description, natural control, artificial control........ 181
Minor Species-
Flocculent Whitefly ................ .. .... ....................... 184
Guava W hitefly ....... ....... ...... ..................... 184
Bay W hitefly ............................... --................... 184
Inconspicuous, or Sweet-potato Whitefly ................................... 184
M ulberry W hitefly .............................. .. ........ ............... .. 185
Other Whiteflies-Spiny Blackfly .................................................... 185
Scale Insects, three kinds .................... -................... 185
Armored Scales, life history ..... ............---... ..... ..187
Purple Scale, life history, broods, association with whiteflies,
damage -............................ .........-.. ......---......... 187
Natural Checks-
Entomogenous Fungi-Red-headed scale-fungus, gray-
headed scale-fungus, black fungus ...................................... 192
Predaceous Insects-Lady-beetles, downy darkling beetle,
lace-winged flies, trash bug, predaceous mites .................. 193
Internal Parasites ...... ...........-......... ........................ ..... 196
Control for Purple Scale .................................................... 197
Long Scale ............. ....... ................... ...................... ........ 199
Florida Red Scale, life history, natural checks, control .................. 200
Minor Scales-
California Red Scale .............................................. 203
Dictyospermum Scale ..................................... 203
West Indian Red or Rufous Scale ............................................. 203
San Jose Scale ...................... -......... ...- -....................... 204
Chaff Scale, life history, natural checks, control measures, food
plants ....... ............... ....... ........................... ......... 204
Snow Scale ......... .... .............. ........... .....................206
Unarmored or Soft Scales, life history ...................................... 206
Turtle-back or Soft Brown Scale, life history, natural checks........ 207
Hemispherical Scale .............-................. .........................- 208
Black Scale ................... ................................................. 209
W ax Scales ..................................... ............. ......... 209
Florida Wax Scale, natural checks, host plants, control ........... 209
Barnacle Scale ............... ............................... ..... ........... .. 211
Japanese or Mexican Wax Scale .................................................... 211
Pyriform Scale ......................................................... ... .212
Mealy Shield Scale ...................-...........-............... .212
Mealy-bugs ........................................--................ ............ 213
Citrus Mealy-bug, life history, predators, control ...................... 214
Long-tailed Mealy-bug ........................... ....... ................ 216
Cottony Cushion Scale, appearance, life history, control, Aus-
tralian Lady-beetle ................. .... ............................. 216
Rust Mite, appearance, life history, natural control, spraying, sul-
phur the best insecticide, sulphur compounds ............................... 220
Red Spiders ...... .... ........ .. .... ... ............................ ... 225
Six-spotted M ite ............................... -................... ... ......... 226
Purple Mite .................................. .......................... 226
Florida Flower Thrips, character and extent of damage, thrips marks
on the fruit, life history, natural control, spraying ........................ 226







168 Florida Agricultural Experiment Station

PAGE
Large Plant-bugs .................... ................. .. .... .... .. 231
Green Soldier Bug or Pumpkin Bug, life history, control, prevention 231
Other Plant-bugs-Northern green soldier bug, gray stink bug,
leaf-footed plant-bug, big-thighed plant-bug ..........................-... 235
Cotton Stainer ....... ..... 235
Minor Pests of theFriit---
Orange Tortricids ..................... ...................... .. ........ 236
Grasshoppers and Katydids .............................. ....---.. 237
Bagworms ............................ ................ 238
Rodents ...............................------- 238
Mediterranean Fruit Fly ..................................................... 239
M orelas Fruit Fly ............... ..... ........ .. .. ............. .... 240
Scavengers .................... ............................. ...... 240
Citrus Root-weevil ...................................... ........ .. .... ..... 240
Borers of Trunks and Limbs-
Orange Sawyer ........................................................ .... 241
Shot-hole Borers, or Pin-head Borers ..... ................. ......... 241
Tineid Miner ......... ........ ...-........................ 241
Bark and Leaf Scavengers-
Psocids, on bark and limbs, on leaves .................................... 242
Hymenorus ...........-...- .....-........ ............... 243
Minor Pests of Young Trees ........................ ................. ...... .. 243
Orange Dog, control .................. ....... ............. 243
Slug Caterpillars-
Puss Moth ........-- .......... ....... ............ ........... 245
Saddle-back ...................... .... ... ................ ...................... 246
Hag M oth ...... ...................... ......... ..... ......... ... 247
Grasshoppers-Bird grasshopper, yellow-lined grasshopper, lub-
berly locust ............................. ........ ........ ........... 247
Katydids-Broad-winged katydid, angular-winged katydid .............. 249
Sharp-shooter or Orange Jassid ................................. ........ 250
Ants, on budded trees, as protectors and carriers of scale insects,
control ....................................... ...... .......... ........ .. 251
White Ants, Termites, or Wood Lice, control ..................... .... 253
Prickly-ash Beetle .................................. ..... -------- ... .. 254
Melon Aphis, control, life history, natural color ......... ............ 254
Striped Cucumber-beetle ......................... ... ... .. ........ -.....--.... 258
ALLIES OF THE CITRUS GROWER ... ................... ....................---- -----...... 259
Birds .................................... ................. .... .................- ........... 260
Other Vertebrates ... ........... ...... ........ ........... ........... ------ 261
Predaceous Bugs .................... ... .............................. ....... 261
W asps ........................ .......... .........................--. ... ................... ... ...... 261
Parasitic Flies ........................ ........... ....- ........-.... ........ 261
TREES THAT HARBOR CITRUS INSECTS ................................... ......262
PUBLICATIONS CONCERNING CITRUS INSECTS IN FLORIDA ............--.. ....---- 263








INSECTS OF A CITRUS GROVE
By J. R. WATSON

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 writer has selected chiefly those insects which have been the
source of much correspondence with citrus growers. Neither
has an attempt been made to present an exhaustive account of
the more important pests, nor to repeat data that are easily
accessible to the average grower thru 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.
All of the photographs used in preparing the illustrations for
this bulletin not otherwise credited were made by the assistants
in the Department of Entomology of this Station,-Messrs. U.
C. Loftin, A. C. Mason, and especially H. L. Dozier. Mr. Dozier
also made the drawings of the lady-beetles and the downy dark-
ling beetle. Some illustrations have been taken from previous
publications by this Station. The Bureau of Entomology, U. S.
D. A., has supplied the photographs from which other cuts were
made. The California experiment station has lent one illustra-
tion, and Florida State Plant Board three. These are duly cred-
ited where used.

INJURIOUS INSECTS
Of the insects and mites treated in this bulletin there are but
five which should be classed as pests of primary importance,








INSECTS OF A CITRUS GROVE
By J. R. WATSON

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 writer has selected chiefly those insects which have been the
source of much correspondence with citrus growers. Neither
has an attempt been made to present an exhaustive account of
the more important pests, nor to repeat data that are easily
accessible to the average grower thru 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.
All of the photographs used in preparing the illustrations for
this bulletin not otherwise credited were made by the assistants
in the Department of Entomology of this Station,-Messrs. U.
C. Loftin, A. C. Mason, and especially H. L. Dozier. Mr. Dozier
also made the drawings of the lady-beetles and the downy dark-
ling beetle. Some illustrations have been taken from previous
publications by this Station. The Bureau of Entomology, U. S.
D. A., has supplied the photographs from which other cuts were
made. The California experiment station has lent one illustra-
tion, and Florida State Plant Board three. These are duly cred-
ited where used.

INJURIOUS INSECTS
Of the insects and mites treated in this bulletin there are but
five which should be classed as pests of primary importance,






Florida Agricultural Experiment Station


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) Common Citrus Whitefly
(2) Purple Scale
(3) Rust Mite
(4) Florida Red Scale
(5) Cloudy-Winged Whitefly
There is a larger number of insects which should be watched,
and against which the grower should take measures during oc-
casional years. They are, again approximately in the order of
their importance:
(6) Red Spiders
(7) Thrips
(8) Woolly Whitefly
(9) Mealy-Bugs
(10) Cottony Cushion Scale
(11) Snow Scale
(12) Orange Dog
(13) Chaff Scale
(14) Pumpkin Bugs and other Plant-Bugs
(15) Termites
(16) Ants
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
Aphids
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 mealy-bugs, or by destroying beneficial insects, as do
certain parasites that live in lady-beetle larvae.
WHITEFLIES
There are eight species of whiteflies that may be found on
citrus in Florida. They are:
(1) Common Citrus Whitefly (Dialeurodes citri)





Bulletin 148, Insects of a Citrus Grove


(2) Cloudy-Winged Whitefly (D. citrifolii)
(3) Woolly Whitefly (Aleurothrixus howardii)
(4) Flocculent Whitefly (A. floccosa)
(5) Bay Whitefly (Paraleurodes perseae)
(6) Inconspicuous, or Sweet-Potato Whitefly (Bemesia in-
conspicua)
(7) Mulberry Whitefly (Tetraleurodes mori)
(8) Guava Whitefly (Trialeurodes floridensis)

LIFE HISTORY
The life history of all whiteflies is very similar and one dis-
cussion will answer for all, altho the time spent in development
will vary with different species. As with all insects, there are
four stages in the de-
velopment of the
whitefly,--egg, larva,
pupa, and adult or im-
ago.
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. 75.-Citrus whitefly: Adults and eggs, on leaf.
wide, barely visible to (From Bul. 97)
the unaided eye. When
abundant the eggs give the citrus leaves an appearance of being
covered with a mealy dust. (Fig. 75.) 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 larvae 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 larvae (figs. 76 and 85) 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 all
legs and feelers are lost so that the second-stage larvae seem





Florida Agricultural Experiment Station


scarcely to resemble an insect, as commonly known. This process
is repeated twice.
The fourth-stage larva (figs. 77 and 86) differs considerably
from the larva in other stages. It takes much less feed, 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 much upon the temperature) the pupal case splits across
the back and the adult insect emerges. In this stage the insect
differs greatly from the larva. It has the
typical 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
appearance, altho the male is a bit smaller
Fig. 76.-Citrus whitefly: than the female.
First-stage larva. (From
Bul. 97) The life of the adult is always brief, only
a few days. They are sluggish insects. The
common citrus whitefly and the cloudy-winged whitefly are un-
usually active. The female lays a hundred or more eggs on the
host plant.
COMMON CITRUS WHITEFLY
Dialeurodes citri (R. & H.)
The common citrus whitefly (fig. 75) is easily the most de-
structive citrus insect in Florida. 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.
(2) The.larvae of whiteflies throw off from their alimentary
tract large quantities of a sweetish nectar-like substance called
honey-dew. This falls on the leaves and fruit, and in this honey-
dew grows a jet-black fungus called "sooty mold."
Sooty mold blackens the entire tree including the fruit which





Bulletin 148, Insects of a Citrus Grove


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 h- a'
of sap.,
Sooty 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 will be treated more
fully under Purple Scale. h pe
LIFE HISTORY
Fig. 77.-Citrus whitefly: Fourth-stage Iarva.
The eggs (fig. 78) of this (From Bul. 97)
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 larval stages; the others a little longer,
up to five weeks. The spring and summer broods usually 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 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





174 Florida Agricultural Experiment Station

last and largest brood the latter part of August or early Sep-
tember. (Fig. 79.)
PARASITES AND PREDATORS
There are but few insects, and virtually no higher animals,
that feed upon this spe-
cies. This is undoubt-
edly because it is an im-
ported insect which has
left its enemies behind.
In India, which is prob-
ably the native home of
this species, there are
several insects which
prey upon or parasitize
it, and an unsuccessful
attempt was once made
to introduce some of
them (Woglum, 1913).
The twice-stabbed
lady-beetle (described
under Purple Scale)
Fig. 78.-Eggs of common whitefly. Magnified. (From
BuL 97) (fig. 92) destroys some
crawlers and occasion-
ally an older larva, but prefers other food. A tiny, dark brown
lady-beetle, Delphastus pusillus, seems to be very fond of the
eggs, but for some unknown reason never becomes sufficiently
abundant to be of much practical benefit. A related species, Del-


l II i l II Il I I 1 I- II 1 1 1 L
It I I 1 | I I II II i i II '.ll I I II iI
I I II t II 14 II I I II I L l I 1
II I I II I I I II 114 :'I :1 I I
i II II I I I Ii i I I If. I I I 1 I

II II I Ii
-. .- I' I I V, 'I I I/ I [ .' ,tL. I I2 1 it t I




Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.
Woolly whitefly. Common citrus whitefly ..... Cloudy-winged whitefly.
Fig. 79.-Diagram showing relative date of emergence of adult whiteflies. (From Bul. 126)






Bulletin 148, Insects of a Citrus Grove


phastus catalinae (fig. 80), a very efficient enemy of another
whitefly in California, feeds greedily upon whitefly eggs, and
has been introduced into Florida by the Experiment Station.


Whether it will multiply here remains to be
seen.
There are three species of entomogenous fun-
gi which do very effective work in keeping this
whitefly in check. They are the brown fungus
(fig. 81), the red aschersonia (fig. 82), and the
microcera. These are described in Bulletin 123
of this Station.
CONTROL
Whitefly control has been treated in many
publications of this Station and of the Bureau
of Entomology, U. S. D. A., and needs only to


Fig. 80.-The Califor-
nia whitefly-eating
lady-beetle (Del-
phastus catalinae).
Enlarged drawing

be summarized,


with a few additions. A detailed treatment will be found in
Bulletin 123 of this Station. Since that was published, Mr.
W. W. Others of the Bureau of Entomology, stationed at Or-
lando, has perfected a modification of the Government formula
for the miscible oils which reduces the cost. The original formula
called for:
W hale-oil soap ............................................ 8 pounds
Paraffin oil ........... ......... ....... .... ........2 gallons
W ater ........................ ........................... 1 gallon
In the place of whale-oil soap any cheap alkaline laundry soap
will do. The chief reason for recommending whale-oil soap in


Fig. 81.-Brown fungus on citrus whitefly. (From Bul. 97)





Florida Agricultural Experiment Station


the original formula was its cheapness, but since the beginning
of the war potash whale-oil soap has advanced greatly in price
and is hard to get. Other soaps are now fully as cheap and are
more easily obtained.
In an effort to reduce further the amount of soap and to
cheapen the product, Mr. Others developed in 1915 a new for-
mula. It is:
Soap........... ...- .......................... .......2 pounds
Paraffin oil ...- .............. .. ..... ... ..... 2 gallons
W ater -......... .............. ..... ................... 1 gallon
This differs from the old formula, with four times as much soap,
in that it must be heated. It should be heated to the boiling













Fig. 82.-Red aschersonia on citrus whitefly. (From Bul. 97)

point and emulsified by forcing it twice thru a hand pump. When
ready to use, this new stock solution is to be diluted, as was
the old. Because of its cheapness this new, heated stock solution
will probably find favor among growers who use large quantities.
When only a little is wanted, however, the old formula will often
be preferred because it does not require heating.
The foregoing formulas require soft water. Hard water must
be softened before being used. Mr. Others has recently (Flor-
ida Grower, Oct. 27, 1917) given the following directions for the
use of water from our deep wells:
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.
A SPRAYING SCHEDULE
The number of sprayings necessary to keep the whitefly in
check will depend much upon the weather and the location of
the grove. For a bearing grove under average conditions the






Bulletin 148, Insects of a Citrus Grove


following procedure will usually control the whitefly to a satis-
factory extent.
Spray in late April or May with a miscible oil. The best time
is about two weeks after the bulk of the spring brood of adults
has disappeared. At this time most of the eggs are hatched
and yet few of the larvae will have reached the third or pupal
stage. It is in this stage they do a considerable percentage of
their damage.
Watch the flight of adults and when they are becoming notice-
ably less numerous note the date, wait two weeks, and then
spray. However, it is not best to spray if the fruit is too young
lest it be injured. If the oranges have not reached the diameter
of one inch by the time the whiteflies have reached the proper
stage for spraying, it is best to postpone spraying a short time.
This spraying should control the spring brood of whiteflies.
With the beginning of the summer rains in June or July, make
an earnest effort to introduce and spread the entomogenous
fungi, especially the red and the brown. These fungi can usually
be found in trees in damp and shady situations in one's own
grove or in a neighboring grove. If not, cultures of the red
aschersonia can be purchased from the State Plant Board,
Gainesville. These are raised on artificial media and are the
safest source of the red aschersonia, as there can be no danger
of introducing any harmful disease into the grove when they
are used. The usual method has been to collect leaves and send
them from one grove to another. Doubtless such diseases as
canker and scab could be so introduced into a grove, altho the
chances are slight if proper care is used.
It is sometimes hard to get a stand of brown fungus as early
in the season as June or July. If not successful, one should
try again in August. The brown fungus does much more thoro
work than the red and also works later in the fall, so much good
execution may be accomplished by its introduction as late as
August.
If one has sufficient good fungus material all the trees should
be thoroly covered with the suspension of spores, but if the
amount available is limited one may spray only a few branches
in each tree and trust to natural agencies for a further spread.
In the latter case, spray a few limbs on the shadiest side, espe-
cially when the trees are far apart and do not shade each other.
Place the spray as high in the tree as can be conveniently reached.
In September, the trees should again be sprayed with the oils.






Florida Agricultural Experiment Station


The exact time to spray should be
determined as before, two weeks
after the adults have largely dis-
appeared. This will be late Au-
gust or early September if in the
southern part of the citrus belt,
and the latter half of September
if in the extreme northern part.
This is perhaps the most import-
ant spraying of the year. If
thoroly done, and all spraying to
be of much value must be thoro,
the trees will be clean all winter.
The oils used at this time will
also loosen the sooty mold that
may have already formed so that
washing the fruit will be more
easily accomplished.
These three spraying each
year should usually suffice to con-
Fig. 83.-Eggs of the loudy-winged trol the whiteflies and also the
whitefly on young citrus leaf. Natural trol the whiteflies and alsoth
size. purple and long scale. However,
the spores of the three scale-de-
stroying fungi should be added to the whitefly fungi for the
summer spraying.

CLOUDY-WINGED WHITEFLY
Dialeurodes citrifolii (Morgan)
The cloudy-winged whitefly is very similar to the common
citrus whitefly; so similar indeed that for many years they were
considered as a single species. Dr. E. W. Berger, then ento-
mologist to the Experiment Station, first separated the two spe-
cies. He named this insect Aleurodes nubifera. The most
marked differences are in the egg, which is black in this species
(fig. 83), and in the fact that this species is attacked by another
species of fungus, the yellow aschersonia, in addition to those
that attack the common citrus 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 south-
ern part of the State, the cloudy-winged species only is found,
but in most groves where it occurs the common citrus whitefly






Bulletin 148, Insects of a Citrus Grove


occurs with it. The cloudy-winged species does not occur in
the northern part of the citrus belt. Before the "big freeze" of
1894-5 this species was found over the entire citrus belt, but
as its food* in Florida is confined entirely to citrus it was ex-
terminated thruout the northern part of the citrus belt by the
entire loss of the leaves from the trees in that region.
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.
84.) The females of this species show an even greater fondness
for new growth, particularly watersprouts, than does citri. The
leaves of watersprouts are often so thickly strewn with eggs as
to be distinctly blackened.' (Fig. 83.)
The larvae (figs. 85 and 86) 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 its shape as does that of citri.
The adult, too, is similar but in the middle of each wing there
is a darkened area
which gives rise to 4
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
requires about two
weeks longer dur-
ing the summer
than that of citri,
consequently there
is no imperfect Fig. 84.-Eggs of cloudy-winged whitefly. Magnified. (From
Bul. 97)
winter brood as
with citri and the summer broods lag behind those of that species,
as shown in the diagram (fig. 79).
The maximum flight of the spring brood of adults occurs in
*It has been reported as infesting Ficus nitida in Cuba, the guava in
Porto Rico, and the tomato in New Zealand.


179






Florida Agricultural Experiment Station


early April, about three weeks later than -..
that of citri; the summer brood 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 proced-
ure desirable is in the time of applying the Fig. 85.-Cloudy-winged
whitefly: First-stage lar-
spray. va. (From Bul. 97)
Whenever the two species are present,
the common citrus whitefly is the more important and the cloudy-
winged species becomes of secondary importance. In this case
spray at the time'recommended for the common species. Altho
-not the most favorable time for the cloudy-winged species, spray-
ing 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 spe-
cies is abundant, one
can do a great deal to-
ward effecting control
by removing the wa-
tersprouts at certain
periods. These periods-
will be when most of
the eggs have been laid
and but few adults
have emerged; in oth-
er words, when the
fewest adults are
about. These periods
Fig. 86.-Cloudy-winged whitefly: Fourth-stage larva. about. These periods
(From Bul. 97) will be in the middle






Bulletin 148, Insects of a Citrus Grove


of May, middle of August, and some time in December, January
or February.
In spraying the fungi where this species is present, the yellow
aschersonia may be added to the others.

WOOLLY WHITEFLY
Aleurothrixus howardii Quaintance
The woolly whitefly (fig. 87) 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













Fig. 87.-Colony of woolly whitefly larvae on citrus leaf. (From Ann. Rep. 1912)

Tampa; however, Dr. A. L. Quaintance, our 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. (Fla. Agr.
Exp. Sta. Bul. 126.) It would seem most probable then that,
altho it is a native insect which has long lived on the sea grape,
it has comparatively recently developed a strain which has taken
to citrus. From the fact that it was first discovered as a citrus
pest in the West Indies it seems probable that this supposed
citrus strain developed elsewhere and was introduced into Flor-
ida about 1908.
Altho not present in all or even the majority of groves in the
State, it is now found in all the main citrus-growing sections of
the State except some sections of the lower East Coast and
the northern part of the citrus belt. Tavares, in Lake County,
2






Florida Agricultural Experiment Station


is the farthest point north from which it has been reported.
This whitefly is not the pest of primary importance that citri
is. It is not even as serious a pest, on the average, as the cloudy-
winged species, altho in one or two groves in the State it has
done more mischief for a few months than either of the other
species ever did. The comparatively innocuous nature of this
species is due entirely to the fact that it is highly parasitized by
a wasp-like insect, Eretmocerus haldemani.
j (Fig. 88.) (Fla. Agr. Exp. Sta. Bul. 126.)
SThe dense mat of wool which persists for
I 1 months on the leaves makes an excellent place
S in which the young of the purple scale can
j= -.? hide, and much woolly whitefly in a grove has
always been followed by a heavy infestation
of purple scale. This is perhaps the most se-
rious phase of an infestation of woolly whitefly.
Fig. 88. -Eretmocerus
haldemani: Male. DESCRIPTION
Greatly enlarged.
(From Bul. 126) The woolly whitefly differs more from the
two other species than they do from each other.
The name is derived from curled waxy filaments which com-
pletely 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. 89)..
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 larvae 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 larvae give off honey-dew 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
short distances. On the other hand, they will cling tenaciously
*






Bulletin 148, Insects of a Citrus Grove


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
Altho 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. 89.-Leaf infested with woolly whitefly. (From Bul. 126)

chief parasite is a small wasp-like insect, Eretmocerus halde-
mani. This insect lays its eggs in the larvae of the whitefly.
The grub of the parasite feeds on the substance of the whitefly
larva 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 thru
a round hole that it cuts in the top of the pupal case of the dead
whitefly. These parasites are so abundant that they have in-
variably controlled infestations 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






Florida Agricultural Experiment Station


the oil be applied before many of the larvae have reached the
third stage, as the dense mat of wool more or less smeared over
with honey-dew, 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. 79.)
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. (J1. Ag.
Res., VI-No. 12, Quaintance & Baker.)
GUAVA WHITEFLY
Trialeurodes floridensis (Quaint.)
The guava 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
Paraleurodes 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, altho 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 bay.
It is a common sight in citrus groves but the insects seldom
become abundant. Only once has the writer 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
Bemesia inconspicua (Quaintance)
The inconspicuous or sweet-potato whitefly is a common pest






Bulletin 148, Insects of a Citrus Grove


of sweet potatoes in the southern part of the State and occa-
sionally gets on the citrus trees. It is markedly smaller both in
the larval and adult stages than the other whiteflies. Otherwise,
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, it can doubtless be
controlled by the same miscible oils recommended for other
whiteflies.

MULBERRY WHITEFLY
Tetraleurodes mori
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. Altho 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
There are five other species of whitefly in other parts of the
world, that are more or less serious pests of citrus. One of
the most serious, the Spiny Blackfly (Aleurocanthus woglumi),
is dangerously near Florida. It has recently been introduced
into Cuba and the Bahamas. Like the two species most trouble-
some to citrus, its native home is in southeastern Asia. The
adjective "spiny" refers to the pupal case and not to the adult
fly. "Black" applies to both the larvae and the adults. As the
body of the adult is dark brown and the wings smoky with a
white cross, the general impression to the unaided eye is bluish-
black. Altho stated by the Imperial Entomologist of Jamaica
to yield to miscible oils, 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.

SCALE INSECTS
Next to the whiteflies the most serious pests of citrus trees
are scale insects. These are usually flat and are closely applied
to the surface of the host plant, hence the name, scale insect.
Like the whiteflies, to which they are related, they are true






Florida Agricultural Experiment Station


bugs and, therefore, sucking insects, altho very degenerate in
structure. While the whiteflies, like most insects, go thru four
stages during their development-egg, larva, pupa and adult-
this process of development 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 retaining
the larval form. Even in the male the adult life is extremely
brief, lasting for but a day or two, and as they are very small
and inconspicuous, gnat-like creatures, the orange grower seldom
notices them. They have only two wings. Having 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.
Like the whiteflies, scale insects give off honey-dew, but only
the mealy-bugs and some of the soft scales produce it as copi-
ously as the whiteflies. The scale insects damage the trees chiefly
by the withdrawal of large quantities of sap.

THREE KINDS OF SCALE INSECTS
This family of scale insects (Coccidae) is 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, altho 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 larva loses its legs and cannot move about after the scales
are formed, which is at an age of one or two days. 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; successfully ex-
tracted 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 with a
coat of waxy 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, mealy-bugs and their relatives (Dactylo-
pinae), no hard coating is formed but the body is usually covered






Bulletin 148, Insects of a Citrus Grove


with flaked wax which give the larvae a mealy appearance. They
retain their legs thruout life and are capable of moving about.

Armored Scales
LIFE HISTORY
In the armored scale group the eggs are 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 other insects which might otherwise
feed upon or parasitize them, also from insecticides. Immedi-
ately after hatching, the young, called "crawlers," push their
way out and wander about for a few hours seeking a satisfactory
place to attach themselves. Having found it, they insert their
beaks composed of four slender threads, and, in the case of
the female, never move 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, how-
ever, the old scale is retained and incorporated with the new
one where it is usually quite conspicuous. It is situated in the
middle or near 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 difference between the males and females begins
to be noticeable. 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 about a week.
The female is fertilized shortly after the second molt and does
not molt again, altho she continues to increase in size. As a
result of this growth after the second molt, the female scales are
much larger than the male and live longer. The males go thru
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 thru with 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 honey-
dew.
PURPLE SCALE
Lepidosophes beckii (Newm.)
After the whitefly, the purple scale is the most destructive
insect in Florida citrus groves. The mature scale (figs. 90 and






Florida Agricultural Experiment Station


91) is shaped somewhat like an oyster shell. It is purplish-
brown in color and 1/8 inch in length. Unlike the whitefly larva,
it is found on the twigs and fruit as well as on the leaves. How-
ever, it is not abundant on the trunk or larger branches except


Fig. 90.-Purple scale on grapefruit, showing reaction to light.
center was in contact with another fruit


The clear spot in the


on young trees. On the leaves it collects especially along the
midribs and at the base; it is also found on the upper as well as
the lower surface.
Like whiteflies and all other true bugs, scales are sucking in-
sects and withdraw large quantities of sap from the trees. Altho
the effect of scattered individuals is not externally apparent,
they check the growth of the infested part and interfere 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






Bulletin .148, Insects of a Citrus Grove


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 afford
avenues of entry for some 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-
main under the shelter of the parent scale for a day or two and
then spend an equal time 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 shade.
On the other hand, if placed in a room near a window, but not
in direct sunlight, the insect will travel toward the window. The
crawlers avoid both deep shade and direct sunlight 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 favor-
able to the insect. (Fig. 90.) Sooty mold slightly loose so that
the crawlers can get under it, forms favorable retreats, as does
also the wool of the woolly whitefly. Their reaction to gravity


Fig. 91.-Purple scale following woolly whitefly. (From Bul. 123)






Florida Agricultural Experiment Station


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
a position near the apex of the mature scale. 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
development takes place much more slowly, altho in our climate
the process probably seldom wholly ceases.
BROODS
There are in the main, three, generations a year. All stages
may be found in one tree at almost any time of the year, yet
there are three periods when crawlers are more abundant than
at other times. They are in March, or early April, June or July,
and September or October.
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






Bulletin 148, Insects of a Citrus Grove


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 counting by the writer have
shown that the percentage of infestation with the parasitic 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 honey-dew with which it is usually en-
tangled form an ideal refuge for the scales and an old colony of
this whitefly almost invariably shows a heavy infestation of
purple scale.* (Fig. 91.)
As first pointed out by Mr. Others, a heavy coating of dust
has about the same effect as one of sooty mold in protecting the
scales. As a consequence, purple scale is apt to be more in evi-
dence along a well-traveled road than elsewhere in a grove.
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.
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; at least 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 doubtless attended
by as serious consequences as on the leaves, altho they do not
show so prominently.
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.

*For further details see Fla. Ag. Exp. Sta. Bul. 126.






Florida Agricultural Experiment Station


The efforts of the crawlers to avoid strong light cause 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
has shown (Fla. Ag. Exp. Sta. Press Bul. 195) 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
As in the case of citrus whitefly, the most efficient parasites
of the purple scale are entomogenous fungi. They are different
species, however, than those that attack whiteflies. There are
four species that are especially common on the purple scale.
Named in the order of their abundance they are the red-headed
scale-fungus, the white-headed scale-fungus, the black fungus,
and the pink fungus. As in the case of those species which
parasitize the whiteflies, these fungi grow most abundantly dur-
ing the rainy season. Their development is not, however, so
strictly limited to the summer season as is that of the whitefly
infesting species. They often grow well and do efficient work
even in mid-winter but only during a period of considerable
humidity. They do not thrive well during a very dry season.
RED-HEADED SCALE-FUNGUS
Sphaerostilbe coccophila Tul.
The red-headed scale-fungus is the most common fungus on
the purple scale. It appears as little bright red points which push
out from under the edge of the scale and project into the air.
These are the fruiting bodies of the fungus, the portion which
bears the spores. There are two kinds of these fruiting bodies;
the more common kind is sharp pointed while the other has a
knob-like ending and bears a different kind of spores. This is
called the perfect stage. These fruiting bodies are supported
and nourished by a mass of fungus threads which ramify thruout
the body of the scale insect, killing it as well as most of the eggs
that may be present. The spores are scattered over the trees by
wind and rain and also by any insect or bird that may touch the
fruiting bodies. When dropped near another scale they will
sprout if the weather is sufficiently moist and push their way
into the scale.






Bulletin 148, Insects of a Citrus Grove


GRAY-HEADED SCALE-FUNGUS
Ophionectra coccicola E. & E.
This gray-headed scale-fungus is also called the white-headed
scale-fungus, altho the fruiting body, whose color gives the name
to the fungus, is never really white. This fungus always ends in
a knob or head, the whole looking very much like a diminutive
mushroom. It is a very common and beneficial fungus.

BLACK FUNGUS
The black fungus makes a dense black mat over a mass of scale
insects, completely covering them. When the scales are close
together these black mats will coalesce so that this fungus may
cover quite an area. It is more often found on the branches and
twigs than on the leaves.
PREDACEOUS INSECTS
The purple scale is much more commonly preyed upon by other
insects than are the whiteflies. These predators are native in-
sects that before the introduction of the purple scale into Florida
fed upon other scale insects. They have gradually acquired a
taste for the purple scale. Since whiteflies are less closely related
to these native scales, it will take longer for the predaceous in-
sects to develop a taste for them, if they ever do.
LADY-BEETLES
Probably the most efficient predators which feed on scale in-
sects are the lady-beetles. Of these the twice-stabbed lady-beetle
(Chilocorus bivulnerus Muls.) (fig. 92) is by
far the most important. It is very common in
citrus groves where it feeds largely upon the
crawlers, and often on the young scales and
eggs. It tears up the females to get them. Like
most of the lady-beetles this one is nearly round
in outline, almost hemispherical in shape. It I,
is shining coal-black in color with a large red Fig. 92.-Twice-stab-
spot on each wing case, as if it had been stabbed bed lady-beetle (Chi-
locorus bivulnerus).
and blood had oozed out; hence its name. It is Enlarged drawing
about a fifth of an inch in diameter.
The young, like the larvae of all beetles, is an 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 lady-beetles (fig. 138) it is covered with spines. These
are black and compound; that is, the spines themselves are





Florida Agricultural Experiment Station


covered with smaller spines. The body of the larva is bluish-
black. When ready to pupate several of the larvae often climb


.1
Fig. 93.-Pupal cases
of the twice-stabbed
lady-beetle. Slight-
ly enlarged

for aphids and


onto a dead twig and attach themselves in a
cluster to it. (Fig. 93.) Lady-beetles do not
crawl out of the larval skin when they pupate,
but the pupa causes the skin to split length-
wise of the back, exposing the pupa within.
The life history of the beetle occupies about a
month.
Another lady-beetle about an eighth of an
inch long is occasionally found in citrus trees
feeding chiefly on scale insects, altho it has
been seen eating whitefly larvae. The wing
cases are red with two 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 blood-red lady-beetle (fig. 137) and the
convergent lady-beetle (fig. 138) also feed on
scale insects. However, their preference is
they will be described under that heading.


DOWNY DARKLING BEETLE
Epitragus tomentosus
The downy darkling beetle (fig. 94), a brown, oval beetle
which is about five-sixteenths of an inch long, is common in citrus
trees. Altho not at all related to lady-beetles its food habits
are about the same. It is very beneficial in controlling 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 in-
sects to a grove.


LACE-WINGED FLIES
Chrysopa
The larvae of lace-winged flies are among
the important checks to the increase of scale
insects. 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. 94.-Epitragus
tomentosus. Four
times natural size.
(Adapted from Hub-
bard)


194





Bulletin 148, Insects of a Citrus Grove


long slender sickle-shaped jaws on which the insect impales its
victims while it sucks their body fluids. This is done thru a
tube formed by the
secondary jaw
maxillaee) fitting
over a groove in the
true jaws (mandi-
bles). These larvae
are voracious, at-
tacking insects much
larger than them-
selves. Indeed, they
do not hesitate to
jab their jaws into
the skin on the neck
or the back of the Fig. 95.-Lace-wing: Empty cocoons. Four times natural
hand of a person size
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
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 glistening white cocoons about
themselves. (Fig. 95.) Here they remain
for a week or ten days and then the per-
fect insect emerges. This is a beautiful
creature. (Fig. 96.) The most common
species, the golden-eyed lace-wing is a deep
iridescent green with eyes that shine like
drops of liquid gold. The four delicate
gauzy wings when not in use are held up
over the body like a roof. The insect
Fig. 96.-Golden-eyed lace-
wing. Twice natural size measures about 11/4 inches across the ex-
panded 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.
The aphis-lions are parasitized by minute wasp-like insects,






Florida Agricultural Experiment Station


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 lace-wing the wasp-like parasites emerge.
S TRASH BUG
Hemerobius
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 quite similar to an aphis-lion but shorter and wider.
*The trash is largely a collection of scalps; that is, the dry skins
of the victims of the larva.
The food habits, life history, and parasites of this trash bug
are similar to those of the golden-eyed lace-wing. The adult,
however, is brown in color, lacks the golden eyes, and is smaller
than the lace-wing.
PREDACEOUS MITES
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 altho
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 usually a pale flesh-
color but varies from white to yellow. Another is dark red.
Many of these mites feed largely or entirely on the dry ma-
terial of dead scales. Others attack living scales altho probably
none of them are able to get at the growing insect under a healthy
permanent scale; but they devour the first-stage young before
the permanent scale is formed. As the scale insects reach matur-
ity and a large number of eggs are laid, the scale is apt to be-
come 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 undoubt-
edly 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






Bulletin 148, Insects of a Citrus Grove


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
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"
altho they are much smaller than the true wasps and belong to a
different suborder. 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 insect or in the scale's eggs either
by inserting her ovipositor under the scale or boring directly
thru 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. Under average grove conditions the plan as
outlined for the control of whiteflies will control the purple scale
at the same time if carefully carried out. When the grower is
spraying the whitefly fungi into his trees he should add as many
of the scale-destroying fungi previously mentioned as he can
readily obtain. The miscible oil emulsions recommended for






Florida Agricultural Experiment Station


whiteflies are also the very best insecticides known with which
to combat the purple scale. All stages except some of the older
females and the eggs under them will be killed by these oils.
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. In heavily
bearing trees it is sometimes objectionable to spray too fre-
quently with these oil emulsions. This may be avoided by using
whale-oil soap alone for'the second spraying.
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.
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 altho 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-
tiply rapidly. 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 kill the fungi
which attack the trees, the entomogenous fungi are also killed
and as a result the scales increase vastly. (Fig. 97.) 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 a month by an appli-
cation of one of the oil emulsions, in order to forestall the increase
of the scales. At the beginning of the rainy season the ento-
mogenous fungi should be reintroduced unless the grower intends
to apply the bordeaux again.


198






Bulletin 148, Insects of a Citrus Grove


In groves free from whitefly, spraying for purple scale should
be done immediately following the time when, crawlers are most
abundant, which is about the middle of April, mid July, late
October, and the middle of February if the weather has been


Fig. 97.-Increase of purple scale due to spraying the tree with bordeaux mixture: Top
row, sprayed fruit; bottom row, unsprayed fruit

warm. It is seen that the more important of these dates cor-
respond quite closely with those which are preferable for spray-
ing to control whitefly. But, as explained under whitefly, the
April spraying should be postponed until the fruit is an inch in
diameter. This may defer the application until May.

LONG SCALE
Lepidosophes 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,





Florida Agricultural Experiment Station


but straighter and much narrower. These are long scales.
(Fig. 98.) They are closely related to purple scales to which
they bear such a marked resem-
blance that growers do not or-
F dinarily distinguish between
them.
According to Ashmead ("Or-
ange Insects") this scale was
introduced into Florida about
1835 at Mandarin. By 1860,
it had spread ver the orange
districts and had become so de-
structive. that it threatened the
existence of the citrus industry.
Glover, in 1857, stated that it
was entirely free of parasites.
This accounts for its rapid mul-
tiplication. Later,, parasites,
both insects- aqd fungi, ap-
peared and wer finally able to
S-control it better. Some of these
parasites were probably intro-
duced from the original home
Sof the scale, thought to be
southern China, and hitive in-
Ssects gradually developed a
taste for the long scale. As late
as 1885 it was, according to
Hubbard, much more common
than the purple scale, altho now
it is much less common.
Its life history, parasites and
Fig. 98.-Long scale (Lepidosophes gloverii). control are practically identical
Twice natural size with those of the purple scale.
It is a little more nearly con-
fined to the twigs and branches and less to the leaves and fruit
than the purple scale.

FLORIDA RED OR ROUND SCALE, OR NAIL-HEAD SCALE
Chrysomphalus aonidum (L.)
Scale for scale the Florida red scale is the most pernicious of
our citrus scare insects. It does not do as much aggregate






Bulletin 148, Insects of a Citrus Grove


damage as the purple scale because it is not as common, but
when it does become abundant it almost defoliates a tree. It
is less common in the northern part of the citrus belt, probably
because it infests mostly the leaves and fruit and when these are
removed by a freeze its numbers are greatly reduced.
This scale is dark reddish-brown in color, with a conspicuous
light brown center, almost circular in outline (fig. 99), and
about a twelfth of an inch in diameter when full-grown. The
lighter colored center is formed by the cast-off first larval skin
or scale. This is 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 Fig. 99.-Florida red scale
(Chrysomphalus aonidum).
this lobe serves to distinguish readily Twice natural size
a male from a young female.
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. Egg-






Florida Agricultural Experiment Station


laying begins when the females are about ten weeks old and
continues for several weeks.
NATURAL CHECKS
The larvae, and especially the crawlers, are preyed upon by
lady-beetles and aphis-lions and the scale is preyed upon by the
same groups of insects as the purple scale.
Of the fungi which parasitize the purple scale only the red-
headed scale-fungus is found at all common on this scale and
there it is not nearly so efficient as on the purple scale.
Another fungus, however, does better work against this scale.
This is the pink fungus. It was first found in Florida by Prof.
P. H. Rolfs, in December, 1912. It seems to be identical with
one discovered in Formosa by two Japanese botanists, Miwabe
and Sawada, and named Microcera fujikuroi (See Fla. Ag. Exp.
Sta. An. Rep. 1914, p. xlvii). This fungus has doubtless been
in the State for many years but has been confused with the red-
headed scale-fungus which it closely resembles. The red fruiting
body is covered with white hairs, absent in the red-headed
fungus, which give it a pinkish color. The mycelium also spreads
out further from the edge of the infected scale than in the other.
This forms a fringe around the margin of the scale and individual
threads (hypliae) from it reach out for some distance whereby
other scales if within a half inch may be reached and infected.
This fungus parasitizes the purple scale also but less commonly.
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 eggs 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 eggs to hatch, but will not allow sufficient
time for a new generation to mature.
In spraying fungus into a grove which has considerable red
scale, the pink fungus should be added to the others if it can be
obtained.
In addition to citrus, the red scale infests many other plants
including royal,.cocoanut and many other palms, camphor, mag-
nolia, oleander, poinsetta, myrtle, and roses. In spraying to






Bulletin 148, Insects of a Citrus Grove


control this scale any of these plants that may be on the premises
should also receive attention.

MINOR SCALES
CALIFORNIA RED SCALE
Chrysomphalus aurantii (Mask)
The California red scale which is one of the worst pests with
which the California grower has to contend is known to be pres-
ent in about a dozen localities in Florida. It does not seem to
be spreading rapidly nor to be likely to become a serious pest.
It has been in the State many years.
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 thru the semi-transparent scale that
gives this scale the name "red." According to Prof. Rolfs (Fla.
Ag. Exp. Sta. Bul. 117) the red-headed scale-fungus attacks this
scale. This may be the reason why this scale has- never become
such a pest in Florida and in the more humid portions of the
West Indies that it has in California.
The closely related California yellow scale, Chrysomphalus
citrinus (Coq.), has been found in one locality in Florida. -As
its name indicates it is more yellow in color than the California
red scale.
DICTYOSPERMUM SCALE
Chrysomphalus dictyospermum (Morg.)
The dictyospermum scale is intermediate in appearance be-
tween the California red scale and the Florida red scale. It has
been reported from about twenty localities in Florida from Pen-
sacola to Key West. Not much is known about this scale on
citrus here, but it does not seem likely to become a serious pest.
It attacks about forty 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.
WEST INDIAN RED OR RUFOUS'SCALE
Selenaspidus articulatus (Morg.)
The West Indian red scale is, as far as known, found in the
State only at Key West, where it infests the lime. It is flat,






Florida Agricultural Experiment Station


about circular, and pale brown in color. Besides citrus it attacks
oleander, Ficus, and several species of palms. It appears to be.
a rather severe pest in Key West and all reasonable precautions
should be taken to prevent its spread to the other keys and to
the mainland. It is common thruout the West Indies.
SAN JOSE SCALE
Aspidiotus pernicious Comst.
The San Jose scale, a deadly pest of peaches, plums, pears,
and apples, attacks Citrus trifoliata. It has been reported 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 develop about each
scale. When abundant they cover the bark and give the whole
tree their gray color.
The control of this scale on Citrus trifoliata would be best
accomplished by spraying with the red-headed and the black
scale-fungus 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 224.
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 nearly 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.
The adult female under the scale is dark purple, tinged with


204






Bulletin 148, Insects of a Citrus Grove


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 lady-beetles 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 thru a hole in the scale.
The red-headed and the black scale-fungus attack this scale.
The latter does especially efficient work in controlling it.
CONTROL MEASURES
This scale is easily-killed by the oil emulsions, or whale-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 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-





Florida Agricultural Experiment Station


ander. These plants also when growing in an infested grove
should be sprayed.
SNOW SCALE
Chionaspis citri, Comst.
The snow scale gets its name from the white color of the male
scales. 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 dis-
tinguished from those of the chaff scale.
The first larval skin is yellowish in color.
Owing to the inconspicuous color of the
females it is the male scales that make a
colony noticeable.
The scale of the female is dark brown
S R 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. (Fig. 100.) It has a prom-
inent longitudinal ridge which with the
color and situation on the tree, readily digs-
tinguish it from the purple scale. The
first larval skin is brownish-yellow.
Like the chaff scale, this one, too, infests
chiefly the small branches but shows a
preference for the larger branches and
trunks. It may so drain the bark of sap
Sas to cause it to die and split.
Control is the same as for the chaff scale.
Unarmored or Soft Scales
Coccinae
Fig. 100.-Snow scale
(Chionaspis citri) In this group of unarmored or soft
scales, no true scale separate from the
body of the insect is formed, but the skin or body wall of the
insect is hardened by a wax-like secretion which is either in-
corporated 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
form. At this time the legs are covered and made useless by
the swelling of the body as the eggs form.






Bulletin 148, Insects of a Citrus Grove


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 honey-dew abundantly. In it
the sooty mold grows so that an infested plant soon becomes
blackened. This honey-dew is greatly relished by ants which
are seen constantly about the scales.
The soft scales are not nearly so destructive as the armored
ones. They are highly parasitized so that the colonies soon dis-
appear. They seldom seriously injure a mature tree, but on
nursery stock and on trees recently set out the 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.
TURTLE-BACK OR SOFT BROWN
SCALE
Coccus hesperidum (L.)
In this species and the next
described, the wax is incorpo-
rated with the skin which be-
comes tough and parchment-like,
resembling in appearance the
covering of the armored scales.
(Fig. 101.) These scales are
larger than the armored scales
and thicker. 19
The full-grown female of the a
turtle-back scale is between an
eighth and a sixth of an inch
long, oval in outline and dark
brown in color. It is much swol-
Fig. 101.-Turtle-back scale. (From U. S.
len in the center but flat at the D. A.)






Florida Agricultural Experiment Station


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
thru 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.
As the larva grows the antennae disappear and as the eggs
begin to form the legs also disappear. The young larvae 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.
NATURAL CHECKS
This scale is attacked by at least a half dozen different
species of wasp-like internal parasites which keep it under fair
control. These parasitized scales turn jet black.
The early stages are easily killed by the oil emulsions and in
groves regularly sprayed with them for whiteflies and purple
scale the turtle-back 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 freely
attacked.
HEMISPHERICAL SCALE
Saissetia hemispherica (Targ.)
The hemispherical scale is similar in size, color, and shape
to the turtle-back; but its center is more swollen and the margin
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 yellowish-
white.
This scale infests guava, avocado, asparagus, japonica, Ficus,
peach, rose, palms, and many other plants. Natural and arti-
ficial control are the same as for the turtle-back scale.






Bulletin 148, Insects of a Citrus Grove


BLACK SCALE
Saissetia oleae (Bern.)
The black scale (fig. 102), the most destructive scale insect
in southern California, has been found in a dozen widely sepa-
rated localities in Florida. Here it is more common on oleander
than on citrus, which it rarely attacks. It is also quite injurious
to citrus in some of the West Indies. In fact, 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
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
honey-dew 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.
WAX SCALES
Ceroplastes
eropstes Fig. 102.-Black scale.
The wax scales are soft scales which se- (Frm QBoarte Bul. 1Stat
Plant Board, Vol. II, No.
create a thick layer of white wax which 1)
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
honey-dew. Even a moderate infestation suffices to blacken
thoroly the host plant.
There are three of these wax scales which are likely to be
found on citrus trees in Florida, but only the first is common.
FLORIDA WAX SCALE
Ceroplastes floridensis Comst.
The Florida wax scale when not stained by sooty mold or





Florida Agricultural Experiment Station


other foreign matter is snow-white, often with a pinkish shade
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. 103.) 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.
The eggs are dark red
and about a hundredth of
an inch long.. They aver-
age in number between 75
and 100 for each scale and
Share placed under the female
S 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.
SThe young larvae are star-
Fig. 103.-Florida wax-scale. (From Quarterlyd and even more beau-
Bul. State Plant Board, Vol. II, No. 1) tiful than the adults. Three
or four months are required
for growth and there are three principal broods of 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





Bulletin 148, Insects of a Citrus Grove


stems of Citrus trifoliata it can retain its hold much better and
sometimes becomes more of a pest. The native food plant of
this insect is chiefly the gallberry (Ilex glabra) of the flatwoods
which is commonly blackened by the sooty mold growing in the
honey-dew given off by the insect. The mature females do not
fall off the gallberry.
The Florida wax scale is parasitized by several wasp-like
insects whose grubs live inside the scale. The scale-eating cater-
pillar, Laetilia coccidivora, (see mealy-bugs) sometimes destroys
this scale.
HOST PLANTS
Besides citrus and gallberry, this scale attacks avocados,
guavas, cherry laurel, sea grape, Ficus, loquat, mango and many
others. The writer has even seen it on sweet potato vines.
CONTROL
Should it become necessary to spray for this scale the oil
emulsions will probably be found perfectly satisfactory.
BARNACLE SCALE
Ceroplastes cirripediformis Comst. -4 .
The Barnacle scale is closely related to the last
named which it resembles in appearance and life -
history. Its most conspicuous difference is in its
height which is about equal to its width. (Fig.
104.) The waxy coat is dirty-white in color
mottled with brown and is divided into distinct
plates. These plates give the scales a hard limy
appearance, and the angular outline which it
shares with the Florida wax scale, suggests a
barnacle in appearance, hence the name. It is
larger than the Florida wax scale, being a fifth
of an inch long and a sixth wide. It is a native
scale, found thruout 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) ali. 10-Barnacle
scale. (From Quar-
The Japanese or Mexican wax scale has been 'terly Bul. State
Plant Board, Vol.
found in three localities in Florida, growing on n. No. )






Florida Agricultural Experiment Station


wild persimmon and 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 thru the wax.
PYRIFORM SCALE
Pulvinaria pyriformis (Ckll.)
The pyriform scale (fig. 105) is found on many plants, in-
cluding citrus, guava, mango, ivy, and many ornamentals. It
frequently becomes very abundant on avocados which it blackens
thoroly with the sooty mold which grows in its honey-dew.
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,
greenish-yellow and without
any signs of cotton.
This scale is easily killed
by contact insecticides, as
the oil emulsions, soap solu-
tion, kerosene emulsion, etc.

MEALY SHIELD SCALE
Pulvinaria psidii Mask.
In Florida the mealy shield
scale, which has been in the
State but a few years, has
attacked chiefly the wild rub-
ber tree, the guava, the man-
Fig. 105.-Pyriform scale (Pulvinaria py-
riformis) on guava leaf go, the sea grape, and the





Bulletin 148, Insects of a Citrus Grove


avocado in about the order named. Only occasionally has it
been taken from citrus, altho it is said to be the worst pest citrus
has in southeastern Asia.
The adult female forms cotton even more abundantly than its
related species, the pyriform scale. The mass finally becomes
many times larger than the scale proper, which is about the


Fig. 106.-Mealy shield scale (Pulvinaria psidii) on mango leaf


size of the pyriform scale but more oval in outline, and lighter
in color. (Fig. 106.) It is greenish-brown. This scale is now
widely distributed in south Florida.

Mealy-Bugs
Dactylopinae
Mealy-bugs 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 thruout 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 quickly killing a tree.
Fortunately, in Florida they are usually well controlled by those
natural checks. They give off large amounts of honey-dew in


213






Florida Agricultural Experiment Station


which a particularly heavy growth of sooty mold develops, black-
ening the whole colony and all surrounding vegetation.

CITRUS MEALY-BUG
Pseudococcus citri (Risso.)
The citrus mealy-bug is common over the entire State and
is frequently in evidence in a citrus grove, especially during the


Fig. 107.-Citrus mealy-bug; infestation on grapefruit


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. The
mealy-bugs often collect around the stem end of a fruit. A
specially favored place is the sheltered nook formed by two or
more fruits in contact. This is more frequently the case with
grapefruit than with other citrus, consequently mealy-bugs are
rather more troublesome to grapefruit. Grapefruit become


214





Bulletin 148, Insects of a Citrus Grove


blackened with a particularly copious
and sticky honey-dew which, with the
sooty-mold (fig. 107) 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, I
with brown legs and antennae. (Fig. Fig. 108.-A mealy-bug. (From
Farmers' Bul. 49)
108.) The male is small, light colored, Farmers' u 49)
and has two long white threads of wax projecting backward.
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
Mealy-bugs are eaten by several other insects which may
usually be depended on to control them fairly well. Among such
predators are the lady-beetles and their larvae, the larvae of
lace-winged flies, trash bugs, and syrphus-fly larvae, and the
scale-eating caterpillar, Liaetilia cocidivora. The latter is a dark
caterpillar a half inch in length. It makes covered passageways
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.
The torrential rains of summer usually check an infestation
of mealy-bugs. The young are knocked off the trees and often
are killed by the rain.
Ants carry mealy-bugs from tree to tree and to some extent
interfere with the insects that would otherwise feed upon them.
CONTROL
Spraying is the best means of reducing the numbers. It is
important to have good pressure to force the liquid into corners
and crevices, which will also 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 miscible


215






Florida Agricultural Experiment Station


oils which are recommended for whitefly, or whale-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
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 thoroly. However, unless one has
a good agitator he should not try this, as burning may result
from indifferent mixing. A spray that is recommended in Cali-
fornia is made by dissolving 2 1/3 pints of crude carbolic acid
and 2 1/3 pounds of whale oil soap in hot water, and diluting
to make 50 gallons of spray. If the first spraying does not result
in satisfactory control, it may be repeated after three or four
weeks.
Mealy-bugs 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, croton, oleander, royal palm
(roots), and lantana. Mealy-bugs commonly infest seed po-
tatoes which are kept over summer for fall planting.
;: LONG-TAILED MEALY-BUG
: Pseudococcus longispinus (Targ.)
The long-tailed mealy-bug is much less common than the last
described, but is occasionally seen on citrus as well as the avo-
cado, mango, bamboo, oleander, coleus and croton. It is some-
what smaller than the citrus mealy-bug 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.
The work, life history, and control of the long-tailed mealy-bug
are the same as those of the citrus mealy-bug.
COTTONY CUSHION SCALE.
Icerya purchase Mask.
This notorious pest of citrus, the cottony cushion scale whose
native home is Australia, was introduced into Florida from
California in 1897. It was carried to California in 1868 and a
dozen years later had reached the citrus sections where it was






Bulletin 148, Insects of a Citrus Grove


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 Australian lady-beetle, Novius (Ve-
dalia) cardinalis, was found preying on the scale and was intro-
duced into California in 1889. It increased rapidly and soon
had the scale under control.
While this mealy-bug has never been as serious a menace here
as in California it caused much trouble un-
til, thru the efforts of the Experiment
Station, the Australian lady-beetle was
brought here also. The experience in Cali-
fornia was repeated here. The Vedalia
never exterminates the scale from a grove
but always keeps it under 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. Its area of distribution now
extends from Key West to Gainesville (to
which place it was carried on contraband
nursery stock), altho not all intervening
sections have it.
APPEARANCE
The cottony cushion scale (fig. 109) 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 Fig. 109.-Larvae of the
lengthwise. Because of these longitudinal Australian lady-beetle or
edalaridges this scale is also called "the flutedthe
ridges this scale is also called "the fluted cottony cushion scale






Florida Agricultural Experiment Station


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 midrib. 'The young look much like those
of the mealy-bug, but when crushed they leave a red stain. Both
young and old have the mealy-bug habit of hiding in the crevices
and forks of twigs.
Besides citrus, the insects are partial to roses. The careless
shipping of cuttings about the State is probably responsible for
the rapid spread of the insect. It is abundant also on wormwood,
myrtle, mulberry, weeds and ornamentals. In the Annual Report
of the Florida Agricultural Experiment Station for 1915, page
lxxiv, 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 mealy-bugs,
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 mealy-bug. 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 has been prepared and
placed on the market especially for use against this insect. As
in the case of mealy-bugs, high pressure is an important con-
sideration. On a few dooryard trees a frequent washing with a
strong soap solution may be effective.
AUSTRALIAN LADY-BEETLE
The only, permanent and satisfactory method of controlling
this scale in a large grove is by the introduction of the Australian
lady-beetle, Novias (Vedalia) cardinalis (fig. 110). This is much
smaller than most of our native lady-beetles, being only one-
eighth inch long. It is of a cardinal-red color, spotted and
fringed with black. The larva (fig. 109) which also feeds on the
scale, is likewise red.
SThe female lady-beetle lays between 150 and 200 eggs. These
are orange-red in color and are most commonly laid in the cot-
tony sack of the female scale. They hatch in five or six days





Bulletin 148, Insects of a Citrus Grove


Fig. 110.-Australian
lady-beetle (Novius
cardinalis). En-
larged drawing
cottony cushion


and 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 and another week is spent in the pu-
pal stage. These pupae are scattered singly
about among the scales and are found most
frequently on the leaves. (Fig. 111.)
It is to be noted that a generation of the
Vedalia requires but a month while that of the
scale requires at least three. This explains the


ability of the lady-beetles to clean up an infestation so quickly.
This is usually accomplished in three or four months after the
introduction of the beetles.
Vedalia lives only on cottony cushion scale or on each other
if the scale becomes scarce. Therefore, when the supply of scale
in a grove runs low, the Vedalia may die out. After the disap-
pearance of the bee-
tles, the scale may
again multiply in the
grove. It may then be
necessary to reintro-
duce the Vedalia altho
experience in Florida
has shown thlis to be
seldom necessary. As
soon as the scale again
becomes abundant, the
beetles almost invari-
ably reappear, prob-
ably flying from ad-
joining groves. Some
observations of the
writer show that the
Vedalia has found a
colony of the cottony
cushion scale at least
two miles from the
grove where the bee-
tles hatched. (Fla. Ag.
Exp. Sta. Ann. Rep. Fig. 111.-Pupae of the Australian lady-beetle. Twice
1915, p. lxxv.) natural size






Florida Agricultural Experiment Station


Vedalias are being supplied to the growers at the cost of col-
lection, by the State Plant Board, Gainesville.
Our native twice-stabbed lady-beetle (fig. 92) does good work
against this as well as other scales, but it cannot be depended
upon to control the scale as well as the Vedalia. Trash bugs and
the scale-eating caterpillar have also been seen to feed upon
this scale.
RUST MITE
Eriophes oleivorus, Ash.
Next to the citrus whitefly and the purple scale the rust mite
is the most expensive guest the citrus grower entertains. It is a
sucking animal which extracts the oils from both leaves and
fruit, altho its work on the fruit attracts more attention. As a
result of this injury the rind turns a russet brown and fails
to develop normally. The rind of a russeted orange is tough and
leathery and much thinner than that of a bright fruit from the
same tree. This alone results in reducing the size of the fruit
and hence more are required to fill a box. The fruit fails to
develop properly, especially if injured early in the season, re-
sulting in a further reduction in size, and as oranges are com-
monly sold by the box, the grower loses money on small fruit.
Also a small fruit that would otherwise be marketable becomes a
cull when its size is further reduced by the mites. Altho the
quality of the interior of the fruit is not damaged and russeted
oranges are as palatable as bright ones, the market demands a
bright fruit and russets uniformly bring a lower price. The
opinion prevails in many quarters that russeted oranges are
even sweeter than bright ones. This is perhaps due entirely to
the fact that russeted fruit is not as apt to be marketed before
it is ripe.
The rust mite then attacks the pocket-book of the grower from
four directions:
1. By withdrawing oil and other juices from the leaves and
fruit it interferes with their normal growth and functions;
2. By detracting from the appearance of the fruit and low-
ering its price;
3. By reducing the size so that it requires more to fill a
box, and increasing the number of culls;
4. By delaying the coloring of the fruit so that it cannot be
marketed early.
Altho they do not show it so plainly, the leaves are really in-






Bulletin 148, Insects of a Citrus Grove


jured fully as much if not more than the fruit. Severely infested
leaves lose their shining appearance and take on a dry look.
Infested grapefruit sometimes develop a grayish leathery-
looking skin called "buckskin." This in its origin is perhaps
not due entirely to the rust mite. Other factors, possibly a fun-
gus, may contribute to its development. However, if the rust
mite is controlled in a grove, "buckskinning" disappears which
shows that the mites are necessary for its development.
APPEARANCE
The rust mite (fig. 112) is very small, scarcely visible to one
with the best of eyesight, but when present in large numbers is
easily recognized by one familiar with
it by the dusty or powdery appearance
of the fruit and leaves.
The mite is light yellow and wedge- /
shaped. It is broadest in front and ta-
pers uniformly to the posterior end
where there are two small lobes, false 0
feet which the insect uses as an aid in
clinging and crawling. It has four short
weak legs by means of which it creeps
slowly over the leaves and fruit. When
full-grown it is 1/200 of an inch long. d
The young are a little paler in color
than the adults and shorter in propor- Fig. 112.-Orange rust-mite: a,
n to teir l h dorsal view; b, lateral view-
tion to their length. enlarged, the dot in circle in-
dicating natural size; c, leg:
LIFE HISTORY d, egg, with embryo just about
The eggs are large for the size of the ready to hatch-more en-
larged. (After Hubbard)
adult female and consequently few in
number. They hatch in four or five days in summer but during
the colder days.of winter may require two weeks or more.
A week or ten days after hatching the mites molt, first resting
for a couple of days. The white skin is left clinging to the leaf
or fruit where it contributes to the dusty or mealy appearance.
Shortly after the molt egg-laying begins so that an entire gen-
eration may develop in a fortnight. This rapid development
enables the mites to multiply enormously in a short time if
weather conditions are favorable.
The mites move about considerably. As they exhaust the oil
from one cell they move to the next. On a smooth surface,
such as an orange leaf, they can cover ten or twelve feet an hour.






Florida Agricultural Experiment Station


In addition to traveling by their own exertions, rust mites are
often carried about by other animals. They are so small that
they can be readily transported by almost any insect as well as
by birds and man. Doubtless many are carried about by other
spiders. Such spiders as the gossamers that spin a frail web
and sail away on it with the wind may carry many rust mites
with them. Rust mites avoid both direct sunlight and dense
shade. As a result, the shaded half of an orange growing in an
exposed situation is often russeted while the part exposed to the
sunlight remains bright. On the other hand, an orange growing
in a shaded place may be russeted on the exposed side and re-
main bright on the other. Sometimes a ring of rust is formed
around the fruit where the intensity of the light is most satis-
factory to the mites. Perhaps as a result of the aversion mites
have for dense shade, fruit grown in a low hammock where the
trees are frequently more or less shaded by other trees are less
liable to attack than fruit grown on the higher, more open lands.
NATURAL CONTROL
Mites multiply most rapidly during dry weather, probably
because heavy dashing rains wash them off the trees in the rainy
season. So it is during dry weather or immediately following
drouths that an especially vigilant watch should be kept for
rust mites. The months of June and November are perhaps, if
a number of years be averaged, most likely to bring a heavy
infestation. But the mites are liable to cause damage during
any month of the year. Mr. W. W. Others has recently shown
(The Florida Buggist, Vol. 1, No. 3) that a sudden severe cold
spell is very fatal to mites, not only the adults and young being
killed but the eggs also are destroyed. The mites do not seem
to be parasitized to any extent. A number of predators feed on
rust mites, syrphus-flies being among the most important. How-
ever, they cannot be depended upon to control the mites.
SPRAYING
The efficient control of rust mites calls for constant vigilance.
Because of their size they are difficult to detect even by one with
good eyesight. The citrus grower should provide himself with
a good hand lens that will magnify fifteen or twenty diameters,
and carry this constantly in the grove. With this he should
examine his fruit every few days, especially any tree that has
a dry, dusty or powdery appearance. Old fruit hanging to the
tree, such as the "June bloom" of the previous year, is most likely


222






Bulletin 148, Insects of a Citrus Grove


to be infested and should receive special attention. If spraying
be delayed until the rust appears on the fruit it will be too
late,-as enough damage will have been done to prevent the fruit
from being graded as "brights." Fruit once russeted will never
be bright again altho the rust may become a little less noticeable
as the fruit colors up. The grower who has permitted his fruit
to become russeted can, and of course, should, prevent further
damage by promptly spraying, provided the mites are still
present.
The only way to be sure of having bright fruit is to watch
it constantly and as soon as the rust mites are noticed apply the
spray. The grower should have his spraying machine always
in working order and a supply of insecticides always at hand so
there will be no delay when the mites are first noticed.
Because of the difficulty of seeing the rust mites, and the
rapidity with which they multiply, some growers make a prac-
tice of spraying their trees every month or more often as a
precautionary measure. Altho this practice is undoubtedly pref-
erable to neglect or carelessness in respect to rust mites, it will
lead to unnecessary expense in spraying. It may be justifiable
when necessary to leave the grove in the hands of a foreman
who is incompetent to notice the first signs of increase in the
number of mites.
SULPHUR THE BEST INSECTICIDE
Like all members of the spider class, rust mites are very
sensitive to sulphur. Sulphur does not kill the eggs but, as it
remains active on the trees for many days, it kills the young
mites as they hatch. It is not necessary that the mite be actually
hit by the sulphur; the sulphur slowly oxidizes on the tree and
will kill all mites within a radius of a small fraction of an inch.
It is thus a sort of fumigation process.
One may use either free sulphur, or some of its compounds,
applying it dry, or in the form of a spray. Free sulphur is one
of the best remedies against red spiders, or mites. It is some-
what slower in its action than some compounds of sulphur, often
taking two or three days or more to do its work, but it remains
active for a long time, frequently two or three weeks, and usually
kills the mites. Sulphur can be applied dry, and be driven into
the citrus tree by means of a blower or duster.
It is usually better to mix 3 parts of dry sulphur with 1 part
of hydrated lime. The lime can be bought or made by adding
32 pounds (4 gallons) of water to every 100 pounds of quicklime.


223






Florida Agricultural Experiment Station


Mix the hydrated lime and sulphur thoroly. Best results will
be obtained by applying the dust at night or in the early morn-
ing when the plants are wet with dew, as the dust adheres better
at that time. It works better when the nights are moist and
the days bright and sunny, as under these conditions the de-
composition of the sulphur takes place more rapidly.
As a spray, from 1 to 5 pounds to 50 gallons of water can be
used. It will spread and wet the plants much better if 3 or 4
pounds of soap are added.
SULPHUR COMPOUNDS
Of the compounds of sulphur, lime-sulphur is one of the best
for use in the citrus grove. Use about 1 gallon to 70 or 75 gal-
lons of water. The grower can make his own lime-sulphur by
boiling lime and sulphur together over a fire, but this does not
ordinarily produce as good a compound as the commercial prod-
uct which is made in large quantities and boiled with live steam.
There are several insecticide houses making the substance in
the State and at some of the packing houses of the Citrus Ex-
change it is being made cooperatively, chiefly for members of the
local sub-exchange, but some is sold. This reduces the cost ap-
preciably as lime-sulphur is rather bulky and the freight becomes
a considerable proportion of the cost on long hauls. The product
is liable to vary considerably in its strength and should be tested
with a Baume hydrometer before being used. The hydrometer
costs but a dollar or two and with care should last for years.
If the product tests 32 degrees, which is standard, 1 gallon to
70 of water is sufficient. If the reading is lower more should
be used. The following table gives the number of gallons of
water to use with a gallon of the lime-sulphur at any degree of
concentration likely to be encountered. For convenient refer-
ence there has also been included the amount to use as a winter
wash to kill San Jose scale on either trifoliata or peaches or
plums and also the amount to use as a fungicide on citrus during
the summer.
TABLE 50.-Dilution Table for Lime-Sulphur Solution
Baume Number of gallons of water to one gallon of lime-sulphur
reading | For a winter wash | As a fungicide I For rust mite
36 9Ya 34 82
35 9 331/4 79
34 8% 32 76
33 81/ 31 73
32 8 30 70
31 7 29 67







Bulletin 148, Insects of a Citrus Grove


Table 50.-Continued.

| Number of gallons of water to one gallon of lime-sulphur


Baume
reading
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15


As a fungicide
28
27
26
241/2
231/2
221/
21
19
181/
17V2
17
16
151/4
14
13%
12%


For rust mite
64
61
57%
54%
51
48/2
45%
42
39 2/3
36%
34
31%
29%
27%
25%
24


Aside from its insecticidal value, lime-sulphur seems to act
as a stimulant to the fruit, increasing its size and causing it to
ripen earlier.
The oil emulsions also kill all rust mites struck, but do not
harm those which only get close to it, as does the lime-sulphur.
A commercial product, "soluble sulphur" or soda-sulphur, is
sometimes added to the oil emulsions to make them more effective
against rust mite. Either of these compounds is often used alone
in place of the lime-sulphur.
The soda-sulphur stock solution is:
Flowers of sulphur.................. ....-........ 30 pounds
Caustic soda .................... ..---.....--20 pounds
W ater ................. ........................... 20 gallons
This should test about 16 degrees Baume. When ready to"
use take 1 part of the solution to 40 of water. When used alone
it is not as effective as the lime-sulphur solution.

RED SPIDERS
Tetranychus

Two species of spider mites infest citrus in Florida. One, the
six-spotted mite, is pale grayish-yellow with six dark spots ar-
ranged in two rows on the back. Some growers restrict the
name "red spider" to this species. Others use it, as here, to
include both species.
Both are sucking pests which withdraw sap from the leaves
and, like the rust mite, are most troublesome in dry weather.
They are preyed upon by many insects and larger spiders. Both
the larvae and the adults of lady-beetles and the larvae of lace-


I For a winter wash
714
7
62
614
6
52
51/4
5
4%
4%
4
3%
3%1
31/
3
2%






Florida Agricultural Experiment Station


winged flies feed upon them altho they prefer other food, espe-
cially aphids. Aleurodothrips also feed upon them.
Control in each case is the same as for the rust mite.
SIX-SPOTTED MITE
T. sexmaculatus Riley
The six-spotted mites attack the under side of the leaves
where they spin thin, tent-like webs under which they stay. As
a result of their sucking the leaves turn yellow in the spots under
the web. These spots increase in size as more sap is withdrawn
until finally the whole leaf becomes yellow, curls, and falls. If
many of the leaves are lost the fruit also falls from the devitalized
trees and the financial loss occasioned thereby is direct and se-
vere. The young show few or none of the spots which are char-
acteristic of the adults.
PURPLE MITE
T. citri, McGregor
The purple mite which is much less destructive than the six-
spotted mite, is found on both sides of the leaves and on the fruit.
The affected parts take on a gray, dry appearance, quite different
from the yellow spots caused by the six-spotted mite.
The reddish-yellow eggs, besides being glued to the leaves, are
held by a series of silken threads arranged in a peculiar and
characteristic fashion. A silken stalk arises perpendicularly
from the upper side of the egg and to the top of this stalk are
fastened fourteen threads of silk which run out in as many di-
rections, like guy ropes of a derrick, and are fastened to the
surface of the leaf.
The eggs hatch in a week or two and the young require about
twelve days for growth. During this period they molt three
times. The very young larvae have, like insects, six legs, but
after the first molt there are eight, the typical number of the
spider class. The female lives for about a month after becoming
an adult, during which time she lays from thirty to seventy-five
eggs.
FLORIDA FLOWER THRIPS
Frankliniella bispinosus projects Watson

The Florida flower thrips (fig. 113) is a minute, soft-bodied
insect about a twenty-fifth of an inch long and is very common
in all flowers including citrus blossoms. Its color varies from
yellow to orange. The abdomen is commonly lighter colored than






Bulletin 148, Insects of a Citrus Grove


the thorax. When the insect is disturbed it curls its abdomen
up over its back as if ready to sting. The insect is harmless,
altho on the tenderer parts of the skin it is capable of causing
some slight pain with its mouth parts. Under a lens it is seen
to have brownish-red eyes and eight-jointed antennae. There




















Fig. 113.-Florida flower thrips: Adult female. Highly magnified. (Drawing by Dozier)

are four wings. These are thin and membraneous and fringed
with relatively long hairs. The young are very similar to the
adults but lack the wings, and are lighter in color.
CHARACTER AND EXTENT OF DAMAGE
Thrips may inflict two types of damage to the crop: (1)
Shorten the crop by causing an excessive dropping of the bloom
and young fruit, and (2) lower the grade of the fruit by scarring
it and making it unattractive in appearance.
Thrips are sucking insects but their punctures are shallow,
very numerous, and close together so that the attacked tissue has
the appearance of having been rasped away. The area attacked
loses its color and becomes sunken.
In the orange and grapefruit bloom the favorite feeding place
is on the inside of the cylindrical column of stamens. Next, the
succulent petals are chosen. A limited amount of feeding on
these evanescent organs probably does little harm, but if the
insects are abundant the tissue of the receptacle about the base






Florida Agricultural Experiment Station


of the ovary is attacked, and then the ovary itself. It is in the
receptacle also that most of the eggs are laid and here the larvae
can often be found feeding after both stamens and petals have
fallen and most of the adult insects have flown to more inviting
fields. If sufficiently injured, this receptacle turns yellow and
finally causes the bloom to drop.
As the orange tree generally produces an abundant bloom,
much of which will necessarily drop, there has been doubt ex-
pressed as to the actual amount of damage the insects do in a
grove. Some investigators have stated that thrips on the whole
are beneficial in a grove in that they carry pollen from one
blossom to another and cause some of the excess fruit to fall,
fruit which would be dropped later by the tree if no thrips were
present; in other words that the thrips perform the function
of thinning out the excess fruit and save to the tree the vitality
that would otherwise be wasted in carrying this fruit for a few
days or weeks. It is quite probable that on trees which have a
heavy bloom and a moderate number of thrips, or even a heavy
infestation of thrips, if the bloom also is very heavy, thrips do
little or no harm and may even be beneficial. The writer has
observed that many groves set a big crop of fruit in spite of a
moderately heavy infestation of thrips. However, our experi-
ments show that if the bloom is moderate or scanty and thrips
unusually abundant they may seriously shorten the crop. On
some trees this reduction was as great as two-thirds.
THRIPS MARKS ON THE FRUIT
The feeding of the thrips on the ovary of the blossoms or the
young fruit causes smooth, brownish, sunken areas in the shape
of streaks and blotches, and often circles about the fruit. (Fig.
114.) These sunken areas have a thinner skin than the remain-
der of the fruit and are more liable to attacks of fungi and
insects, such as the pumpkin bug, than is the healthy skin. This
damage is usually done when the fruit is less than three weeks
old. It is mostly the work of the young thrips that hatch out
in the receptacle at the base of the fruit after the petals and
stamens have fallen. These young crawl onto the fruit and feed
there until they acquire wings, when they fly away. Few adults
are ever found on the fruit after the petals and stamens have
fallen.
In one grove in which a rather careful estimate was made
twenty-three percent of the fruit was sufficiently scarred to
lower its grade in the hands of a careful grader, and four percent






Bulletin 148, Insects of a Citrus Grove


was counted as culls. This is the greatest amount of damage
noted. It will usually not exceed five to ten percent of the fruit
even in a grove where thrips have been abundant.
LIFE HISTORY
The eggs are laid mostly in the enlargement of the stem (re-
ceptacle) at the base of the blossom. They are placed just under


Fig. 114.-Thrips marks on grapefruit


the epidermis in a shallow slit made by the saw-like ovipositor
of the female. They hatch in two to four days, three days being
the average time required. The larval stage is of ten to twenty-
four days' duration, averaging fifteen days. The last two days
are spent as pupae. Altho capable of moving during this stage
the insect feeds virtually not at all. The wings show as short
pads on the back. The adult female begins to lay eggs freely
when about five days old. It is seen that the entire life history
thus requires about twenty-three days. This is true only during
5


229






Florida Agricultural Experiment Station


the warmer part of the year. During the winter, development is
much slower and reproduction ceases altogether in the coldest
weather. While some breeding usually goes on in every winter
month it is limited to the warmer periods. During the coldest
weather thrips lie inactive in the depths of flowers. There are
probably a dozen generations in the course of a year.
In breeding cages the adults have lived for eight weeks in
winter and for four weeks in March. Out of doors, under natural
conditions, they may probably live longer.
NATURAL CONTROL
Apparently, very few insects or other animals feed upon
thrips; their very insignificance protects them. Neither do they
seem to be much parasitized by entomogenous fungi.
Inclement weather is by all odds the most efficient agency in
checking multiplication. A heavy dashing rain has frequently
been observed to nearly exterminate them, only a small fraction
of one percent surviving. The rain knocks them from the flowers
and pounds them to death on the ground.
SPRAYING
As previously stated our present information would indicate
that thrips are usually substantially harmless or are only a minor
pest of citrus. Only when abundant, at least a dozen per blossom
as an average, will it pay to spray for them. Yet the past three
seasons' work of the Station would indicate rather clearly that
in case of a heavy infestation of thrips, even in a grove with
abundant bloom, spraying even once will increase the amount
of fruit set from three to eight percent. On a few trees with
scanty bloom and abundant thrips it has increased the amount
three hundred percent. On the average the proportion of scarred
fruit was reduced about fifty percent by one spraying.
The first spraying should be given when the trees are in full
bloom and the nozzle should be pointed straight into the blos-
soms. Some dropping will result from this spraying but it will
consist entirely of fruits that would have dropped later if no
spraying had been done. A week or ten days afterward, if there
are still many thrips in the later bloom or on the young fruit, a
second spraying may be given.
In view of the effect of dashing rains on thrips, the importance
of using strong pressure is evident. Indeed, water alone does
much good if driven at a pressure of at least 200 pounds. How-
ever, to do effective work an insecticide is necessary. Tobacco is






Bulletin 148, Insects of a Citrus Grove


very efficient and a little soap or lime-sulphur to give it body
increases the effectiveness of the spray. The following, first used
against a closely related thrips in the orange groves of Califor-
nia, has given the best results in Florida:
Commercial lime-sulphur solution, 32 degrees Baume......:...........2 2/3 quarts
Black Leaf 40.......................................------ ..... .......................... 31% ounces
W ater........................................ ........................................................... 50 gallons
Some growers spray lime-sulphur into the bloom to control
scab, using it at a strength of 1 part to about 40 of water. In
that case it is necessary only to add the 31/2 ounces of black
leaf 40 to the lime-sulphur solution. Some growers have re-
ported damage from the use of lime-sulphur at this strength.
LARGE PLANT-BUGS
There are a number of large plant-bugs which attack almost
any succulent plant and at times become very annoying pests.
On citrus they inflict two kinds of injury. They suck the sap
from the young and tender twigs, often causing them to wilt and
finally die. It is only on young trees that this type of injury
is worthy of attention. A habit fraught with much more danger
to the financial interests of the grower is that of attacking the
ripening fruit in the fall. From this the bugs sometimes extract
so much juice that the fruit drops. Sometimes as much as half
of the crop is lost in this manner. Even if the fruit clings to the
tree the punctures made by the bugs give to fungi and other
organisms that cause decay an avenue of entry into the fruit.
Naturally those varieties of citrus that have thin skins suffer
most. Tangerines, including satsumas, are the first choice of
the bugs, and oranges second. Grapefruit is not much troubled.
GREEN SOLDIER BUG OR PUMPKIN BUG
Nezara viridula Linn.
The pumpkin bug or green soldier bug is by far the most
common and destructive of the large plant-bugs. It breeds
particularly on such legumes as cowpeas and beggar-weed and
when these are grown as a summer cover crop in the groves and
allowed to stand too long,, the bugs may attack the fruit. The
color of this bug is usually bright green, but some of the bugs,,
especially hibernating ones, are dark olive-green or pinkish in
color. The females are a little more than a half inch long and
slightly more than half as wide, being broadly oval in outline.
(Fig. 115.) The males are a little shorter and considerably
narrower, on the average.






Florida Agricultural Experiment Station


The young are quite different in appearance from the adults.
They are bluish with some red markings and are more nearly
circular in outline. Like all members of the "stink bug" family,
to which they belong,
pumpkin bugs give off
a strong, disagreeable
odor.
LIFE HISTORY
The eggs of the
pumpkin bug are laid in
clusters on the food
plant. They hatch in
about a week. The
young feed together in
groups or colonies for
some time after hatch-
Fig. 115.-Green soldier bugs (Nezara viridula). Nat-
ural size ing. They probably re-
quire about two months
to complete their growth, molting four times. With a fifth molt
they become adult with wings and reproductive organs fully
developed. The adults live for several weeks; the last generation
in the fall lives for several months. No breeding takes place dur-
ing the winter, at least in most of the State. At Gainesville hi-
bernation is only partial. Altho many may be found under the
bark of logs, in Spanish moss, and other sheltered places where
they apparently remain until the return of warm weather, others,
in constantly decreasing numbers, remain on juicy plants and are
more or less active and feed all winter. They are abundant in
October, plentiful in November, common in December but rather
scarce in January and February. In March and April they again
become more common due to many bugs coming out of hiberna-
tion. In April and May young appear.
In spite of the bad smell birds occasionally eat these bugs.
They are also attacked by other bugs, one of the most important
of which is Euthrynchus floridensis. Probably the most efficient
check on their increase are tachinid flies whose larvae live as
parasites inside of the bugs.
CONTROL
Because of their large size no spray safe to use on citrus trees
will kill the adults. The larvae may be killed by the oil emulsions,
soap, or tobacco solutions. It may be found economical to col-






Bulletin 148, Insects of a Citrus Grove


lect the adults from the fruit. For this purpose large nets (fig.
116) at least three feet in diameter and of equal depth should
be made. Muslin is a good material from which to make this net.


Fig. 116.-Type of net used in collecting pumpkin bugs from small citrus
trees

Each net should have a short handle which if extended across
the diameter to stiffen the opposite rim will permit the use of
telephone wire to complete the skeleton for the net. Bend the
wire into a loop and nail the loose ends to a wooden handle.
One man can manipulate this net, but two may work to better
advantage. One places the net under a limb of fruit and the
other gives the branch a quick, vigorous shake which causes the
bugs to roll into the bottom of the net. After the men have
finished a tree the bottom of the net is dipped in a bucket
containing kerosene. This keeps the net constantly wet with
kerosene.






Florida Agricultural Experiment Station


The work cost in one grove of ten-year-old trees set 20 by 30
feet between 50 and 75 cents an acre, and from 30 to 100 bugs
a tree were collected. Two men with a net covered at least an
acre in two hours.
Th6 labor cost $1.50 a day for each man. This is less than
the cost of spraying even if a safe and effective solution were
known. On larger trees with more bugs the cost is greater, but
should in no case exceed $1.50 an acre,-still much less than
the cost of spraying.
For large trees not too close together and with few limbs touch-
ing the ground to prevent a ready manipulation, the nets should
be larger. The writer has used some nets 6 by 12 feet. These
were suspended from a light wooden frame like those used for
holding quilts or stretching curtains, the net sagging two or
three feet in the center. The net should be of closely woven can-
vas so that insecticide oil, crude oil or kerosene can be placed in
the bottom, into which the bugs will fall. Cotton waste placed
in the net will absorb the oil and in rolling around will thoroly
wet the bugs. Two men will be required to manipulate the net
and at least another to shake the branches.
For large trees these nets will be found more economical than
the smaller ones strung on telephone wire. They are effective,
however, only at a temperature below 70 degrees. Above that
the bugs will take to wing as they drop, before they strike the
canvas. The use of the large nets is therefore restricted to the
very early morning, to moonlight nights and to cold days. The
smaller nets can be used all day, tho more effectively in the early
morning.
If the bugs are not thoroly saturated with the oil chickens will
eat them. They are probably worth at least five cents a pound
as chicken feed. Chickens turned into a grove will eat many of
the bugs if other insect food is not too abundant. Chickens can-
not, of course, reach those high in the trees, but the majority of
the bugs usually collect on the lower branches. Or, better, the
chickens can be turned into the grove while the bugs are still on
the cover crop.
PREVENTION
If proper precautions are taken these bugs will seldom get on
the fruit. Their attacks are usually brought on either by allow-
ing the cover crop of cowpeas, beggarweed, or velvet beans to
remain on the ground too long, or by the lack of sufficient thoro-


234






Bulletin 148, Insects of a Citrus Grove


ness in cutting (as by leaving uncut patches between the trees)
or by using the wrong method in cutting. The cover crop should
be cut by the middle of September. The man with the scythe
should precede rather than follow the mowing machine; that is,
the spaces about and between trees in the rows should be cut first,
leaving the middles to be cut later. There are but few winged
adults at that season, but there are many wingless nymphs which
cannot fly nor crawl far. This method of cutting drives these
young away from the trees into the middles where they will
perish when the last of the crop is cut. As a result there will be
but few others produced before cold weather puts an end to their
breeding. Neglect of the cover crop does not always result in an
outbreak of bugs for other factors may enter in to keep them
down, yet it is a dangerous practice.

OTHER PLANT-BUGS
Mingling with the pumpkin bugs are occasional specimens of
the northern green soldier bug, Nezara hilaris. More common
is the brownish-gray stink bug, Euchistus variolaris.
The leaf-footed plant-bug, Leptoglossus phyllopus L, and the
big-thighed plant-bug, Acanthocephala femorata (Fab.), altho
more common in truck gardens, sometimes attack citrus fruits.
Thistles on which the bugs congregate in large numbers, should
be cut out of the citrus groves.
Control measures for all four of these insects is the same as
for the pumpkin-bug.

COTTON STAINER
Dysdercus suturellus Herrich-Sch.
This dark red bug which gets its name from its habit of feed-
ing in cotton bolls the lint of which it stains red, sometimes in-
vades citrus groves in hordes and attacks the fruit in the same
manner as the pumpkin bug. The cotton stainer is markedly
gregarious; scattering specimens are seldom seen. In some years
large numbers invade the groves and then for several years they
will be almost entirely absent. The opinion is quite general that
the growing of cotton in the vicinity of citrus groves is responsi-
ble for these invasions. But the fact that the insect shows in
cotton fields the same tendency to be abundant during occasional
years only, as in citrus groves, casts some doubt on the opinion.
The mature bug is a little less than a half-inch long and is
about 3/16 of an inch wide. Its shape is between oblong and






Florida Agricultural Experiment Station


oval. The head and most of the thorax and the base of the legs
are red. The wings are dark brown edged with yellow. When
the wings are crossed over the back in the manner characteristic
of the true bugs, these yellow edges form two rather conspicu-


Fig. 117.-Grasshopper injury to orange

ous lines which cross diagonally on the back. This is a tropical
and sub-tropical insect which becomes more abundant toward the
south.
CONTROL
These bugs may be collected in the same way as the pumpkin
bugs. Also, advantage may be taken of their fondness for cotton
seed by placing small piles of the seed under the trees. The bugs
will collect on these piles where they can be sprayed with kero-
sene or, better, killed with a gasoline torch. By using the torch
the seed will last for some time, but if sprayed with kerosene the
seed becomes unattractive to the bugs and will have to be re-
newed.
MINOR PESTS OF THE FRUIT
ORANGE TORTRICIDS
Caterpillars of two or three species of small moths which be-


................................. .. .........





Bulletin 148, Insects of a Citrus Grove


long to the same family as the moth which infests woolen gar-
ments, occasionally drill tunnels in citrus fruit. They are appar-
ently more common in low hammock groves than on high pine-
land. Also, they are more common in grapefruit than in oranges,
doubtless because grapefruit hang in bunches with the fruits
touching. In the most heavily infested grove observed about
one percent of the fruit was mined. The mine invariably starts
from the point of contact of two fruits or of a leaf and a fruit.
In the latter case
the leaf is fasten-
ed to the fruit by
strands of silk
spun by the cater-
pillar. The hole
does not extend in-
to the pulp but it
affords an avenue
for the entrance of
molds and other
organisms which
invariably destroy
the fruit in time.
Consequently, a
mined fruit can-
not be shipped but
must be culled. Fig. 118.-Work of the bagworm on orange
The caterpillars are flesh-colored and are a half inch or less
long when full-grown. They are hairless, therefore are commonly
called "worms." Fortunately they seldom become sufficiently
abundant in a grove to make control measures worth while.
They feed also on the tender young leaves which they web
together with silk. Probably many could be killed with an arsen-
ical spray made by adding 1 pound of lead arsenate to 50 gallons
of oil emulsion or 50 gallons of water and the milk obtained by
slaking 3 pounds of lime. They sometimes cause sufficient dam-
age to young nursery trees to warrant spraying.

GRASSHOPPERS AND KATYDIDS
Grasshoppers and katydids sometimes feed on the skin of a
growing orange and cause large, smooth, sunken areas in the






Florida Agricultural Experiment Station


rind as it develops. (Fig. 117.) These marks will usually cause
an orange bearing them to be graded as a cull. The writer has
never observed an instance of this type of injury being suffi-
ciently common in a grove to make control measures profitable.
Should it ever become so the Kansas bait should be sown over
the trees as high as one can reach. A formula for this bait and
a longer discussion of grasshoppers in young trees will be found
on page 247.

BAGWORMS

A somewhat similar but less deep wound in the young fruit
is caused by the feeding of bagworms.
(Fig. 118.) These are caterpillars that
.. construct, out of small sticks, straws,
etc., fastened together with silk, coni-
cal-shaped bags for shelters (fig. 119).
From this bag only the head and legs
are pushed out to feed and travel. When
.,. the insect is resting, as during the
'" colder part of the winter, the bag is
fastened securely to the tree by means
of silk. The adult is a small moth.

RODENTS

Flying squirrels and rats will some-
Stimes gnaw into oranges for the seeds.
S Rats also sometimes do serious damage
to a citrus tree by gnawing the bark of
trunk and limbs and girdling them. This
... always occurs near an old rat-infested
building.
Fig. 119Case of the bagworm. Perhaps the best and cheapest poison
Twice natural size for rats is barium carbonate. This is
thoroly mixed with three times its bulk
of cornmeal and placed in a dark corner. This substance is not
very poisonous to man nor to domestic animals and is conse-
quently safer to have about the place. It has the further advan-
tage that rats eating it will usually leave the building in search
of water and die outside.






Bulletin 148, Insects of a Citrus Grove


MEDITERRANEAN FRUIT FLY
Ceratitis capitata Wied.
There exists on every continent of the globe except North
America a small fly with striped wings, known as the Mediter-
ranean fruit fly. (Fig. 120, a). This fly deposits her eggs in a
great variety of ripening fruits and vegetables including man-
goes, guavas, peaches, avocados, and oranges. Little maggots
















Fig. .120.-Mediterranean fruit fly. (From Howard, U. S. D. A.)

hatch from these eggs and burrow thru and thru the fruits ut-
terly ruining them. This pest has become established in the Ha-
waiian Islands, and in the Bermudas just off our coast. In both
places it has ruined the fruit industry with the exception of grow-
ing bananas, pineapples and a few other fruits. It is stated that
the only way in which one can raise an orange in Hawaii is to tie
a paper bag around it while the fruit is still green. This fly
would undoubtedly ruin. our fruit industry as well as prevent the
growing of many vegetables, including tomatoes, were it to be-
come established here.
Because the larva lives buried inside the fruit it is out
of reach of insecticides. The adult two-winged flies can be killed
by poisoned sweets but that method of control does not seem to
be successful. The only hope for successful control would seem
to lie in the introduction and breeding of parasites.
It is hoped that with the present strict quarantine measures
of the Federal government and the State Plant Board, which
should receive the hearty support of the growers, this insect can


239






Florida Agricultural Experiment Station


be kept out of the United States. Nevertheless, it is well for the
growers of the State to be on the watch for it that they may
report its presence at once should it gain entrance. Any one
finding maggots in an orange that has an apparently sound skin
should send the fruit to some entomologist.

MORELAS FRUIT FLY

In Mexico there exists a fly called the "Morelas Fruit Fly" that
belongs to the same family and works in a similar manner. At
present the greatest danger from this fly is its possible introduc-
tion into the United States thru Gulf ports which have consid-
erable commerce with Mexico.

SCAVENGERS

Many insects breed in injured and rotting oranges. The most
common of these are sap beetles (Nitidulidae) and pomace flies.
Sap beetles are small, with wings too short to cover the abdo-
men. They quickly invade an orange that has split from any
cause but do not, as is often supposed, cause the splitting.
Pomace flies are small two-winged flies that lay their eggs in
rotting fruit. These hatch into maggots that develop in the rot-
ting fruit. They do not attack sound fruit.
Termites, or white ants, also attack rotting fruit on the ground.

CITRUS ROOT-WEEVIL
Pachnaeus opalus Oliv.

The citrus root-weevil (fig. 121) is a greenish-blue beetle
from 1/3 to 1/2 inch long, with a short thick snout. The adult
feeds on the blossoms and leaves of citrus
and does considerable damage to the lime
groves on the Keys and less to the groves on
the mainland, altho it is found over the
southern part of the State. The larvae feed
on the roots of the trees and do even more
damage than the adults altho they are not
as conspicuous.
Related species are among the worst pests
of citrus in Cuba and other West Indian is-
Fig. 121.-Citrus root- lands. The adults can be poisoned by spray-
weevil; adult beetle.
Enlarged 2 times ing the trees with lead arsenate.






Florida Agricultural Experiment Station


be kept out of the United States. Nevertheless, it is well for the
growers of the State to be on the watch for it that they may
report its presence at once should it gain entrance. Any one
finding maggots in an orange that has an apparently sound skin
should send the fruit to some entomologist.

MORELAS FRUIT FLY

In Mexico there exists a fly called the "Morelas Fruit Fly" that
belongs to the same family and works in a similar manner. At
present the greatest danger from this fly is its possible introduc-
tion into the United States thru Gulf ports which have consid-
erable commerce with Mexico.

SCAVENGERS

Many insects breed in injured and rotting oranges. The most
common of these are sap beetles (Nitidulidae) and pomace flies.
Sap beetles are small, with wings too short to cover the abdo-
men. They quickly invade an orange that has split from any
cause but do not, as is often supposed, cause the splitting.
Pomace flies are small two-winged flies that lay their eggs in
rotting fruit. These hatch into maggots that develop in the rot-
ting fruit. They do not attack sound fruit.
Termites, or white ants, also attack rotting fruit on the ground.

CITRUS ROOT-WEEVIL
Pachnaeus opalus Oliv.

The citrus root-weevil (fig. 121) is a greenish-blue beetle
from 1/3 to 1/2 inch long, with a short thick snout. The adult
feeds on the blossoms and leaves of citrus
and does considerable damage to the lime
groves on the Keys and less to the groves on
the mainland, altho it is found over the
southern part of the State. The larvae feed
on the roots of the trees and do even more
damage than the adults altho they are not
as conspicuous.
Related species are among the worst pests
of citrus in Cuba and other West Indian is-
Fig. 121.-Citrus root- lands. The adults can be poisoned by spray-
weevil; adult beetle.
Enlarged 2 times ing the trees with lead arsenate.






Florida Agricultural Experiment Station


be kept out of the United States. Nevertheless, it is well for the
growers of the State to be on the watch for it that they may
report its presence at once should it gain entrance. Any one
finding maggots in an orange that has an apparently sound skin
should send the fruit to some entomologist.

MORELAS FRUIT FLY

In Mexico there exists a fly called the "Morelas Fruit Fly" that
belongs to the same family and works in a similar manner. At
present the greatest danger from this fly is its possible introduc-
tion into the United States thru Gulf ports which have consid-
erable commerce with Mexico.

SCAVENGERS

Many insects breed in injured and rotting oranges. The most
common of these are sap beetles (Nitidulidae) and pomace flies.
Sap beetles are small, with wings too short to cover the abdo-
men. They quickly invade an orange that has split from any
cause but do not, as is often supposed, cause the splitting.
Pomace flies are small two-winged flies that lay their eggs in
rotting fruit. These hatch into maggots that develop in the rot-
ting fruit. They do not attack sound fruit.
Termites, or white ants, also attack rotting fruit on the ground.

CITRUS ROOT-WEEVIL
Pachnaeus opalus Oliv.

The citrus root-weevil (fig. 121) is a greenish-blue beetle
from 1/3 to 1/2 inch long, with a short thick snout. The adult
feeds on the blossoms and leaves of citrus
and does considerable damage to the lime
groves on the Keys and less to the groves on
the mainland, altho it is found over the
southern part of the State. The larvae feed
on the roots of the trees and do even more
damage than the adults altho they are not
as conspicuous.
Related species are among the worst pests
of citrus in Cuba and other West Indian is-
Fig. 121.-Citrus root- lands. The adults can be poisoned by spray-
weevil; adult beetle.
Enlarged 2 times ing the trees with lead arsenate.






Bulletin 148, Insects of a Citrus Grove


BORERS OF TRUNK AND LIMBS
ORANGE SAWYER
Elaphidion inerne Newm.
The orange sawyer, a dark brown, long-horned beetle a little
more than a half-inch long, lays her eggs in rotten citrus wood.
Stubs of dead wood left by a careless or ignorant pruner are a
favorite situation. The larva is a white cylindrical grub which
grows to a length of one inch. The head also is cylindrical so
that borers of this family are called "round-headed borers" to
distinguish them from the larvae of the metallic wood borers
which have a flattened head. These borers eat dead or injured
wood by preference but if the dead stub is not large enough to
raise the grubs to maturity they are forced to work down into
the living wood and may so weaken the limb that it breaks off.
In trimming citrus or any other tree a dead branch should be
cut off close to its junction with the larger living branch so that
bark will grow over and heal the wound. Painting the cut sur-
face will help to keep out this borer and other pests until the
wound has had time to heal. The dead ends of freshly budded
stocks should be treated with special care.

SHOT-HOLE BORERS, OR PIN-HEAD BORERS
Several species of small cylindrical beetles sometimes attack
weakened trees. They and their larvae make holes in the bark
and sapwood, about the size of a pin. They are often so numer-
ous in a dying tree that the holes they make give the trunk the
appearance of having been struck by a load of small shot, hence
the name "shot-hole borer." These pin-head borers cannot live
in a vigorously growing tree as they are drowned by the copious
flow of sap, but often when a tree is checked in its growth by
transplanting or by some disease it is attacked by the beetles,
which usually quickly kill it. Trees found in a dry weakened
condition may be given partial protection by a coating of white-
wash to which has been added a handful of salt for every 3 gal-
lons. It is hardly worth while to attempt to save a tree that has
been invaded by these beetles. It is better to cut and burn it at
once so as to kill the beetles.

TINEID MINER
The caterpillar of a small moth sometimes mines young twigs
of citrus. (Fig. 122.) It is not common and can be ignored by






Florida Agricultural Experiment Station


the grower. This is fortunate as it would be a very difficult in-
sect to control as it is out of reach of insecticides. Pruning out
and burning infested twigs would
probably reduce its numbers.

BARK AND LEAF SCAVENGERS
PSOCIDS

A common sight on trunks and
S leaves of citrus trees are groups of
large-headed insects which, when dis-
turbed, crawl off in single file. They
seldom fail to excite the curiosity
S when seen for the first time and are
very frequently sent in for identifica-
tion. They are psocids and feed upon
the lichens which grow on citrus trees.
These lichens are of many shapes
and colors and sometimes thickly cover
the trunk of a tree. They are often
spoken of as "moss." True moss is
not common on citrus trees. Citrus
growers commonly regard lichens as
harmful. They may interfere some-
what with the supply of air and light
Sto the bark of the tree, but probably
do not do a great deal of harm. If
lichens are harmful, psocids must be
considered beneficial insects. The av-
erage citrus grower who does not like
:j to see lichens on his trees will regard
S the psocids with favor.
n, There are two species of psocids
common on citrus in most of Florida.
The larger, Psocus venosus Burm., is
from a fifth to a third of an inch long,
Fig. 122.-Mine of Tineid on or-
ange twig. Enlarged brown, with feet and a few wing
spots yellow. This species lives in
groups of two dozen or less on the bark of citrus limbs and
trunks. The eggs are oval and white and are laid in :a
cluster and then covered with wood which has been powdered
by the insect. Unlike most insects the female watches the eggs






Bulletin 148, Insects of a Citrus Grove


until they hatch when she leads the young about much like an old
hen does her brood.
The smaller species, Psocus citricola, Ashmead, is usually
found on the under surface of leaves where it spins a scanty web
under which it lives and breeds. This insect is from 1/12 to 1/8
inch long, pale yellow, and so nearly transparent that the con-
tents of the intestine are plainly visible thru the body. It feeds
on the wax and other excretions of scale insects, on minute fungi,
and on honey-dew.

HYMENORUS OBSCURUS Say.
This is a small Cistelid beetle that sometimes collects in groups
of hundreds which quickly clean the bark of lichens and similar
growths. These beetles feed only in the early morning and late
afternoon, resting during the day in a dense mass that blackens
the trunk of the tree. The beetle is a little less than a quarter
of an inch long. The body is jet-black but covered with short
grayish-brown hairs. Nothing is known of its life history. It
occurs on the bark of other trees also, especially magnolias.

MINOR PESTS OF YOUNG TREES
There is a number of insects that feed on
the young leaves and twigs of citrus but
which never become sufficiently numerous to
damage seriously a mature orchard with a
large crown. On a young tree, however,
their depredations may cause a serious set-
back or be a contributory cause to the death
of the tree. Of these the pumpkin bug and
other plant-bugs have already been men-
Fig. 123.-Young orange
tioned. Others will le mentioned here. dogs

ORANGE DOG
Iapilio cresphontes Cramer
The caterpillar of the orange dog is common on citrus, feeding
boldly exposed on the upper side of the leaves and eating so
greedily that two or three may entirely defoliate a young tree in
a few days. The caterpillar (figs. 123 and 124) grows to a
length of 21/2 inches. It is dark brown with light yellow patches,






Florida Agricultural Experiment Station


The front part of the body is enlarged and when not feeding the
caterpillar pulls the head back into these large segments and
causes the whole front part of the body to resemble somewhat the
head of a dog, hence the name. The head of the caterpillar rep-
resents the nose of the
Sdog and two velvety-
black spots on the thor-
ax resemble eyes. When
disturbed the caterpil-
lar pushes out from a
fold of the skin back of
the head a red organ
which forks at the base
and forms two long
hor n-li k e processes.
This organ gives off a
strong and disagreeable
smell which apparently
protects the caterpillar
from many predaceous
animals that might oth-
erwise eat it.
The caterpillar re-
quires about thirty days
Fig. 124.-Orange dog: Full-grown to complete its growth
and then suspends it-
self from a twig and turns into a chrysalis. This chrysalis (fig.
125) is a mottled grayish-brown and resembles a dead twig so
closely that it is seldom noticed. The chrysalis hangs from ten
days to two weeks, or all winter, in the case of the last gener-
ation.
The Mdult (fig. 74, frontispiece) is a large yellow and black
butterfly. It is one of the largest and commonest species in
Florida and is seen abundantly among flowers every day in sum-
mer. The female lays about 500 eggs scattering them over new
growth of citrus and prickly ash. They hatch in from ten days
to two weeks. Thus a generation occupies about two months
and there are four generations in a year. The last generation
which feeds from August to October, is the largest and most de-
structive.





Bulletin 148, Insects of a Citrus Grove


CONTROL
The quickest way to control these caterpillars on young orchard
trees usually is to pick them
off by hand. On nursery trees,
if they are at all abundant,
spraying is cheaper. A pound
of lead arsenate to 50 gallons
of water will not ordinarily -
cause any scorching of the fo-
liage but if there is much new
growth it would be advisable
to add the milk obtained by
slaking 2 or 3 pounds of quick-
lime in a little warm water. .
The milk of lime should be
strained before it is added to
the spray.

SLUG CATERPILLARS
PUSS MOTH
Megalopyge opercularis S. and A.
Occasionally may be seen
feeding on the leaves of an
orange tree a flat, wide cater-
o g t e w d Fig. 125.-Pupa of the orange dog butter-
pillar covered with very long aly. Natural size
silken hairs which give rise to
its name, puss moth. (Fig. 126.) Scattered among the soft
hairs are some stiff ones in which is a substance that acts like
a nettle on the skin of a person who inadvertently touches this
caterpillar. On some persons this substance causes a very pain-
ful swelling, on others only a momentary itching sensation.
These caterpillars are at first white but turn darker as they be-
come older. They are more common on oak than on citrus.
The pupa (fig. 127) also is odd in appearance and never fails
to excite the curiosity of one who sees it for the first time. At
the front end is a trap door thru which the moth can easily
emerge. Midway on the side there is an elevation which is an
exact copy of a dormant bud. The whole pupa looks so much like
a twig that in its natural position among the branches it is easily
mistaken for one. The perfect insect is a brown and yellow moth.
(Fig. 128.)






Florida Agricultural Experiment Station


Fig. 126.-Larva of the puss moth. Twice natural size


There are two broods of caterpillars each year, one in early
summer and the other in late fall. The latter spends the winter
in the cocoons.
These insects never have become
sufficiently abundant to require
control measures. Should they be-
come so they could easily be pois-
oned by lead arsenate.

SADDLE-BACK
Sibene stimylea Clemens
The saddle-back is another slug-
gish, nettling caterpillar t h a t
causes extreme annoyance to one
who touches it. It grows to a length
of more than one inch. It is brown
on both ends. The middle is green
with a purple spot in the center.
The whole looks like a small saddle
with a large green blanket under
it.
The cocoon is almost spherical
and has a trapdoor-like lid in the
Fig. 127.-Cocoon of the puss moth on
twig front. The adult is a dark, red-






Bulletin 148, Insects of a Citrus Grove


dish-brown moth with light brown and yellow markings. The
caterpillar is more common in corn fields than in groves.
HAG MOTH
Phobetron pithecium S. & A.
Another stinging sluggish caterpillar, the hag moth, has four
fleshy, curved, hairy appendages that look like locks of dishev-
eled hair p r oj e ctin g
from its sides, hence the
name hag. When full-
grown is is about 3/5 of
an inch long. Several of
these caterpillars work-
ing together sometimes -
gnaw off a vigorous cit- -
rus twig and afterward
p a c e their spherical .
cocoons among the brown
leaves. These cocoo.ns Fig. 128.-Puss moth (Lagoa operoulata). Slightly
are partly covered with enlarged
tan-colored hairs taken from the body of the caterpillar.

GRASSHOPPERS

Grasshoppers sometimes eat the leaves of trees as well as
the young fruit. On large trees their damage is inconsequential
but on young grove trees and nursery stock it may be necessary
to take measures against them. They are especially abundant
in young groves that are allowed to grow up in weeds.
The trees may be sprayed with the arsenicals recommended
for the orange dog, but the Kansas bait can be more quickly and
cheaply applied. This is made as follows:

Bran .... .................... .................. ...20 pounds
Paris green ....................... ............................... 1 pound
Water ... -.................. ..... ................. 2 gallons
Lemons ....---..... --------.........-....... 3 or 4
Syrup .................. ......--........ ---- 2 quarts

The paris green and bran should be thoroly mixed (dry). Lead
arsenate should not be used. It does not work as well. The
lemons should be thoroly grated or chopped very fine, rind, pulp
and juice, and added to the water. Moisten the bran with the
water until the Whole is damp but not sloppy, so that when sown
broadcast over the land it will fall in small flakes. Last of all add


247






Florida Agricultural Experiment Station


the syrup and thoroly knead it into the bran. This should be
sown in the early morning, about sunrise or before. Grasshop-
pers do not eat at night and consequently have a good appetite
in the early morning, and the bait should be on hand for their
breakfast.
If sown in small flakes over the field there will be no likelihood
of chickens or other domestic animals picking it up, nor will
wild birds be endangered. Ordinarily there will be no danger
to chickens or other fowls eating the dead grasshoppers as the
fowls will not in this way get enough arsenic to harm them.














Fig. 129.-Lubberly locust or grasshopper: Adult. Natural size
Altho almost any species of grasshopper may occasionally at-
tack citrus most of the damage is done by three species:
The Bird Grasshopper, Schistocerca serialis (Thurn.) is long
and slender and is a powerful flier, hence the name. It is light
brown, striped and mottled with black. The female is often more
than 2 inches long and the male 13/ inches. The wings average
nearly a half-inch longer than the body.
The Yellow-lined Grasshopper, Schistocerca aleutacea, is dark
brown with a yellow streak down the middle of its back. The
adult female averages nearly 2 inches long and the male 11/2
inches. The wings are longer than the abdomen but not so long
as in the bird grasshopper in this respect. The female has a
much heavier body.
Both of these species are present in groves the year around
but are inactive during the coldest days. Thruout the winter no
young are seen.
The Lubberly Locust, Dictyophorus reticulatus, Thunb., is a
short-winged insect that never flies. (Fig. 129.) The adult fe-


'248






Bulletin 148, Insects of a Citrus Grove


male is often 21/2 inches long and the male 2 inches. They are
yellow, more or less marked and shaded with black. The fore
wings are tinged with red and the hind wings are a deep red
fringed with black. The young are jet-black with red "trim-
mings," and live in colonies which keep close together, particu-
larly at night. These locusts are usually scarce on the high pine-
lands but often become abundant on flatwoods and muck lands.
Altho most grasshoppers are greedily eaten by birds, snakes,
lizards, toads, frogs and skunks the lubberly locust is an excep-
tion. Doubtless they have a flavor which is distasteful to those
predators.
Grasshoppers lay eggs in the ground, usually in the late sum-
mer, which hatch in the following spring' In the three species
mentioned there is but one brood a year.

KATYDIDS
Katydids do about the same injury in citrus groves as grass-
hoppers but usually are not so numerous. These insects are
bright green and
their wings are
veined so as to re-
semble very closely
the leaves of the
trees, making the
insects extremely
hard to see. Their
eggs are a common
sight in citrus
groves and are the
subject of numer-
ous inquiries. The
call of our species is Fig. 130.-Broad-winged katydid (CrytophyUus concavus).
not "katydid" but Natural size.
simply "katy."
Two species are common in citrus groves. One, the broad-
winged katydid (Crytophyllus concavus) (fig. 130) has broader
and shorter wings than the other. The eggs in this species (fig.
131) are flat, oval, flesh-colored disks which are placed like a
fringe around the edge of the leaf; each glued on its flat side and
overlapping the one next to it on the leaf in an almost perfectly
symmetrical pattern. Often they completely encircle the leaf.
The egg is about 3/16 of an inch long by 1/8 of an inch wide.






Florida Agricultural Experiment Station


The other species, the angular-winged katydid (Microcentrum
retinerve), usually lays its eggs in a double or triple row on a
dead twig (fig. 132) each egg standing on end. The egg is nar-
rower, 1/12 of an inch, and much thicker than that of the broad-
winged species.
Both species are highly parasitized by a wasp-like insect which
develops in the egg and escapes
thru a small round hole which
it makes in the shell. A large
percentage of most egg-masses
show these holes.
Katydids can be controlled in
the same manner as grasshop-
pers.

SHARP-SHOOTER, OR ORANGE
JASSID
Oncometopia undata Fab.
This oblong, bluish bronze
leaf-hopper (fig. 133) is nearly
1/2 inch long. The head is the
widest part, about 1/8 of an
inch. It is triangular in shape
and bronze in color. The thorax
and fore wings are steel-blue
marked with grayish lines. The
sharp-shooters infest the twigs
of citrus, roses and other shrubs
from which they suck the sap.
When approached they quickly
Fig. 131.-Eggs of the broad-winged katy-
did. Natural size move around to the opposite side
of the twig in an effort to keep
out of sight. They may cause the young and tender twigs to wilt
or the bark of the older twigs to crack.
The insects are usually not sufficiently abundant to render
spraying necessary but the oil emulsions or a spray of 6 pounds
of soap and 1/3 pint of black-leaf 40 in 50 gallons of water will
kill them. Usually, if control measures are deemed advisable, it
will be found cheaper to knock the insects off into a pan
of kerosene, unless there are whiteflies or scales on the tree that
need attention at the same time. In this case spray with the oil
emulsions.







Bulletin 148, Insects of a Citrus Grove


Small black a


Fig. 132.-Eggs of the
angular-winged katy-
did. Natural size


ANTS
ON BUDDED TREES
nts often become troublesome in a citrus grove.
They are especially annoying in that they are
likely to cut out very tender buds, and are
most severe on buds which have been re-
cently inserted and are just beginning to
grow. In the southern part of the State the
leaf-cutting ants sometimes do considerable
damage to citrus trees by cutting off pieces
of the leaves and carrying them away.
KEEP ANTS OFF TREES
One method of keeping ants from climbing
the trees is to band the tree with tow worked
in a mixture of corrosive sublimate and lard,
or some other oily substance like lard, and
then allowed to dry. Since corrosive sub-
limate is extremely poisonous, care must be
taken that too much of the substance does
not adhere to the tow, otherwise it is likely
to soak into the bark and kill it completely
around the tree, thus doing more harm than
good. As long as this band remains close
to the tree, and the material does not dry out,
the ants refuse to cross it. Sometimes they
build bridges of soil across it and get over


the tow in this way.
Another method of prevent-
ing ants from getting into the
trees is to make a circle of air-
slaked lime in a cleared space
about the trees, being careful
of course that no ants' nests
are included within the circle.
As long as the lime remains
dry and the wind does not
blow it away, the ants will
not cross it.
The following formulas will
last longer:


rc.

a--


Fig. 133.-Sharp-shooter. (From Farmers' Bul.
890, U. S. D. A.)


251






Florida Agricultural Experiment Station


(1) Tree Sticky ...................................... ..... .......... ............................... 6 parts
Powdered corrosive sublimate ........................ ...... .................... 1 part
(2) Flowers of sulphur, by weight ........................................ 1 part
Tree Sticky, by weight ..................................................................... 6 parts
Mix thoroly with a wooden paddle. This will last from three to five months.
(3) Black axle grease .................... .................................... 1 part
Tree Sticky ............................. ..... .......- ...-... ........... 2 to 3 parts

AS PROTECTORS AND CARRIERS OF SCALE INSECTS
In addition to the direct damage certain species do to the tree,
most ants damage the tree indirectly by the care they take of
scale insects, and especially mealy-bugs. Ants are very fond of the
honey-dew these insects, aphids and some other bugs give off and
for the sake of the honey-dew they virtually domesticate those
insects, interfering with their parasites and carrying the bugs
from one tree to another.
There is one small compensation to be derived from this rela-
tion between ants and mealy-bugs, scales, etc. The presence of
numerous ants in a tree is to the grower the sign of the presence
of the scales, and, as the ants are more readily noticed than the
scales, they often call his attention to an infestation that would
otherwise be missed. On the whole, however, ants are distinctly
harmful to the interests of the grower and should be killed out
as far as practicable.
There exists in the groves of parts of California, Louisiana
and Mississippi,.a particularly pernicious species called the Ar-
gentine ant. This has been introduced from tropical countries
and has proved a very serious pest to citrus by protecting mealy-
bugs and other scale insects. It is also a very difficult species to
control. Its nests are very diffuse, in fact being spread over a
large proportion of the ground in infested territory. Altho this
species is not now known to be in Florida, it is probably only
a question of time when it will arrive.

CONTROL
The best fumigant to use against ants is a solution of sodium
or potassium cyanide in water, applied to their nests. For this
purpose dissolve an ounce of cyanide in a quart of water, and
with a cane or sharp stick punch a hole to the depth of a foot or
more in the center of the hill and pour into it a few ounces of the
solution. As soon as the liquid has soaked away cover up the
hole and tramp the surface solid. The gas given off will pene-
trate the galleries and kill the ants and their pupae. It is best to






Bulletin 148, Insects of a Citrus Grove


do this in the early morning, or at night when most of the ants
are in the nest. Care must be taken in treating a nest near a
tree, especially a young tree, or the tree may be killed.
Cyanide must be handled carefully as either the solid material
or the fumes given off are among the most powerful poisons
known. Great care should be used not to swallow even a trace
of it nor allow it to come in contact with a sore or to be inhaled.
Potassium cyanide can be purchased from almost any drug
store, and frequently from jewelers, or from insecticide or ferti-
lizer houses in the State. Sodium cyanide is much cheaper.
Carbon bisulphide can be used, but it is more expensive and is
highly inflammable. Kerosene can be used in the same manner,
but it does not penetrate the nests well. Gasolene is better, but
is inferior to carbon bisulphide or potassium cyanide. Boiling
water will kill all the ants it touches, but it is not effective to
any great depth as it cools too rapidly.

WHITE ANTS, TERMITES, OR "WOOD LICE"
Termes flavipes Kollar
Soft-bodied, pale insects called white ants, termites or wood
lice are very common in rotting wood and sometimes give con-
siderable trouble in new land especially to young trees which are
banked during the winter as a precaution against cold. In many
groves wood is piled in heaps among the trees ready for use
during a cold night. If not used it rots in the grove and becomes
heavily infested with these white ants or termites. If wood is
piled near a tree or included in the earth when the tree is banked,
the termites may attack the bark of the tree and girdle it if the
tree is young. Careless trimming which leaves a stump of wood
to rot near or below the surface of the ground will-attract these
insects which may gnaw into the living wood when the rotten
stump has been consumed. All such stumps should be trimmed
close and the cut surface painted. Setting the young tree too
deep is another common cause of termite attack.

CONTROL
Wood for heating purposes should be piled as far as possible
from the trees and care should be taken not to include any dead
wood in the bank around young trees.
These insects cannot tolerate daylight and can be driven from
any tree they have attacked by scraping away the earth and leav-
ing the part exposed. It is well to plant newly cleared land to






Florida Agricultural Experiment Station


some other crop for a year or two before putting out the trees.
Termites will gradually disappear from cultivated land with the
rotting wood. Do not set young trees much, if any, deeper than
they stood in the nursery row. Flickers and other woodpeckers
are fond of termites.
The winged males and females of termites are black. They
issue from the nests in countless numbers at certain times,
usually just after a rain. When a nest has been located by these
winged swarms it can be treated with carbon bisulphide or
cyanide solution as recommended for the true ants.

PRICKLY-ASH BEETLE
Trirhabda brevicollis Lec.
In the spring the prickly-ash beetle is often very abundant on
prickly ash (Xanthoxylon clava-herculis, L)* which it often com-
pletely defoliates. The larvae appear in March and usually feed
until some time in April. After a few days spent in the pupal
stage the adult emerges and also feeds on the leaves of the
prickly ash. If they are sufficiently numerous to defoliate the
trees, they may fly to citrus trees and finish feeding there. Not
only young trees but old bearing ones as well are sometimes de-
foliated. The beetles never lay eggs on citrus and the larvae are
not found on citrus. Indeed, when larvae are confined with citrus
leaves they will refuse to eat them, even tho very hungry.
The beetles may easily be poisoned by spraying the trees with
lead arsenate. To prevent an attack it is only necessary to cut
down all prickly ash shrubs in the vicinity of the grove.

MELON APHIS
Aphis gossypii Glover
The melon aphis, a very destructive pest of cucumbers and
melons, which is also found on cotton and many other plants in-
cluding weeds, is the common plant-louse of citrus. It attacks
only the young leaves and especially those on watersprouts. As the
latter should always be cut out of a bearing tree the presence of
aphids on them is of no importance except that they act as cen-
ters of infestation for young trees, melons, cotton, etc. But
aphids sometimes do a little damage to nursery and to young
orchard trees by attacking the young leaves which are dwarfed
and curled as a result of the loss of sap. (Fig. 134.)
*Another shrub, Aralia spinosa, is also called "prickly ash" or "Hercules
club." The beetle is not found on this species.






Bulletin 148, Insects of a Citrus Grove


The melon aphis is dark green with red eyes. The winged
forms are almost black. The young are a lighter green, some-
times a light yellowish-green.


Fig. 134.-Citrus twig infested with Aphis gossypii
CONTROL
Altho of little importance in the citrus grove, the grower
should in the interest of general agriculture and especially for
the benefit of the melon grower, make it a point to destroy the


255


'Wk 1






Florida Agricultural Experiment Station


melon aphis wherever found. This is particularly important in
the early spring before the winged females leave the trees for
the melon and other fields. When infested watersprouts are
found they should be cut off and destroyed by burning or dipping
into oil or tobacco solution.
On young trees the grower will probably find that the most
satisfactory method of dealing with an outbreak is to spray with
a soap and tobacco decoction. .He will generally find it cheaper
to buy the tobacco ex-
S tract already made, but
if the stems and refuse
are handy and cheap he
can profitably make his
own. This may be done
by placing the material
in enough water to cover
it well and keeping it at
a high temperature just
below boiling for an hour
or allowing it to soak
over night. The solution
should then have the col-
or of strong tea. Before
using it is diluted with
10 parts of water. If it
is desired to keep the so-
lution long salicylic acid
should be added, 1 ounce
for every 4 gallons of
the undiluted solution.
The ready-made tobac-
Fig. 135.-Parasitized bodies of Aihis gossypiz CO decoctions, of which
there are many on the
market, vary much in the amount of nicotine present, and conse-
quently in the proportions in which they should be diluted. Black
leaf 40 should be used in the proportion of 1 part to 1000 of
water. The weaker solutions such as Black leaf 2 1/3 should be
diluted with about 50 parts water. It is of advantage to put into
the solution something to make it spread and wet the surface bet-
ter. A good formula is the following: Dissolve whale-oil or other
caustic soap in 5 gallons of water. If the water to be used for
spraying is soft, use 2 or 3 pounds of soap; if hard, use more.


256






Bulletin 148, Insects of a Citrus Grove


Add 1/4 pint of Black leaf 40 and heat gently for 5 minutes.
When ready to use, dilute with water to 50 gallons.
LIFE HISTORY
Like all aphids, the melon aphis breeds with extreme rapidity.
The young are brought forth alive, ready to begin sucking the
sap from the leaves. In less than a week they become mature
and begin to reproduce. Several young are produced each day.
Males are entirely unknown. Young lice are produced from un-
fertilized eggs which usually hatch inside of the female. There
are two forms of females, a winged and a wingless. Both forms
may be found at any season of the year. The winged ones fly to
other plants and thus spread the species.
Aphids give off abundant honey-dew that is eagerly sought by
ants. Ants regularly tend the aphids for which reason the in-
sects are often called "ants' cows."
NATURAL CONTROL
Aphids have many predators and parasites which always keep
them in check in a citrus grove but not in a melon patch. The
smaller birds such as wrens, fly-catchers, and warblers destroy
great numbers of aphids.
In a colony of aphids many dead ones are usually found which
are so greatly swollen as to be nearly spherical in shape. (Fig.
135.) These have been killed by the larva of a minute wasp-like
parasite which lives in the interior of the aphid. The larva of
the parasite pupates in the dead aphid, and when the adult
parasite is ready to emerge it bites a hole in the top of the aphid.
The egg from which the parasitic
larva hatches is laid inside the aphid
that the female parasite pierces with
her ovipositor. This is one of the
most important checks to the increase
of aphids in a citrus grove.
Fig. 136.-A syrphus fly. (Month-
Several kinds of soft-bodied larvae iy Bul., Cal. Hort. Comm.)
move among the aphids and destroy
them. One is a dirty-white, legless maggot which impales aphids
on its sharp anterior end and sucks their body fluids. This is
the larva of a family of two-winged flies known as syrphus flies.
(Fig. 136.) There are many species. Another is flat, pale,
wedge-shaped, with well developed legs and a pair of jaws with
which it pierces the aphids. These are aphis lions. The adults






Florida Agricultural Experiment Station


are lace-winged flies (Chrysopa), bright green insects which
measure nearly an inch across the four gauzy wings and have
bright golden eyes. (Fig. 96.) The eggs are laid in groups and
are raised on stalks a half-inch above the surface of the leaf.
This arrangement prevents those first born from using for their
food the unhatched eggs in the group.
A similar larva (Hemerobius) makes a case to cover its body
out of the remains of the victims which it has
sucked dry. This case is carried about by the
(- Tlarva, hence it is called a "trash bug." The
adult is similar to the golden-eyed lace-wing,
but is brown.
Aphids are the choice food of many lady-
Fig. 137.- Blood-red beetles and their larvae. The species most com-
lady-beetle (Cyclo- mon in Florida citrus groves is the twice-
neda munda). En-
larged drawiAn stabbed lady-beetle (fig. 92). Other species
often seen are the blood-red lady-beetle (Cyclo-
neda munda Say) (fig. 137), the convergent lady-beetle (Hippo-
damia convergens Guer.) (fig. 138), and the Scymnus termina-
tus (fig. 139).











b b- cb
<4 4




Fig. 138.-Convergent lady-beetle: a, adult; b, pupa; c, larva. (From Farmers'
Bul. 914, U. S. D. A.)

STRIPED CUCUMBER-BEETLE
Diabrotica vittata

This notorious pest of the northern cucumber grower has been
unusually abundant in parts of Florida for the last two years.
Among other plants it attacks citrus, particularly young' trees
and satsumas. It attacks not only the leaves but the fruit as
well.






Bulletin 148, Insects of a Citrus Grove


The adult beetle (fig. 140) is yellow, striped with black, and
is about 2/5 of an inch long. The larva feeds on the roots of
cucumbers and related plants. A brief sketch of the life history
of this insect can be found in Fla. Ag. Exp. Sta. Bul. 134, p. 88.
Trees attacked by this beetle should be sprayed with lead
arsenate, using 1 pound of powder and 2 of lime to 50 gallons of
water. The spraying must be thoroly done so that every part of














Fig. 139.-Scymnus terminatus: Figure at left, adult; center figure, larva; figure
at right, pupa. (From Farmers' Bul. 914, U. S. D. A.)

the leaves and fruits is covered, otherwise the beetles will col-
lest on the unsprayed portions.
These insects have recently been prevented from injuring
cucumbers by scattering flour or cornmeal over the plants for the
beetles to eat. Doubtless this would work just as effectively on
citrus.

ALLIES OF THE CITRUS GROWER

Under the heading of the principal pest preyed upon or para-
sitized many insects whose activities aid the grower of citrus,
have already been described. Here, a few more will be men-
tioned. These are mostly the ones which prey upon or parasitize
a variety of pests, and no single species in particular. It must
be borne in mind, however, that just as all men cannot be classi-
fied as either "good" or "bad," it cannot be said that all the activ-
ities of any species of insect aid the citrus grower. Even the
most useful of the insects prey upon other useful insects to some
extent and some of the most troublesome pests give some aid in
controlling other pests. It can only be said that the benefit any






Florida Agricultural Experiment Station


species does seems to outweigh the harm, or vice versa. As an il-
lustration, the sap-suckers undoubtedly do much good in the
grove but they occasionally attack the trees and feed upon the
green layer of the bark (cambium), making rows of holes in the
trunk or limbs.

BIRDS

The farmer has been told so many times of the great service
birds do to agriculture that it seems like thrashing old straw to
repeat it. Nevertheless the heedless and foolish shooting of
birds, our allies in the struggle against insects, still goes on at
a scarcely diminished rate. There is probably no phase of agri-
culture unless it be
forestry where birds
do so little harm as in
orchards, including
citrus groves. Except-
SS i ing for an occasional
i tree attacked by sap-
suckers, birds do vir-
c tually no direct injury

/ whereas in corn fields,
b a d small fruit gardens,
Fig. 140.-Striped cucumber-beetle: a, adult, six times and grain fields the
natural size; b, larva; c, pupa. (From U. S. Bur. of des of
Ent.) depredations of birds
are considerable altho
greatly outweighed by the benefit derived. Indirectly, birds
do a little damage in a citrus grove by eating useful predators,
but this is of little importance when compared with their ben-
eficial effects. Most of the parasites that attack the insect pests of
citrus are too small to receive any attention from birds.
Altho the worst pests of citrus, the whiteflies, are apparently
ignored by all birds, large numbers of the scale insects which are
almost as serious are eaten by the smaller species of birds, such
as creepers. Nor should it be forgotten that the minor import-
ance of many crop pests is due at least in part to the activities of
birds. Even birds that feed themselves largely on seeds feed
their young on an animal diet exclusively of which insects form
the major portion.


260






Bulletin 148, Insects of a Citrus Grove


OTHER VERTEBRATES
Skunks or pole-cats do not deserve the persecution to which
they are usually subjected. They feed largely on mice and the
larger insects such as white grubs and grasshoppers. The far-
mer would do well to protect them. Chicken houses should be
made proof against them.
Snakes, toads, frogs and lizards are all destroyers of insects
and mice.

PREDACEOUS BUGS


A number of the larger bugs do
good work in keeping down such
pests as orange dogs, tortricids, and
other caterpillars as well as other
bugs, including the pumpkin bug.
One of the most notable of these pre-
daceous bugs is the wheel-bug (fig.
141).


Fig. 141.-Wheel-bug. Natural size


WASPS
Several species of wasps are quite common in citrus groves. In
spite of the fact that they may cause some annoyance to pickers
and other workmen if carelessly disturbed, wasps should not be
molested by the growers. They use as food for the young, grass-
hoppers, crickets, caterpillars, or spiders, according to the species
of wasp. Grasshoppers and caterpillars are directly injurious
to the trees. Spiders, at least the larger species, are probably
indifferent for. while they catch many insects the injurious forms
do not enter largely into their diet.

PARASITIC FLIES


Many kinds


Fig. 142. Tachinid
fly (Archytas later-
alis). Natural size
7


of flies are, in their larval stages, parasitic on
citrus insects. Syrphus-flies have been men-
tioned as parasites of the melon-aphis. The
larvae of some species feed on rust mites.
Others parasitize caterpillars.
Another family of flies which frequently par-
asitizes caterpillars is that of the tachinid fly.
(Fig. 142.) Most flies of this family are larger
than the common house fly. One species, Tri-
chopoda pennipes Fabr., is a common parasite




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