Title: Florida Entomologist
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00098813/00242
 Material Information
Title: Florida Entomologist
Physical Description: Serial
Creator: Florida Entomological Society
Publisher: Florida Entomological Society
Place of Publication: Winter Haven, Fla.
Publication Date: 1947
Copyright Date: 1917
Subject: Florida Entomological Society
Entomology -- Periodicals
Insects -- Florida
Insects -- Florida -- Periodicals
Insects -- Periodicals
 Record Information
Bibliographic ID: UF00098813
Volume ID: VID00242
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: Open Access

Full Text


Florida Entomologist
Official Organ of the Florida Entomological Society

VOL. XXIX JULY, 1947 Nos. 2, 3

United States Department of Agriculture, Agr. Res.. Adm., Bureau of
Entomology and Plant Quarantine

The Florida red scale is widely distributed over the world, especially
in tropical and subtropical regions. In the United States it has been found
in practically every State, but in the Northern States it occurs chiefly
on plants in greenhouses. In Florida, where it is the most abundant and
destructive, the distribution is general over the State, but the heaviest
infestations occur along the lower east coast, where the temperatures are
most favorable for continuous development. In the northern part of the
State, where citrus trees are occasionally defoliated by freezes, it is not
so abundant, and when a tree is defoliated, infestations may be practically

The Florida red scale (Chrysomphalus aonidum (L.)) was
first described in 1758 by Linn6 (5) under the name Coccus
aonidum from specimens collected in India. He gave nonde-
ciduous trees as hosts and mentioned Camellia specifically. In
1879 Ashmead (1) received citrus leaves infested with the Flor-
ida red scale in a letter from Orlando, Fla. He sent some of
these to C. V. Riley, then entomologist of the Department of
Agriculture in Washington, who gave the manuscript name
Chrysomphalus ficus to the species, and informed Ashmead that
the insect had been collected previously from Ficus nitida, now
F. retusa, but that he had published no description of it. Ash-

1Acknowledgments are due Herbert Spencer for planning the first
methods of study and assisting in the collecting of historical data, Max
R. Osburn for advice and suggestions throughout the work, and F. M.
Wadley for assistance in presenting the statistical data.


VOL. XXIX JULY, 1947 Nos. 2, 3



Executive Committee 1. C. MILLRI


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VOL. XXIX No. 2, 3

mead described the eggs, the crawling larvae, and the covering
of the female from additional specimens from Florida, and re-
corded his correspondent's remedy of strong salt water applied
just before the growing season, which was an effective control,
since it caused defoliation of infested (and uninfested) leaves.
There is no reference in the paper to the earlier description by
Linn6, and it was probably overlooked by Riley and Ashmead.
In 1880 Comstock (3) added many details to the Ashmead
description and gave the microscopic characters from the last
abdominal segment of the mature female and a drawing of the
pygidial fringe. His characters for the male and its scale cover-
ing are excellent, and he gave useful drawings of infested orange
leaves, male and female scales, newly hatched larvae, and the
formation of the dorsal scale over a newly settled larva. He
reared the insect through five generations on potted orange
plants in Washington, D. C., and from his work surmised that in
Florida there would be at least six generations per year. After
thorough searches in orange groves of California and Florida, he
found this scale present at that time only in the Florida grove
near Orlando, from which specimens had been sent to Ashmead,
and he traced this infestation to the shipment of a sour orange
tree from Havana, Cuba, in 1874. The conclusion of his paper
was prophetic: "The species is certainly one that is greatly to
be feared, and there is no doubt that it would be a good invest-
ment for the orange growers of Florida to eradicate the pest,
even if in doing so it is found necessary to purchase and destroy
all infested trees. This could be done now easily, but if delayed
a few years the species will doubtless become permanently es-
tablished." In a short paper in 1881 Comstock (2) called attention
to the differences between the Florida red scale and the Califor-
nia red scale, which he described as Aspidiotus citri, now
Aonidiella aurantii (Mask.). He stated that the species Chry-
somphalus ficus (Riley MS) Ashmead was simply an Aspidiotus
and should be called Aspidiotus ficus, and that it was not present
in California. Comstock (3) stated that up to 1883 he had
obtained specimens only from Cuba and Florida, and in this
paper referred the species to the genus Aspidiotus Bouch6.
Although the Florida red scale has been present in Florida
for more than 60 years, very little has been published on its
biology in this state. The economic importance of this scale has
increased in recent years, especially on the lower east coast,


and studies on its biology were conducted at St. Lucie, Fla., from
1939 to 1943, in order to be better able to investigate control

Methods of Spread:
In investigations conducted at St. Lucie, settled larvae were found
as far as 19 inches from the .mother scale on a citrus tree, and the crawlers
probably could have traveled farther, if necessary, to find a suitable place
for settling. They may also be distributed within a tree by being blown
from leaf to leaf. It is doubtful, however, whether many that fall to the
ground get back to the tree through their own locomotion. Other insects
may aid in the distribution of the crawlers, but ants probably have less
to do with the distribution of this scale than they do with some other
insects, since no honeydew is secreted by the scales to attract the ants.
Heavily infested leaves that fall may be blown about in a grove, and low
branches that come in contact with the ground may be a source of infesta-
tion. Scales may also be distributed on infested host plants that are car-
ried into uninfested areas, and on equipment that is moved from grove
to grove.
In Florida this species is classed as one of the most destructive pests
of citrus (8, p.5) and it also infests many other plants. On citrus, after
a Florida red scale has been on a leaf for some time, a yellow spot
appears under the scale, and as the infestation increases the entire leaf
turns yellow. Heavily infested leaves eventually fall, and a severe in-
festation will almost defoliate a tree, lowering the vitality and the yield
of the fruit. Fruits infested with this species have an unattractive ap-
pearance, inasmuch as the contrast in color makes the scales very notice-
able, and infested fruits do not color uniformly. This results in a lowering
of the grade and a reduction in returns to the grower. Heavily infested
fruits are sometimes refused at canning plants, because of the difficulty of
removing the scales during washing, and the possibility of their being
incorporated into the finished product.


Records of occurrence of the Florida red scale in Florida
were made available by G. B. Merrill, entomologist of the State
Plant Board. In the preparation of the following host list from
these records, valuable assistance in classification was given by
Mr. Merrill and Erdman West, mycologist at the Florida Agri-
cultural Experiment Station.

Acacia sp. (Leguminosae) Acacia
Acrocomia sp. (Palmaceae) Acrocomia palm
Agave sp. (Amaryllidaceae) Agave
Agave americana L. (Amaryllidaceae) Centuryplant

VOL. XXIX No. 2, 3

SCIENTIFIC NAME (Species and Family)


Aleurites moluccana Willd. (Euphorbiaceae) Candlenut-tree
Allamanda sp. (Apocynaceae) Allamanda
Aloe sp. (Liliaceae) Aloe
Aloe vera L. (Liliaceae) True, or Barbados aloe
Annona sp. (Annonaceae) Annona hybrid
Annona muricata L. (Annonaceae) Soursop
Annona squamosa L. (Annonaceae) Sugar-apple
Aralia sp.- (Araliaceae) Aralia
Araucaria araucana Koch. (Pinaceae) Monkeypuzzle tree
Archontophoenix sp. (Palmaceae) Archontophoenix palm
Archontophoenix cunninghamiana Wendl. & Drude
(Palmaceae) Seaforthia palm
Ardisia sp. (Myrsinaceae) Ardisia
Areca aliciae Muel. (Palmaceae)
Areca madagascariensis Mart. (Palmaceae)
Areca triandra Roxbg. (Palmaceae)
Arecastrum romanzoffianum Becc. (Palmaceae) Plumy coconut palm
Artabotrys sp. (Annonaceae) Artabotrys
Artabotrys odoratissimus R. Br. (Annonaceae) Climbing ylang-ylang
Asparagus plumosus Baker (Liliaceae) Asparagus fern
Aspidistra sp. (Liliaceae) Aspidistra
Azalea spp. (Ericaceae) Azaleas
Balaka sp. (Palmaceae) Balaka palm
Bauhinia sp. (Leguminosae) Mountain ebony
Belamcanda chinensis DC (Iridaceae) Blackberry-lily
Bischofia sp. (Euphorbiaceae)
Bougainvillea sp. (Nyctaginaceae) Bougainvillea
Butia capitata decc. (Palmaceae) Pindo palm
Calophyllum inophyllum L. (Guttiferaceae) Kamini
Calycanthus sp. (Calycanthaceae)
Camellia spp. (Ternstroemiaceae) Camellias
Camellia japonica L. (Ternstroemiaceae) Camellia
Cananga odorata Hook. f. & Thors. (Annonaceae) Ylang-ylang
Canna sp. (Cannaceae) Canna
Carissa sp. (Apocynaceae)
Carya pecan Ascerts. & Graebn. (Juglandaceae) Pecan
Caryota sp. (Palmaceae) Fishtail palm
Casimiroa edulis Llave & Lex. (Rutaceae) White sapote
Castanospermum australe Cunn. (Leguminosae) Moreton Bay chestnut
Cassia sp. (Leguminosae)
Cedrela odorata L. (Meliaceae) West Indian cedar;
Spanish cedar
Ceiba pentandra Gaertn. (Bombacaceae) Silk-cotton tree
Chamaedorea sp. (Palmaceae) Chamaedorea palm
Chrysalidocarpus sp. (Palmaceae) Areca palm
Cinnamomum camphora Nees & Eberm. (Lauraceae) Camphor-tree
Cinnamomum zeylanicum Breyn. (Lauraceae) Cinnamon tree
Citrus aurantifolia (Christm.) Swingle (Rutaceae) Lime
Citrus aurantium L. (Rutaceae) Sour orange
Citrus grandis Osbeck (Rutaceae) Grapefruit
Citrus limonia Osbeck (Rutaceae) Lemon
Citrus mitis Blanco (Rutaceae) Calamondin
Citrus nobilis var. deliciosa (Tenore)
Swingle (Rutaceae) Tangerine
Citrus nobilis var. unshiu (Mak.) Swingle
(Rutaceae) Satsuma
Citrus sinensis (L.) Osbeck (Rutaceae) Orange
Coccolobis uvifera Jacq. (Polygonaceae) Seagrape
Cocos nucifera L. (Palmaceae) Coconut palm
Codiaeum sp. (Euphorbiaceae) Croton (ornamental)


SCIENTIFIC NAME (Species and Family)
Crotalaria sp. (Leguminosae)
Cycas circinalis L. (Cycadaceae)
Cycas revoluta Thunb. (Cycadaceae)
Dictyosperma sp. (Palmaceae)
Dictyosperma album Wendl. & Drude (Palmaceae)
Dictyosperma album var. rubrum (Palmaceae)
Dictyosperma alexandra (Palmaceae)
Diospyros kaki L. f. (Ebenaceae)
Dizygotheca elegantissima Vig. & Guill.
Dracaena sp. (Liliaceae)
Duranta sp. (Verbenaceae)
Elaeagnus sp. (Elaeagnaceae)
Elaeagnus angustifolia L. (Elaeagnaceae)
Epibaterium sp. (Menispermaceae)
Eriobotrya japonica Lindl. (Rosaceae)
Erythea armata Wats. (Palmaceae)
Eucalyptus sp. (Myrtaceae)
Eucalyptus rudis Endl. (Myrtaceae)
Eugenia sp. (Myrtaceae)
Eugenia jambos L. (Myrtaceae)
Eugenia uniflora L. (Myrtaceae)
Euonymus sp. (Celastraceae)
Euphorbia pulcherrima Willd. (Euphorbiaceae)
Ficus sp. (Moraceae)
Ficus benjamin L. (Moraceae)
Ficus elastica Roxb. (Moraceae)
Fortunella sp. (Rutaceae)
Gardenia sp. (Rubiaceae)
Gladiolus sp. (Iridaceae)
Glycosmis pentaphylla (Retz.) DC. (Rutaceae)
Gordonia lasianthus (L.) Ellis (Ternstroemiaceae)
Grevillea robusta Cunn. (Proteaceae)
Hedera sp. (Araliaceae)
Hedera canariensis Willd. (Araliaceae)
Hedera helix L. (Araliaceae)
Hibiscus sp. (Malvaceae)
Howea sp. (Palmaceae).
Hydriastele wendlandiana Wendl. & Drude
Hyophorbe sp. (Palmaceae)
Ilex spp. (Aquifoliaceae)
Illicium so. (Magnoliaceae)
Iris sp. (Iridaceae)
Ixora sp. (Rubiaceae)
Jasminum sp. (Oleaceae)
Jasminum humile L. (Oleaceae)
Jasminum primulinum Hemsl. (Oleaceae)
Jasminum pubescens Willd. (Oleaceae)
Jasminum sambac Soland (Oleaceae)
Lagerstroemia indica L. (Lythraceae)
Latania sp. (Palmaceae)
Laurus nobilis L. (Lauraceae)
Ligustrum sp. (Oleaceae)
Ligustrum lucidum Ait. (Oleaceae)
Lilium sp. (Liliaceae)
Lilium longiflorum Thunb. (Liliaceae)
Linum sp. (Linaceae)
Liriope sp. (Liliaceae)

Queen sago palm;
fern palm
Sago palm

Japanese persimmon

Coral bead
Desert gum
Rose apple

Weeping laurel
Rubber plant

Australian silk-oak
Algerian ivy
English ivy
Kentia palm

Hydriastele palm
Hyophorbe palm
White ixora

Arabian jasmine
Latania palm


White lily

VOL. XXIX No. 2, 3

SCIENTIFIC NAME (Species and Family)
Litchi chinensis Sonn. (Sapindaceae)
Livistona sp. (Palmaceae)
Livistona australis Mart. (Palmaceae)
Magnolia sp. (Magnoliaceae)
Magnolia soulangeana Soul (Magnoliaceae)
Magnolia virginiana L. (Magnoliaceae)
Mammea americana L. (Guttiferae)
Mangifera indica L. (Anacardiaceae)
Marantd sp. (Marantaceae)
Melaleuca leucadendra L. (Myrtaceae)
Meratia praecox Rehd. & Wils. (Calcycanthaceae)
Michelia fuscata Blume (Magnoliaceae)
Monstera deliciosa Leibm. (Araceae)
Moraea iridioides L. (Iridaceae)
Morus sp. (Moraceae)
Muehlenbeckia sp. (Polygonaceae)
Musa sp. (Musaceae)
Myrtus sp. (Myrtaceae)
Myrtus communis L. (Myrtaceae)
Nerium oleander L. (Apocynaceae)
Ochrosia parviflora Hemsl.
Olea sp. (Oleaceae)
Ophiopogon sp. (Liliaceae)
Osmanthus sp. (Oleaceae)
Osmanthus fragrans Lour. (Oleaceae)
Pachysandra sp. (Buxaceae)
Paurotis wrightii (Griseb. & Wendl.) (Palmaceae)
Persea sp. (Lauraceae)
Phoenix sp. (Palmaceae)
Phoenix canariensis Chaub. (Palmaceae)
Photinia serrulata Lindl. (Rosaceae)
Pittosporum sp. (Pittosporaceae)
Podocarpus sp. (Taxaceae)
Pritchardia sp. (Palmaceae)
Prunus spp. (Rosaceae)
Prunus caroliniana Ait. (Rosaceae)
Prunus laurocerasus L. (Rosaceae)
Psidium sp. (Myrtaceae)
Pyracantha sp. (Rosaceae)
Pyrus malus L. (Rosaceae)
Rapanea guianensis Aub. (Myrsinaceae)
Ravanela madagascariensis Gmel. (Musaceae)
Rosa sp. (Rosaceae)
Roscheria melanochoetes Wendl. (Palmaceae)
Roystonea regia 0. F. Cook (Palmaceae)
Sabal sp. (Palmaceae)
Sabal palmetto Lodd. (Palmaceae)
Schaefferia frutescens Jacq. (Celastraceae)
Scindapsus sp. (Araceae)
Senecio mikanioides Otto. (Compositae)
Serenoa repens Sm. (Palmaceae)
Severinia sp. (Rutaceae)
Spiraea sp. (Rosaceae)
Strelitzia sp. (Musaceae)
Syringa sp. (Oleaceae)
Tabernaemontana sp. (Apocynaceae)
Tamala sp. (Lauraceae)
Ternstroemia sp. (Ternstroemiaceae)
Thea sinensis L. (Ternstroemiaceae)
Thrinax sp. (Palmaceae)

Livistona palm


White bay
Mamey apple
Cajeput-tree; punk tree




European osmanthus

Phoenix palm
Canary date palm

Pritchardia palm
Cherry, plum

Royal palm
Palmetto, Sabal palm
Cabbage palmetto
German ivy
Saw palmetto

Tea plant
Thrinax palm


SCIENTIFIC NAME (Species and Family)
Trachelosperum sp. (Apocynaceae)
Trachelospermum jasminoides Lem. (Apocynaceae)
Trachycarpus fortune H. Wendl. (Palmaceae)
Trevesia palmata Vis. (Araliaceae)
Viburnum sp. (Caprifoliaceae)
Viburnum tinus L. (Caprifoliaceae)
Vinca major L. (Apocynaceae)
Washingtonia sp. (Palmaceae)
Wisteria sp. (Leguminosae)
Zamia sp. (Cycadaceae)
In addition to these host plants, the following
Lucie County:2

Bidens pilosa radiata Sch. Bip. (Compositae)
Carica papaya L. (Caricaceae)
Croton glandulosus L. (Euphorbiaceae)
Smilax tamnifolia Michx. (Liliaceae)

Fortunes palm;
windmill palm


Washingtonia palm

have been found in St.

Croton (wild)

The egg is oval in shape, lemon yellow in color, and has a smooth
chorion that is slightly sticky. The color remains about the same from the
time the egg is oviposited until it hatches. The first noticeable change in
the shape is a considerable flattening and widening, which occurs imme--
diately before hatching. One hundred eggs, measured before any change
in shape occurred, averaged 0.18 mm. in length and 0.10 mm. in width.

First Instar:
The active larva, or first instar, is bright yellow, broadly oval in out-
line, and widens toward the anterior end of the body. The antennae are
5-jointed, and two very short setae are found on the posterior end of the
body. One hundred active larvae averaged 0.20 mm. in length and 0.15
mm. in width. The dorsal scale of the settled larva is dark gray with a
white tip (the remains of the white cap) in the center. No change, except
growth, occurs in the body of the larva from the time it settles until the
first molt. As the larva enters the first molt, the body becomes tightly
stuck to the dorsal scale, the color of which changes to a light brown.

Second-Instar Female:
The larva sheds its legs, setae, and antennae during the first molt.
The upper portion of the cast skin is incorporated with the dorsal scale,
and the lower portion forms the first part of the very thin ventral scale.
The dorsal scale in this stage has two distinct rings, the inner one being
light brown and the outer one much darker. As in the first instar, the
body becomes tightly stuck to the dorsal scale immediately before the
second molt, and the color of the dorsal scale becomes reddish brown.

2 Identification of these plants was made by the Bureau of Plant
Industry, Soils, and Agricultural Engineering.

VOL. XXIX No. 2, 3 21

Adult Female:
The cast skin from the second molt of the female is incorporated with
the dorsal and ventral scales, as in the first molt. The dorsal scale is
circular and convex, and has three distinct rings. The innermost one,
which is nearly central, is light brown, the second is reddish brown, and
the third varies from a dark reddish brown to black, with a thin gray
margin. The third ring is wider than the other two combined. The meas-
urements of 100 dorsal scales averaged 2.1 mm. in diameter. Ferris
(4, SII-201) gives the following description of the female body:
"Length about 1.1 mm. Derm at full maturity membranous or at times
with very slight sclerotization in the cephalothoracic region. Pervivulvar
pores present in five groups of three to six pores in each. Pygidium short
and broad, the apex quite obtuse. Three pairs of well developed lobes
present, these all of about the same size and shape; fourth lobe indicated
merely by a rounded projection. Beyond the fourth lobe the margin is
sclerotized and is twice notched. Plates from the meson to the third lobe
all finely and evenly fimbriate at the apex, those beyond the third lobe of
a different form, the first two normally showing two large and somewhat
club-shaped processes, the third with one club and a varying number of
variously shaped fimbriations. Marginal scleroses or paraphyses distrib-
uted in the manner described for the genus, [From the description of the
genus by Ferris: (4, SII 198) 'Slender scleroses or paraphyses arise from
the bases of the median to third lobes and from the margin in the inter-
segmental areas . .'] there being none beyond the third lobe. Dorsal ducts
of the pygidium of two sizes. Three or four stout ducts arise from pores
between the median and second lobes and extend to about the center of
the pygidium. From near the bases of the third and fourth lobes there
extend zones of small pores from which arise long and slender ducts, the
anterior-most of which extend beyond the anterior margin of the pygidium.
These bundles of slender ducts are conspicuous features of the species.
In the zones of pores the striations of the derm tend to lie transversely.
A conspicuous, submarginal cluster of small, short ducts is present on
the dorsum of what is here considered to be the second abdominal segment,
other than these there being not more than one or two small ducts on any
segment anterior to the fifth. Thoracic spur well developed, acute,
sclerotized. Anal opening."
The body of the female decreases in size as the eggs are oviposited,
and if the oviposition period is completed, the remains of the body are
practically clear and very much shriveled.

Second-Instar Male Larva:
Under field conditions, no distinction can be made between the sexes
until 3 or 4 days after the first molt, when the second ring of growth,
which is in the process of being formed, becomes noticeably darker in the
male than in the female. As growth continues, the scale covering of the
male becomes more convex than that of the female. As the larva nears
the end of the second period of growth, purple eye spots are formed which
are retained through all the succeeding immature stages, eventually be-
coming eyes in the winged adult. The eye spots can hardly be seen at


first, but become very conspicuous as development continues. After they
are formed, the last external change occurs, in which a thin gray lip is
formed at the posterior end of the scale covering. The pygidial charac-
teristics and color are the same for the two sexes during this stage.

Male Prepupa:
After the second molt the male enters the prepupal stage. In this
stage the width of the body at the anterior, middle, and posterior parts
is almost the same, and the tip of the abdomen is very blunt, except for
two small spines. The color is about the same as that of the larva, and
by the time the growth for this stage is completed, the outlines of the
antennae and wings can be seen. One hundred prepupae averaged 0.62
mm. in length and 0.40 mm. in width.
Male Pupa:
The pupa has the general shape of the adult male, and the outlines
of the wings, antennae, style, and legs can be seen clearly. The color varies
from a bright yellow to a yellowish brown. One hundred pupae averaged
0.72 mm. in length.
Adult Male:
The adult male is a delicate, two-winged insect, light orange-yellow in
color, with a dark-brown band around the thorax, purplish-black eyes, and
vestigial mouth parts. The average length of the male, including the
style, was about 0.74 mm., and the wing expanse was 1.36 mm.

The Egg:
The eggs are deposited underneath the dorsal scale of the female,
where they remain until they hatch. Since no observations could be made
under natural conditions because of the dorsal scale, it was lifted from
females that were on fruits, and observations were made on those found
ovipositing. Females continued to oviposit for a time after the scale
covering was removed, and under this condition the eggs were laid in
chains, being lightly stuck together end to end. During the summer months
the rate of oviposition was fairly rapid, as 2 eggs were laid by a female
in 1 hour, and 334 crawlers were removed from an isolated female on a
fruit in a 51-day period.
The length of the incubation period at various temperatures was
determined from tests in which ovipositing females were held in a constant-
temperature cabinet. With one group of 70 eggs held at 90 F. the first
egg hatched in less than 1 hour; with a group of 37 eggs held at 800
the first egg hatched after 3 hours and the last one after 26 hours. The
last egg from a group of 14 held at a mean room temperature of 670
hatched after about 48 hours.
After the egg flattens, the covering splits at the anterior end, and the
larva gradually works the skin back over its body. During the summer
months the hatching is very rapid, and the larva may be seen crawling
before the cast skin is completely off, but during cool weather the crawler
may remain partially hatched for several days.

VOL. XXIX No. 2, 3 23

In order to determine the minimum and maximum temperatures at
which they would hatch, eggs that had been removed from ovipositing
females were held in groups of 50 at different constant temperatures and
left until some hatched or it was apparent that none would hatch. This
procedure was repeated until the highest and lowest points at which any
eggs hatched were reached. The minimum point was 530 1 F. Only
1 out of 50 eggs hatched at 107.5 2.5 F., and the larva died without
moving after casting its skin. Other eggs appeared to flatten, preparatory
to hatching, but never completed the process. No hatching*occurred from
a group of 50 eggs held at 110.50 1.5o, and after 24 hours the eggs
appeared to be shriveled.
The percentage of eggs that hatched was determined by removing
them from ovipositing females, placing them on filter paper in a petri
dish, and leaving them at room temperatures until they hatched or became
discolored. From these tests conducted during the winter and spring
months, 99 per cent of 980 eggs hatched. This high percentage of hatch-
ing was also borne out in the records taken under grove conditions, as
very few discolored eggs were found under females unless signs of predators
were noticed.

Active Larva:
The percentage of crawlers found alive under females ranged from 40
in March to 100 in June. In February and March, when the percentages
were lowest, many predaceous mites were found under the scales with
the dead crawlers. The lowest percentage of living crawlers found in any
of the other months was 78. In most cases where the female had ap-
parently completed its normal life cycle, large numbers of cast skins were
found, and all larvae had emerged or settled under the old scale covering.
One female was observed to have 14 immature scales under it. No accurate
method was found for determining what percentage of the crawlers under
an ovipositing female emerge. From the foregoing counts, however, the
indication is that the dorsal scale of the ovipositing female does not hinder
emergence, since very few females were found with large numbers of dead
crawlers under them unless some signs of predaceous enemies were
The distance traveled by active larvae was determined in tests made
in the screened insectary. Crawlers were placed on smooth paper and on
grapefruits, their movements were traced with a pencil, and the distances
traveled were measured with a map measure. From observations made
over 2-hour periods it was found that the average distance traveled by
six crawlers on smooth paper was 38 inches when the mean temperature
was 86 F., and by four crawlers, 20.6 inches at a mean temperature of 69'.
All crawlers were still alive at the end of the 2-hour periods. The dis-
tances five crawlers traveled on a grapefruit ranged from 1.5 to 9 inches,
and the time required before settling ranged from 15 minutes to 1 hour.
In an experiment where larvae were placed on dry sandy soil they
had great difficulty in traveling. Two hours was the minimum time ob-
served for a crawler to travel from the center to the edge of a 6-inch
circle of such soil. The minimum temperature at which crawlers made any


effort to move about was 55. Movement was very slow until the tempera-
ture reached 60.
The ability of a larva to live without food on slightly moistened filter
paper ranged from 6 to 13 days, as compared with 3 to 4 days on dry
filter paper. Crawlers that were transferred to leaves after living for
4 days on slightly moistened filter paper were able to settle, but those
kept on the paper longer were not. Living crawlers were found up to
the 25th day on leaves picked during the winter months and placed in
petri dishes without additional moisture. By this time all ovipositing
females had died and all eggs had hatched.
Observations made during this study indicated that crawlers will
settle as readily on leaves as on fruits, and will settle on leaves or fruits of
any age, with the exception of very immature fruits. Some scales were
found on green wood, but rarely unless the infestation was extremely heavy.
No scales were found on gray wood.
A larva, upon being placed on a leaf, usually moves over both the
upper and lower surfaces. After this activity has continued several min-
utes, it moves very slowly over a selected area and inserts its mouth
parts. The body moves considerably while the mouth parts are being
inserted. The first waxlike threads of the scale covering appear on the
posterior end of the body, and as they are being secreted the body is
slowly rotated, the mouth parts being used as a pivot, until it is turned
completely around, and then the movement is retraced. About 30 minutes
is required for a scale to make a turn of 3600. This rotating continues as
long as the body can be seen. During the movement some contractions of
the body and movement of the legs are visible. The first waxy covering
is easily removed; from one scale six coverings were removed as soon as
each was completed, before the scale died. After the larva is completely
covered with the wax, it is considered to be in the white-cap stage. At
this stage the covering is round and the sides are vertical. A thin gray
ring is then formed around this central nipple. From data secured during
the summer months, when the temperature ranged from 72 to 910 F.,
the average time from emergence to settling was 95 minutes, from set-
tling until the white-cap stage was 100 minutes, and the time spent in
the white-cap stage was 21 hours and 20 minutes.
Data on the percentage of the crawlers that settled were obtained
by placing eggs in gelatin cylinders on fruits at room temperatures and
leaving them until they hatched and the crawlers settled. Under these
conditions 76.5 percent settled of 443 larvae that were observed. Wind,
rain, predaceous enemies, and extreme temperatures are some of the hazards
encountered in settling under grove conditions.

First Instar:
Artificial infestations were started in 1939 for a study on the length
of time the scale spends in each instar under grove conditions. The in-
festations were made by fastening leaves heavily infested with the Florida
red scale to uninfested leaves and fruits. In warm weather many crawlers
had transferred to the clean surfaces within 2 days, and the leaves that
were the source of infestation were removed; in cool weather the leaves

VOL. XXIX No. 2, 3 25

were left on for about 4 days. The newly settled larvae were then circled
with India ink for identification. Each individual was examined every 2
days when possible, and its stage of development recorded. A hygrothermo-
graph was operated in the screened insectary in the grove for temperature
and humidity records during this study, and the data on the duration of
each stage of development were correlated with temperature.
During the first part of this work new infestations were started
monthly, but later they were started twice each month to obtain more
data. In the 64 infestations made over a 3-year period 12,603 scales were
marked for study, but only 4,942 completed the first instar. Some were
removed for microscopic examinations, and some were destroyed by
premature dropping of leaves from frequent handling. When these had
been deducted, mortality in the remaining larvae ranged from 76 percent
in December to 37 percent in September.
From data from these infestations it was possible to calculate the
effect of seasonal variations in temperature upon duration of development
of the first instar. The time required for development for each infestation
was inverted to obtain the rate of development. These rates were cor-
related with the temperature, the regression equation being Y = -75.6246
+ 1.6633X, and the correlation coefficient r = 0.9526. The rates esti-
mated from the regression equation were inverted to give estimated times
of development which, when plotted, gave a smooth hyperbolic curve
(Fig. 1).
The length of the instar was calculated from the time the infestation
was made until the scale was considered to be through the first molt.



o 35

20 .3

15 .2

10 h Z d7

Figure 1.-Relation between temperature and the time required for
development of the first instar of the Florida red scale.


Considerable variation in development occurred at the same temperatures,
but many factors could have caused this. The time required for comple-
tion of the instar ranged from 46 days at 590 F. to 15 days at 820. The
optimum temperature for development was between 78 and 830, but there
was little difference in the rate of development between these points,
although below 780 the time required for development was increased.

Second-Instar Female:
After the scales had completed the first molt, examinations were
continued to determine the length of the second instar. From these in-
festations 3,325 females were observed, of which 877 completed the second
instar. Owing to the high mortality from November through March,
female scales were able to complete the second instar in only 51 of 64
infestations. The development of the male and female differs after the
first instar, and data on only the females are included in Figure 2, which
gives the number of days required for the completion of the second instar
correlated with the mean temperatures for the period. The curved line
represents the expected time required for completion of the instar at any
given mean temperature between 610 and 830 F. This line was plotted in
the same way as the one for the first instar, the regression equation in this
case being Y -101.1596 + 2.1046X and the correlation coefficient r= 0.9258.

4 .2

10 25
60 62 64 66 68 70 72 74 76 78 80 82

Figure 2.-Relation between temperature and the time required for
development of the second instar of the female Florida red scale.

The length of the instar ranged from 36 days at 610 F. to 11 days at
810. The variation between the actual number of days recorded and the
expected number of days was not so great in this instar as it was in the
first. As in the first instar, the optimum temperature for development
was between 780 and 83. It was found that temperature affected the
development of the second instar less than it did the first, and that the
greatest difference in time occurred at 69.

VOL. XXIX No. 2, 3

The natural mortality during each month, computed as for the first
instar, ranged from 96 percent in March to 51 percent in September.
It varied considerably from month to month, but was obviously higher
during the winter months. Natural mortality was unusually high in the
grove where the work was conducted. From infestations made in the fall
and winter months, when the parasites were the most effective, very few
of the marked scales reached maturity.
During January, February, and March 1942, examinations were made
to secure additional information on the number of parasitized second-
instar females. Each month 50 leaves picked at random from 10 trees in
the laboratory grove were examined under a binocular microscope. Of
5,039 second-instar females examined, 40, 50, and 55 percent were found
with parasites in the respective months. The percentage of living scales
ranged from 13 in January to 3 in March. A scale was considered to be
parasitized if the parasite's body or any portion of it was found in the
scale's body, or if the dorsal scale showed the characteristic round emer-
gence hole with the shell-like body of the scale under it. Most such females
had entered the second molt before the parasite had developed enough to
kill them, and very few ever completed the molt.

Adult Female:
Very little definite proof has been obtained on how or when fertiliza-
tion occurs, but it is believed to occur at night shortly after the female
completes the second molt, as the males of the same age emerge at this
time. Inasmuch as Schweig and Grunberg (6) proved that fertilization
by the male is necessary for reproduction, no experiments were made along
this line, although additional evidence was obtained in a few cases when
females isolated for reproduction records failed to reproduce, evidently
having been isolated before fertilization occurred. The time from the
completion of the second molt until the first eggs were deposited ranged
from 2 to 4 weeks; the oviposition period ranged from 1 to 8 weeks.
Reproduction records were obtained in a screened insectary from
adult females isolated in gelatin cylinders on leaves of potted citrus plants
and on fruits picked from trees in the grove. If crawlers or settled larvae
were found in a cylinder within 3 days after isolation in summer, or
within 5 days in winter, the female was discarded because of the pos-
sibility that it was already reproducing when isolated. The remaining
cylinders were examined at intervals, and all newly settled scales or active
larvae were counted and removed. When no crawlers were found in a
cylinder for several days, the female scale was turned over, and the
number of scales that had settled under it was recorded. In this way the
total number of crawlers produced by each female was obtained.
The number of crawlers produced by each of 30 females on fruits
ranged from 32 to 334, with an average of 145; the number produced by
25 females isolated on leaves ranged from 21 to 156, with an average of
80. Not only did the females isolated on fruits produce more young than
did those on leaves, but they did so in a shorter period of time. The total
number of crawlers produced was the same in cool and warm weather.
The minimum time from infestation to oviposition was 45 days and the


maximum was 153, the latter occurring during abnormally low tempera-
tures. Very few of the females deposited all their eggs, as some could
still be seen in their bodies after death.

Immature Stages of the Male:
Inasmuch as temperature proved to be the main factor that determined
the rate of development of the immature stages of the female, it was
assumed that the same would be true of the male scale. However, one
infestation was made in 1940 to secure data on the changes that occur
in the male and on the time required for the completion of each change.
On August 3, 840 scales on the upper surfaces of leaves were marked for
identification. Every 2 to 4 days after the first molt was completed
about 15 males were examined to determine the stage of development.
It was found that about 5 days after completion of the first molt the
eye spots could be seen, 5 additional days were required for the lip to be
formed on the dorsal scale, and after 3 more days the prepupal stage was
reached. The prepupal and pupal stages so overlapped that it was diffi-
cult to determine their length, but each is very short, as winged adults
were found 15 days after completion of the first molt. The body of the
male does not stick to the dorsal scale in any molt except the first, and
the cast skins of the second, third, and fourth molts are pushed out under
the lip of the dorsal scale.

Adult Male:
To determine the duration of the developmental period of the male -
that is, the time from artificial infestation to the end of the pupal stage -
the dorsal scales of many individuals were carefully removed. When a
winged adult was found, the time from infestation to that date was cal-
culated. If prepupae or pupae were found, they were placed in petri
dishes on moistened filter paper to complete their transformation into
winged adult males, and then the number of days from infestation to
the time the last molt was completed was calculated. The time required
for development was correlated with the mean temperature for each ii-
festation (Fig. 3). The curved line, which represents the estimated rate of
growth, was calculated as for the first- and second-instar females, the
regression equation in this case being Y = -49.2057 + 1.0164X, and the
correlation coefficient r 0.9798. In the examinations 106 winged males
were found, and the period of development ranged from 78 days at 610 F.
to 28 days at 83.
Some variation in the rate of development at the same temperature
occurred, but this was expected as the numbers were small and the dates
on which males were found could have been either the earliest or latest
days for completion of development and not the average. It was found,
however, that the calculated rate of development of the male corresponded
closely with the calculated time required for the female to complete the
second molt at the same temperatures. At no temperature was the varia-
tion greater than 3 days. After a male emerges, its life is very short,
as no food is taken. The longest period that one was kept alive was
4 days.

VOL. XXIX No. 2, 3

TE R A T U R .
Figure 3.-Relation between temperature and the time required for the
development of the male Florida red scale.

Number of Generations a Year:
To determine whether an adult female has reached the ovipositing
period, the dorsal scale must be lifted. After females of the artificial
infestations reached the adult stage, such examinations were made at
irregular intervals, and when a female that had apparently just entered
the oviposition period was found, the time that had elapsed since the in-
festation date was recorded. It was found that five or six generations
would occur over a period of 12 months at a mean temperature of 740 F.
Schweig and Grunberg (6) state that three to four generations were pro-
duced in Palestine at a mean yearly temperature of 19.30 C. (670 F.) and
five generations at a mean temperature of 22.50 C. (730 F.).
Ratio of Males to Females:
Each month when the seasonal-history counts discussed in the fol-
lowing section were made, the males and females were recorded separate-


ly if their development had reached a point where the sexes could be
distinguished. Of the 15,738 scales so recorded during a 12-month period,
59 percent were females, the range being from 52 to 68 percent.
Distribution of Males and Females on Leaf Surfaces:
From the same seasonal-history counts records were also kept of the
numbers of males and females found on the upper and lower surfaces of
the leaves. It was found that 96 percent of the males and 13 percent
of the females were on the upper side of the leaves. It was thought that
light or gravity might be factors influencing this distribution. If this were
true, scales that settle in the absence of light should have an equal
distribution. In the case of gravity, the distribution of the sex should be
reversed if the leaf surfaces wete reversed.
To determine the influence of absence of light on the distribution,
infestations were made on potted citrus plants in a photographic dark room
by clipping infested leaves onto the clean leaves of the plants, just as
was done in making the artificial infestations in the grove. Several days
later the clipped-on leaves were removed, but the plants were left in the
dark for an additional day to give all the crawlers time to settle before the
plants were removed from the dark room. The scales were then allowed
to develop until their sex could be determined, and counts were made
of the males and females on the upper and lower surfaces of the leaves.
To determine the effect of gravity on the distribution, potted citrus plants
were suspended in an inverted position and infested. Table 1 gives the
results of these experiments.


Males Females
Date of Infestation (Percent) (Percent)

In the Absence of Light

77 68
78 35


On Inverted Plants, to Test Effect of Gravity



VOL. XXIX No. 2, 3 31

In the experiments in which the crawlers settled in the absence of
light, the females were evenly distributed between the two surfaces,
whereas 76 percent of the males settled on the upper leaf surfaces. In
the experiments to determine the effect of gravity, a fairly even distribu-
tion was secured for each sex. The experiments indicated that light is
one of the most important factors influencing the distribution of the
females, but no definite indications were secured for the male although,
while it seems that both light and gravity affect their distribution, evi-
dently other factors also exert influence.

Once each month from April 1942 through March 1943 a sample of
5 leaves was picked at random from each of 80 orange trees, and the
numbers of scales in each stage were recorded. Table 2 gives the number
of living scales and of ovipositing females found at each examination.


De of En Number of Scales on 400 Leaves
Date of Examination
Living Ovipositing


The number of living scales appears to be unusually high in April,
but no explanation can be given for this. The number decreased in May
and June, and this is believed to have been caused partially by the falling
of the old, infested leaves. In June it was impossible to secure a ran-
domized sample of fully matured leaves, because there was so much new
growth, and probably the distribution of the scales was not general over
the new growth. The number of living scales increased from June to
September, when the peak was reached, and thereafter decreased each
The number of ovipositing females followed the same trend as the
number of living scales, except that the peak was reached in August.
The percentage of parasitized scales was calculated from the number
of settled scales, exclusive of those in the first instar, since only two first-
instar scales were found with visible parasites in them. The percentage of


parasitized scales ranged from 7.4 in August, to 20.0 in November. The
percentage of parasitization was also calculated separately for the males,
for second-instar females, and for third-instar females. More males were
parasitized than either instar of the females, 32.5 percent in November.
Very few third-instar females were found with parasites, the highest para-
sitization being 5.6 per cent in February.

Cultural Practices:
In recent years it has been the opinion of many investigators that the
general condition of a grove influences the abundance of scales. Schweig
and Grunberg (6) reported that a grove well supplied with water and
fertilizer was likely to have a heavier infestation of scales than a poorly
kept grove. Thompson (7) reported that populations of the purple scale
were higher in groves in which the mineral deficiencies had been cor-
rected, as more green leaves were produced and were retained longer.
Results of preliminary work at this laboratory seem to support these
statements. In 1942 a comparison was made of Florida red scale infesta-
tions found on citrus trees growing in areas which were clean cultivated
or contained a cover crop. The experimental arrangement consisted of 8
plots, each approximately 6 trees by 14 trees. Half of these plots were
disked at intervals to keep them clean of all vegetation, and in the other
half a cover crop was maintained and no cultivating was done. The first
cultivating was done in March and the last in September. At monthly in-
tervals from April through December, 200 leaves from each treatment were
examined for scale infestations. Only the living, settled scales were used
in comparing the infestations in the two treatments. The results of these
examinations are summarized in table 3.


Month Average Number of Living Scales per Leaf
Cultivated Plots Cover-Crop Plots


In April the average number of scales per leaf was practically the
same in the two treatments, being only slightly higher in the cover-crop
plots. In May and for the remainder of the year the average was slightly
higher in the cultivated plots. When the data were analyzed statistically,

VOL. XXIX No. 2, 3

it was found that the treatments were significantly different only in De-
cember, despite the fact that the greatest difference in the average number
of living scales per leaf occurred in October.
The differences in the infestations from the two treatments on the
same dates are believed to be due to the physical condition of the trees.
In July, after the trees in the cultivated treatment had been disked three
times, the difference in the appearance of the trees in the two treatments
was apparent, as those in the cultivated areas had much greener leaves and
much more flush growth than those growing in the cover-crop areas.
Immediately after a period of low temperatures in January 1940,
examinations were made of scales in two groves, one where the tempera-
ture was freezing or below for three nights in succession with a minimum
temperature of 27.50 F., and the other where the temperature was freezing
or below for five nights in succession with a minimum temperature of 23.
All examinations were made from leaves, and only third-instar females
that were alive or that appeared to have died recently, -supposedly from
the cold, were included.
From the count of 506 adult females from the first grove 68 percent
were killed, and from the second grove 84 percent of the 510 examined
were killed. Others (9) stated that 94 percent of the Florida red scales
examined on a camphor tree at a minimum temperature of 22 in 1917
were killed. In 1934, with the same minimum temperature, Yothers and
Osburn (10) found that approximately 70 percent of the mature females
were killed on grapefruit fruit, slightly more on oranges, and 94 on grape-
fruit foliage.
A tropical storm on August 11, 1939, with 60-mile winds and 2 inches
of rain in 24 hours, eliminated 90 percent of a lot of 178 scales that had
settled and been marked the week before. Many crawlers that had emerged
but had not settled were undoubtedly destroyed by wind and rain.

Parasites and Predators:
The following parasites and predators of the Florida red scale were
collected in St. Lucie County during the period of this study: Aspidiotipha-
gus lounsburyi (Berl. and Paoli), Chilocorus stigma (Say.), Chrysopa
lateralis Guerin, and Hemisarcoptes malus (Shimer).3
Pseudhomalapoda prima Gir.4 was collected in Orlando, Fla. Only the
first two are of any importance. Aspidiotiphagus lounsburyi, a hymen-
opterous parasite, is abundant in some groves during the fall and winter
months. It seems to attack only the immature stages of the scale, espe-
cially those of the male and the second instar of the female. Only a few
mature females have been found parasitized by this or any other species.
Chilocorus stigma, the twice-stabbed ladybeetle, is also numerous in some
groves during the latter part of the winter, and both the larvae and adults

SDetermined, respectively, by A. B. Gahan, E. A. Chapin, A. B.
Gurney, and H. E. Ewing, all of the Bureau of Entomology and Plant
4 Determined by A. B. Gahan.


feed on all stages of the Florida red scale. When this ladybeetle cannot
pull the covering off the scale, it chews a hole through the dorsal scale and
devours the body.
The larva of Chrysopa lateralis is a voracious feeder. One larva was
fed 12 mature females in 1 hour. It pulls at the dorsal scale until it is
loose, and then inserts its mandibles under the scale. Hemisarcoptes malus
is a predaceous mite that is occasionally found under mature female scales.
When this mite is found under an ovipositing female, many dead crawlers
are usually present. Watson and Berger (8) state that the larvae and es-
pecially the crawlers are preyed upon by ladybeetles and aphislions and
that the scale is destroyed by Epitragodes tomentosus (Lec.) and trash
Several other insects undoubtedly feed on crawlers and newly settled
larvae, but not enough control is exerted by the entire group to be depended
upon alone, for they usually appear after the scales have reached their
peak and have done most of their damage.

Other Factors:
Some natural control is secured when the fruit that is infested is
picked, and also by the falling of the old, infested leaves.

The Florida red scale (Chrysomphalus aonidum (L.)) has become one
of the most destructive pests of citrus in the State. In St. Lucie County
this scale continues its development throughout the year, and all stages
can be found at any time. Temperature is the main factor that determines
the rate of development.
Eggs are deposited under the dorsal scale, and the crawlers emerge
and settle on fruits and leaves in a short time during the warmest seasons.
When heavy infestations occur, the vitality of the trees and the yield and
grade of the fruit are lowered.
Two molts occur in the development of the female and four in the
male. The time required to complete these molts, at mean temperatures of
830 to 61 F., ranged from 28 to 78 days for the male and from 26 to 76
days for the female. Fertilization of the female, which is necessary for
reproduction, is believed to occur shortly after completion of the second
molt. The females on fruits produce more young than those on leaves,
and five or six generations occur each year, the development for a genera-
tion requiring from 45 to 153 days in the tests conducted.
Of the scales found on leaves, 59 percent were females, and 96 per-
cent of the males and 13 percent of the females were found on the upper
surfaces. Gravity and light seem to be predominating factors affecting this
distribution, gravity having the greatest effect on the males, and light on
the females.
The largest number of ovipositing females was found in August, and
the peak of living scales (all stages) was reached in September. The
lowest for each was found in March. Preliminary work indicated that the
physical condition of the trees influences the scale population, and that
trees in the best physical condition are likely to have the most scales.

VOL. XXIX No. 2, 3

Parasites and predators were most effective during the winter months.
Only one parasite, Aspidiotiphagus lounsburyi (Berl. and Paoli), was
found in any numbers, and it usually attacked the immature stages.
The most abundant predator was Chilocorus stigma (Say.), of which both
the larvae and adults fed on the scales. However, neither the parasites
nor the predators gave effective control, for they were most abundant after
the peak of scale infestation had occurred and most of the damage had
been done.

(1) ASHMEAD, W. H. 1880. On the red or circular scale of the orange
(Chrysomphalus ficus Riley ms.). Amer. Ent. 3:267-269.
(2) COMSTOCK, J. H. 1881. Notes on Coccidae. Canad. Ent. 13:8-9.
(3) COMSTOCK, J. H. 1880. Report on scale insects. In Report of U. S.
Commissioner of Agriculture, 1880, pp. 276-349. Reprinted in 1916,
N. Y. (Cornell) Agr. Expt. Sta. Bul. 372:425-603, illus.
(4) FERRIS, G. F. 1938. Atlas of the scale insects of North America.
Chrysomphalus, Ashmead, S. 11-198. Chrysomphalus ficus Ashmead,
S. 11-201. Stanford University, California.
(5) LINNE, C. 1758. System naturae, regnum animal. Ed. 10, p. 455.
(6) SCHWEIG, C., and GRUNBERG, A. 1936 The problem of the black
scale (Chrysomphalus ficus Ashm.) in Palestine. Bul. Ent. Res.
(7) THOMPSON, W. L. 1939. Cultural practices and their influence upon
citrus pests. Jour. Econ. Ent. 32:782-789.
(8) WATSON, J. R., and BERGER, E. W. 1937. Citrus insects and their
control. Fla. Agr. Ext. Serv. Bul. 88, 135 pp., illus.
(9) YOTHERS, W. W. 1917. The effects of the freeze of February 2-4,
1917, on the insect pests and mites on citrus. Fla. Buggist 1: 30-35,
(10) YOTHERS, W. W., and OSBURN, M. R. 1935. The effects of the
freeze of December 12 and 13 on citrus pests in Florida. Fla. State
Hort. Soc. Ann. Proc. 48: 122-126.


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