Group Title: Bulletin
Title: The Purple scale
Full Citation
Permanent Link:
 Material Information
Title: The Purple scale
Physical Description: 3 p., p. 319-340 : ill., maps ; 23 cm.
Language: English
Creator: Quayle, H. J ( Henry Josef ), 1876-
Donor: unknown ( endowment )
Publisher: Agricultural Experiment Station, University of California
Place of Publication: Berkeley, Cal.
Publication Date: 1912
Subject: Scale insects   ( lcsh )
Citrus -- Diseases and pests   ( lcsh )
Genre: bibliography   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 339-340).
General Note: Cover title.
General Note: At head of title: University of California publications. College of Agriculture. Agricultural Experiment Station.
General Note: University of California Agricultural Experiment Station no. 226
Statement of Responsibility: by H.J. Quayle.
 Record Information
Bibliographic ID: UF00095571
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: oclc - 14051194
lccn - a 34001018

Full Text




(Berkeley, Cal.)


BENJAMIN IDE WHEELER, President of the University.
E. J. WICKSON, M.A., Director and Horticulturist.
E. W. HILGARD, Ph.D., LL.D., Chemist (Emeritus).
W. A. SETCHELL, Ph.D., Botanist
LEROY ANDERSON, Ph.D., Dairy Industry and Superintendent University Farm Schools.
M. E. JAFFA, M.S., Nutrition Expert.
R. H. LOUGHRIDGE, Ph.D., Soil Chemist and Physicist (Emeritus).
C. W. WOODWORTH, M.S., Entomologist.
RALPH E. SMITH, B.S., Plant Pathologist and Superintendent of Southern California
Pathological Laboratory and Experiment Station.
G. W. SHAW, M.A., Ph.D., Experiment Agronomist and Agricultural Technologist, in
charge of Cereal Stations.
E. W. MAJOR, B.Agr., Animal Industry.
B. A. ETCHEVERRY, B.S., Irrigation Expert.
F. T. BIOLETTI, B.S., Viticulturist.
W. T. CLARKE, B.S., Assistant Horticulturist and Superintendent of University Exten-
sion in Agriculture.
JOHN S. BURD, B.S., Chemist, in charge of Fertilizer Control.
J. E. COIT, Ph.D., Assistant Pomologist, Plant Disease Laboratory, Whittier.
GEORGE E. COLBY, M.S., Chemist (Fruits, Waters, and Insecticides), in charge of
Chemical Laboratory.
H. J. QUAYLE, M.S., Assistant Entomologist, Plant Disease Laboratory, Whittier.
H. M. HALL, Ph.D., Assistant Botanist.
C. M. HARING, D.V.M., Assistant Veterinarian and Bacteriologist.
E. B. BABCOCK, B.S., Assistant Agricultural Education.
W. B. HERMS. M.A., Assistant Entomologist.
J. H. NORTON, M.S., Assistant Chemist, in charge of Citrus Experiment Station, River-
W. T. HORNE, B.S., Assistant Plant Pathologist.
C. B. LIPMAN, Ph.D., Soil Chemist and Bacteriologist.
R. E. MANSELL, Assistant Horticulturist, in charge of Central Station grounds.
A. J. GAUMNITZ, Assistant Agronomist, University Farm, Davis.
N. D. INGHAM, B.S., Assistant in Sylviculture, Santa Monica.
T. F. HUNT, B.S., Assistant Plant Pathologist.
P. L. McCREARY, B.S., Chemist in Fertilizer Control.
E. H. HAGEMANN, Assistant in Dairying, Davis.
R. M. ROBERTS, Farm Manager, University Farm, Davis.
B. S. BROWN, B.S.A., Assistant Horticulturist, University Farm, Davis.
J. I. THOMPSON, B.S., Assistant Animal Industry, Davis.
J. C. BRIDWELL, B.S., Assistant Entomologist.
L. BONNET, Assistant Viticulturist.
F. C. H. FLOSSFEDER, Assistant in Viticulture, University Farm, Davis.
P. L. HIBBARD, B.S., Assistant Fertilizer Control Laboratory.
F. E. JOHNSON, B.L., M.S., Assistant Soil Chemist.
C. H. McCHARLES, M.S., Assistant Agricultural Chemical Laboratory.
B. A. MADSON, B.S.A., Assistant Experimental Agronomist.
HOWARD PHILLIPS, B.S., Assistant Animal Industry, Davis.
WALTER E. PACKARD, M.S., Field Assistant Imperial Valley Investigation, El Centro.
L. M. DAVIs, B.S., Assistant in Dairy Husbandry, University Farm, Davis.
S. S. ROGERS, B.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier.
H. A. RUEHE, B.S.A., Assistant in Dairy Husbandry, University Farm, Davis.
C. O. SMITH, M.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier.
E. H. SMITH, M.S., Assistant Plant Pathologist.
C. L. ROADHOUSE, D.V.M., Assistant in Veterinary Science.
F. M. HAYES, D.V.M., Assistant Veterinarian.
M. E. STOVER, B.S., Assistant in Agricultural Chemical Laboratory.
W. H. VOLCK, Field Assistant in Entomology, Watsonville.
E. L. MORRIS, Field Assistant in Entomology, San Jose.
E. E. THOMAS, B.S., Assistant Chemist, Plant Disease Laboratory, Whittier.
A. B. SHAW, B.S., Assistant in Entomology.
G. P. GRAY, M.S., Chemist in Insecticides.
H. D. YOUNG, B.S., Assistant in Agricultural Chemistry, Plant Disease Laboratory,
A. R. TYLER, B.S., Assistant in Plant Pathology, Plant Disease Laboratory, Whittier.
E. W. RUST, A.B., Assistant in Entomology, Plant Disease Laboratory, Whittier.
L. T. SHARP, B.S., Assistant in Soils.
W. W. CRUESS, B.S., Assistant in Zymology.
J. F. MITCHELL, D.V.M., Assistant in Veterinary Laboratory.
W. B. BOYS, Assistant Cerealist.
ANNA M. LUTE, Scientific Assistant, United States Department bf Agriculture.
J. C. ROPER, Patron, University Forestry Station, Chico.
E. C. MILLER, Foreman, Forestry Station, Chico.
D. L. BUNNELL, Secretary to Director.



DISTRIBUTION ----------._-
OVER WORLD ----__--___..
IN CALIFORNIA _________________.


FOOD PLANTS __---__________. -

THE EGG _____________________
THE PROPUPA -__--._----
THE PUPA ----.............
THE ADULT MALE -- ---- ______-- -
THE ADULT FEMALE ___-________

THE EGG _--------
THE ACTIVE LARVA _--_-__.. --
SETTLING _-_- ---_-__----





_____ __ ___ 319
___ 319

_-__ ___ ______ 321
..-------.--- 321
.__ _____________ 321

1 --- - - -- 323
---.______ _.___-_ 326
.--___--.._-__ 326
---__-_ -__ 320
_-----__- ___. 326
.-----_ -_._-_-_ 328
---- -__-_-_- ..._ 320
.-- --. ----_-. -. 328
....--------..- 328
..---_-_- ....-__ 328
-_---_-_-___- __- 328

----_-_____ 330
._- _ 330
---. .._.___-_.__ 330
-----__.______- 332
_._ _.__________ 333
_._. _____._._. _ 334
------_____ 335
.......------_. 336

---________ 337
-------_ 337

- 330


Lepidosaphes beckii Newm.


The purple scale, Lepidosaphes beckii, was first made known by New-
man in an account appearing in the English publication "The Ento-
mologist" in Februrary, 1869.1 In August of the same year Packard2 in
this country gave a brief description of the same insect, calling it
Aspidiotus citricola. Newman had given it the genus name Coccus,
which has since been changed, while his species' name beckii still stands.
From 1870 to 1876 a few articles appeared on this insect in France and
Italy. Glover has the second notice of its occurrence in the United
States in the United States Department of Agriculture Year Book
for 1876. He stated that it was found on imported lemons in Jackson-
ville, Florida, in 1857.
The description of this insect given by Packard was made simply from
unpublished figures and, of course, was inadequate. The first complete
description was given by Comstock in his 1880 report, but he adopted
the same specific name as that given by Packard.
Introduction into California.-The purple scale seems to have been
introduced into California directly from Florida in 1888 or 1889. In the
report of the California State Board of Horticulture for 1893 Alexander
Craw states that "four years ago two carloads of orange trees were
received in this State from Florida and planted in Los Angeles and
San Diego counties without disinfection. The result is that the climate
that has been preached us by importers of Florida stock as unfavorable
to the development of this species of scale has proved to be the opposite,
for on a visit to the above counties last summer I was shown trees
completely covered with purple scale." The May number of the Rural
Californian for 1889 was largely occupied with discussions of the prob-
able damage which would result from the importation of Florida
scales, among which the purple was the most important. Dr. Riley,
writing in Insect Life in 1889, states that "we have received a number
of letters from California asking our opinion on the necessity for quaran-
tine, and have replied that while there seems reason to believe, and we
are inclined to believe, from the evidence at hand, that the scales men-
'The Entom. IV, p. 217 (1869).
"Guide to the Study of Insects, p. 527 (1869).

FIG. 1.-Map indicating distribution of purple scale over world.


tioned will not flourish in certain parts of southern California, like
Riverside, where the heat and dryness are great, yet it will be unwise to
depend too much on the limited experience of the past. We have,
therefore, reiterated our convictions as to the necessity of using every
precaution to prevent their introduction."


0 L nsAo -- -

Sh- -Corona



on Diego

FIG. 2.-Map showing distribution of the purple scale over the southern
California citrus belt.

Over World.-The purple scale is widely distributed over the world,
as reference to the map will indicate. The localities as represented by
the +s on the map are as follows: Europe, Maderia, West Africa,
Mauritius, Ceylon, Japan, Australia, Tasmania, New Zealand, Fiji,
Hawaiian Islands, Bermuda, Java, West Indies, Paraguay, Florida,
Louisiana. Colorado, and California.
The Paraguay locality given above is based upon material received
in July, 1911. Mr. C. F. Mead collected some orange leaves that had a
sickly appearance from Pirapo, Paraguay, and sent them to Professor
Coit of this station. The leaves proved to be infested with typical purple
scale. Hitherto there have been no published records, to our knowledge,
of this scale occurring in that locality or even on the continent of
South America.
In California.-At the present time the purple scale occurs in the
following counties in California: San Diego, Los Angeles, Orange,



Ventura, and Santa Barbara. It does not occur, thus far at least, in the
citrus sections of the San Joaquin and Sacramento valleys. Neither
does it occur in Riverside or San Bernardino counties. From its distri-
bution in the above coast counties it would appear that it thrives best
in a cooler and moister climate, and in this respect it is similar to the

FIG. 3.-Half of orange tree defoliated by purple scale.

black scale. But the fact that it does not occur in the warmer and drier
locations may be due to the very rigid quarantine that has prevailed
against this scale in those sections. Its present eastern limit, or distance
from the coast, is in the eastern part of Los Angeles County, but here
the climatic conditions approach that of the still more interior sections


of Redlands and Riverside, so that there are no well defined climatic
zones, and therefore it is not improbable that the purple scale would
establish itself in those sections.

Considering the scales of the whole of the southern California citrus
belt, the purple is probably entitled to rank as the third most important.
Its distribution is not so general as that of either the black, red or
yellow, but where it does occur it is the most serious of them all, because
it yields less readily to treatment. Where this scale occurs among
others, fumigation work is directed primarily against the purple, and
usually successful treatment against it readily controls the red or black
The purple scale infests leaf, branch and fruit, often becoming
completely incrusted upon these, but it is usually only a portion of the
tree that becomes thus infested. The lower side or interior of the
tree is where the insect thrives best, and here it is that the injury is
most evident. We have never seen the greater part of a citrus tree
actually killed by this scale, but a goodly portion of one side or the
lower and interior branches are very frequently thus killed. The scale
causes a marked yellowing of the leaves and there is consequently a
heavy dropping so that many of the branches will be completely
The injury is due directly to the feeding, as is the case with the red
scale, since no honeydew is excreted. The scales on the ripening fruit
often have a tendency to delay the coloring, and a marked green spot
will be seen about the scale while the rest of the surface is yellow. On
account of their firm attachment to the fruit they are with great
difficulty removed therefrom, so that the ordinary brushing or washing
of the packing-house has little effect upon them.
The economic status of this scale is due largely to its resistance to
such treatments as fumigation or spraying. It is not a particularly
prolific insect for the maximum number of eggs will not exceed eighty,
and there are not more than three, or at most four, generations a year.
It is in the egg stage that it is most resistant to fumigation. This must
be largely on account of the very complete protection afforded the
eggs by the secretion of the ventral scale, which together with the dorsal
scale completely envelops them. The only, opening is at the posterior
tip where the young upon hatching emerge. It has frequently been
noticed that in cases of incomplete fumigation a few eggs at the extreme
tip will be killed by the gas while the more interior and better protected
ones will remain unharmed.



FIG. 4.-Orange leaf infested with purple scale. x2.


Lepidosaphes beckii is essentially a citrus fruit scale, and while it may
occur on several other plants, it is restricted as a pest in California
entirely to the different varieties of citrus. Fortunately, it does not

FIG. 5.-A cluster of oranges badly infested with purple scale.

attack, or at most but very rarely, any of the common trees or shrubs
growing in the vicinity of citrus trees, so that the problem of treat-
ment and control is limited to the commercial grove.
The complete list of food plants from which Lepidosaphes beckii has
been recorded is as follows: Orange, lemon, citron, grape fruit, fig,
olive, croton, oak, Elaeagnus, Banksia integrifolia, Taxus cuspidata,
Cercidiphyllum japonicum, Pomaderris apetala.




FIG. 6.-Purple scale after first molt, and mature female. x90.

The egg is oval in shape measuring .25 mm. long and .i5 mm. broad.
The color is pearly white with the surface very minutely granulate.


FIG. 7.-Active larva
of purple scale.

The active larva is a flat, oval-shaped creature,
white in color with the posterior tip brown. The
total length is .78 mm. and the greatest width is
.64 mm. The antenna are six jointed, the first
joint broadest, the last longest and distinctly
annulate. There are two small lobes widely sep-
arated at posterior end, and near each of these
on the inner side is a spine which extends beyond
the tip of the lobes. There are two other similar
spines beyond the lobes.
The second stage male length .8 mm., width
.25 mm.; general color purple. In the earlier
part of this stage the purple pigment is confined
largely to the anterior lateral margins. The rest


of the insect, excepting the posterior tip which is brown, is white in
color. There are no distinct eyes at this time, but later the purple
granules coalesce into definite areas forming the two pairs of eyes which
are conspicuous in the latter part of the stage. The dorsal and ventral
eyes are connected by a narrow neck so that they are continuous. These

FIG. 8.-Stages of the purple scale male. 1. Second stage. 2. Propupa with
exuvium of second stage still adhering to tip of body. 3. Propupa.
4. Pupa. 5. Adult male. x40.

are very dark purple. The median lobes are large and broad at base
with the margin serrate. The second pair of lobes which are not con-
spicuous are strongly notched in middle. Two long tapering plates
occur between the median lobes and also two similar in size and shape



between the first and second, and second and third lobes. Two other
similar plates or spines are found beyond the third pair.
The propupa is purple in general color and measures .8 mm. long and
.25 mm. wide. The sheaths enclosing the antennae legs and wings may
be distinguished, but they are closely associated with the body and are
not conspicuous. The pygidial characters have disappeared and the
posterior end is now truncate with no evidence of the style. The ventral
eyes are large, very dark purple in color, and lie close together. The
dorsal eyes are smaller and farther apart.
The pupa, length exclusive of style .1 mm., width .28 mm. at widest
part, which is near posterior end. Color purple. Sheaths of the
appendages conspicuous and more or less free from the body. Eyes
purple, the ventral pair closer together than the dorsal.
Adult male, length exclusive of style .58 mm., style .21 mm., wing
expanse 1.6 mm., antennae 10 jointed; comparative lengths 5, 5, 19, 23,
22, 20, 20, 18, 20, 15. General color, yellowish with purple pigment scat-
tered about with most at anterior end. This pigment also extends into
the joints of the antennae excepting the last two joints. The thorax is
light brown with a darker band extending between the wings.

M1 A

'l" h 1 i) ; i' *wyM

FIG. 9.-Pygidium of adult female purple scale. x160.

The adult female will average 1.2 mm. in length and .7 mm. in width.
On the lateral margin, beginning at the anterior end, are from three to
four broadly rounded extensions, and following these from three to
four pointed protuberances, all excepting the most anterior having
short, blunt spines at tip. There are always three pairs of lobes visible
and often a fourth. The median lobes are broad and bluntly pointed,
with more or less indication of serrations. The second pair is broad
and deeply notched, the third short and broad with serrated edge.
FIG. 10.-Purple scale. 1. Development of scale covering. x13. 2. The beginning
of the formation of the scale covering. x120. 3. Male and female scales, showing
comparative size and shape. x27. 4. Dorsal and ventral view. 5. Two stages of
larva of Aspidiotiphagus citrinus within purple scale. 6. Pupae of same within
scales. 7. Exit holes of A. citrinus. 8. Formation of covering after first molt.






FIG. 10.-See opposite page for legend.


There are two. spine-like plates between the median pair between the
first and second, and second and third. There are also two between
the third and what might be called the fourth pair, which show dis-
tinctly in some of the specimens. Another pair of these spine-like
plates is found at the extreme edge of the segment. The spines that are
conspicuous are two on each of the median lobes and one at the incision
of the second.

The Egg.-The eggs of the purple scale are protected, not only on the
upper side of the scale covering, but on the under side, by a lighter
and more cottony secretion, so that they are practically surrounded on
all sides excepting at the posterior end. They are arranged in regular
rows and standing partly on end. The number will vary from forty to
eighty. These are deposited over a period of three or four weeks. The
time of hatching will vary from fifteen days in summer to three weeks
or longer in the winter months. Those nearest the tip are the oldest
and are the first to hatch. As the quota of eggs are deposited, the insect
diminishes in size and contracts toward the anterior end of the scale,
filling the space thus left with eggs.

The active larva usually wanders about over the plant for a short
time before settling. This period will vary from a few hours to two or
three days, the majority becoming fixed within one day after emerging
from the parent scale. The scales upon hatching may not make their
way from beneath the scale immediately, especially if the weather is
cool. But not many, generally not more than two or three, will be
found hatched and not yet emerged.
Locomotion.-The rate at which the young larva will crawl over
smooth paper varies considerably, according to the temperature. With
a temperature of 64 F., the maximum distance traveled during a two-
hour period was 27 inches, while a distance of 111 inches was covered
when the temperature was 890:


Number Date Time. Tempera- Distance. Average
examined. ture. distance.

1 November 18, 1910 -- 9:20-12:20 p. m. 64' 9 inches
1 November 18, 1910 .---- 9:20-12:20 p. m. 64' 21 inches
1 November 18, 1910-..--- 9:20-12:20 p. m. 64' 27.50 inches 19 inches
2 November 2, 1910 --- 9:30-11:30 p. m. 68' 28 inches
2 November 2, 1910 .--.... 9:30-11:30 p. m. 68 37.75 inches 33 inches
3 July 21, 1910--.. 1:20- 3:20 p. m. 89 111 inches 111 inches


FIG. 11.-Actual tracings of the movement of young purple scales for a
two-hour period; reduced 7 times. Above, the temperature was 640 and
the average distance covered was 19 inches. Below, the temperature was
890 and the distance covered was 111 Inches.

FIG. l1.--Actual tracings of the movement of young purple scales for a
two-hour period; reduced 7 times. Above, the temperature was 64 and
the average distance covered was 19 inches. Below, the temperature was
89 and the distance covered was 111 inches.



The rate and distance of travel noted above was on smooth paper.
The conditions were thus more favorable than will ever be likely to
obtain in nature. Counting the maximum length of life as an active
larva when deprived of food at four days, the highest possible record
under the most favorable conditions would be a total of 444 feet. But
obstacles to travel, such as a pulverized soil, make a very different story.
With a temperature of 86' at 9 a. m., twenty-five active young were
placed unharmed in the center of an area of sand, having a five-inch
radius. None reached the edge during the same day or the day fol-
lowing. Another similar experiment resulted negatively. A third,
similar to the others, was started, and out of twenty-five scales liber-
ated, one reached the margin in 51 hours. This was the only one that
succeeded in crossing a five-inch strip of sand.
The following records were made on a three-inch radius of sand:

Number Temperature. Time. Results.
liberated. i Rs t

20 63 F 1:30 p. m. None reached margin
20 82F 9:45 a. m. 2 out at 12:30
10 65F 9:30 a. m. 2 out at 1 p. m.

Other tests were made with orchard soil, but there seemed to be little
difference over that of sand. It will thus be seen that the young purple
scales are able to make but little progress over soil that is well cultivated.
Only an exceedingly small percentage of those liberated crossed but
three or five inches of such soil. If the soil is compacted as after heavy
rains or in irrigation furrows considerable progress may be made, but
even here the factor of their own powers of locomotion in their dis-
tribution is very small.
Settling.-Out of 240 scales liberated in leaf cages at different times
from March to September, 122 or about 50 per cent became established.
This should represent a fair average, or, if anything, an under estimate
of the percentage, since the young were liberated on suitable leaves and
protected from all outside agencies. There seems no doubt that condi-
tions as they ordinarily obtain in nature would decrease the above
percentage considerably. It may, therefore, be counted that at least
50 per cent of the scales fail to become established even under the most
favorable conditions.
The young purple scale may settle either on the branch, leaf, or fruit.
The branches or leaves are the first to become infested, but if they are
abundant on these, the fruit in the vicinity will become badly infested
also. Where the numbers are not large there is a tendency for the
young scales to settle along the midrib or large veins of the leaf. This
tendency was usually strongly shown in our breeding cages. They do


not migrate far from the parent as a rule. It is most usual to find this
scale limited to but a portion of the tree, and while this portion may be
so severely infested as to be killed, the rest of the tree may be in a
healthy condition and comparatively free from the scale. The infested
portion is nearly always on the lower side of the tree and later extends
upward covering the greater part of one side of the tree. This side is
not necessarily away from the sun for it has been noted on the east,
south and west sides of the trees.
Formation of the Scale.-Upon settling, the young larva of the purple
scale very soon secretes a couple of rather coarse cottony threads from
the anterior end of its body, apparently from just under the margin
of the anterior end. These are long entangling threads that extend
entirely over and around the insect. The function of these is undoubt-
edly a provision for protection while the more compact covering is
being secreted. At any rate these entangling threads answer this pur-
pose, for it has been many times observed that a young Coccinelid larva
upon striking them will immediately back away or turn in another direc-
tion without molesting the insect thus protected. These entangling
threads remain until the insect is about half grown, and, where the
young scales are numerous, they form a fuzzy coating over the infested
surface. Some practical fumigators use this as a criterion that the
insect is in the best stage for treatment; and this is correct, for such
threads are lost as they approach maturity.
After these two long protecting threads are formed the insect begins
the secretion of the permanent scale. These threads are very much
finer than the first ones and cover the insect more compactly. The cov-
ering for a day or two is of course thin enough to make out very
readily the insect beneath. This covering is started at the posterior end,
and, after about one day, only the anterior one fourth of the insect is
free. The long, entangling threads are still present and these remain for
a considerable time. Later, however, after the scales are about one
half grown they are lost. After the covering has reached the anterior
end and the insect is completely covered, it still extends the covering
in two horn-like projections as shown in Figs. 10-12. If these are care-
fully lifted the antenna will be found beneath so that they serve as a
protection to the antenna for a time. As the insect grows older, the
scale becomes more compacted. When the first molt occurs, the entire
skin is incorporated in the dorsal scale. The insect works its way out
beneath, leaving the covering which has been secreted, and the cast
skin, above it. Very soon, however, the scale is extended posteriorly so
that the cast skin becomes an oval, dark brown plate at the anterior tip
of the scale. The second cast skin, which is very much larger than the
first, is also incorporated into the dorsal scale covering. The secretion
is continued and the scale extended beyond the second exuvium until the



part beyond becomes the length of the rest of the covering. As the
female becomes mature and egg laying begins, a considerable secretion
is formed on the under side. This is secreted from the sides of the insect,
the two films meeting down the central line. A narrow strip of this
ventral scale is formed on either side of the scale beneath during the
earlier stages, particularly at the anterior end, and this gradually
widens and extends more posteriorly as the insect becomes mature. But
no part of the cast skins are found in this ventral scale which is entirely
the secretion of the insect.
In the case of the male only the first cast skin is incorporated into the
scale covering. This is exactly similar to that of the female, since there
is no difference in the sexes until after the first molt. But all succeeding
cast skins of the male are pushed back and from beneath the scale
covering. The narrow, elongate covering, typical of the male insect, is
formed entirely during the second stage of the insect.
The Process of Molting.-In the case of the purple scale the molting
process is very different from that of Chrysomphalus aurantii and also
different from that of the unarmored scales as
,-,"- -. represented by Saissetia olece. In the case of
the red scale, the rent in the old skin occurs
1i .. along the margin of the body, so that the dorsal
S half becomes incorporated in the dorsal scale
Sand the ventral half of the ventral scale. In
SSaissetia olece, Coccus hesperidum, and others
of the unarmored group, the skin is split at the
Anterior end and pushed backward and entirely
Free from the insect.
SThe rent in the skin of the purple scale
"occurs on the ventral side in a more or less
^ "'f*i' .? irregular line a short distance from the margin.
At the anterior end this is between the rostrum
tand the antenna, on the sides, between the legs
and the body margin; and at the posterior end,
FIG. 12.-First cast skin of just anterior to the pygidium. The insect first
purple scale; ventral
view, showing how skin emerges, presumably at the anterior end (the
is split and ventral por-
tion with legs and mouth process can not actually be observed) and later
parts pushed back. pulls the posterior end forward and downward,
leaving the old skin directly above it. From the appearance of the cast
skin the insect could very readily, simply by a contraction of the body,
free itself from the narrow projecting portion of the ventral scale at the
anterior end. In the case of the posterior end, the rent does not occur
so near the margin, hence the projecting scale is somewhat broader than
that at the anterior end. But once the anterior end of the insect was
free, it would be easy to liberate itself from this posterior pocket. That


the anterior end is first freed from the old scale is further shown by the
fact that the old ventral skin is pushed backward, which would not be
possible in any other case.
The exuvium, therefore, is entirely in the upper or dorsal part of the
scale covering. After clearing in potash it will be seen that the antenna
are intact at the anterior end, the rent having occurred posterior to
them, so that their position has not been changed in the molting process.
At the posterior end all the characters of the pygidium can be made out
as clearly as in the perfect insect, for these, likewise, have not been
disturbed. As in the opposite end the insect has simply pulled itself
from within, leaving all the characters undisturbed. The ventral por-
tion of the molted skin, instead of being simply laid down beneath the
insect, is pushed posteriorly as far as the pygidium, or to the edge of
the rent at the posterior end. Here the legs and rostrum may be made
out, the whole being more or less doubled up from the process of pushing
backward underneath the insect.
Development.-The first molt of the purple scale occurs about twenty-
six days after birth. Up to this period there is no difference between
the sexes, but the difference becomes sharply marked immediately after
this stage. In the case of the female, the period between the first and
second molts is about the same as that from birth to the first molt. The
second molt brings the female to maturity, at least so far as the molting
is concerned.
Ten or twelve days after the first molt, the male undergoes a second
molt, bringing it to the propupal stage. This stage is distinguished
from the true pupa chiefly by the less fully developed appendages, as
shown by their enclosing sheaths. After eight or ten days in this stage,
it changes to the true pupal condition, and a similar period is passed
in this stage before emerging as an adult. The male, therefore, issues
as an adult about sixty days from birth. The period will be from ten
to twelve days less during the warmest part of the season, and extended
as much as twenty or twenty-five days in winter.
The female will begin depositing eggs about seventy-five days from
birth, or fifteen days after fertilization by the male. Egg laying will
continue for three or four weeks. The eggs hatch and young will
emerge from the scale on an average of three months from birth; this
again varying from ten or twelve days less in midsummer to a month
or more in winter. After the female has deposited her quota of eggs,
numbering from thirty to eighty, she dies, making the complete life
cycle from four months in summer to from five to six months in winter.





103 ---.------ 3-19-09
125--.------ 3-830-09
116----..........------- 3-24-00
152 -.-----.- 5-19-09
153----..----- 5-20-09
154-.........---------- 5-20-09
155 .-----. 5-20-09
162...------ 5-22-09
163----------- 5-22-09
166----.----- 5-25-09
167__ .------. 6-25-09
199---------. 6-28-09
206--.-----. 7- 1-09
205-------- .. 7- 1-09
250..--------. 7-19-09
305 .------. 8-20-09
308 .-----. 8-21-09
580 _------_ 6-18-10
581.------- 6-18-10
582--.------.. 6-18-10
583...------.- 6-18-10
584.--.-----. 6-18-10
--- 2-18-11
--- 6- 8-11

Summary av erages _


g 1 -
i~e e.Q ii 8. .

; B 3 0 0
0t a 0
I- ij a ;

N: 51

10 -- --
12 3 ---------

17 5 .......
-- ..- 6-18
S 6-18

52 28 ----- ----
37 21 ....
46 36 ..........

6 1 -------
87-- ----------
.. ..... .

15 5 8-11

--- -- 7-10
- --- --- ------
15 7 --...--
15 9 -----
15 4 ----_--
.- ....-- 3-6
...-- .-. 6-30

---- --- 26 days


50 days 36 days

--------- -------

----- 6-26
-- -- -- --- - -
7 6
7-10 .------
7-6 6-30

---7-2--- ------ --
7-26 ,- -......
7-26 - - -

6-10 I--- --_ _----
6-6 6-10 ----------
6-10 6-15 -------

7-16 ......... 8-16
--- -- ---- ---- -----
7-21 7-24 8-10 8-16
-- ..... 8-1 8-18

--- ------ 8-18

8-18 ----- 9-16
--- --- 9-20 9-26

10-27 11-2 --- 11-30

8-6 ------..-----.... 9-11
8-5 ------------ 9-10
8-10 8-14 ---- -
- __-------__ 9-9
8-7 ---- ....-----.. 9-11
5-6 -----------
7-30 --- --

60 65 75 90


Since the time required for the life cycle, from young to young,

during the summer months is about three months and in winter may

be prolonged a month or more longer, the number of generations will

not exceed four. In fact, during ordinary seasons there will be but

three generations, with probably a partial fourth. From May to

October, inclusive, they will go through their development in three

months, or slightly less, so that there will be two full generations dur-

ing this period. A third will get fairly well started before the colder

wet weather of January and February. But the development of this

generation will be prolonged by the lower temperature so that it may

require four months for the cycle. This will bring it into March again,

when at best the fourth generation will only be partially developed by

the last of April. During May, and also in June, young scales begin

appearing in large numbers, which is the first definite spring hatch.

It is altogether likely that in many cases these are the progeny of the

third generation. During the remainder of the summer young scales

will be found continuously in considerable numbers. Eggs will be

found at any season of the year, but during the winter months the
young will appear mostly during the warmer periods.

7-17 -
----.- -




7-25 -
-----I---- -



Practically nothing has been written about any parasites of the
purple scale in California. This scale has been considered to be freer
from parasites than any of the other citrus fruit scales. While this,
in general, is true, yet in certain places the purple scale is as heavily
parasitized as the red or yellow, and the parasite in question has been
known to occur in the State since 1891. But in many sections of the
citrus belt where the purple scale occurs, little or no trace of this
parasite will be seen. In sections, as Whittier, where fumigation is so
generally practiced as it was in 1910 (98 per cent of the acreage)
there is no doubt about its effect on the parasites. In considerable
purple scale material collected from this vicinity during the past two
or three years, there have been but occasional instances where parasites
were obtained. But just outside the Whittier section, where trees
infested with purple scale had never been fumigated or sprayed, as
high as 30 per cent or 40 per cent of the scales at one time were found
This same fact holds true for the yellow scale parasite, for it is the
same parasite that attacks both scales. Yellow scale material has fre-
quently been obtained from sections where fumigation is generally prac-
ticed, but none or few parasites were secured. But yellow scale material
taken from Santa Barbara County, and in the northern sections where
no fumigation is practiced, had a considerable percentage of the scales
parasitized in many instances.

Aspidiotiphagus citrinus Craw.*
Aspidiotiphagus citrinus Craw. is the only parasite that we have
taken thus far from the purple scale. This is the insect referred to
above, and, while occurring in certain limited localities in considerable
numbers, it is not common throughout the purple scale belt. This is a
strictly internal parasite and attacks the scale only between the first
and second molt. The scale has shed its first skin and approaches very
nearly the time when it should cast its second skin. But thus far no
instance has been observed where the scale had actually molted the
second time.
The egg is deposited within the insect and there hatches a very
minute, white larva, with a tail-like appendage. This is afterward
lost, and as the larva becomes mature it is about .85 mm. long and
.35 mm. wide, tapering slightly toward the anterior and more strongly
toward the posterior end. It pupates within the scale, the pupa at
first being white or light colored but later turning very dark. The adult
makes its way out through a circular exit hole in the posterior one third
*For a more detailed account of this parasite, see Cal. Exp. Sta. Bull. 222.



Aymes and Trabut: Bul. Agr. de Alg. et del Tunisie, xiv, 9, pp. 222-223. (190S). Fig.
Kirk, T. W .: A )
Cockayne, A. H.: Am. Rep. N. Z. Dept. Agr. Div. Biol. and Hort. p. 283 (1909).
Essig, E. O.: Bull. No. 2. Claremont Pomological Club. Apr. 15, 1909.
H done, E. : Can. Ent., xii, 8, p. 299 (1909).

Carnes. E. K.: 3d Biennial Rept. Com. Hort. Cal., p. 25 (1909).
Dean. Geo. A.: Trans. Kans. Acad. of Sciences XXII, p. 275 (1909).
Woodworth, C. W.: Jn. Econ. Entom. Vol. II, No. 5, p. 359. Oct. 1909.
Barber, T. C.: Jn. Econ. Entom. vol. 3, No. 5, p. 425. Oct. 1910.
Recorded on orange, Citrus trifoliata and Camellia japonica from Audubon
Park, New Orleans, La.

1896. Report of the Viticultural Work during the seasons 1887-93, with data regard-
ing the Vintages of 1894-95.
1897. Resistant Vines, their Selection, Adaptation, and Grafting. Appendix to Viti-
cultural Report for 1896.
1902. Report of the Agricultural Experiment Station for 1898-1901.
1903. Report of the Agricultural Experiment Station for 1901-03.
1904. Twenty-second Report of the Agricultural Experiment Station for 1903-04.

Irist. Endurance of Drought in Soils of No.
the Arid Regions.
128. Nature, Value, and Utilization of
Alkali Lands, and Tolerance of
Alkali. (Revised and Reprint,
133. Tolerance of Alkali by Various
147. Culture work of the Sub-stations.
149. California Sugar Industry.
153. Spraying with Distillates.
159. Constribution to the Study of
162. Commercial Fertilizers. (Dec. 1,
165. Asparagus and Asparagus Rust
in California.
167. Manufacture of Dry Wines in
Hot Countries.
168. Observations on Some Vine Dis-
eases in Sonoma County.
169. Tolerance of the Sugar Beet for
170. Studies in Grasshopper Control.
171. Commercial Fertilizers. (June
30, 1905.)
172. Further Experience in Asparagus
Rust Control.
174. A New Wine-cooling Machine.
176. Sugar Beets in the San Joaquin
177. A New Method of Making Dry
Red Wine.
178. Mosquito Control.
179. Commercial Fertilizers. (June,
180. Resistant Vineyards.
181. The Selection of Seed-Wheat.
182. Analysis of Paris Green and
Lead Arsenic. Proposed In-
secticide Law.
183. The California Tussock-moth.
184. Report of the Plant Pathologist
to July 1, 1906.
185. Report of Progress in Cereal In-
186. The Oidium of the Vine.
187. Commercial Fertilizers. (Janu-
ary, 1907.)
188. Lining of Ditches and Reservoirs
to Prevent Seepage and Losses.
189. Commercial Fertilizers. (June,
190. The Brown Rot of the Lemon.
191. California Peach Blight.

192. Insects Injurious to the Vine in
193. The Best Wine Grapes for Cali-
fornia; Pruning Young Vines;
Pruning the Sultanina.
194. Commercial Fertilizers. (Dec.,
195. The California Grape Root-worm.
197. Grape Culture in California; Im-
proved Methods of Wine-mak-
ing; Yeast from California
198. The Grape Leaf-Hopper.
199. Bovine Tuberculosis.
200. Gum Diseases of Citrus Trees in
201. Commercial Fertilizers. (June,
202. Commercial Fertilizers. (Decem-
ber, 1908.)
203. Report of the Plant Pathologist
to July 1, 1909.
204. The Dairy Cow's Record and the
205. Commercial Fertilizers. (Decem-
ber, 1909.)
206. Commercial Fertilizers. (June,
207. The Control of the Argentine Ant.
208. The Late Blight of Celery.
209. The Cream Supply.
210. Imperial Valley Settlers' Crop
211. How to Increase the Yield of
Wheat in California.
212. California White Wheats.
213. The Principles of Wine-making.
214. Citrus Fruit Insects.
215. The House Fly in its Relation to
Public Health.
216. A Progress Report upon Soil and
Climatic Factors Influencing
the Composition of Wheat.
217. Honey Plants of California.
218. California Plant Diseases.
219. Report of Live Stock Conditions
In Imperial County, California.
220. Fumigation Studies No. 5; Dos-
age Tables.
221. Commercial Fertilizers (Oct.
222. The Red or Orange Scale.
223. The Black Scale.
224. The Production of the Lima Bean.
225. Tolerance of Eucalyptus for


No. 1. Texas Fever.
7. Remedies for Insects.
9. Asparagus Rust.
11. Fumigation Practice.
12. Silk Culture. '
15. Recent Problems in Agricul.ture.
What a University Farm is For.
19. Disinfection of Stables.
29. Preliminary Announcement Con-
cerning Instruction in Practical
Agriculture upon the Univer-
sity Farm, Davis, Cal.
30. White Fly in California.
32. White Fly Eradication.
33. Packing Prunes in Cans. Cane
Sugar vs. Beet Sugar.
36. Analyses of Fertilizers for Con-
39. Instruction in Practical Agricul-
ture at the University Farm.
46. Suggestions for Garden Work in
California Schools.
48. Butter Scoring Contest, 1909.
50. Fumigation Scheduling.
52. Information for Students Con-
cerning the College of Agricul-

No. 54. Some Creamery Problems and
55. Farmers' Institutes and Univer-
sity Extension in Agriculture.
58. Experiments with Plants and
Soils in Laboratory, Garden,
and Field.
60. Butter Scoring Contest, 1910.
61. University Farm School.
62. The School Garden in the Course
of Study.
63. How to Make an Observation
64. Announcement of Farmers' Short
Courses for 1911.
65. The California Insecticide Law.
66. Insecticides and Insect Control.
67. Development of Secondary
School Agriculture in Cali-
68. The Prevention of Hog Cholera.
69. The Extermination of Morning-
70. Observations on the Status of
Corn-growing in California.
71. Grains Recommended for Trial.

University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs