Official Organ of the Florida Entomological Society
VOL. XXVI MARCH, 1943 No. 1
THE MEXICAN BEAN BEETLE IN FLORIDA1
A. N. TISSOT
Since its discovery in the East, in the vicinity of Birmingham,
Alabama, in 1920, the Mexican bean beetle, Epilachna varivestris
(Muls.) has been of much interest and concern to American en-
tomologists and agriculturists. Presumably a native of the Mexi-
can plateau, the beetle was first recognized in the United States
in 1864, and Chittenden (1919) states that it did serious injury
to wax beans in Colorado in 1883. The insect received little at-
tention, however, and there are very few references to it in en-
tomological literature prior to 1920. Since then the picture has
changed completely. The beetle has been the subject of numer-
ous studies and investigations, the results of which have filled
hundreds of pages of literature. That the beetle is still consid-
ered of major importance is evidenced by the fact that Index V
of American Economic Entomology, covering the years 1930-
1934, contains 113 references to it, and Index VI for the period
1935-1939 contains 100 references.
During its early years in the East the Mexican bean beetle
amazed everyone with the unprecedented rapidity of its spread.
Howard (1924b) states that in 1921 the beetle spread north and
east a distance of more than 200 miles and the next year it ad-
vanced more than 100 miles farther. By 1930 it had been dis-
covered in all but seven of the states east of the Mississippi
River. When the beetle became established in the East, under
environmental conditions so different from those in its native
home, entomologists began to conjecture as to the effect of climate
upon it and to speculate regarding its ultimate range. There was
considerable difference of opinion and the statements were often
misleading and sometimes contradictory. Hinds (1920) stated
that there were not any climatic or geographic barriers in the
East to prevent the pest from spreading. Howard (1924a) said
'Contribution from the Department of Entomology, Florida Agricultural
Experiment Station, Gainesville, Florida.
THE FLORIDA ENTOMOLOGIST
that in time it undoubtedly would extend its range over most
of the hilly portions of the United States east of the Mississippi
River and was of the opinion that its spread from the original
point of infestation in northern Alabama was accomplished
mainly by flight, assisted by the prevailing winds. Graf (1925)
constructed climographs for Mexico City, Albuquerque, New
Mexico, and Springfield, Illinois, which differ widely as regards
temperature and moisture. As the beetle was able to maintain
itself successfully in these three places he concluded that tempera-
ture and moisture are not important factors in limiting the dis-
tribution of the insect. Other workers believed that these factors
could have a very marked effect upon the beetle. Howard (1921)
considered a temperature of 100 F. or over in dry weather to
be very destructive and found later (1931) that the larvae were
killed in a few minutes when in direct sunlight, if the shade tem-
perature was above 90 F. Eddy and McAllister (1927) during
the drought of 1925 noted limited areas of eradication of the
beetle in South Carolina and the next year when the heat and
drought were still more severe, they found on the eastern edge
of the infested area an actual recession averaging about 35 miles.
Thomas (1924) studying the beetle in Alabama, noted a natural
control by heat during a hot spell when the temperature was
1000 F. to 101 F. in the shade.
Among the first to study the Mexican bean beetle under con-
trolled conditions were Marcovitch and Stanley (1930). They
assumed that since the beetle is a native of the Mexican table-
lands, which have a rather uniform, cool climate with low maxi-
mum temperatures, it must be best adapted to such conditions.
Their breeding work showed that a temperature of 770 F. was
most favorable for survival and that higher temperatures has-
tened development but produced greater mortality. Using a
formula based on the temperature and precipitation relationships
of the beetle, they predicted the probable future range of the in-
sect in the United States. They predicted that the beetle would
reach Florida by way of the Atlantic coast and believed that the
climate of the northeastern and southern parts of the state would
be favorable for it.
Landis and Plummer (1935) made a survey of the Mexican
bean beetle in Mexico and carried on some life history studies
near Mexico City. They found the insect widely distributed in the
country and recorded it from elevations ranging from 3 to 8,845
feet. However, it was found most prevalent in the area delimited
VOL. XXVI-No. 1
by the 200 C. (680 F.) isotherm which follows quite closely the
boundaries of the central plateau. At Mexico City, the beetle had
a single generation a year and the average developmental period
from egg to adult was 57 days. On the basis of these studies and
their observations that the beetle was not particularly destruc-
tive there, they contended that contrary to the statement of Mar-
covich and Stanley, optimum conditions for the beetle are not
found in the Valley of Mexico.
A review and summary of previous work on the ecology of
the bean beetle was given by Sweetman (1932). He concluded
that temperature and moisture are very important limiting fac-
tors in the economic distribution of the insect. He used relative
humidity rather than precipitation as the measure of the moisture
conditions of the environment, and gave more importance to
temperature extremes, than had been given by other workers.
His predictions regarding the probable ultimate distribution of
the beetle agree fairly well with those of Marcovich and Stanley.
He concluded that moisture conditions would be suitable for the
beetle in the Gulf Coast region but believed that high summer
temperatures would prevent economic damage in much of the
area, including northern and central Florida. However, he con-
sidered that a narrow strip along the coasts of the northern half
of Florida would be sufficiently favorable to permit occasional
damage from the insect and the southern half of the state was
believed favorable for greater damage by the pest.
A few years later the bean beetle appeared in Florida and
thus made it possible to compare its actual behavior with the
predictions made for it. The first known infestation of the beetle
in the state was discovered in a garden at Monticello, May 20,
1933, by Fred W. Walker who collected numbers of the adult
insects. It was presumed that the source of the infestation was
at Thomasville, Georgia, which is about twenty miles north of
Monticello. The infested beans were destroyed and apparently
the infestation was eradicated as no evidence of the insect could
be found later in the summer of 1933 and there were no further
reports of the beetle from there for several years.
In July, 1937, Professor J. R. Watson and the writer observed
a rather heavy infestation of the beetle in a garden at Florala,
Alabama, just north of the state boundary and there were uncon-
firmed reports that it was present across the line in Florida. How-
ever, the second definite record of a Florida infestation was made
July 11, 1938, when Mrs. A. S. Snider of Havana, in northern
THE FLORIDA ENTOMOLOGIST
Gadsden County, sent in to the Entomology Department an egg
cluster and five larvae which she had collected in her garden.
Four adults and a pupa were taken at Quincy, August 11, 1938,
and specimens were taken on butter beans at Tallahassee, August
16, 1938. Since then the insect has become rather widely estab-
lished in western Florida as is shown by the following records
compiled from the records of the Florida State Plant Board, the
records and correspondence of the Entomology Department of
the Experiment Station, and the Insect Pest Survey Bulletin.
No new localities were infested in 1939, but reports from
Havana indicated that the infestation there was becoming better
established and a single record showed that the Tallahassee in-
festation still persisted. On April 9, 1940, A. H. Madden re-
ported that adult beetles were appearing in considerable abun-
dance in bean fields at Havana and later he reported the insect as
fairly widespread throughout Gadsden County. Other records
for 1940 are: Gretna (Gadsden Co.), April 26; Milligan (Oka-
loosa Co.), August 24; Marianna (Jackson Co.), August 29; and
Greensboro (Gadsden Co.), October 14. The Gadsden County
infestations remained active in 1941 and new infestations were
discovered at Glendale (Walton Co.), August 6, and at River
Junction (Gadsden Co.).
The year 1942 produced more records of the beetle than any
previous year. Adults became active in Gadsden County bean
fields in April, and specimens were taken at Tallahassee on June
10. On June 11, all stages of the insect were collected at Monti-
cello and the beetle was reported to be present in several sections
of Jefferson County. This year also produced the first known in-
festations of the bean beetle in the peninsular part of Florida.
On May 7, a grower from Hawthorne, brought in to the Experi-
ment Station a few dozen large bean beetle larvae which he had
collected in his field of lima beans. Professor J. R. Watson visited
the planting the same day, collected a few more larvae, and re-
ported that the infestation was very localized and that all the
larvae had been taken within an area of a few square yards. On
May 30, Professor Watson visited another infested field at Island
Grove, about ten miles south of Hawthorne and collected larvae
and pupae. On June 11, it was reported to the author that some
insects, supposed to be the Mexican bean beetle, had been
observed in the gardens of the College of Agriculture at
Gainesville. On visiting the garden it was evident that the beetle
had been feeding on some pole and lima beans and a search of
VOL. XXVI-No. 1
the plants soon produced four beetles and 20 pupae. Another
visit on June 26, produced two prepupae, one large larva and two
egg masses. At that time there was some evidence of feeding on
the beggarweed, Meibomia purpurea (Mill.) Vail.
These three infestations, all located in Alachua County, are
of interest because they are so far from any other known infes-
tation. Most of the county agents in the northern half of Florida
were asked to be on the lookout for the beetle but the nearest in-
festation thus far reported was the one at Monticello. The air
distance from Monticello to the Alachua County infestations is
at least 125 miles which seems rather too far for flight by the
beetles. The fact that the infested fields at Hawthorne and Island
Grove were less than a mile from a main north-south highway
much traveled by produce trucks and the Gainesville infestation
was within fifty yards of another similar highway may have
The owners of the infested fields at Hawthorne and Island
Grove used insecticides on their beans, apparently with good re-
sults since later checks failed to show any evidence of bean
beetles. However, no control measures were used on the Gaines-
ville infestation and it too disappeared. Most of the bean plants
were dead by the end of June but a flush growth of beggarweed
had sprung up and close by was a small planting of cowpeas.
Although the beggarweed showed considerable signs of beetle
feeding on June 26, when the last insect specimens were taken,
later examinations during July failed to show any evidence of
beetles feeding nor have any signs of the beetle been seen since
All of the known infestations of the beetle have been in the
extreme northern and interior portions of Florida, areas which
both Marcovitch and Stanley, and Sweetman indicated as prob-
ably being unfavorable for the insect. It still remains to be seen
how serious it may become if its finds its way into and becomes
established in the coastal strip or the southern part of the state
which are believed to offer climatic conditions better suited to its
There are three other records of the Mexican bean beetle in
Florida, which do not represent infestations, of this insect but
which are interesting nonetheless because they indicate one
method by which the beetle has been able to enter the state. The
records of the State Plant Board show that on September 7, 1932,
J. W. McGlamery captured a bean beetle on top of a cantaloupe
THE FLORIDA ENTOMOLOGIST
in a store in Coral Gables. Some inquiry brought out the fact
that the cantaloupe probably came from New Jersey. On Sep-
tember 29, 1937, Alec White, the county agent in Hillsborough
County, sent in to the Experiment Station an imperfectly formed
adult bean beetle which had been taken to his office. Careful
inquiry indicated that the insect had been found on some green
beans in a Tampa market and that the shipment of beans origi-
nated at or near Franklin, North Carolina, a region known to be
heavily infested by the beetle. On September 23, 1940, H. E.
Westbury, the county agent at Palatka, sent a few specimens of
the beetle to the Entomology Department of the Experiment
Station and wrote as follows: "One of our farmers brought the
inclosed beetles to my office this morning and stated he had col-
lected them off of lima and string beans brought in from Georgia
and South Carolina at the Produce Market in Jacksonville,
Florida." A noteworthy fact in regard to these three collections
is that all were made in September when the fall planting of
beans is getting well started. If these immigrant beetles had
chanced to find their way into suitable bean fields, new infesta-
tions could very easily have been started.
No work had been done on the life history of the bean beetle
in Florida so an attempt was made to obtain some information
on this phase of their biology. The 60 larvae collected May 7,
1942, in the infested field at Hawthorne were placed in a large
screen cage in the laboratory. Fresh bean plants or leaves with
their stems in water, were placed in the cage as needed to furnish
a steady supply of suitable food. Most of the larvae pupated,
the first pupating on May 8, and the last on May 10. The 49
adult beetles that were produced emerged during the three day
period, May 14-16. Except for the four taken out for individual
records, the adults remained in the cage until they died. Two
pairs of beetles taken from the cage before egg laying began,
were placed in separate cages and a daily record was kept of all
eggs produced. One female began egg laying on May 30, laid a
total of 1032 eggs in 19 clusters during the oviposition period of
50 days. The other female began producing eggs May 31 and
laid a total of 721 eggs in 14 clusters during the oviposition period
of 30 days. A second generation female laid her first eggs on
August 3, and produced a total of 246 eggs in 8 clusters, during
the oviposition period of 18 days.
The eggs hatched in 5-6 days with an average incubation
period of 5.6 days for 119 eggs. The larval period varied from
VOL. XXVI-No. 1
15 to 17 days with an average of 15.2 days for 28 larvae. The
total developmental period from egg to adult varied from 24 to
28 days with an average of 25.6 days.
Longevity records were obtained for 55 adult beetles. A few,
which were badly malformed died within a day or two of emer-
gence. The greatest length of life was 110 days and the average
length of life was 54.5.
Seventy-five per cent of the eggs in the first clusters laid May
31 and June 2 hatched and a fair proportion of the larvae reached
maturity. Within a few days the percentage of eggs hatching
decreased very rapidly and less than 1 per cent of the eggs laid
after June 10, hatched. The larval mortality rose very rapidly
and the few that became adult were so badly deformed that they
died without producing any eggs. These results appear to ex-
plain the natural eradication of the Gainesville infestation and
they closely parallel the situation found during hot, dry periods
in other parts of the Gulf Region.
The first known infestation of the Mexican bean beetle in
Florida was discovered at Monticello, May 20, 1933. The infes-
tation was eradicated during the summer and there was no
further evidence of the beetle in the state until 1938 when a
second infestation was found at Havana, in Gadsden County.
This infestation has persisted and has caused some damage each
year. Other infestations have developed in Gadsden and neigh-
boring counties, and in 1942 three isolated infestations were
found in Alachua County, more than 125 miles from any other
known infestation. The beetle has not yet become established
in those pafts of the state presumed to be ecologically better
suited to its needs. Life history studies at Gainesville in 1942
showed that the eggs failed to hatch during hot weather, that
larval mortality was very high, and that many of the adults pro-
duced then were badly malformed.
CHITTENDEN, F. H. 1919. The bean ladybird and its control. U. S. D. A.
Farm. Bul. 1074: 1-7.
EDDY, C. 0. and L. C. McALISTER, JR. 1927. The Mexican bean beetle. S. C.
Agr. Exp. Sta. Bul. 236: 1-38.
GRAF, J. E. 1925. Climate in relation to Mexican bean beetle distribution.
Jour. Eco. Ent. 13: 486-488.
THE FLORIDA ENTOMOLOGIST
HOWARD, NEALE F. 1921. The Mexican bean beetle in its bearing on Florida
citrus growing. Fla. St. P1. Bd. Quar. Bul. 6:15-24.
1924a. The Mexican bean beetle in the East. U. S. D. A. Farm Bul.
1931. U. S. D. A. Y. B. pp. 375-376.
HOWARD, NEALE F. and L. L. ENGLISH. 1924b. Studies of the Mexican bean
beetle in the Southeast. USDA Dept. Bul. 1243: 1-50.
LANDIS, B. J. and C. C. PLUMMER. 1935. The Mexican bean beetle in Mexi-
co. Jour. Agr. Res. 50: 989-1001.
MARCOVITCH, S. and W. W. STANLY. 1930. The climatic limitations of the
Mexican bean beetle. Ann. Ent. Soc. Am. 23: 666-686.
SWEETMAN, HARVEY L. 1932. The effects of temperature and moisture on the
distribution of the Mexican bean beetle, Epilachna corrupt Muls.
Ann. Ent. Soc. Am. 25: 224-240.
THOMAS, F. L. 1924. Life history and control of the Mexican bean beetle.
Ala. Agr. Exp. Sta. Bul. 221: 1-99.
WATSON, J. R. 1942. The spread of the Mexican bean beetle. Fla. Ento-
WAR AND ITS EFFECT ON THE INSECTICIDE INDUSTRY
R. L. MILLER
(Continued from page 56, Vol. XXV)
NICOTINE COMPOUNDS will probably be available since
the supplies are mostly domestic. The demand for such chemicals
is very temperamental, depending on seasonal conditions which
favor the deevlopment of sucking insects; but it is the writer's
opinion that supplies of nicotine will be available in sufficient
quantity. Black Leaf 155 and Black Leaf 10 have been developed
for use as poisons as well as contact materials and in some in-
stances have given excellent results against chewing insects.
PYRETHRUM at one time came largely from Japan but since
the quality and uniformity of this product was too often tam-
pered with, more recently the major production has come from
Kenya Colony, on the east coast of Africa. Although the product
is still available, transportation of such a bulky material over
such a long distance will probably restrict the supplies available
in the United States. This will be a handicap to the fly spray
industry as well as to most vegetable growers. On June 11, 1942,
the War Production Board issued Preference Order M-139 on
Pyrethrum Flowers which, however, does not specify definite
uses but requires that manufacturers using Pyrethrum Flowers
get authorization for purchase of supplies from the War Produc-
VOL. XXVI-No. 1
ROTENONE is the one example of a very limited supply of
an insecticide, on the regulation of the use of which a Govern-
ment president has been set. Conservation Order M-133 re-
stricts and specifies the use of rotenone compounds in the United
States in connection with the war effort. If this is an example,
and it most likely is, of the method in which other scarce chem-
icals will be distributed by government order if and when it is
necessary, such a regulation can probably be worked out very
nicely. In the case of rotenone, its use is prohibited in non-
essential places and allowed for the Government or for the pro-
duction of food crops on which no other insecticide is satisfac-
tory. The rotenone supply comes almost entirely from the East
Indies and South America and these sources have been practically
SULPHUR is almost entirely of domestic production and
great supplies are available in Texas. For example, the Texas
Gulf Sulphur Co., maintains more than a world year supply above
ground at all times. It only remains for us to get sufficient trans-
portation and manufacturing facilities to make available all sul-
phur products that are necessary.
It will probably be necessary to use sulphur compounds in
place of other fungicides or insecticides wherever this is possible
and it may be advantageous to exploit the uses of sulphur, as
much as possible since large supplies of this are available do-
ZINC SULPHATE is available in considerable quantities in
the United States although the war effort demands considerable
quantities of zinc metal. In 1925 forty per cent of the world's
production was produced in the United States. Both zinc oxide
and zinc sulphate have been used, although zinc sulphate is by
far the most used, in Florida agriculture. This material must be
applied as a nutritional spray for citrus and this can be done
most effectively during the spring or early summer. It is quite
possible that, for a conservation practice, dilute sprays will be
necessary annually or occasionally when frenching or zinc de-
There are a large group of miscellaneous spreaders, stickers,
wetting agents, and emulsifiers which are mostly organic chem-
icals and are from time to time quite restricted in their supply.
It behooves every insecticide manufacturer to have alternate
THE FLORIDA ENTOMOLOGIST
compounds available which can be substituted for some commod-
ity whose distribution has been restricted by the war effort.
The use of stickers is usually a very advantageous one, par-
ticularly when smaller quantities of chemicals will likely be avail-
able. Any compound that can be added to improve the effective-
ness of one of the essential chemicals should certainly be used.
Considerable experimental work has been done with reduced
dosages of many of the essential insecticides and fungicide chem-
icals with apparently quite satisfactory results. For example,
it, has been suggested that Rotenone Dust mixtures could be re-
duced to .5% Rotenone with satisfactory results. The same has
been found to be the case with seed treating chemicals, fungi-
cides, and many insecticides. In making recommendations, how-
ever, with reduced concentrations, care should be taken to make
thorough enough applications so that the reduced toxic ingre-
dients will be effective enough to give satisfactory control.
All entomologists can be of considerable service to growers
now in pointing out the first or earliest stages of insect develop-
ment so that populations can be prevented from building up.
Considerably less chemicals are necessary for treating light in-
festations of small or young pests, whereas much greater
amounts of heavier concentrations are necessary after dense
populations have been built up.
All that has been said about the scarcity of essential insecti-
cide and fungicide chemicals can be repeated regarding spray
and dust equipment. In many cases special metals are used or
particular brass or bronze parts are necessary; and these are
and will be particularly hard to get.
High pressure spray hose is and probably will be scarce or
limited in quantity just as all other rubber products are limited.
Transportation of insecticides and fungicides, as mentioned
previously, is a considerable item and the shipment of all com-
modities is delayed. Growers can facilitate their own business
by anticipating their demands as soon as possible and allowing
the suppliers of their insecticides and fungicides as much time
as possible to make delivery. Calculations as to the amount of
material necessary should be very accurately done and request
for return of unused products should be made as infrequently
as possible. Since the movement of many insecticide and fungi-
cide chemicals was by water, and freight rates were based on
water transportation, which has now been discontinued to a
VOL. XXVI-No. 1
large extent, the cost of shipping coastwise moving chemicals
has been increased considerably because of the difference in rail
freight and water freight.
Containers for insecticides and fungicides have become more
scarce and have increased in price. The supply of 55 gallon steel
drums will probably be the greatest handicap of all container
problems. Conservation of these drums by users is very essen-
tial to their being able to obtain additional supplies of those
commodities that are transported in drums. As soon as the
drum is empty, it should be returned to the manufacturer from
whom it was obtained, in order that additional supplies may be
As stated before, the writer is certainly not magician enough
to tell specifically what particular items of insecticides and fungi-
cides will be scarcest or will disappear from the market; but it
is our suggestion that, since we are not sure as to the available
supply, every effort be made to conserve both chemicals and
equipment; and you may rest assured that every effort is being
made by manufacturers and suppliers to obtain either the orig-
inal insecticide and fungicide chemicals or to do sufficient re-
search to establish the use of a substitute product so that the
production of crops will not be handicapped.
FOR ALL PURPOSES
Carefully Executed 0 Delivered on Time
PEPPER PRINTING COMPANY
Official Organ of the Florida Entomological Society
VOL. XXVI MARCH, 1943 No. 1
J. R. WATSON, Gainesville .......--------......---.... -------..Editor
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C. B. WISECUP, Box 309, Plant City.-..........-----... Business Manager
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vance; 35 cents per copy.
SOME PRELIMINARY INVESTIGATIONS OF THE GREEN
SCALE, Coccus viridis (GREEN), IN SOUTH FLORIDA
JOHN M. FREDRICK, Assistant Grove Inspector,
State Plant Board of Florida,
The green scale, Coccus viridis (Green), also known as the
green coffee scale, soft green scale, and green bug, a pest of citrus
and other woody and herbaceous plants, was discovered by grove
inspectors of the State Plant Board of Florida near Davie,
Florida, during May of 1942. Since then studies have been con-
ducted on the life history, habits, and control of this scale. It is
not known how long the green scale has been in South Florida;
however, indications are that it has been there for several years.
The name given this scale is very descriptive of its main character
which is its color. It is bright pale green, being more or less transparent.
The young stages are easily confused with the young of the green shield
scale, Pulvinaria psidii Mask., but the adult does not have an egg sac out-
side the body as does the green shield scale and some other soft scales. The
outline shape of the green scale is elongate oval and the actual body meas-
urements on citrus are as follows:
Length, from 2.35 mm. to 3.3 mm.
Width, from 1.35 mm. to 1.65 mm.
VOL. XXVI-No. 1
On groundsel trees, the favorite host, they are only about three-fourths
as large as on citrus.
The crawlers and adults have small black eyes and the legs and an-
tennae are light green. On the dorsum of adult scales and those nearing
maturity a black U-shaped or irregular internal marking, the closed end
of which is at the anterior, is visible to the naked eye. At times this mark-
ing pulsates with regular beats varying from 27 per minute in some scales
to 45 per minute in others. The movement of this internal marking seems
to originate at the closed end of the U and working toward the rear. After
the scales die they turn a light brown or buff color and the black markings
are no longer apparent.
Green scales appear in a rather definite pattern on citrus leaves. The
undersurface of the leaves toward the base is preferred, and the adults
sometimes line up along both sides of the midrib, 2 or 3 abreast. On heavily
infested citrus limbs as many as 250 to 325 scales per leaf have been found.
Infestations were usually spotted on the individual trees; occasionally one-
half of the tree was infested and the remainder had few or no scales. All
stages of the scales were found infesting immature oranges and immature
and mature limes. Although the foliage of grapefruit was often heavily
infested, no scales were found on the fruit itself. On groundsels the scales
were usually distributed over the entire plant.
KNOWN DISTRIBUTION IN FLORIDA
Indications are that the green scale has been limited to the
present time to the extreme lower east coast of Florida. It is
known to be established from 5 miles north of Ft. Lauderdale
to a few miles south of Florida City.
According to the records of the State Plant Board, this scale
has been found on 72 different species of plants in Florida, so it is
far from host specific and can reproduce itself on several species
of plants in a grove should conditions become too adverse to per-
mit further development on citrus. Apparently the preferred
host of this scale is the groundsel tree, Baccharis halimifolia.
Another common name of this plant is "silverling" and in South
Florida it is best known as "glades myrtle." Although several
young citrus trees were found to be heavily infested, citrus did
not appear to be an especially preferred host. The. following
plants have been observed by 0. W. Calkins, a State Plant Board
Inspector, to be more heavily infested than some others on the
host list: Groundsel, tropical currant, wild coffee, citrus, sapo-
dilla, buttonbush, guava, ti-es, marlberry, seagrape,. poisonwood,
goldenrod, Tetrazygia, bustic, southern sumac, Nectandra sp.,
banana, Ixora coccinea, gardenia, wild primrose and ragweed.
THE FLORIDA ENTOMOLOGIST
Apparently, heavy infestations of green scales eventually will
kill groundsels. This was demonstrated in Davie where several
heavily infested groundsels were tagged at random for observa-
tions. The trees began to lose foliage and 3 months after the in-
festation had reached a dense population, the trees were bereft
of foliage and some of them were dead to the base.
APPARENT ECONOMIC IMPORTANCE
The green scale in Florida has not been under observation
sufficiently long to determine its economic importance. In two
groves in Davie only a small percentage of the trees were in-
fested. Since the groves were only 3 to 5 years old, it might be
possible that the scales had not been on the trees sufficiently
long to build up a heavy infestation. No extremely heavy infes-
tations have been found on large mature citrus trees.
There is evidence indicating secondary damage which may be
as severe and perhaps more so than the injury caused by green
scales. In Florida and parts of the West Indies it has been ob-
served that the populations of purple and long scales on citrus
seem to increase considerably following heavy green scale infes-
tations. According to W. L. Thompson,' one of the probable
reasons for this increase is the presence of sooty mold that grows
on the honeydew which is exuded by green scales. Furthermore,
green scales are parasitized by a white-fringed fungus, Cephalos-
porium lecanii Zim., and after this fungus kills the scales, young
purple and long scale crawlers hide under these dead mycelia-
enveloped bodies. This was observed quite frequently while mak-
ing counts. Green scales infected with C. lecanii will show the
mycelium for 30 days, and observations indicate that these fruit-
ing bodies cause the dead scales to stick to the leaves for a much
LIFE HISTORY AND HABITS
For experimental convenience the stages of green scales were
divided into three classes:
1. First stage-all eggs and crawlers under the adults.
2. Intermediate stage-all not included in 1 and 3.
3. Egg depositing adults.
Green scales are parthenogenetic and oviparous. The eggs,
whitish green in color and elongate oval in shape, are laid singly
SAssociate Entomologist, Citrus Experiment Station, Lake Alfred,
VOL. XXVI-No. 1
and remain under the adult until hatched. In hatching the egg
case splits at the anterior, leaving the fore appendages free to
struggle and work out of the remainder of the chorion which is
sloughed off at the posterior. Eggs hatch from a few minutes to
several hours after deposited. During September, October, and
November 85 or more eggs were deposited per female. Due to
C. lecanii and other parasitic fungi, considerable variation oc-
curred. There was also a variation in the number of days in
which adults deposited; some apparently completed deposition
in 8 days, and a few under observation deposited over a 42-day
period. In South Florida, the average length of time that passed
from the egg to egg-depositing maturity was 59 to 62 days during
the late summer months, and variations of from 50 to 70 days
The number of molts a green scale goes through was not de-
termined; however, 3 different sizes of scales were observed drag-
ging molt skins. According to Miller,2 "The larvae in any stage
and the mature females as well are able to change their feeding
position at any time, and the habit is very noticeable on branches
which through any cause have begun to wither. The migration
of the scales in search of fresh foliage takes place very soon after
withering begins and very few individuals die in their old feeding
positions upon such branches."
Miller's statement regarding the mobility of this scale was
well substantiated in South Florida by observations made of the
frequent migration of scales in search of fresh foliage.
A test was conducted to determine how long green scales
would live without food. Some heavily infested groundsel twigs
were cut and placed in a paper sack of double thickness. This was
then placed in a can which had one inch of water in it. The sack
was placed on a block to keep it out of water, and the can was
sealed. Six examinations of the scales were made at various
intervals and on the twenty-first day one living green scale craw-
ler was observed. The scales that were living near the twenty-
first day were not the scales that were living at the beginning
but crawlers that had been deposited by adults up to the eigh-
(To be continued)
Miller, 1931. The "Green Scale" of Coffee. Federal Malay States
Dept. Agr. Science, Ser. 7.