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6 HISTORICAL NOTES ON BEE DISEASES.
Consideration of papers on the causes of bee diseases—Continued.
White, (November 6; 9062:... 2.2 - 2 ee ee er eee ee
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Hander® VOW LNs sels eye Stee hb eet ees cen ae
Pander. 1901... ... “edocs a es tela spel BS A you co a laren ee eee
Brief chronological summary of the work on the causes of bee diseases........-
The different diseases that attack bees:..--...-G2o2/-82 seseeaue- - Sessa
The causes of bee diseases......-.-------- 2) eRe JAtiien 2.5). eae
PREFACE.
Bees, like many other members of the animal kingdom, are
known to suffer from diseases. Simultaneously with the good work
that has been done during the last half century toward the deter-
mination of the causes of the various diseases of man and animals,
there has been some work done on the causes of bee diseases. This
work has caused considerable literature to be written on the subject.
Although this literature contains much that is valuable, it abounds
in statements that are erroneous and in conclusions that seem
unjustifiable. Many of the inaccurate statements and conclusions
have been frequently copied in the past and they are still too often
copied into the current literature on bee diseases. The bee keeper,
therefore, in reading is often at a loss to know what is true and
what is untrue; what is actually known and what is not known.
For the purpose of aiding the bee keepers with this literature,
we have reviewed here portions ot several original papers dealing
with the causes of bee diseases. It is hoped that this bulletin may
serve aS a means whereby the bee keeper may solve for himself
some of the apparent mysteries found in beekeeping literature.
In selecting the papers for review, for the most part, those were
chosen which were written by men who had worked more or less
on the causes of bee diseases. The reviews that have been made
contain the more important beliefs concerning the causes of these
diseases that were entertained by the authors of the different papers
at the time they wrote. The classification of the diseases of bees as
understood by these different men is also frequently included. The
original papers naturally contain much that has not been mentioned
in these brief reviews, and therefore the reader is urged, if oppor-
tunity permits, to read the papers cited in this bulletin rather than
the reviews. It is probable that the papers here considered might
with profit have been more completely reviewed and that other papers
might with profit have been considered, but if either had been done
it is probable that the length of the bulletin would have defeated its
object.
It is hoped that the readers of bee-disease literature will learn, so
far as possible, to judge correctly an article that discusses in any
way the causes of bee diseases. To do this, one should first of all
learn who are actually doing work on the causes of these diseases.
7
8 HISTORICAL NOTES ON BEE DISEASES.
The writings of all these men should be read. If an investigator
has done work on the causes of other diseases than bee diseases, but
chooses to write on bee diseases, the reader will usually profit by
reading his papers. The great mass of literature, on the other
hand, created by those who have not worked on the cause of any
disease can as a rule with profit be rejected.
Having determined whose papers should be read, the character
of the work of each investigator should be carefully noted. If the
character of a man’s work proves to be good, give weight to all his
statements, but if the character of a man’s work is poor, expect
untrue statements and erroneous conclusions. If one will learn in
this way to judge the different papers, one will soon know what to
believe and what to suspect, but if one does not learn to do this he
will be forever at the mercy of printed pages.
As the reader forms his opinion of the character of the work done
by the different men referred to in this bulletin, permit the sugges-
tion that he exercise some leniency inasmuch as the time at which
a man works and the circumstances under which he labors are
frequently in a measure responsible for mistakes. The reader will
note, however, that many times the mistakes made in the study of
bee diseases have been made only because insufficient and careless
work was done by the investigator. In such cases no leniency is to
be exercised in arriving at conclusions.
The writers of this bulletin have commented very little on the
character of the work done by the different authors of the papers
reviewed. ‘The views of these men as they are found in the papers
are given and the reader is allowed and urged to judge for himself
whether or not such views are true. To aid the reader, however,
the writers have made a few suggestions when it was thought that
they might prove advantageous. The page references refer to pages
in this bulletin.
In reading a paper there is always the danger of misinterpreting
an author’s conception. This danger is greatly increased if the
author of the paper criticized uses a foreign language. Realizing
this possible source of error, we have endeavored in every case to be
cautious. When quotations from papers written in a foreign lan-
guage were selected, rather free translations of them into English
have been made.
We disagree with a very large number of the statements which
have been made by different authors referred to in this bulletin con-
cerning the causes of bee diseases. Therefore let it be emphasized
that the reviews which are here made are intended to express the
opinion of the author of the paper reviewed, and not by any means
the opinion of the writers of this bulletin.
PREFACE, 9
To entomologists who feel an interest in the causes of insect dis-
eases and who wish to be able to judge with some satisfaction the
work that has been and is being done on insect diseases this bulletin
will be of special interest. It is believed that by the learning of the
‘mistakes made by workers on bee diseases, and by the learning of
the causes for such mistakes, the careful reader will be enabled to
judge more accurately the value of the various reports that appear
on the diseases of insects.
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HISTORICAL NOTES ON THE CAUSES OF BEE DISEASES.
INTRODUCTION.
Bee keepers, as a rule, manifest a keen desire to know about the
causes of bee diseases and they show a lively interest in the investiga-
tions leading to the determination of the causes. This is gratifying
to those working on these diseases and will be a great benefit to
the apiarist who must treat the diseases. The losses to apiculture
from diseases are enormous, and inasmuch as the successful treat-
ment of a disease depends largely upon a knowledge of the cause of
the disease to be treated it behooves every owner of an apiary to
become as familiar as possible with the causes of bee diseases.
The facts that are known about the causes of bee diseases unfor-
tunately are altogether too few. As this can be said of all diseases
affecting the animal kingdom, the bee keeper has no cause for despair.
An attempt, however, will be made in this bulletin to furnish data
from which the bee keeper may be able to inform himself concerning
the facts that are really known about the causes of bee diseases.
In this introduction it might be well to classify the bee diseases as
the writers of this bulletin understand them. Bee diseases can be
conveniently classified under those affecting the brood and those affect-
ing the adult bee. The most important brood diseases are American
foul brood, European foul brood, and the so-called ‘‘pickled brood.”
The disorders affecting adult bees that are of most importance are
being referred to at present under the names of paralysis, dysentery,
and Isle of Wight disease.
American foul brood.—American foul brood is a very widely dis-
tributed disease and better known to bee keepers than European foul
brood. It is the one which is generally referred to by the bee keeper
at the present time when he speaks of ‘‘foul brood.’’ The brood
affected with this disease is usually capped before it dies. The
color of the dead brood presents in general various shades of brown.
The marked ropiness of the decaying remains of the dead larve is
probably the most characteristic and well-known feature of the dis-
ease. The punctured cappings, the scales formed from dried-down
larvee, and the disagreeable odor sometimes present are aids to its
diagnosis. This disease is clearly an infectious one. The exciting
cause of it is a bacterium known as Bacillus larve.
il
1 HISTORICAL NOTES ON BEE DISEASES.
European foul brood.—Kuropean foul brood is the disease which
Cheshire and Cheyne (p. 25) described in their studies of foul brood.
Howard (p. 44), of Texas, made a very brief and unsatisfactory
study of this disease at one time and named it ‘‘New York bee dis-
ease” or ‘‘black brood.’ We are strongly inclined to believe that
Burri (p. 68) was working with this disease for the most part during
his study of the condition which he refers to as ‘‘sour brood.”’ Euro-
pean foul brood is less widely distributed in this country than is
American foul brood. In European foul brood one finds, as a rule,
most of the diseased brood as yet uncapped. In general, the brood
dead of this disease presents various shades of yellow. Usually there
is no ropiness; at times, however, there is. That degree of ropiness,
however, which is so characteristic of American foul brood is seldom
present in European foul brood. There is frequently a slightly sour
odor to the diseased brood. The rapidity with which this disease
spreads in a new territory and the marked destructiveness of it are
features which most bee keepers have experienced who have been
so unfortunate as to have the malady affect their apiary. The dis-
ease is clearly, therefore, an infectious one. The exciting cause is
not known. Claims are made by some that certain species of bacte-
ria stand in direct etiological relation to the disease, but satisfactory
evidence to prove such contentions are wanting.
The so-called ‘‘ pickled brood.’’—Howard (p. 42), of Texas, described
what he chose to call pickled brood. His findings have never been
confirmed. The name “‘pickled brood,’’ however, is very frequently
used by bee keepers in referring to a diseased condition of the brood.
Howard’s description of ‘‘pickled brood”’ (p. 43), however, does not
apply to such a condition. Since the name ‘‘pickled brood”’ is not
accurately applied and is, moreover, entirely inappropriate for the
condition which we find, we prefer for the present to use the expres-
sion ‘‘so-called pickled brood.’’ In this condition the brood dies
about the time of capping. The body wall of the larva, in a case
which might be called typical, is intact and rather tough. When
this wall is broken, one often finds a watery content in which is sus-
pended a granular substance. As a rule a very small proportion of
the brood is affected. The disease does not seem to be infectious,
The loss to the colony in comparison with European foul brood and
American foul brood is slight. This disorder, therefore, should
arouse no great amount of fear. While the number of colonies lost
from this disease is comparatively small, in the aggregate many bees
die as a result of the condition. The disease has a very wide dis-
tribution. The exciting cause is not known. is
There is very little that is definitely known about the diseases of
adult bees. They have not been sufficiently investigated to make it
possible to classify them with any degree of satisfaction.
SCHIRACH, 1771. 13
Paralysis.—But little is definitely known about paralysis of bees.
The disease has not been demonstrated to be infectious. Many sup-
positions have been made by different writers as to the cause of the
trouble, but no satisfactory evidence has been produced to prove the
cause.
Dysentery—aA condition known as dysentery has often been
observed by the bee keeper. But little is known about the disorder.
There is considerable evidence that the nature of the winter food
plays a part in its causation. Zander (p. 89) has recently suggested
that there are two forms of this affection, a noninfectious one and
an infectious one. To an infectious form he ascribes Nosema apis
as a cause. Much work must yet be done upon this condition.
Isle of Wight disease-—The disorder known as Isle of Wight dis-
ease was first reported from the Isle of Wight by Imms (p. 79).
Malden (p. 93) reports that the disease has more recently spread to
the mainland (England). This disorder has so far not been found
in any other country. The cause has not been definitely established.
It is urged that the reader peruse the preface to this bulletin
(pp. 7-9) carefully. By so doing the intent of the writers of this bul-
letin will be better understood and the chances of misinterpretation
will be lessened.
CONSIDERATION OF PAPERS ON THE CAUSES OF BEE DISEASES.
ScHIRACH, 1771.
Schirach' in 1771 classified the diseases which most frequently
attack bees as follows: (/) Dysentery; (2) disease of the antenne;
(3) foul brood; (4) queens laying drone eggs only; (4) sterile queen;
(6) queenless colonies.
Dysentery he considered to be dietary in origin. No belief is
expressed as to the cause of the disease of the antennex, to which
he refers, but he states that with this disease the danger is not great.
The disease which he designates as foul brood, however, he believed
to be quite dangerous, very fatal, and a true pest after it has reached
a certain stage. To this condition he attributed two causes, one
cause being ascribed to the improper food which was consumed by
the larve, and the other being a fault of the queen in permitting
the brood to be so arranged in the cells that the heads point inward.
Considering these two widely different causes ascribed to an abnor-
mality in the brood, one might suspect that there was more than
one disease in the condition which he designated as foul brood.
That part of the disease condition, to which as a cause he ascribed
the food, could well be an infectious disease—either American foul
1 Schirach, A. G., 1771. Histoire naturelle de la reine des abeilles, avec l’art de former des essaims.
LaHaye. Pp. Lxm+269; 3 plates,
14 HISTORICAL NOTES ON BEE DISEASES.
brood or European foul brood. The other form of the disease, in
which the brood was supposed to be placed with the head directed
inward, most probably was not an infectious disease. In the treat-
ment of foul brood Schirach recommends the removal of all combs
from the bees. This principle is the one upon which is based the
methods which are most successful at the present time in the treat-
ment of the infectious brood diseases.
The other abnormalities in the colony which are mentioned in
the paper relate to the condition of the queen. These are conditions
familiar to the bee keeper, but which may occur more often when an
infectious brood disease is present. Mention is also made of the fact
that brood is sometimes killed by chilling. Schirach refers to this
as an accident and not as a disease.
LEUCKART, NOVEMBER 12, 1860.
Leuckart ! had entertained the opinion that infectious foul brood
was due to a fungus, and he felt that his view was strengthened by
some work which was done on the diseases of the silkworm. During
the summer of 1860, however, he had an opportunity to see much
infectious foul brood in samples of comb and in colonies. In the
diseased material he found no fungi that he could not attribute to
the phenomenon of decay. He states in the paper that foul brood
is obviously a collective name that includes various forms of disease
with the features in common of being epidemic, attacking early
stages, and being usually fatal. One sample was examined, and a
number of diseased and dead larve was found to contain an uniden-
tified fungus. The majority of them, however, did not contain the
fungus; yet these latter larvee were thought to be dying of the usual
type of foul brood. From his summers’ experiences Leuckart ar-
rived at the conclusion that the infectious foul brood was not due to
a fungus.
Mouiror-MUnHLFELD, ApriIL 15, 1868.
Molitor-Mihlfeld 2 in 1868 reported some startling observations
relative to the cause of foul brood. He writes that foul brood is of
two kinds, the mild kind and the so-called infectious or virulent one.
The mild form of foul brood, according to his views, resulted from a
chilling of the brood. During the early warm days of spring, he
argues, brood rearing is stimulated to such an extent that when
colder weather follows it is impossible for the bees to care for all the
brood, and as a result the neglected brood is chilled, dies, and be-
1 Leuckart, Dr., November 12, 1860. Zur Naturgeschichte der Bienen. 3. Zur Kenntniss der Faul-
brut und der Pilzkrankheiten bei den Bienen. WHichstiidt Bienenzeitung, 16 Jahrg., Nro. 20, pp. 232-233.
2 Molitor-Miihlfeld, April 15, 1868. Die Faulbrut, ihre Entstehung, Fortpflanzung und Heilung. Eich-
stidt Bienenzeitung, 24 Jahrg., Nro. 8, pp. 93-97,
PREUSS, OCTOBER 1, 1868. 15
comes foul. From this condition, this author stated, no danger is
to be feared, as the bees afterward remove all this dead brood, leay-
ing the colony free from danger. The cause of the virulent form of
foul brood is attributed by .Molitor-Mihlfeld to a small parasitic
ichneumon fly, reddish-yellow in color and scarcely one-sixth of an
an inch long, to which he gave the name Jchneumon apium mellifi-
carium. He writes that this fly had already been observed about
foul-brood colonies by another writer, but that it was thought to be
a carrion fly. Concerning the life history of these flies, he says that
they press into the hives and lay their eggs in the bee larve. The
larvee live in spite of this until the cell is capped and the cocoon is
spun. During this time the fly larve feed upon the fat of the bee
larve, and finally bore their way out of the body into the cell, undergo
metamorphosis, and in a few days escape from the cells through
openings which they make in the center of the cell-capping. These
young adult flies now mate, sting other bee larve, lay their eggs, and
continue the cycle. The time which elapses from the egg of this
parasitic insect to the adult is given as about from 10 to 12 days.
This, to his mind, explained the rapid increase of the exciting cause
of foul brood. As a result of the parasitic existence of this fly in the
bee larve, these larve die and change into a ropy, sticky, ill-smelling
mass which the bees can not remove.
Furthermore, he argues that if instead of the diseased larvee dying,
as they do, after capping, they should die before this stage was
reached, then the dead bodies would be removed early and with them
the larve of the fly; but since the brood is always capped before death
takes place the capped cells afford a protection for the parasitic
insect until it becomes an adult ready to emerge.
In making a diagnosis, it is stated, the cell-cappings should be
examined, and if they are punctured then the disease is positively
the infectious foul brood. As a treatment for the infestation of the
brood by this insect in a colony in which infectious foul brood already
exists, it is recommended that the combs be removed to a clean hive
with new foundation, and that the treated colonies and other colonies
in the apiary be protected by pouring at frequent intervals camphor
dissolved in oil of turpentine, between the hives in the yard and also
sometimes on the alighting boards. This is done to prevent, by the
odor of the turpentine and the camphor, the entrance of the ichneumon
fly into the hives.
Preuss, OcToBER 1, 1868.
In a paper written by Preuss,! in. 1868, his views on the causes of
foul brood are given. The distinction which he would make between
1 Preuss, Dr., October 1, 1868. Das Wesen der bésartigen Faulbrut besteht in einem mikroskopischen
Pilze, Cryptococcus alvearis. Sie kann verhutet und geheilt werden. Eichstidt Bienenzeitung, 24 Jahrg.,
Nro. 19 u. 20, pp. 225-228,
16 HISTORICAL NOTES ON BEE DISEASES.
mild and virulent foul brood is, that virulent foul brood is caused
by a fungus which he named Cryptococcus alvearis, and that the mild
foul brood is due to some other cause. His conclusion concerning
the virulent foul brood was reached through a microscopic study of
foul-brood material. Preuss had been somewhat familiar with bee-
keeping since early boyhood, and had had the opportunity of visit-
ing numerous apiaries in the Vistula Valley, but had not encountered
foul brood until in 1866, when a friend had called his attention to the
disease in an apiary of the latter in which he was using the Dzierzon
hives. Preuss immediately undertook the investigation of the char-
acter of the disease by studying microscopically the larvee which had
died of the disease. A small bit of the dead larvee was added to a
little water, covered with a glass, and studied in the fresh condition.
Numerous spherical bodies measuring 2 » in diameter were seen and
identified by him as belonging to the genus Cryptococcus, to which
he gave the name Cryptococcus alvearis. Larger objects which were
present were recognized as fat bodies.
Very nearly related to this organism, Preuss writes, is a fungus
that causes fermentation, Cryptococcus fermentum. It was his belief
that if this latter species infected or fell upon a larva it might, under
favorable temperature and moisture conditions, change into Crypto-
coccus alvearis and in this way produce foul brood. Practical bee
keepers had, prior to this time, emphasized the danger of foul brood
transmission by the feeding of fermented honey. One bee keeper of
large experience had attributed foul brood to meal feeding, and since
meal is a good medium for the growth of fungi, Preuss was inclined
to favor the view. He argued that since the fungus of fermentation
is widespread in nature, the brood dying from cold or neglect of any
kind may constitute a fruitful soil in which this fungus could grow
and thus become the cause of infectious foul brood. Medication in
the treatment of the disease Preuss held to be quackery and recom-
mends instead the removal of the diseased frames from the hive, but
not the destruction of the hives. The hives were to be washed with
10 per cent sulphuric acid, followed by water, and afterwards put
into an oven and heated to the boiling temperature for some hours.
The frames containing diseased material were to be burned, and
those frames which were free from such material were to be used
again. All dead bees were to be buried, as they might become a
source of fungous growth, and the ground in front of the hive was to
be sprinkled with sulphuric acid and then dug up deeply.
SCHONFELD, NOVEMBER 15, 1873.
|
In the absence of conclusive experimental proof, the theories |
advanced by Preuss in the paper just considered were not univer-
SCHONFELD, NOVEMBER 15, 1873, - 17
sally accepted. Schonfeld,’ therefore, set about to supply incontro-
vertible evidence to prove the cause of infectious foul brood. He
received a small mass of decaying larvee about the size of a pea and
placed it under an inverted funnellike apparatus. An opening for
the admission of air was made from below; the exit was an opening
above in which was placed a stopper made of cotton. Placing this
apparatus near the window, that it might receive the heat of the sun,
he hoped, by the current of air which wouid thus be produced, to
collect on the cotton, filling the exit, the spores of the fungus which
would be floating off in the air from the foul-brood mass. Upon
examining the cotton he found what he supposed was the fungus in
the form of a micrococcus. This was the first part of his experiment.
In the second part of it he used this cotton to infect healthy larve.
Four square inches of brood was covered by a layer of cotton. The
cotton was taken from one of the stoppers that had been contami-
nated with the fungus by means of the apparatus. After two unsuc-
cessful trials he made a third attempt, which was considered by him
as being successful. After a lapse of four days seven larve had
died and numerous micrococci were found in their dead bodies.
In another experiment the same author used the larve of the blow-
fly (Musca), Calliphora vomitoria. Some cotton contaminated in
the manner outlined in his first experiment was placed upon some
meat upon which these larve were feeding. Nine days after adding
his supposed virus he found dead larvee which upon microscopic
examination revealed to him again the presence of numerous micro-
cocci. The results of these experiments convinced him that this
thicrococcus was the cause of infectious foul brood, and he believed
that the fact would be accepted without question.
The experiments of Schénfeld were not, however, universally
accepted as conclusive. This induced him to perform other infec-
tion experiments. This time he used caterpillars of (Pieris) Pontia
brassice and (Pieris) Pontia rape. The virus was mixed in dis-
tilled water and painted on the exterior of the insect, with the result
that those so treated died while the checks developed normally to
healthy pup. Microscopically, however, the check caterpillars
showed also the presence of the fungus. This caused him to doubt
somewhat his conclusions relative to the blowfly experiment. He
believed, however, that sufficient evidence had now been produced
to justify the conclusion that infectious foul brood is a mycosis and
that the fungus Cryptococcus alvearis is the exciting cause of the
disease.
1 Schonfeld, Dr., November 15, 1873. Faulbrut-studien, Pt.I. Eichstiidt Bienenzeitung, 29 Jahrg., Nro.
21, pp. 250-254; January 15, 1874. Faulbrut-studien, Pt. II, Eichstiidt Bienenzeitung, 30 Jahrg., Nro. 1,
pp. 3-5.
13140°—Bull. 98—12——2
18 HISTORICAL NOTES ON BEE DISEASES.
DzieRzon, 1882.
For many years Dzierzon and others entertained the belief that
there existed two forms of foul brood, a mild form and a virulent one.
In his “‘ Rational Bee Keeping,’’ Dzierzon'! has written the following
concerning the kinds of foul brood.
There is one kind that is mild and curable, and another kind malignant and incura-
ble; both kinds are, however, contagious.
The curable occurs in this way: More of the larvee die still unsealed, while they are
still curled up at the bottom of the cell, rotting and drying up to a grey crust, that may
be removed with tolerable ease. The brood which does not die before sealing mostly
attains to perfection, and it is only exceptionally that individual foul-brood cells are
met with sealed.
This is exactly reversed in the malignant kind of foul brood. In this the larvee do
not generally die before they have raised themselves from the bottom of the cell, have
been sealed and begun to change into nymphs. The rotten matter is, therefore, not
found on the cell floor, but on the lower cell wall; it is brownish and tough, and dries
up to a firm black crust, both in consequence of the heat prevailing in the hive, and
of a small opening bitten in the depressed cover. This matter the bees are not able
to remove; and when they are in some strength, they can at most get rid of it by entirely
biting down the tainted cells and making fresh ones.
The description which Dzierzon here gives of the ‘‘mild”’ form of
foul brood applies very well to European foul brood, and his de-
scription of the ‘‘malignant”’ form applies equally well to American
foul brood. It is fair to suppose that he encountered both European
foul brood and American foul brood, but instead of recognizing them
as two distinct diseases, he thought them to be two forms of the same
disease.
CHESHIRE, AuausT 1, 1884.
The work of Cheshire on the cause of bee diseases is of much in-
terest and should be somewhat carefully considered, inasmuch as it
has directly and indicectly caused much confusion in the minds of
bee keepers concerning the nature, cause, and treatment of foul
brood.
The first paper * by him to be considered was the outgrowth of an
invitation by a committee of the British Bee Keepers’ Association
about the last of May, 1884, to give an address before the association
on foul brood.
laboratory conditions was in 1903. For this purpose a special agar
medium was used, made from the larve of bees. A somewhat similar
medium had been used by Lambotte (p. 55), but with it he did not
obtain a germination of these spores. This special agar was used
in a test tube, and Liborius’s method for making inoculations was
WHITE, JANUARY 15, 1904. 63
employed. Until the organism could be further described, and until
there was more evidence that there was a causal relation existing
between the species and the disease with which it was found asso-
ciated, it seemed best to refer to the bacterium as Bacterium ‘‘X’’
and to the disease as ‘‘X brood.” Seven samples of this disease
were studied in 1903, and Bacterium ‘‘X” was found by cultures in
all of them.
The disease called ‘‘pickled brood” received some further study at
this time. The most striking feature in the results was the record of
no growth from the cultures. The following is taken from the
report:
The results of the examinations showed that ‘‘Aspergillus pollinis’’ was not found.
Further investigations must be made before any conclusion can be drawn as to the
real cause of this trouble.
Concerning paralysis in adult bees, the following was written:
The disease known to the apiarists as palsy or paralysis attacks the adult bee.
The name is suggestive of the symptoms manifested by the diseased bee. A number
of bees affected were received from Messrs. Wright and Stewart taken from apiaries
in New York State. Bacteriological examinations have been made of a number of
the bees so affected but no conclusions can be drawn from the results thus far obtained
as to the cause of this disorder.
The following is a brief summary of the results obtained during
the year 1903:
1. Bacillus alvei was found in all samples of European foul brood
examined.
2. A causal relation between Bacillus alvei and European foul
brood seemed questionable.
3. Bacillus alvet was not encountered in any sample of American
foul brood.
4. The sampleg of American foul brood did contain, however, a
species which was referred to as Bacterium ‘‘X,’’ in such numbers
and with such.constancy as to suggest an etiological relation to the
disease.
5. A growth of this species was obtained on artificial media.
6. Neither ‘‘black brood” nor ‘‘ Bacillus milii” was found. The
work of the year seemed to confirm the idea that the so-called “ black
brood” was simply the foul brood of Cheshire and Cheyne.
7. The cultural results obtained from the so-called pickled brood
were practically negative.
8. The ‘‘Aspergillus pollini”” named by Howard was not found in
any disorder of the brood of bees.
9. A disease called palsy or paralysis by the bee keepers seemed to
be a malady, but no cause was found.
10. Formaldehyde gas as ordinarily used in the apiary would not
insure complete disinfection.
64 HISTORICAL NOTES ON BEE DISEASES.
Banr, 1904.
A paper on the diseases of bees by Dr. L. Bahr,’ of Denmark,
bears the date 1904. The author gives a brief review of the work
on bee diseases, together with some interesting observations by him-
self. In that portion of his paper describing his own observations
the following is recorded:
A number of samples of brood have been sent to me from various parts of the country
(Denmark) having the following symptoms: Some of the diseased larvee were quite
small, while some of them are older—from 4 to 6 days. They never become ropy as
those of foul brood, but retain their form until they approach the consistency of gruel.
The color is whitish yellow but sometimes somewhat darker. In the gruel-like mass
of the diseased larvee I found a very small oval bacterium.
Bahr mentions that the disease seems to be quite contagious.
From his description of the disease ‘and from his bacteriological
findings there is a strong suggestion that the disease to which he
refers is European foul brood. Sufficient facts, however, are not
given to make this point at all positive. The author states that his
studies were not completed.
Burri, OCTOBER AND NovEMBER, 1904.
We shall now consider a very excellent piece of work on foul brood
by Dr. Burri.2 In his introductory remarks this author very aptly
refers to the need and value of a scientific study of foul brood.
Burri began his work on foul brood apparently in the spring of 1903.
He observed that the foul odor which is emphasized so much in the
literature on ‘‘foul brood”’ is not constant for all samples. Studying
the different samples he concluded that the ropiness of the decaying
larvee and the tonguelike scales on the lower side wall of the cell were
characteristic of typical “‘foul brood.”’
He also calls attention to the very large number of spores in the
decayed foul-brood larve, and the Scene of any vegetative forms.
Cultures were made from these dead larval remains, but there was no
germination of the numerous spores. The occasional colony which
did appear he attributed to an accidental contamination with a
different species. Failing in his attempt to obtain a growth of these
numerous spores, Burri came to the conclusion that they were a new
species that would not grow on the media ordinarily used in the
laboratory. He added to his medium some cooked healthy larve
somewhat similar to the medium used by Lambotte, but with this
special medium he did not obtain the growth desired. Failing still
to obtain a growth of the species, he proceeded with the study of its
morphology as observed in the various stages of decay of the brood.
Septbr. 1904. Saertryk af Tidsskrift for Biavl Nr. 16 og 17.
2 Burri, Dr. R., October and November, 1904. Bakteriologische Forschungen tiber die Faulbrut. Schwei-
zerische Bienenzeitung, Nro. 10, pp. 335-342; Nro. 11, pp. 360-365.
BURRI, OCTOBER AND NOVEMBER, 1904. 65
Further attempts were then made to study the species culturally.
He smeared some freshly infected larvee supposed to contain only
rods upon a certain medium and obtained spore-bearing rods and
spores similar to those which had been observed in the diseased
larve. He made a similar inoculation from the dead larve which
had turned brown and which contained only spores, and as a result
of this inoculation he obtained motile rods which later formed spores.
Burri was somewhat inclined to believe that pure cultures had been
obtained by his method of inoculation, although he states that the
obtaining of pure cultures of this organism had to remain an unful-
filled wish.
From his studies Burri came to the conclusion that the organism
is neither Bacillus alvei nor Bacillus mesentericus, but a new one.
He repeated some of the experiments reported by Lambotte (p. 53),
but was inclined to believe that the latter was in error. Besides
studying from a number of samples this form of foul brood to which
he referred as the nonstinking form (most probably American foul
brood), Burri received and studied other samples of foul brood to
which he referred as the foul-smelling form (most probably European
foul brood). ‘In the latter disease he found a large number of bacteria
unlike those observed in samples of the other disease studied. The
species which was present in large numbers in the latter samples
grew without difficulty when sown on artificial media, and he identified
it as Bacillus alvei Cheshire and Cheyne (p. 25).
We are not inclined to think of this latter disease (European foul
brood) as the one which is the more foul smelling of the two, nor the
former the ropy form (American foul brood) as the less stinking one
of the two. It is true that only a few of the samples of American
foul brood have a disagreeable odor when they reach the laboratory;
nevertheless, the most disagreeable odor encountered in diseased
brood when it is examined in the apiary is present in those colonies
that are affected with American foul brood. It is American foul
brood that the American bee keepers think of when they refer to the
foul-smelling foul brood.
Burri encountered other bacteria than Bacillus alvei and the one
which was difficult of cultivation. He mentions the presence of
bacteria which he associated with a condition referred to as sour
brood. He reports that he had always found foul brood present with
this latter condition.
The following are the conclusions drawn by Burri in his paper:
1. There are in Switzerland, and also in other places, at least two distinct kinds of
bacteria which can produce a typical contagious foul brood. In one case it is Bacillus
alvei described by Cheshire and Cheyne; in the other a species of bacterium not
formerly known, which is difficult to cultivate.
13140°—Bull. 98—12——5
66 HISTORICAL NOTES ON BEE DISEASES.
2. The two kinds of foul brood are easily distinguished from each other in the dried
remains of the larve. That form of the disease in which Bacillus alvei is found exhibits
an offensively smelling residue in which microscopically are found rods 2 p» in
length, together with numerous spores. The larval remains in which are found the
organism that is difficult to cultivate are almost odorless, and on microscopic exami-
nation spores 15 » in leagth are recognized, but no rods.
3. Occasionally other bacteria which stand in a certain relationship to the so-called
foul-brood germs obtain local significance as the cause of foul brood. Lambotte’s
view, on the other hand, that the potato bacillus (B. mesentericus vulgatus) is to be
considered the cause of foul brood is yet without demonstration.
4. In choosing the methods for eradication of the disease, the fact that there are at
least two kinds of foul-brood bacteria must be taken into consideration.
5. In every case a certain amount of knowledge of the bacteria in question is desired,
not only from the scientific but from the practical point of view as well.
Some of the interesting facts noted in Burri’s paper might be
summarized as follows:
1. He recognizes two forms of foul brood.
2. He refers to the ropy type of foul brood (American foul brood)
as the non-smelling form of the disease, and to European foul brood
as the foul-smelling form.
3. He did not obtain a growth of the spores present in American
foul brood either on the media ordinarily used in the laboratory or
on a special medium to which cooked bee larvee were added.
4. He studied the morphology of the organisms present in the
foul-brood larve in a manner similar to that followed by Cheshire
(p. 19).
5. He expressed doubt concerning the accuracy of the results
reported by Lambotte.
6. In one disease (probably European foul brood) he obtained
Bacillus alvei in very large numbers.
7. He found a condition to which he referred as sour brood, and
with it he found associated a species to'which he referred as sour-
brood bacteria.
8. In his investigations he says foul brood always accompanied
sour brood.
WHITE, JANUARY 14, 1905.
The work on bee diseases was continued during the year 1904 in
New York State and was followed by another report.1 The work
of the year was devoted to the diagnosis of the brood diseases in the
laboratory; to a study of ‘‘foul brood”? (European foul brood) and
‘‘X”’ brood (American foul brood); and to a study of palsy or paral-
ysis in bees.
The similarity that exists between samples of the different brood
diseases was observed to be so marked at times that a diagnosis of a
condition often could not be positively made without a bacterio-
l White, G. Franklin, January 14,1905. State of New York, Department of Agriculture, Twelfth
Annual Report of the Commissioner of Agriculture, for the year 1904, pp. 106-107.
WILSON, 1905, 67
logical examination. This called for considerable work in diagnosis
in the laboratory. The results of the examinations showed that
European foul brood and American foul brood were the diseases of
bees which attracted most interest in the State.
Bacillus alve. was found to possess a number of flagella arranged
peritrichic instead of one flagellum at a pole, as Harrison at first
reported, but later accredited Cowan with the statement (p. 56).
The fact that Bacillus alvei was supplied by more than one flagellum
had already been pointed out by Lambotte.
Concerning Bacillus “X’’ (Bacillus larve) the following is found:
It is a slender rod with moderate motility having a tendency to form in chains.
The formation of spores and the arrangement of flagella is somewhat similar to that
found in B. alvei. While B. alvei grows quite well on all the artificial media com-
monly used in the laboratory, the growth of Bacillus ‘“X” is not so easily obtained.
The medium which is most successful in the cultivation of this species is the one made
from the larvee of bees. Growth has been obtained with difficulty upon ordinary
agar and gelatin.
- The so-called palsy or paralysis received some attention, but after
beginning this work it was soon realized that before it could be done
satisfactorily it would be necessary to know something of the normal
bacterial flora of the healthy bee. A brief study of the bacterial
species most frequently found within and upon the normal bee was
therefore made.
Waite, JUNE, 1905.
About the time that this last report was published, a manuscript
embodying all of the work done on bee diseases at the New York
State Veterinary College for the State of New York was prepared
as a thesis.t. Since the manuscript is available to but few, it will
not be reviewed here. With very few changes this manuscript was
published as Technical Series No. 14, Bureau of Entomology, United
States Department of Agriculture (p. 76).
Witson, 1905.
Of course it is very frequently impossible on account of inadequate
descriptions to identify certain organisms. Inthecase of Bacillus alvei
there is but little excuse for any mistake, since the description which
Cheyne has made is entirely adequate for this purpose. In this con-
nection a paper by Wilson? is of interest.
He used a culture for demonstration purposes in a medical school,
which he isolated from the tonsils of a patient with suspected diph-
theria and identified it as B. alvei. He claims that B. alvei is fre-
1 White, G. Franklin. June, 1905. The bacterial flora of the apiary with special reference to bee diseases.
Thesis, Cornell University, Ithaca, N. Y.
2 Wilson, Dr. R. J., 1905. Morphological characteristics of the Bacillus alvei. Proceedings of the New
York Pathological Society, vol. 5, pp. 79-81.
68 \ HISTORICAL NOTES ON BEE DISEASES.
quently seen in cultures from the throat. Now,it may be that Wilson
made a correct identification, but inasmuch as the source of the
culture was the throat, he should have been very careful about
making the identification positive.
It might be mentioned here that not a few bee keepers have been
startled by an announcement that B. alvei is found in human sputa.
Some of them have reasoned, very naturally, that if all reports were
true the sputum might be the source of foul-brood infection, but
there is no convincing evidence, of course, that such is the case.
Burrt, JANUARY, 1906.
Burri’s next paper! was on “foul brood” and “sour brood.”
His discussion of foul brood is quite similar to that which appeared
in his former paper (p. 64). We shall therefore direct attention at
this time to that portion devoted to ‘sour brood.”
The origin of the name ‘sour brood” is indefinite. Quoting from
C. P. Dadant, an American writer, Burri writes that there are three
diseases of the brood recognized in America—foul brood, sour brood,
and black brood. This view would make sour brood synonymous
with pickled brood, but as it will be learned later in his work on sour
brood, Burri was studying for the most part at least European foul
brood.
In his work Burri did not find a uniformity in the diseased brood
examined either in the gross or the miscroscopic appearance. In
one sample he found no bacteria, although the outward appearance
of the larve indicated disease. In another sample the gross ap-
pearance did not suggest foul brood, and there were absent the bac-
teria which are commonly found in the disease; and in their stead
there were present millions of bacteria which to the investigator did
not seem to stand in etiological relation to the disease. In still a
third instance the larve gave no outward sign of being killed by the
bacteria of foul brood, but when studied culturally, they showed
the presence of a very large number of unidentified bacteria together
with a few of those which frequently accompany ‘foul brood.”
These findings illustrate, he says, some of the difficulties which are
encountered in a study of the brood diseases bacteriologically.
Putting aside all samples which were unquestionably “foul brood,”’
he attempted to group the remaining ones according to certain
characteristics observed in a study of the gross appearance of the
diseased brood. One character which seemed to be emphasized was
the sour odor emitted by certain samples. On account of this he
classified this condition as ‘sour brood.” In testing the odor of
brood dead of the disease, Burri recommends the holding of the nose
1 Burri, Dr. R., January, 1906. Bakteriologische Untersuchungen tiber die faulbrut und Sauerbrut der
Bienen. Pp. 39, pl.1. Vorwort by U. Kramer,
BURRI, JANUARY, 1906. 69
very near the combs, or, better, the removal of a larva and testing
it. He calls attention to the fact that “foul brood’”’ (American foul
brood) and “sour brood’’ (European foul brood) have probably
often been confused by bee keepers of little experience and placed
under one name, “foul brood.”
Another point of difference between ‘‘foul brood” and ‘‘sour
brood,” as pointed out by Burri, is in relation to the consistency of
the dead -larvee in the two conditions. In ‘‘foul brood,” he says, a
uniform ropy mass is all that remains of the decaying larva dead of
the disease, while in ‘‘sour brood” the chitinous covering of the
decaying larva permits its removal as a whole from the cell.
Besides the odor and consistency of the dead brood, Burri refers
to the color as a third characteristic that serves to aid in the differ-
entiation of ‘‘foul brood” and ‘‘sour brood.’ He writes that the
larvee of ‘‘foul brood” are cream colored soon after the development
of the bacteria has begun, but later are a pale coffee brown, and finally
a dark brown. In ‘‘sour brood,” he says, the larvee become discol-
ored. At first they are a dirty yellow. The dry scales are less black
than those of ‘‘foul brood.”
Burri received samples which were reported to him to be ‘‘black
brood.” The older larvee seemed to be affected and the microscopic
and cultural examinations gave negative results. This strongly sug-
gests that this is not the condition to which the term ‘‘black brood”
has been referred in America. No conclusion was reached by him
as to the cause of this trouble. Certain differences were noted by
Burri between the descriptions by Dadant of the different brood dis-
eases and his own observations. It is not difficult to understand why
such differences should exist when one recalls that so many descrip-
tions of the brood diseases in the past by Americans have been based
largely upon faulty work.
Further on in his paper, Burri gives the microscopic findings and
describes the gross appearance of a few larve taken from each of the
eight samples of sour brood which he examined. He mentions in
‘‘sour brood” the yellowish color of the larve, the uncapped cells,
and the presence of rather long rods. Short rods were also found,
resembling in morphology Bacterwum giintheri. On account of this
similarity, in recording the presence of this latter species, Burri has
referred to it as the ‘‘giintheri-forms.”’ These facts concerning the
gross appearance of the microscopic findings in ‘‘sour brood” suggest
strongly that the condition is the same as the foul brood of Cheshire
and Cheyne (European foul brood).
In summing up the results of his study on ‘‘sour brood,” Burri
emphasizes two observations: First, that there is a form of disease
found all over Switzerland which possesses the characters mentioned
for ‘‘sour brood”’; and, second, that in the condition there is a certain
‘
70 HISTORICAL NOTES ON BEE DISEASES.
uniformity in the microscopic findings. There were medium-sized
and small bacterial rods present together with forms resembling in
morphology Bactervum giintheri. There was an absence of spores
and of the corresponding vegetative forms. It was observed that
one group of bacteria may predominate in some samples and another
group may predominate in others. Where rods of relatively large
size were found in brood which in gross appearance resembled sour
brood, it was supposed that a double or mixed infection of foul brood
and sour brood was present. This double infection, it was believed,
occurred very frequently.
In continuing his bacteriological study of ‘‘sour brood” Burri
encountered a few rather interesting species. Bacillus alvei was pres-
ent in many samples of ‘‘sour brood” examined. From most of the
samples examined difficulty was encountered in obtaining cultures
of the microorganism to which he refers as the giintheri-forms. He
reports, however, that this difficulty had been overcome and that he
had obtained pure cultures of this species. He made some compari-
sons between the cultures of this species and those of Bacterium giin-
thert which resulted in the conclusion that while there was a certain
relationship existing between them, the two were not the same.
Burri sums up the results of his study of ‘‘sour brood” as follows:
1. There is a disease of the brood accompanied by a rapid growth of bacteria, which
have no direct relation with the bacteria of foul brood.
2. The larvee attacked are characterized by the following symptoms: (a) More or
less noticeable sour odor; (b) comparatively pale, dirty yellow color; and (c) a great
resistance of the chitinous covering which allows the dead larva to be lifted intact
from the cell as a moist mass.
3. In microscopic examination the contents of these larve are characterized by the
presence of forms resembling sour milk bacteria (giintheri-forms) beside medium-sized
and small rods. It is characterized also by the absence of large spore-bearing rods
and spores.
4. Pure culture experiments with such bacterial material give proof of a certain
relationship between the true sour milk bacteria and the giintheri-forms. The cul-
tures also show that the medium-sized and small rods are strong acid producers. The
name ‘‘sour brood” is therefore entirely justified.
With respect to the occurrence of “‘foul brood” and ‘‘sour brood”
in the same colony one finds the following in Burri’s paper:
In describing each attempt to isolate the sour brood giintheri-forms the rarely
expected fact was demonstrated that in a whole series of cases, a growth of colonies of
Bacillus alvei, the easily cultivated producer of stinking foul brood, was obtained from
typical sour broody cells instead of the giintheri-forms desired. The series of cases of
this kind could be greatly increased. Moreover, in the course of my investigations
such findings have been repeated such a surprising number of times that I was forced
to think there must be some close connection between the two diseases. For some
time I was even inclined to believe that the sour brood bacteria represented only a
certain stage of development in the foul brood bacteria but gave up this view when
the morphological question was explained by means of culture experiments. To-day
it can safely be affirmed that foul brood bacteria, sour brood giintheri-forms, and the
BURRI, JANUARY, 1906. 71
other types of rods found in sour brood cells are independent organisms, each with its
own cycle of development. If various pathogenic bacteria are met with in a disease,
medical men speak of the condition as a mixed infection. It seems that generally in
sour brood we have to deal with such a mixed infection. As already pointed out, I
have, occasionally in the microscopic examination, but particularly in the cultural
tests of the comb material sent in, encountered the mixed infection of sour brood and
foul brood so regularly, that I scarcely expect to meet with a case of pure sour brood.
By this I mean a comb with sour brood cells in which at the same time foul brood
germs are not to be found. This presumption, however, proved not to be true, for the
specimen from Kaltbrunn must be considered as a case of ‘‘pure’’ sour brood. The
first specimen from Murten which similarly gave the impression at first of being
‘“pure,’’ had to be considered subsequently to be foul brood, for the second specimen
from the same source showed unquestionably the presence of Bacillus alvei.
The samples containing dead brood, which Burri studied from May,
1903, to September, 1905, were grouped under four headings, viz,
“sour brood,” ‘‘stinking foul brood,” ‘‘nonstinking foul brood,” and
“dead brood free from bacteria.”
In summing up Burri’s work on ‘‘sour brood” the following inter-
esting facts might be mentioned:
1. The origin of the term ‘‘sour brood”’ is not definite.
2. Burri considered three gross characters to be of especial value in
the diagnosis of ‘‘sour brood’’—a sour odor, a lack of ropiness of the
decaying larvee, and a dirty yellow color of the brood recently affected.
3. In ‘‘sour brood’’ were found a large number of short rods which
resemble, on microscopic examination, Bacterium giintherr found in
sour milk, and with these he found other rods of medium and large size.
4. When cultures were made from the larve dead of ‘‘sour brood,”
the giintheri-forms did not grow as a rule, but in their stead cultures
of Bacillus alvei appeared sometimes in pure culture.
5. The cultivation of the giintheri-forms is reported as having been
successful.
6. Burri believed that ‘‘sour brood” and the ‘“‘stinking foul brood”
are usually found together. This was suggested to him by the
frequent presence of Bacillus alvei and the giintheri-forms in the same
diseased colony. ‘“‘Sour brood” was reported to have been found
alone in one instance.
7. He grouped the samples of comb which contained dead brood
into four conditions, viz, ‘“‘sour brood,” “stinking foul brood,”’ ‘“‘non-
stinking foul brood,” and ‘‘dead brood free from bacteria.”’
8. The true menace to bees he believed to be due ‘to a bacillus
which is difficult to cultivate.
We are not inclined to agree with all the views expressed by Burri
in his work on “sour brood.” The condition referred to as ‘sour
brood” and “stinking foul brood” are probably but one disease,
European foul brood; the ‘‘non-stinking foul brood” is the same as is
now known.as American foul brood, and the samples which were
reported as containing no bacteria together with those which were
72 HISTORICAL NOTES ON BEE DISEASES.
received labeled ‘‘black brood” were in most instances very probably
the so-called pickled brood.
This completes for the present the consideration of the investiga-
tions made by Dr. Burri. His work is executed with much care, and
his results are correspondingly valuable. For this reason we feel that
anything which he writes on bee diseases can be recommended to the
bee keepers for careful study.
MAASSEN, JUNE, 1906.
Several interesting papers on bee diseases have been written by
Maassen, of Dahlam, Germany. The first paper! to be considered
is on “‘foul brood.”
Of the samples received from 119 apiaries, 112 were found upon
examination to be diseased. Of these 112 samples which were
declared diseased, Bacillus alvet was found in only 13.
Maassen fed colonies large amounts of cultures of Bacillus alvei in
both the vegetative and spore form during the brood-rearing season
without producing the disease. An attempt was also made to inocu-
late the brood directly, but negative results were obtained by this
method (p. 59). The conclusion was therefore drawn that Bacillus
alver had not the significance in brood infection that had ordinarily
been attributed to it. In all cases where Bacillus alvei was not
found there were other spore-bearing species observed. The pres-
ence of one species is especially emphasized which offered much diffi-
culty in cultivation on the usual media of the laboratory (p. 60).
This species he refers to as Bacillus brandenburgiensis. No definite
proof was obtained of a causal relation between this spore-bearing
species and the disease.
It seemed to Maassen at this time that spore-bearing bacteria were
probably only secondary invaders in this disease condition. He was
strengthened in his belief by the finding of what he supposed was a
protozoan to which he gave the name Spirochexte apis. In all brood
affected with the disease he records the presence of this micro-
structure. It was yet to be determined, he says, whether this last
finding bore any causal relation to the disease in which it was found.
In this paper by Maassen the following points are of special
interest :
1. Maassen was examining samples of brood which were suspected
by the bee keepers to be ‘‘foul brood.”
2. He does not mention two forms of ‘‘foul brood.”
3. He found Bacillus alvei in 13 samples of “foul brood” out of
112 samples diseased.
1 Maassen, Dr. Albert, June, 1906. Faulbrutseuche der Bienen. Mitteilungen aus der kaiserlichen
biologischen Anstalt fiir Land- und Forstwirtschaft. Heft 2, pp. 28-29.
MAASSEN, JUNE, 1906. 73
4. He found in all the samples of foul brood examined, in which
Bacillus alvet was absent, another species present which offered diffi-
culties in its cultivation on artificial media and refers to the species
as Bacillus brandenburgiensis.
5. He reports this species to be present in some of the samples,
together with Bacillus alvei.
6. He’ used a large amount of the culture of Bacillus alvei in the
inoculation of healthy bees and did not produce disease.
7. “Foul brood” was not produced with pure cultures of Bacillus
brandenburgiensis.
8: He was inclined to the belief that bacteria are secondary
invaders in ‘‘foul brood.”’ :
9. He believed that this view was strengthened by the finding of a
microorganism to which he gave the name Spirochxte aps.
10. He reports this microstructure present in all samples of the
disease which he had examined up to that time.
MAASSEN, JUNE, 1906.
Another paper appeared by Maassen,' in which he briefly refers to
a disease which he says is known to the bee keepers as ‘‘stone brood.”
The condition, he says, is characterized by the hard, leathery,
brittle, odorless, and mummylike masses into which the larve and
pupe of bees are transformed with no marked change in their form.
Accompanying the condition is a higher death rate among the adult
bees.
The peculiar change in the brood was attributed to a fungus that
grows well at a warm temperature, and whose characteristics when
studied in pure cultures were found to be similar to those of Asper-
gillus flavus. The method of transmission of this germ was not
determined. According to the observations that were made it was
supposed that bees were very susceptible to the disease. This was
especially true if the temperature was high or the hive was badly
ventilated, and it was therefore recommended that these conditions
be avoided in the treatment of the disease. Maassen expresses the
belief that ‘‘stone brood”’ has often been referred to by bee keepers
as ‘“‘black brood,’ “‘new bee disease,’ “‘bee pest,’ and “pickled
brood.”
We are not familiar with the condition “‘stone brood,” and we are
not aware of its presence in America. The symptoms given do not
correspond to those observed in the so-called black brood or in the
pickled brood that are met with in this country. It is intimated in
Maassen’s paper that a publication on the mycotic diseases of bees
was being prepared.
1 Maassen, Dr. Albert, June, 1906. Die Aspergillusmykose der Bienen. Mitteilungen aus der kaiser-
lichen biologischen Anstalt fiir Land- und Forstwirtschaft. Heft 2, pp. 30-31.
74, HISTORICAL NOTES ON BEE DISEASES.
Baur, 1906.
Another publication by Bahr?’ appeared in 1906, in which he gives
the results obtained from his further investigations. He reports that
more than 200 cases of foul brood had been examined. The following
points are noted in Bahr’s paper:
1. One can not be sure with what disease he was working.
2. He does not always find Bacillus alvei in foul brood.
3. With cultures of Bacillus alver he was not able to produce foul
brood either by spraying the larve or by feeding cultures of the
bacillus. He failed also to produce the disease by using the contents
of the dead larve for spraying or as food in sugar sirup.
4. He suggests that the reason for these negative results may be
either that Bacillus alvei is not the cause of foul brood or that the
proper time or manner in which such infection can be produced
experimentally had not been discovered.
5. He did not find any other bacillus as a possible cause of the
disorder. Bacillus alvet was not found in the eggs or in tlie sexual
organs of the queen, as had been reported by Cheshire (p. 21), Har-
rison (p. 49), and others.
6. He suggests that possibly the cause of the disease is an ultra-
visible virus and that possibly the disease is transmitted through the
queen.
It appears likely that Bahr was working with European foul brood,
but this is not at present positively known. If he studied American
foul brood, he must have overlooked the fact that there are numerous
spores (Bacillus larve) present in the decaying remains of the larve
which do not grow on the artificial media commonly used. In sup-
port of his theory that the disease is transmitted by the queen he
says thav he has introduced a queen from a diseased colony into a
healthy one and produced foul brood as soon as the queen could lay
the eggs, and that he has introduced queens from healthy colonies
into apparently doomed ones with the result that the diseased colonies
quickly recovered.
These experiments should be repeated for a confirmation of the
results. If, as is probable, Bahr worked with European foul brood,
there were probably other factors present which were not accounted
for. His failure to find Bacillus alvei in all the samples examined
is interesting, and his failure to produce foul brood with cultures
of Bacillus alvei repeats the experience of some others.
1 Bahr, L., 1906. Om Aarsagen til Bipesten og dennes Bekzempelse. Foredrag holdt ved DBF’s Dis-
kussionsm¢de d. 2 Septbr. 1906 i Esbjerg. Seertryk af Tidsskrift for Biavl. Nr. 17.
ERNE, NOVEMBER, 1906. 75
Puiiirs, OcroBer 3, 1906.
In 1906 a brief circular! was issued by this bureau giving the
symptoms and treatment of the two brood diseases. This paper is
of interest at this time only because it was the first occasion for the
use of the names ‘‘American foul brood” and ‘European foul brood”
in a publication of the bureau.
Since the name ‘‘black brood” had been, on account of an
error, applied (p. 45) to the foul brood which Cheshire and Cheyne
(p. 25) described, the name ‘‘black brood”’ was no longer needed.
The name ‘‘foul brood,” however, was being applied by the bee
keepers (p. 60) to a disease which was clearly different from the foul
brood described by Cheshire and Cheyne. This latter disease, there-
fore, needed a name. The laws that were in existence in some of
the States at that time provided for the inspection of apiaries in
which foul brood was found. In order that these laws could be inter-
preted, in accordance with their intent, to cover the brood diseases
of an infectious nature, the name ‘‘foul brood”’ was retained in the
names of these two brood diseases. To distinguish the two diseases
by name, the adjective ‘‘European” was selected for the disease
which had been early creditably studied by a European (p. 29) and
the adjective ‘“American’”’ was selected for the disease which had
been studied by an American (p. 62). These names were chosen only
after consultation with a number of the leading bee keepers in
America, who agreed that the names were well chosen.
The words ‘‘American” and “European” were not chosen to sug-
gest a geographical distribution of the two diseases, as the opinion
was held that both diseases exist in Europe as well as in America.
Concerning the selection of these names the facts were emphasized in
the preface of a paper to be discussed later (p. 76).
)
ERNE, NOVEMBER, 1906.
In 1906 Dr. Erne,’ of Freiburg, Germany, reviewed Burri’s work
on the brood diseases and gave the results of his own investigations.
Erne, too, obtained negative results in an attempt to produce “foul
brood”’ with a culture of Bacillus alvei. This species was not found
by him in 64 samples of ‘‘foul brood” received from different parts
of Germany. For these reasons he expresses a doubt concerning any
etiological relation between the species and the disease as found in
Germany. He found, however, in all samples of the disease a bacte-
rium which he thought probably was identical with the one which
1 Phillips, E. F., October 3, 1906. Thebrood diseases of bees. U.S. Department of Agriculture, Bureau
of Entomology, Circular No. 79. Pp. 5. (Superseded by Farmers’ Bulletin 442, U. 8S. Department of
Agriculture, ‘‘The treatment of bee diseases.’’)
2Erne, Dr. November, 1906. Bakteriologische Untersuchungen iiber die Faulbrut und die Sauer-
brut der Bienen. Die Europiiische Bienenzucht, pp. 148-151.
76 HISTORICAL NOTES ON BEE DISEASES.
Burri observed to be difficult of cultivation. As this species was not
obtained in pure culture, no inoculation experiments were made with
it. By feeding foul-brood material to ten colonies, however, Erne
proved that the disease with which he was working was infectious,
since in every case typical foul brood was produced which contained
the same bacillus previously observed.
To make clear his position, Erne summarizes as follows:
1. Burri has not furnished proof that sour brood is a contagious disease and that the
bacterium described by him is the cause of the same.
2. It is not proven that there is more than one foul brood germ.
3. I consider as the cause of the epidemic foul brood causing the greatest destruction
at the present time, a bacillus which I have found in all of my investigations, which
can not be cultivated on the usual media, and which may perhaps be identical with the
bacillus that Burri found to be difficult of cultivation.
In Erne’s paper the following interesting facts are noted:
1. He was working probably only with American foul brood.
2. Erne took exception to the methods used by Burri in the attempt
to obtain pure cultures of the bacillus which was found difficult of
cultivation.
3. He emphasizes the importance of the experimental inoculations
*of healthy colonies in the demonstration of the cause of a disease of
bees.
4. He did not find Bacillus alvei in 64 samples of foul brood exam-
ined from Germany.
5. He obtained negative results when healthy bees were fed pure
cultures of Bacillus alvei.
6. He questioned an etiological relation between Bacillus alvei and
‘‘foul brood.”
7. He demonstrated the infectiousness of foul-brood material by
the production of ‘‘foul brood” in healthy colonies.
8. He met with a species of bacterium in foul brood which was
difficult to cultivate on artificial media.
9. He considered this germ to be the cause of foul brood, although
the fact was not demonstrated.
10. Erne did not in his study of ‘‘foul-brood”’ material meet with
a microorganism corresponding to Spirochete apis.
While Erne does not devote much time to bee-disease investiga-
tions, his writings show that considerable care is exercised in his work.
The bee keepers, therefore, will be profited by reading any papers
written by this author.
Waiter, NovEMBER 6, 1906.
In 1906 the manuscript mentioned on page 67 was published as a
bulletin! In the preface the reason for the selection of the names
1 White, G. F., Ph. D. November 6,1906. The bacteria of the apiary, with special reference to bee
diseases. U.S. Department of Agriculture, Bureau of Entomology, Technical Series, No. 14. Pp. 50.
WHITE, NOVEMBER 6, 1906. cr
‘European foul brood” and “American foul brood”’ for two of the
infectious diseases of the brood of bees is explained.
The technique used by the writer of the bulletin in making the
investigations is given in Part I. In this portion also is discussed
somewhat the normal flora of the apiary. It was not the intention
in making this study of the normal flora to give a complete list of the
bacteria which might be encountered, but to study those species
which occur most frequently, and to describe them with sufficient
care to make their identification possible.
The results of the study indicate that comparatively few bacteria
are present in healthy colonies, on combs, in honey, in larve, or on
adult bees. In the intestine of adult bees, however, there were
usually found a very large number of individual bacteria, which, as a
rule, however, represented comparatively few species. One species,
an anaérobe, is of much interest since it occurs quite constantly and
in very large numbers. It might be mentioned that the bees that
did not show this intestinal flora were usually the younger adults.
A number of fungi and yeasts were also encountered.
The subject-matter in Part II, ‘‘The diseases of bees,” is not mate-
rially unlike that which appeared in earlier publications to which
references have already been made. The author of the paper under
consideration had reached no definite conclusion concerning the etio-
logical relation of Bacillus alvei to European foul brood, the disease
in which this species is usually found in large numbers. That any
direct causal relation did exist seemed questionable.
In American foul brood, Bacillus larve was found in large numbers
in the larve dead of the disease in all the samples examined. Pure
cultures of the organism had been obtained, but not in a suitable
form for making inoculation experiments. The author of the paper
did not feel justified in stating positively that Bacillus larve is the
cause of the disease. All that seemed justified was the statement
that the organism had been found constantly present in the disease.
The following brief summary was made of the results obtained
from the study of the bee diseases:
(1) There are a number of diseased conditions which affect the apiary.
(2) The disease which seems to cause the most rapid loss to the apiarist is European
foul brood, in which is found Bacillus alvei—first isolated, studied, and named by
* Cheshire and Cheyne in 1885.
(3) The distribution of Bacillus alvei in the infected hive is as follows:
(a) The greatest number of infecting germs are found in the bodies of dead larve.
(b) The pollen stored in the cells of the foul-brood combs contains many of these
infecting organisms.
(c) The honey stored in brood combs infected with this disease has beea found to
contain a few bacilli of this species.
(d) The surface of combs, frames, and hives may be contaminated.
(e) The wings, head, legs, thorax, abdomen, and intestinal contents of adult bees
were found to be contaminated with Bacillus alvei.
78 HISTORICAL NOTES ON BRE DISEASES.
(f) Bacillus alvet may appear in cultures made from the ovary of queens from Euro-
pean foul-brood colonies, but the presence of this species suggests contamination from
the body of the queen while the cultures are being made and has no special significance.
(4) The disease which seems to be most widespread in the United States we have
called American foul brood, and the organism which has been found constantly present
in the disease we have called Bacillus larve. This disorder was thought by many in
this country and other countries as well to be the foul brood described by Cheshire
and Cheyne, but such is not the case.
(5) From the nature of American foul brood it is thought that the organism has a
similar distribution to that of Bacillus alvet.
(6) It appears that European foul brood was erroneously called ‘‘New York bee
disease’’ or ‘‘black brood” by Dr. William R. Howard in 1900.
(7) There is a diseased condition affecting the brood of bees which is being called
by the bee keepers ‘‘pickle brood.’’ No conclusion can be drawn from the investi-
gation so far as to the cause of the disease.
(8) Aspergillus pollinis, ascribed by Dr. William R. Howard as the cause of pickle
brood, has not been found in this investigation and is not believed by the author to
have any etiological relation to the so-called ‘‘pickle brood.”
(9) Palsy or paralysis is a diseased condition of the adult bees. No conclusion can
yet be drawn as to its cause.
(10) Formaldehyde gas, as ordinarily used in the apiaries, is insufficient to insure
complete disinfection.
MAASSEN, FEBRUARY, 1907.
In 1907 Maassen ' reported on his work of the preceding year on
foul brood. Samples were received from 100 apiaries. An exami-
nation gave evidence of disease in 79 of them. Disease was not
found in the other 21. ‘‘Spirochexte apis” was reported in samples
from 67 apiaries. Accompanying it B. brandenburgiensis was reported
in 66 cases and B. alvet in one. JB. alvei was not found generally in
the samples from Germany, occurring only in 11 of the cases.
Among the 100 samples examined there were 2 in which was found
a species in almost pure cultures which before had been found accom-
panied by Bacillus alvei. This species Maassen named Streptococcus
apis. He says that it belongs to the pneumococcus group, being dif-
ferent from other members of the group by its marked peptonizing
character. Upon a certain medium he reports that the species could
be cultivated very easily. In 10 cases in which B. alver was found
Streptococcus apis was reported in 8. No conclusive results were
obtained in his attempts to demonstrate the relation between any of
the organisms and the disease condition.
In his report the following points of special interest are noted:
1. Maassen did not express any suspicion that two distinct infectious
diseases might be present in the condition he was studying as foul
brood.
2. He reports the presence in samples from 67 apiaries of a micro-
_ organism which he had previously named Spirochete apis, and with
1 Maassen, Dr. Albert, February, 1907. Uber die sogenannte Faulbrut der Honigbienen. Mitteilungen
aus der kaiserlichen biologischen Anstalt fir Land- und Forstwirtschaft. Heft 4, pp. 51-53. 6 figs.
IMMS, JUNE, 1907. 79
it he finds associated Bacillus brandenburgiensis in 66 cases and
Bacillus alvei in one case. .
3. He found Bacillus alvei in 11 cases of diseased brood. The
majority of these samples probably were from apiaries affected with
European foul brood.
4, He observed and cultivated a species which he named Strepto-
coccus apis. This species, he states, belongs to the pneumococcus
group and is easy of cultivation. In 10 samples in which Strepto-
coccus apis was found Bacillus alvet was found in 8.
5. He states that he had not reached a final conclusion concerning
the relation between the microorganisms and the disease encountered.
Imus, JuNE, 1907.
The Board of Agriculture and Fisheries of Great Britain requested
Mr. A. D. Imms, of Christ College, Cambridge, to make a study of
the cause and nature of a disorder among bees. References to this
disorder have been made in the last f w years as the Isle of Wight
disease. Imms‘ made a report on his work in 1907.
From this report an idea of the rapid losses which were attributed
to the disease can be obtained. It is stated that the disease was so
prevalent that it seemed almost impossible to keep a colony healthy
for 12 months. Seventy colonies were reduced to 8 in two years.
One bee keeper lost 20 colonies out of 22. Three other bee keepers
in the same district lost their entire apiaries, consisting of 12, 8, and
4 colonies, respectively. Another bee keeper lost over 50 colonies
and about a dozen other bee keepers had no bees left.
Imms gives the following in his description of the symptoms of the
disease: .
The earliest noticeable symptom of the disease is the inability of the affected bees
to fly more than a few yards without alighting. As the disease progresses, the bees
can only fly a few feet from the hive and then drop and crawl about aimlessly over
the ground. They are often to be seen crawling up grass stems, or up the supports
of the hive, where they remain until they fall back to the earth from sheer weakness,
and soon afterwards die. In a badly infected stock great numbers of bees are to be
seen crawling over the ground in front of the hives, frequently massed together in
little clusters, while others remain on the alighting board. If the hives be opened,
numbers of diseased individuals will be often met with inside. They are found
clustered together around the queen and show very little inclination for movement
until disturbed and are entirely unable to fly. Badly diseased individuals show very
little inclination for stinging; those that are less severely attacked often sting very
actively.
If a badly diseased bee be carefully examined it will be seen to have lost its power
of flight, and it crawls about with the hinder extremity of the body dragging on the
ground; frequently it walks about with its wings ‘‘out of joint,’’ the hind wings pro-
truding obliquely upwards and above the anterior pair. The only other external
symptom of the disease is seen in the abdomen, which is frequently distended beyond
1Imms, A. D., June, 1907. Report on a disease of bees in the Isle of Wight. Journal of the Board of
Agriculture, Vol. XIV, No. 3; pp. 129-140, 4 figs.
80 HISTORICAL NOTES ON BEE DISEASES.
its normal proportions. This distension, however, is not by any means constant,
and was chiefly noticed in the case of the native bee; in the half-breed with the
Italian bee, with its longer and slightly more slender abdomen, no unusual distension
could be observed.
The disease appears to differ from what is usually termed ‘‘bee-paralysis,’’ in that
the infected individuals do not exhibit the characteristic black and shiny appear-
ance, and neither I myself, nor any bee keepers who have paid attention to the dis-
ease, have observed the curious trembling motion of the limbs and body which is
regarded as a symptom of that disease.
The disease appears to be entirely confined to the adult bees, the brood remaining
unaffected. I have conducted a microscopical examination of a large number of
eggs, larvee at all stages of development, and pupz, and have failed to detect any-
thing of a pathological nature among the brood. All had the characteristic pearly
white appearance of healthy specimens although belonging to a badly infected hive.
The eggs were undergoing development and showed not the slightest trace of discol-
oration or shriveling, the larvee were healthy in every way and were coiled up in
their normal attitude, and nothing wrong could be detected with the pupe or the
newly hatched bees.
In describing the ‘‘ Nature of the disease’? Imms writes in part as
follows:
The disease is eminently one of the digestive system and might be described as
being a condition of enlargement of the hind intestine. Over 150 diseased bees
have now been examined and all have been found to exhibit the same symptoms.
The author states that the bacteriological work on the disease was
in progress. The work which had already been done demonstrated
the presence of a large number of bacterial rods. No conclusion was
reached as to the cause of the disease, nor had any remedy been found
in the treatment that was successful in the hands of all bee keepers.
Some of the more important points in the paper might be summa-
rized as follows:
1. The disease, so far as was determined, was of recent origin.
2. The disorder described seemed to be very rapidly fatal to adult
bees. The brood seemed to be unaffected.
3. To Imms the trouble seemed to be neither dysentery nor the
so-called paralysis.
4. No conclusion was reached as to the cause of the disorder.
5. No treatment was demonstrated to be successful.
Waite, JuLy 29, 1907.
On July 29, 1907, there was issued a circular‘! briefly describing
some experiments which demonstrated for the first time the cause of
American foul brood. Although spores had been observed in very
large numbers in the larve dead of this disease, no satisfactory
medium had yet been devised by which pure cultures could be
obtained that were suitable for purposes of experimental inoculations.
1White, G. Franklin, July 29,1907. The cause of American foul brood. U.S. Department of Agri-
culture, Bureau of Entomology, Circular No. 94. Pp. 4,
WHITE, JULY 29, 1907. 81
The way by which this difficulty is overcome is reported in the pub-
lication under consideration. Young pups were used in making the
medium. ‘These were picked from a comb containing healthy brood,
crushed, strained through cheesecloth, and then diluted by adding
water equal to from 20 to 50 times the volume of the crushed brood
used. This solution was then passed through ordinary filter paper
and subsequently through a Berkefeld filter. In this way a sterile
filtrate was obtained. About 2 c. c. of the sterile filtrate was then
added by means of a sterile pipette to liquefied agar which had been
cooled to 45° or 50° ©. If pure cultures were desired, agar tubes
thus prepared were inoculated with a small amount of diseased brood
and plates were poured. If, however, culture growth was desired
for the inoculation of bees or experimental animals, it was obtained
from these specially prepared agar tubes by first inclining them
and then securing the growth by inoculating the surface of the
inclined agar with a pure culture of Bacillus larve obtained from the
plates. At no time was this special medium to reach a high temper-
ature.
Two colonies were now fed the scales of American foul brood,
suspended in sirup. American foul brood resulted from these inoc-
ulations with symptoms the same as are found in an apiary in which
the disease appeared through the natural means of infection.
Similar results were reported by Erne (p. 76). These experiments
were sufficient to prove that American foul brood can be produced
experimentally by feeding; also, that the scales of the disease
contained the virus.
Having demonstrated the fact that American foul brood can be
produced by feeding and having obtained pure cultures of Bacillus
larve in suitable form for inoculation purposes, the next step to be
taken, very naturally, was to inoculate healthy colonies with pure
cultures of Bacillus larve. .This was now done, and as a result of
such inoculations American foul brood was produced with symptoms
identical with those produced when the scales were used in feeding.
The decaying brood in the disease thus produced contained the large
number of spores that are always found in brood dead of this disease,
and from the diseased material pure cultures of Bacillus larve were
obtained.
The results obtained from these experiments in which pure cul-
tures of Bacillus larve were used in making the inoculations justified
for the first time the statement that American foul brood was caused
by a specific microorganism.
It seemed to the author of the circular that probably the species
which had given different workers considerable difficulty in culti-
vation, in many cases at least, was nothing other than Bacillus
13140°—Bull. 98—12——6
82 HISTORICAL NOTES ON BEE DISEASES.
larve. The “microorganism” named Spirochete apis by Maassen
(p. 72) was shown to be giant whips which have their origin in the
growth of Bacillus larve.
Puitiies, DECEMBER 31, 1907.
In connection with the study of American foul brood it was noticed
that the scales formed by the drying down of the dead larve are not
destroyed if the comb becomes infested with either of the two wax
moths. These observations were recorded in a publication! of this
bureau. Sometimes it is desirable to have the dried scales of Amer-
ican foul brood in large quantities. These can be easily obtained
free from the comb by allowing a well dried and badly diseased
sample to become infested with wax moths.
MAASSEN, 1908.
Another paper? by Maassen appeared in 1908. In his former puoli-
cations this author has dealt with only oneform of foul brood. In this
paper, however, he states that two forms of the disease have been
known for many years, a ‘‘mild”’ form and a ‘‘virulent”’ one.
Maassen’s description of the gross appearance of the brood affected
with the ‘‘mild”’ form is similar to that given by Dzierzon (p. 18) and
others. The disease therefore is quite probably European foul brood.
This view is further strengthened by the bacteriological examinations
which he reports. His description of the ‘‘virulent”’ form is also
similar to that given by Dzierzon (p. 18) and others. The condition
is most likely, therefore, American foul brood.
Following the discussion of these two forms of ‘‘foul brood” Maassen
discusses the etiology of ‘‘foul brood.’’ He expresses the belief that
foul brood is a disease of the digestive apparatus of the larvee and can
be produced by various causes. As producers of ‘‘foul brood”’
Bacillus alvei, Streptococcus apis, and Bacillus brandenburgiensis are
mentioned by him. Besides these three species he reports the pres-
ence in the diseased brood of a species of yeast and spore-bearing
bacilli. Bacillus alvet and Streptococcus apis are reported to have been
found in both forms of foul brood, while Bacillus brandenburgiensis was
found in only one of them.
In that form of the disease in which uncapped brood seemed mostly
to be affected, Maassen reports the presence of Bacillus alvet in 51
samples out of the 53 examined. When Bacillus alvet predominated
in the sample, he interpreted the odor as being more ‘‘sweat-like”’ in
character than when Streptococcus apis was in predominance; and
culture, Bureau of Entomology, Bulletin No. 75, Part II. Pp. 19-22.
2Maassen, Dr. Albert, 1908. Zur Atiologie der sogenannten Faulbrut der Honigbienen. Arbeiten aus
der kaiserlichen biologischen Anstalt fur Land- und Forstwirtschaft. Bd. V1, Heft I, pp. 53-70. 2 pls.
MAASSEN, 1908. 83
when the latter species predominated the odor was likened to that of
sour paste. In samples from two apiaries Maassen failed to find
Bacillus alvei, but found Streptococcus apis in large numbers. ‘The
two cases in which Bacillus alvei was absent were suspected of being
the sour brood referred to by Burri (p. 68). Maassen was inclined to
believe that the latter condition is more widespread in Switzerland
than in Germany. In 41 samples of the 51 containing Bacillus alvei,
the species was accompanied by Streptococcus apis. The relative
number of Bacillus alvei and Streptococcus apis varied.
The ‘‘guntheri-forms’’ mentioned in Burri’s paper (p. 69) are very
probably the species to which the name Streptococcus apis Maassen
has been applied. Maassen expresses a similar belief. The following
description of Streptococcus apis is an abbreviation of the one by
Maassen.
Occurrence.—This species is found in ‘‘foul brood,” occurring most
frequently in that form in which the larve when attacked are
uncapped.
Morphology.—In form it is not perfectly spherical but is a lancet-
like, pointed coccus that appears as either a Diplococcus or a Strep-
tococcus in the body of the larvee as well as in artificial media. -o5 sen =k sae 45-47
Man Oriiis Gps, GEREMPUON . nt ee an a2 ou. ele ye. op ee pe aa pee ees 87-88
pestis.....- Peete ete Srey ooee ein a oa aids iaey ea nis Scone here ene apts 5S eS 87
thoracis, supposed connection with “black brood” .........-....----- 46
X (see also Bacterium X and Bacillus larvx).
ST STET/E EE es he SpA pap a ES Sl eon gece See HR 67
LOS STILTETIG U2 3 RG Re gr, i eR ce Ena Opa ee eg 86
MMP MMIRTIIIMMCNU ne on to cin cS aoe aie ais oais ah inanMeyew aside Je oles Lees 28 69-71
X (see also Bacillus X and Bacillus larvex).
SRS TAT EVR 1STS 0 Was le Oe ee Pea veg 2 RN an et ae Oe 63
PEERS ONE EO SCASE hoe Sa 8 Soe oi aie Se Sec widigm a en eee ae - FES 64, 74
“Black brood” (see also European foul brood).
RENE SP WCE ME ONS aes as oN ad ae 44
PREM eS CREMENIA LACICORM. 2.055512 510.05 =/=/2 22-2 hae min igs wince naps ee = . ithe sc ee sa heeds a’ ob alecs oe tne nae Dae Sw aRe 17
(8 OFS se sly ie hy RIN Dad RE SE A ey Ae ee oe: 17
RPI MMENC HIRD 18a Bhd 2 AE ip Pa OR ale wave hd 2 cleo eine wloniain es 19
Mee AG ORLONL OF ANJUTY <<< |e co Bens ie ade gens s dee deine a as eae 19
Pirin: Gistributiams.. J2/se area aeees USS. SUDSRK salons nti ge 20
MT ONL TOR: oe ose LR SSS SSR LW dled tad & rege 21
oreammniniorl beat Soa tN rs ah CEO eels o sdansed Gop Sel. eid SBE 21
SEDI yo no Sars cates en, ha IE = tyste fee vgn SL Sh eee 21
RCA Let Cay bs Piss a togroar Gen de se gieitesl see tH Jamas eiotepee Se 21
SITE SEO LATV A). v0. <'. ws 2 alejeia cits See nic ae o/s Sms may Ge Pee! DE ae 21
fine pecond-siage or mature larva. 025.55. 6 1.25) 22. een.- ce ees cae 22
Pia waune Nivtmioh OF Prepupss.'s -Ssi- = ae cists os se a ee tees a awn = 22
orm -orowmi Wy TA pn.OP PUPA. 20... 2-022 tes se se ow tate de ewe ns 23
COCR een eae ra. «fda Daladtan oe cate ae sO Sol aula aageS serptele 23
UTE SPD CR os in ao ciatesas o's - 2 nic eRe ec sesso oS sitehe cctid sialaceteye 24
PE MEMERHOMAT OME Mae kin he ho de he A IAs a Odom woes e bial 24
ter Lhe proevups atid: Pipa: ..c.22 ket. 20 sel .5 5 226s yee oe ve es “~- 25
OE gy ARS ed SSR a Se Se er oe, oe 25
CE Pa SIS «ote ae 6a va wm ae » eee 25
TEE Ae Crna se See: ones Ve a whe d= aa ~ ec e've ease pee 28
te EER Hr Se CE Sa oc op ini nie Winns oe ie wae Cece ee 28
at eR MS oe alte oe . DEPARTMENT OF AGRICULTURE,
BUREAU OF ENTOMOLOGY—BULLETIN No. 99, Part I.
L. O. HOWARD, Entomologist and Chief of Bureau.
PAPERS ON INSECTS INJURIOUS TO CITRUS
AND OTITER SUBTROPICAL FRUITS.
feat ORANGE THRIPS:
A REPORT OF PROGRESS FOR THE
YEARS 1909 AND 1910.
BY
P. R. JONES anp J. R. HORTON,
Agents and Experts, Deciduous Fruit Insect Investigations.
IssuepD Marcn 6, 1911.
“snsonian Insti,
en" Sti tut;
=
WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1911.
BUREAU OF ENTOMOLOGY.
L. O. Howarp, Entomologist and Chief of Bureau.
C. L. Martarr, Entomologist and Acting Chief in Absence of Chief.
R. S. Currron, Hxrecutive Assistant.
W. F. Tastet, Chief Clerk.
F. H. CHITTENDEN, in charge of truck crop and stored product insect investigations.
A. D. Hopkins, in charge of forest insect investigations.
W. D. Hunter, in charge of southern field crop insect investigations.
F. M. Wesster, in charge of cereal and forage insect investigations.
A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.
E. F. PHILips, in charge of bee culture.
D. M. Rocers, in charge of preventing spread of moths, field work.
Rotia P. Curriz, in charge of editorial work.
MABEL CoLcorD, librarian.
DeEcipuouS FRuIT INSECT INVESTIGATIONS.
A. L. QUAINTANCE, in charge.
FRED JOHNSON, S. W. Foster, E. L. JENNE, P. R. Jones, A. G. HamMMar, C. W.
Hooker, J. R. HortoN, WALTER Postirr, J. B. Gitt, R. LL. NouGaret, W. M.
Davipson, agents and experts.
E. W. Scort, J. F. Zimmer, entomological assistants.
II
CN TEN, Eon
a REIDERERISES Shelter nh ota an tole So, anas S ohms SY emis mimi vale S a ws Ro aes
marina! home and distribution. 5. -.......2--.--=-----.------ mee op eye
© TEER Eaped< San oeh 240 A IR eee eer ee or eee
(0 pc) 22 TO INES gee ao) as ha tg ed ee ee ee
Reema annie NSLOLY << So8e telson te aie hose Soe Seep ee ee ee eee
eter Tet Bey re ete orgs PLE ate Oe Sd eine oti ielaiae ae gar eee eae
RR MRO ere et Eee tome nie, Vera = i ene bie sig See eee
ne RPR Tee ett Ae ete te Pe cae Searle Sele a as ere
SeTT Till Ory Lh a eee Ona Se Oar Aba acs ect rnttem aaa a Arn re ayes comcea:
Interrelation of abundance of thrips and food plants.........-...-..-----
OF RCs See SPS RE Sec eae eee i cee eee ee
2 Tne athe SAS Re ee Se oe eee easel
ee eeemin wally MeLHOdS OF CORWOl 1-2/2. 2. op 2 oe ee on we ee 2 2s ee HM
PRIMER er te ide tee ee ean 2s Jee OE idem oe aes aed ctes'aa beens
(PUD LA SEIN. Spe Si BE A SRS cirri Se Oe eg A
Bf STS eS SR ee EE a ee
Experiments to determine killing effect of different sprays. - -
Experiments to prevent marking of the fruit...................-----
Heenimnenis with nursery trees... =... 52s 2 one cee bs - oe neers eee
SLE NY STL geet en ASS ea ier Ot Sa Ee
ee PM aA aT te Si a ye A ES PA en oe ie ate eS ee ee
SPR REPRE NLC MIEN oi, Shaye a= lees ome en cas See an Shares = = amslate
SOLES GL) TE Sa OS SO” Ra = eg ge
IMIR EPIL arse Sete ee oc Scien ce a a we cise Nc So OS mee a Se J
(Lc Si et a AR ee A are ie ae, Ae ee
iil
Page.
ee e
cope ereanoaarnark rh wWN NN
a |
C5) iGo (hO) G-e
Se
Ol te © CO
PVE Sd ROS:
PLATES.
Prate I. Fig. 1.—Young oranges showing injury by the orange thrips (Euthrips
citri). Fig. 2.—Young oranges showing injury to stem and _ blos-
som énds*by the orange thrips:.-. 2. 4.2.42 se2sse6-e ee
II. Mature oranges showing injury due to the orange thrips. .......---
III. Orange foliage showing curled and distorted condition of leaves due
towork ofthe orange thrips... 225. 2.222 a.ceecee eee eee
TEXT FIGURES.
Fie. 1.—Diagram illustrating the relative abundance of orange thrips on oranges,
on orange foliage, and on other plants during the season. .....--...-
2.—Power spraying outfit in use in spraying for the orange thrips........-
IV
Page.
14
U.S. D. A., B. E. Bul. 99, Part I. D. F. I. I., March 6, 1911.
PAPERS ON INSECTS INJURIOUS TO CITRUS AND OTHER SUBTROPICAL
FRUITS.
THE ORANGE THRIPS: A REPORT OF PROGRESS FOR
THE YEARS 1909 AND 1910.
By P. R. Jones and J. R. Horton,?
Agents and Experts, Deciduous Fruit Insect Investigations.
INTRODUCTION.
The orange thrips (Huthrips citri Moulton), a small, yellow, active
insect belonging to the order Thysanoptera (popularly known as
thrips), scars the fruit and curls and distorts the leaves of the orange.
At the present time its control constitutes the chief imsect prob-
lem confronting the citrus growers of the San Joaquin Valley
orange belt of California, which winds along the Sierra Nevada foot-
hills, from east of Fresno to south of Delano. This insect, the work
of which was first noticed 15 or 16 years ago, has increased in num-
bers with the growth of the citrus industry and recently has assumed
serious economic importance.
At the urgent request of a number of orange growers of Tulare
County, an investigation of the insect was begun the latter part of
April, 1909. The present paper is a preliminary report of the results
obtained during the seasons 1909 and 1910.
The writers wish to acknowledge the financial assistance of the
Tulare County board of supervisors, the Lindsay Citrus Growers’
Protective League, and the Tulare County Fruit Exchange; they
desire to acknowledge the kindness of Messrs. P. M. Baier, Harry
Postlethwaite, and R. H. Shoemaker in allowing the Bureau of Ento-
@The investigation of the orange thrips by members of the force engaged in
studies of deciduous-fruit insects appeared desirable, because these men were
familiar with a closely related species—the pear thrips—which is very destruc-
tive to prunes, pears, cherries, etc., in the San Francisco Bay region. However,
in order to keep together the articles dealing with insects damaging citrus and
other subtropical fruits, the present paper is published in a series of articles
dealing with insects of that class——A. L. QUAINTANCE, in Charge of Deciduous
Fruit Insect Investigations.
1
> INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
mology the use of their orchards for experimental and demonstration
purposes; and they would express their indebtedness to the large
number of orange growers in Tulare County who have put into effect
in their own orchards the recommendations of the Bureau, thereby
demonstrating the value of the spraying treatments advised.
ORIGINAL HOME AND DISTRIBUTION.
The orange thrips is probably native to North America. Its natu-
ral habitat is probably the Sierra Nevada foothills or the adjoining
plains of the southern San Joaquin Valley, and it was no doubt
attracted from its natural food plants by the more succulent and
luxuriant orange trees. This insect is distributed throughout the
entire orange belt of the San Joaquin Valley and has been collected -
in several places in Southern California and at Phoenix, Ariz., by
the senior author. The infestation in Arizona embraces orange
groves in the Salt River Valley surrounding Phoenix, and was re-
ported upon by Prof. J. Eliot Coit in a bulletin of the Arizona Agri-
cultural Experiment Station.*. This gentleman, in sending specimens
to Dr. W. E. Hinds for identification, probably did not obtain the
true orange thrips (Zuthrips citri Moulton), but some specimens of
Euthrips occidentalis Pergande, which is found occasionally upon
citrus trees, but which rarely causes any serious injury. The true
orange thrips was described as a new species by Mr. Dudley Moulton
in a bulletin of the United States Department of Agriculture, issued
February 11, 1909.°
The orange thrips has also been reported from Hermosillo, Sonora
Province, Mexico, but the writers have not been able to obtain speci-
mens from that locality.
The occasional scarring of oranges in the north-central portion of
California is caused by the grain thrips (Luthrips tritici Fitch), and
not by the orange thrips.
FOOD PLANTS.
Although the orange thrips, when described, was thought to infest
only citrus trees, the writers have taken it from a number of other
host plants. The following list shows the wide range of food plants
upon which this insect can exist:
Of citrus fruits the following are affected: Citrus aurantium vay.
sinensis (Washington Navel, Australian Navel (?), Thompson Im-
proved, Valencia Late, Mediterranean Sweet, Parson Brown, Ruby
« Arizona Agricultural Experiment Station, Bulletin No. 58, Citrus Culture in
the Arid Southwest, p. 319, 1908.
oU. S. Department of Agriculture, Bureau of Entomology, Technical Series
Non d2, Part VL:
THE ORANGE THRIPS. 3
Blood. St. Michael, Homosassa, and seedlings) ; Citrus nobilis (Sat-
suma and tangerines) ; Citrus decumana (grapefruit) ; Citrus medica
var. limon (lemon) ; Citrus medica var. acida (lime, varieties of) ;
and Citrus japonica (kumquat).
The following miscellaneous plants are infested: Punica gramatum
(pomegranate) ; Vitis vinifera (European grape, varieties of) ;
Schinus molle (California pepper tree); “umbrella tree;” Pyrus
communis (pear); Prunus armeniaca (apricot); Prunus persica
(peach) ; Prunus domestica (European plum, varieties of) ; Salix sp.
(willow) ; Rumex sp. (dock); Portulaca oleracea (purslane) ; Olea
europea (olive); Rubus idwus (red raspberry); Rosa sp. (rose) ;
Solanum sp.
CHARACTER AND EXTENT OF INJURY.
Injury to citrus trees and fruit is caused directly by the feeding
of both adults and larve upon the surface of the parts attacked.
This feeding may be on the young fruit (Plate I, figs. 1,2), the nearly
mature fruit (Plate II), or the new, tender foliage (Plate IIT), and
generally takes place on all of these. The injury to foliage is gen-
erally on young leaves, but may also occur on the axillary buds.
The manner of feeding of both the adult and larva of the thrips is
identical, and consists in piercing the plant tissues with the sharp
mouthparts with which both stages are equipped and then rasping
the wound by a “ rooting ” motion of the head. The vegetable juices
thus liberated from the plant cells are sucked into the alimentary
canal of the insect. The characteristic marking or scabbing of the
fruit, so noticeable at picking time, is started when the fruit is very
small—just after the petals have fallen from the blossoms. This
scabbed area is small at first, but as the fruit grows and the thrips
continue to feed the markings deepen and at the same time the area
of injury is enlarged. The continued feeding of a large number of
thrips results in the scabbing of nearly the entire surface of the fruit.
Often the marking is so large and deep over a portion of the orange
that it causes the fruit to be misshapen and aborted. Frequently the
entire surface is scarred while the fruit is still small, with the result
that it ceases to grow and falls from the tree.
Orange trees in the Tulare County citrus belt make about four dis-
tinct growths a year, and it is on this tender foliage that the orange
thrips multiply in greatest numbers. The feeding of large numbers
of these little insects causes the young leaves to curl and become dis-
torted and the whole growth to present a sickly appearance. Young
trees are often held back a year or more in growth by the prompt
destruction of the terminal buds soon after these make their
appearance.
4 INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
DESCRIPTION AND LIFE HISTORY.
THE ADULT.
The adult female of the orange thrips is a small, four-winged,
orange-yellow insect, which moves very rapidly by running, leaping,
and flying. The mouthparts, which are suctorial in nature, form a
sharp cone projecting from the underside of the head. The adult
male is smaller than the female and much more rapid in its
movements.
The original description of the adult female by Moulton? is as
follows:
Euthrips citri n. sp.
Measurements: Head, length 0.75 mm., width 0.15 mm.; prothorax, length 0.09
mm., width 0.18 mm.; mesothorax, width 0.24 mm.; abdomen, width 0.25 mm.;
total body length0O.86mm. Antenne: I, 124; I], 364; III, 394; 1V, 394; V. 304;
VI, 34u; VII, 64; VIII, 124; total, 0.205 mm. Color, yellow to orange-brown,
with thorax and segment 2 of antennse more noticeably orange-brown.
Head twice as wide as long, retracted considerably into the prothorax,
broadly rounded in front, with only slight depressions to receive the basal
joints of the antennz; two spines on anterior margin, other spines not conspic-
uous; cheeks almost straight and parallel. Hyes large, occupying almost one-
half the length of the head, prominent; pigment deep red to purple; facets of
eyes large, eyes pilose. Ocelli subapproximate, margined inwardly with yel-
low-brown crescents. J/outh-cone short, reaching almost to posterior margin
of prothorax, broadly rounded and with black spot at tip; maxillary palpi
8-segmented. Antenne S-segmented, with segment 2 orange-yellow, other seg-
ments uniformly light brown; segments 2, 4, 5, and 6 almost equal in length;
style about one-half the length of segment 6. All spines inconspicuous; sense
cones transparent.
Prothorax about twice as wide as long, posterior angles broadly rounded;
with long brown and outer small spine at each posterior angle, other spines not
conspicuous. Mesothorar largest and with anterior angles broadly rounded.
Legs light yellow-brown, with tarsi lighter but dark brown at the tip; spines
on legs brown. Wings present and fully developed, forewings broadest near
base and pointed at tips; with the ring vein and a single longitudinal vein
which divides at about one-third the length of the wing from the base, the
anterior part running parallel and approximate to the anterior part of the ring
vein, and ending abruptly near the tip, the posterior paralleling and approach-
ing the posterior part of the ring vein and ending about one-half the wing’s
length from the end, each branch with a dark-brown marking immediately at
its tip. The costa bears a row of about 29 regularly placed spines. Other
spines placed as follows: A group of 5 near base of median longitudinal vein; 2
on either side of where second vein branches from the first, and 5 scattered
spines about equidistant on each branch vein and in each case ene of these
spines immediately at the end of the vein; several rather long spines on scale.
Veins of the forewing unusually strong and conspicuous, somewhat orange
colored near base but fading to yellow near tip. Membrane of wings trans-
parent.
@ Toe. cit.
Bul. 99, Part |, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE I.
Fila. 1.—YOUNG ORANGES, SHOWING INJURY BY THE ORANGE THRIPS (EUTHRIPS CITRI).
SOMEWHAT ENLARGED. (ORIGINAL.)
FIG. 2.—YOUNG ORANGES, SHOWING INJURY TO STEM AND BLOSSOM ENDS BY THE
ORANGE THRIPS (EUTHRIPS CITRI). SOMEWHAT ENLARGED. (ORIGINAL.)
Bul. 99, Part |, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE Il.
MATURE ORANGES, SHOWING INJURY DUE TO THE ORANGE THRIPS. (ORIGINAL.)
Bul. 99, Part |, Bureau of Entomology, U. S, Dept. of Agriculture. PLATE III.
ORANGE FOLIAGE, SHOWING CURLED AND DISTORTED CONDITION OF LEAVES DUE TO
WORK OF THE ORANGE THRIPS. (ORIGINAL.)
THE ORANGE THRIPS. 5
Abdomen ovoid, tip conical, all spines, excepting a very few at tip, incon-
spicuous.
Described from many female specimens collected from orange foliage and
fruif at Exeter, Tulare County, Cal.
The males are similar to the females, but smaller and more active,
with the orange-colored testes prominent.
THE. EGG.
The egg is a bluish white, bean-shaped object measuring from 0.2
mm. in length to about 0.075 mm. in width, with a very thin shell.
-
THE LARVA.
First-stage larva—tLength 0.041 mm.; width of mesothorax 0.011 mm.;
general shape fusiform. The antenne, head, and legs are large and unwieldy
in proportion to the rest of the body. Color translucent white. Antenne, length
0.015 mm.; distinctly 4-segmented; I short, cylindrical; If more than twice as
long as I, slightly urn-shaped, longer than wide; III about as long as II,
obtusely fusiform; IV about as long as the other joints combined, fusiform,
very finely drawn out at the distal end. Segments II, III, IV (II very ob-
scurely) ringed, the distal rings on segment IV appearing as segmental
divisions. A few fine hairs present on all segments, most numerous on IV but
not very conspicuous on any of the segments. Head subquadrate; eyes reddish-
brown. Abdomen gradually tapering, 10-segmented, first S segments subequal ;
IX and X large and more abruptly tapering, hairs inconspicuous. Legs stout,
femora and tibiz nearly equal in length, tarsi one-jointed, ending in a single
claw.
Second-stage larva—Length 0.9 mm.; head length 0.1 mm.; width 0.085 mm. ;
length of antennze 0.175 mm.; width of mesothorax 0.266 mm.; width of
abdomen 0.3 mm.: Antenne, I, 2u; II, 84; III, 94; IV, 454; V, 9u; VI, 15h;
color orange-yellow. In shape similar to first-stage larva except that the
abdomen is oval to ovate and generally more robust. Head quadrate, small in
proportion to body, eyes reddish. Antennze apparently 4-segmented under 2/3
objective, but under 1/6 objective distinctly 6-segmented, the chitin not extend-
ing into the fifth and sixth segments; I short, conical, about as broad as long;
If eylindrical, broader than long and slightly longer than I; III obtusely
spindle-shaped, about twice as long as broad and about as long as I and II
combined; IV obtusely spindle-shaped but blunt on the distal end, about as
long as III; V very short and thick, slightly broader than long, about one-
fifth as long as IV; VI cylindrical, longer than broad, about one-third as long
as IV. Abdomen oval to ovate, 10-segmented, the last segment tubular. Legs
short and stout, hind femora and tibize about equal, hairs everywhere incon-
spicuous except a few under 1/6 objective, which are the most prominent on
last segments of antenne.
THE PUPA.
First-stage pupa.—Length 0.56 mm.; width of head 0.15 mm.; width of
mesothorax 0.18 mm.; width of abdomen 0.25 mm.; antennie, length 0.2 mm,
Color pale translucent yellow; antennie, legs, and wing-pads lighter. Shape
similar to advanced first-stage larva; abdomen elongate ovoid. Antenne pro-
jecting cephalad, 4-segmented; I short, thick, slightly wider than long; II ob-
tuse, urn-shaped, about as wide as long; III obtusely spool-shaped, about as
78562°—Bull. 99, pt 1—11--—2
6 INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
long as I and II combined and about twice as long as wide; IV about as long
as III, tapering to obtuse apex. Wing-pads extending to distal margin of the
second abdominal segment, those of hind wings slightly longer. Legs stout,
hind femora and tibizw about equal. Hairs present on live specimens but not
prominent, short, slightly longer on tip of abdomen.
Second-stage pupa.—Length 0.666 mm.; width of head 0.13838 mm.; width of
prothorax 0.1838 mm.; width of mesothorax 0.166 mm.; width of abdomen 0.133
mm. Shape similar to that of the adult. Color translucent white to pale yel-
lowish; eyes reddish, more prominent than in first-stage pupa. Antenne 4-seg-
mented, projecting backward over the head and thorax and reaching to the
middle of the prothorax, second segment forming a kind of elbow from which
3 or 4 long sete project cephalad. Prothorax nearly twice as broad as long;
wing-pads in pupze just entering the second pupal stage extending to the
distal margin of the sixth abdominal segment; in pupze in which the adults
are nearly ready to emerge the wing-pads extend to the distal margin of the
ninth abdominal segment. Abdomen similar in shape to that of the adult.
Legs stout, hind femora and tibiz about equal in length, sets more prominent
than in first-stage pupa, longer at the tip of the abdomen; conspicuous in fresh
specimens but not in mounted ones. Tip of abdomen often with a cremaster-
like formation resembling in shape a fork with 4 tines. Male pup smaller,
resembling the adults, their wing-pads usually reaching past the tip of the
abdomen. Sete usually not so prominent.
SEASONAL HISTORY.
The orange thrips passes the winter in the adult state, and it is
generally the adult form which first becomes conspicuous upon the
orange trees in the spring. Although no large number of adults
2as been collected in hibernation, these undoubtedly ‘pass the winter
in sheltered places, such as the dead leaves and twigs forming the
trash under most orange trees; they are occasionally found on living
plants and on citrus nursery stock in midwinter.
Adult thrips appear in limited numbers during March. ‘They
deposit very few eggs in the early part of April, prior to the blossom-
ing of the Navel orange trees, but soon after most of the petals have
fallen larve become quite numerous. Oviposition has not been
observed, but it 1s probable that it takes place mostly at night.
Examinations for eggs revealed the fact that most of them are placed
in the new, tender growth, being inserted into both upper and lower
leaf surfaces, and also in the shoots. They are also placed in the
receptacles of the blossoms after the petals have fallen and in young
fruit and fruit stems.
The larve are wingless and when full grown are orange colored.
When ready to pupate they fall from the trees, get into a curled dead
leaf, amid cobwebs, dust, and leaf particles, and hide until the trans-
formation is completed. Pup are not found in numbers propor-
tionate to the larvee and adults, since it is in this stage that the
mortality rate of the insect is greatest. The pupe are very soft-
bodied and less active than larve and adults. They move readily,
however, when disturbed.
THE ORANGE THRIPS. ‘4
Fees. larve, and adults are found on the trees, and pup in the
dead leaves under them, from early May until early November, all
four forms being present during the entire period. The broods thus
overlap so closely that it is very difficult to separate them.
INTERRELATION OF ABUNDANCE OF 'THRIPS AND FOOD PLANTS.
The orange thrips feed only on very tender plant tissues, namely,
the young leaves, shoots, and tender fruit. This makes it necessary
for them to pass from foliage to fruit and from plant to plant as the
suitability of the tissues as food changes. They first make their
appearance in April and May on the new growth of the Navel orange,
reaching the first maximum of abundance about the time four-fifths
of the petals are off. When most of the petals have fallen a few
thrips pass to the more advanced fruit and the number feeding on
the latter rapidly increases as the first growth of foliage becomes
hardened and distasteful. The thrips continue feeding on the fruit
until the latter, in turn, becomes somewhat tough, and reach a second
le~oo
Q
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89
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$8
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5
RAPES, UMBRELLA TREES. &
Fic. 1.—Diagram illustrating the relative abundance of orange thrips on oranges, on
orange foliage, and on other plants during the season. (Original.)
and greater maximum in May, June, and July. They then pass
once more to the succulent growth which has come on in the mean-
time, and reach the third and final maximum of concentration in
August and September.
As the first citrus growths are becoming tough and before the fruit
is quite tender, the thrips begin to work on the leaves of the grape,
pepper tree, umbrella tree, and some uncultivated plants, reaching
a minor maximum of abundance on these at the time of greatest
abundance of tender leaves and stems. A second maximum of concen-
tration is reached on some of these secondary food plants in the fall,
when most all of the summer growths on citrus trees have become
tough.
The relative abundance of the orange thrips on its various food
plants, at different times during the season, is shown diagrammatic-
ally in the accompanying chart (fig. 1); the diagram represents the
results of observations made at regular intervals in different parts
of the Tulare County citrus belt.
8 INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
LIFE CYCLE.
In ascertaining the length of the life cycle the average lengths
of egg, larval, and pupal stages were added together, and to this an
additional 8 days, which was the usual time from the appearance of
the adult female until ovipositing began. The life cycle thus in-
cludes the period from egg to egg, or from the time the ege has left
the abdomen of the female of one brood until the eggs of the next
brood appear.
Egg stage—The length of the egg stage was determined by con-
fining adult thrips on potted orange plants overnight, then remoy-
ing all insects and examining the plants twice daily, and counting
the larve hatched until they cease to appear. The length of the
ego stage of 19 eggs during the month of August, 1909, was found
to be 24 days for a minimum and 8 days for a maximum, with an
average of 6.2 days. Eggs deposited the latter part of September
required from 20 to 24 days for incubation. During May, June,
July, and August, 1910, observations on 45 eggs gave a minimum of
5 days, a maximum of 13 days, and an average of 8.1 days for 3
months. It is probable that the majority of eggs deposited during
May, June, July, and August would require from 6 to 8 days for
incubation, while in March, April, September, and October the
length of the egg stage would be considerably more.
Larval stage.—The number of days required for the development
of the larva varied from a minimum of 3 days to a maximum of 13
days, with an average of 6.06 days for 55 individuals: and a mini-
mum of 3 days, a maximum of 13 days. and an average of 7.2 days
for 73 individuals during April, May, June, July, and August. The
length of the larval stage would probably be extended, similar to the
egg stage, during September and October. Two distinct larval
stages were observed. The first stage is usually about two-thirds as
long as the second, and the larvee more active.
Pupal stage-—The pupal stage was best observed by keeping larvae
in confinement until they pupated. The total length of the pupal
instar for 30 individuals, under observation during June and July,
1909, varied from 2 to 5 days, with an average of 3.6 days; while
287 observations during April to August, 1910, gave a variation of
2 to 7 days, with an average of 4.8 days. Two pupal stages were
observed, there being a distinct molt from the first to the second
stage, which begins with a splitting of the skin from the head back
dorsally to about 7 to 9 abdominal segments. The pup are more
active in the first than in the second stage.
Total life cycle-—The life cycle, obtained by adding the aver-
wge lengths of egg, larval, and pupal stages, and allowing 3 days
THE ORANGE THRIPS. 9
before eggs were deposited by the newly formed adults, made a
total of 18.68 days for May to August, inclusive, 1909. For the
months April to August, inclusive, 1910, this period was 23 days.
The length of the life cycle of 8 individuals actually recorded from
the egg, upon potted plants, allowing 3 days, as before, for the
adults to oviposit, varied from 20 to 36 days. The data upon the 8
individuals was obtained during September and October, and the life
eycle was undoubtedly longer at this time than in midsummer. The
length of life of the adults observed on confined individuals was
from 4 to 36 days.
Number of broods—Although the number of generations in a sea-
son has not been definitely observed, there are probably four and a
partial fifth during the period of May to July, inclusive, and one
generation in each of the months March, April, August, September,
and October, making in all a possibility of eight to ten generations
for the season.
HABITS.
The orange thrips is very active, especially in the adult form. Its
ability to run, leap, and fly is much greater than that of any other
thrips so far observed by the writers. This activity and their
small size allow them easily to pass unobserved. The writers have
frequently seen adults fly from one tree to another 20 feet or more
distant. They undoubtedly move about to a certain extent, and will
go from one orchard to another in search of suitable food. Fre-
quently they will desert the orange groves, between periodical
growths, for grapes and certain deciduous fruits.
The orange thrips appear to thrive best in sunny and even very
hot weather. On cool cloudy days they are less active and generally
group themselves on the underside of the leaves.
Their reproductive habits are only partially understood. Males
are present part of the year, but usually in more limited numbers
than the females.
EXPERIMENTS WITH METHODS OF CONTROL.
CULTIVATION.
Attempts have been made to control the orange thrips, in part, by
means of cultivation, but none of these endeavors has been in the
least successful. One orchard was hand-raked under the trees and
the soil stirred up in the fall, with the hope that pupa would be de-
stroyed, but results were negative. Another orchard which was
plowed deeply in the fall yielded similar results.
10 INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
FU MIGATION.
Some experiments have been conducted in the hope that fumiga-
tion with hydrocyanic-acid gas would prove effective in controlling
the orange thrips, but all results have been unsatisfactory, because
of the activity of the insects, the large number of generations, and the
expense of the operation.
SPRAYING.
The only method of control which has given good results is spray-
ing at high pressure with a contact insecticide. No sprays aside from
those which kill by contact have been tried because such sprays have
been unsuccessful in controlling other species of injurious thrips.
EXPERIMENTS TO DETERMINE KILLING EFFECT OF DIFFERENT SPRAYS.
The following sprays were tested in the field for killing effect on
the thrips: Homemade distillate-oil emulsion, in combination with
black-leaf tobacco extract, which is a dark, almost viscid liquid con-
taining 2% per cent nicotine; and commercial lime-sulphur (33°
Baumé) in combination with the tobacco extract. All sprays were
applied with a hand pump, maintaining a pressure of 140 pounds.
A large number of young fruit was examined for live and dead
thrips. While this method did not give absolutely accurate results,
because of the number of thrips knocked off by the force of the
spray, it offered some means of comparison. Table I shows the
relative killing effect of the various washes:
TABLE I.—Jilling effect of various sprays on orange thrips.
Total Percent-
Number of fruits iotmachillp number plete age of
examined. 2G of thrips dunde thrips
| counted. por dead.
HnO's Sees cee Blackleaf 1-50 and distillate-oil emulsion 1 per cent. | 129 126 97.6
7100 ee ese Ae ere Blackleaf 1-60 and distillate-oil emulsion 1 per cent. - 182 170 93. 4
OQ ae eo crsieres Blackleaf 1-80 and distillate-oil emulsion 1 per cent. _| 67 64 92. 5
Several hundred...| Blackleaf 1-85 and distillate-oil emulsion 1 per cent.)..........]...--..--- 75
DOE ea eee Commercial lime sulphur 1-75 and blackleaf 1-50....;.........-]...-..-..- 90
1D Yes eeeebeere oe Commercial lime-sulphur 1-50 and blackleaf 1-100... ..........|.--------- 95
EXPERIMENTS TO PREVENT MARKING OF THE FRUIT.
Euperiment No. I—X block of 150 Washington Navel orange
trees was sprayed three times with distillate-oil emulsion and black-
leaf tobacco extract; the former at the strength of 2 per cent and
the latter in the proportions of 1 to 80 and 1 to 100 parts of spray.
The spraying was tried as a means of preventing the thrips from
curling the tender foliage and marking the young fruit. The first
application was made May 4, 1909, after most of the petals had fallen
THE ORANGE THRIPS. i.
and when both larve and adults were present. The second applica-
tion was made eight days later, and the third three weeks after the
second, at which time the thrips began again to be numerous. All
the spraying was done with a hand outfit, maintaining a pressure of
140 pounds.
In recording the results of the spray applications to ascertain their
efficiency it was necessary to class the fruit, as regards injury, in four
grades, as follows:
Sound: No thrips marking.
Slightly marked: A slight marking at one end or a few streaks on the surface.
Moderately marked: Both ends of fruit marked and some scabbing on the rest
of the surface.
Badly marked: Nearly one-half to three-fourths of the surface marked, often
with misshapen fruit.
At picking time 20 loose, or “lug,” boxes of oranges from the
sprayed trees and 20 from an adjoining block of unsprayed trees
were counted. The results obtained are given in Table II.
TABLE II.—IJnjury to sprayed and unsprayed fruit by orange thrips.
SPRAYED.
|
+ | Total | Ny | | Per cent
— number | Num- | Number Number | Number Per cent Per cent | of moder- Per cent
ver of : a ~ | moder- ae of slightly] ~o4.). of badly
igecs of oranges} ber slightly tele badly of sound aia ately eae
Bakes | oa sound. |} marked. | iano marked. fruit. | fruit. sonEned fruit.
| |
| 20 | 2,070 | 1, 533 506 31 heroes sh 74.5 | 24.5 1 0
|
UNSPRAYED.
| lire |
20 2,365 337 1,047 710 271 14.5 44.5 30 11
| |
A commercial grading of the sprayed fruit would have placed
nearly 75 per cent as “ Fancy ” and the remainder as “ Choice,” while
the unsprayed fruit would have run not more than 15 per cent
“Fancy” and 50 per cent “Choice,” the remainder going out as
“ Standards ” and * Culls.” Of the fruit counted from the unsprayed
trees, 85.5 per cent was marked, while 25.5 per cent only of that from
the sprayed trees showed injury, indicating that 60 per cent of the
sound fruit was due to the spraying. The thrips-marked fruit was
smaller than the sound fruit, as will be seen by comparing the total
number of oranges from the 20 boxes of sprayed fruit with that from
the 20 boxes of unsprayed fruit. The writers have frequently noticed
in the packing houses that the smaller fruit is worse marked than the
larger, making it appear that the thrips injury holds back the growth
of the oranges.
12 INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
The sprayed block contained 121 bearing trees. These yielded 165
loose boxes of oranges. The unsprayed block contained 152 bearing
trees, which yielded 162 loose boxes of oranges. The sprayed block,
therefore, produced three more boxes of fruit, though containing 31
less trees, than the unsprayed block.
Eueperiment No. I1—
“a
}
BUREAU OF ENTOMOLOG Y.
L. O. Howarp, Entomologist and Chief of Bureau.
C. L. Maruatr, Entomologist and Acting Chief in Absence of Chief.
R. S. Currron, Executive Assistant.
W. F. Taster, Chief Clerk.
F. H. Currrennen, in charge of truck crop and stored product insect investigations.
A. D. Horxrns, in charge of forest insect investigations.
W. D. Hunter, in charge of southern field crop insect investigations.
F. M. Wesster, in charge of cereal and forage insect investigations.
A. L. QuAINTANCE, in charge of deciduous fruit insect investigations.
E. F. Putuies, in charge of bee culture.
D. M. Roaesrs, in charge of preventing spread of moths, field work.
Rota P. Currie, in charge of editorial work.
Mase CotcorD, in charge of library.
II
DDITIONAL COPIES of this publication
may be procured from the SUPERINTEND-
ENT OF DoCuUMENTS, Government Printing
Office, Washington, D. C., at 5 cents per copy
CONTENTS:
Se TTIOT SETTER a ns tee OS SRE a Oe MAN RRB onto Sayers KE Oe Seine ee es
aKtOry:..---'.--
Recent records
Mpremer extent OF INJUFY.>. 22>. ---5... 25-50 5s5 fe nl eee - Biba MITE
Origin and dist:
Classification. .
Description. ...
The adult.
The first-st
ELEN TT ETO Tee eee ieee Ne eh ee ae oe ee RS Sel
SERIE SL er eet ee Tee ee eae ee Se Oe et Re AE
Pee epoend stare On miairedarvalc 5 ee 22th ads. 2. J eS eee - =
The young
AGMIPET OMFS PH doe oc eye rs oars Soc wat mg hag
Pheer wh Ba ph: OF PUPN-~.-% -.- 2 2. Se 2s sais. e+ =| -- see - =
Habits of the adult..... Shc coy SN gl ek lary AD ye) Seater te aie ese ee tee Soe
Habits of the p
FapH paar OUpN ee ees = Boek t soe be. he ose Re esc ==
aT ms breed 20 58 6 eg od et PS ih Neo os Sante sje ghe SS des oa ome S
ER eae Aide Re ee ke 9 CaN al ac ar ot aca = s For full description of this species see Franklin’s paper, 18 pp. 719-723
57371°—Bull. 99—12——2
22 INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
THE SECOND-STAGE OR MATURE LARVA.
(Pl. V, fig. 2.)
Length 1.0117 mm.; width of mesothorax 0.2718 mm. Body long and cylindrical,
the head and thorax considerably narrowed, and the abdomen gradually converging
to the end. Color of thorax and abdomen translucent white to orange-yellowish.
Contents of the alimentary tract showing through as a greenish mass extending from
the mesothorax to the fifth abdominal segment; the posterior half of segment 1 and all
of segments 2 and 3 of the abdomen bright red; last segment of the abdomen also bright
red. Surface of the body covered with minute granules and with numerous short
setze which are black in color and swollen at the tips. Head 0.0906 mm. in length,
0.1559 mm. in width, front rounded and sides bulging considerably, constricted behind
the eyes to adistinct neck. Eyes made up of a few large facets, red, no ocelli present.
Antennz seven-segmented, about 0.3473 mm. long; segments 3 and 4 long, slender,
spindle-shaped, and annulated; 5 short, cylindrical; 6 longer than 5, slender, cylindri-
cal; 7 slightly longer than 6, very slender; near the distal end of each segment are a
number of set#. Prothorax with the anterior margin considerably narrower than the
posterior, sides rounded, a pair of sete on each side, a pair on dorsum near anterior
margin, and another pair near posterior margin. Mesothorax and metathorax with a
number of sets near sides and a pair of spiracles on the anterior mesothoracic angles.
Legs translucent white. Abdomen 0.6795 mm. in length, 0.3473 mm. in width, fusi-
form, no evidence of ovipositor in female larva, a pair of spiracles on the sides of seg-
ments 2 and 9; segments 9 and 10 about equal in length, 10 with four long, stout sete,
0.2265 mm. in length. Segments of abdomen bearing longitudinal rows of sete at
sides, just within outline, and two incomplete rows on the dorsum.
THE YOUNG NYMPH OR PREPUPA.
CEL Voie. a.)
Length 1.087 mm.; width of mesothorax 0.2567 mm. Shape fusiform, similar to that
of the adult. Head:length 0.1057 mm.; width at the eyes 0.1812 mm. Head rounded
in front and on angles so that the sides bulge strongly, sides strongly converging to
posterior margin. Head translucent white, more or less blotched with orange; eyes
red or orange, not large; ocelli absent; a pair of setee behind the eyes, another pair
between the eyes, and a third pair back of pair 2 more widely separated. Antenne
7-segmented, translucent white, except segment 1, which is orange, extending forward
about twice the length of the head; segment | cylindrical, broader than long; segment 2
cylindrical, narrowed at distal end, about twice as long as | and not so broad; 3 about as
long as 2, more slender, base constricted; 4 shorter than 3, somewhat rounded and con-
stricted at the base; 5 as long as 3 and 4 together, slender cylindrical; 6 short cylindrical
and not as stout as 5; 7 cylindrical, longer than 6, and tapering at the tip; a few sete
present on the segments. Prothorax more than twice as wide as long; sides rounded,
with the posterior margin the widest; translucent white, marked with orange; three
setee on each side, that at posterior angle longest, and four sete in a transverse row
on the dorsum near the anterior margin. Mesothorax with prominent angles, trans-
lucent white, with some orange on the dorsum. Wing cases translucent white, dis-
tinct from each other; those of the fore-wing extending to the posterior edge of segment
2 of the abdomen, and those of the hind wings extending to beyond anterior edge of
segment 3. Legs translucent white to faint yellow, strong, with a number of white
setee. . Abdomen fusiform like that of the adult, translucent white to yellowish orange,
with a bright red band on posterior half of segment 1 and on all of segments 2 and 3
(in some examples, dashes of red on side of 2 or segments following), last segment also
bright red. Abdomen with about six longitudinal rows of white setze increasing in
length toward the posterior end of the body. Length of the abdomen 0.6644 mm.;
width 0.2869 mm.
THE RED-BANDED THRIPS. 28
THE FULL-GROWN NYMPH OR PUPA.
(Pl. V, fig. 4.)
Length 1.017 mm.; width at mesothoracic angles 0.2567 mm.; shape similar to adult.
Color translucent white to yellowish orange, first three segments and last segment of
the abdomen bright red. Head 0.1208 mm. in length, 0.1963 mm. in width; white,
with more or less orange (in older pupz surface distinctly reticulated); eyes oval,
dark red, larger than in prepupal stage, facets large; three ocelli present in close tri-
angle between the eyes in older pup, white, surrounded by orange. Antenne laid
backward on head and reaching to beyond anterior edge of mesothorax; segments
indistinct, transparent white; segments | and 2 projecting more or less forward and
upward; on segment 2 a long slender seta, 0.1208 mm. in length, projecting forward.
Thorax (very plainly reticulated in older pupz) translucent white, with some
yellowish orange on mid-dorsal region. Prothorax 0.1057 mm. in length, 0.2114 mm.
in width, sides rounded. The entire body well supplied with setz, those on posterior
angles of prothorax, on wing-cases, and on sides of the abdomen quite long. Wing-
cases 0.4934 mm. in length, extending to beyond anterior margin of segment 6 of the
abdomen, translucent white to faint yellow. Length from head to end of wing-pads
0.755 mm. Legs translucent white, very plainly reticulated in older pupze. Abdo-
men fusiform, surface reticulated in older pup, general color translucent white to
yellow with the first three segments and the last bright red; in some examples a patch
of bright green was observed, caused by food in the alimentary canal. Length of
abdomen 0.5889 mm.; width 0.302 mm.; length of posterior setae 0.906 mm.
HABITS OF THE ADULT.
The adults are found feeding on both the surface and underside of
the foliage. In many cases they are to be found mingling on the
same leaf with Heliothrips hemorrhoidalis Bouché. The adults also
are found feeding in a colony with the pupe and larvee, all in close
proximity to each other. They feed on the leaf content as do other
thrips, and in many cases rest alongside the leaf vein or under the
webs of the red spider. If disturbed or alarmed these insects were
observed to make long quick jumps or to crawl rapidly over the leaf
much faster than Heliothrips hemorrhoidalis ever moves. There is
another peculiar trait possessed by members of this species, namely,
that the adults are often observed crawling on a leaf with the abdomen
lifted and curved forward over the body. They are apparently very
sensitive to cold, as adults that were placed on a cake of ice became
motionless at once, but began to move actively again within a short
time after removal.
This species, like H. hemorrhoidalis, selects the tender young foliage
to feed upon, and while doing so the female deposits the eggs in the
leaf. After the female has deposited each egg she seals the opening
with a large drop of excrement which dries to a flat scale so that the
egg-pocket is concealed. As these leaves begin to become exhausted
from the excessive feeding of the adults and larve that have hatched,
the adults forsake them and attack the newer leaves of the plant.
While this insect was under the observation of the writer, flight
24 INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
was never observed, but Urich** observed it in flight in the cool
of the evening. The writer has never observed the male and it seems
to be quite rare, as Urich observed it on only afew occasions. Repro-
duction for portions of the year is parthenogenetic, but at other
times bisexual. The adults seem to be very sensitive to lack of
moisture and die rapidly in breeding vials. On mango trees in the
greenhouse individuals have been observed to live as adults for from
14 to 17 days, when, although still very active, they were lost. Prob-
ably this adult has a more extended period of life as the author has
kept specimens of a related species, Heliothrips fasciatus, alive for
three months.
HATCHING OF THE EGG.
The eggs, as they near the end of the period of incubation, become
considerably swollen, so that if the scale covering each egg is removed
there is a slight elevation of the leaf noted. The larva hatches by
the same process as that used by Heliothrips hemorrhoidalis, but
emerges from under the dried scale at one side, and in many cases, as it
moves away. carries this scale on its back.
HABITS OF THE LARVA.
The larve feed on the leaves in company with the adults and
generally prefer the underside, but the writer has frequently observed
them in large numbers on both sides of the leaf. They feed clustered
together in colonies, in folds of the leaf, or along the main vein, or
even under red-spider webs. As they feed, the leaf becomes full of
minute brown spots where the chlorophyll has been extracted, and in
severe cases these run together and the entire leaf becomes brown and
dried up. At all times the larva holds the tip of the abdomen in the
air and bears a drop of reddish liquid, which is held more or less in
place by the stout anal hairs. As this increases in size it falls to the
leaf and the surface becomes covered with drops of excrement, as
occurs with plants affected by Heliothrips hemorrhoidalis. The
larve when disturbed crawl rapidly away, or, if exposed to the light,
endeavor to reach the shade again. In some cases the molted skin
was observed being carried on the tip of the abdomen, but this may
have been accidental.
The larve when full grown cluster in a fold of the leaf, near the
midrib or under the web of a red spider, to change to prepupe. The
skin at the head then splits and gradually, by contractions of the
body, the prepupz work their way out. When they have emerged
they leave the empty skins on the leaf, or in some cases carry them
around on the end of the abdomen.
Bul. 99, Part Il, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE V.
THE RED-BANDED THRIPS (HELIOTHRIPS RUBROCINCTUS).
Fig. 1.—Adult female. Fig. 2.—Full-grown larva. Fig.3.—Prepupa. Fig.4.—Pupa. (Original.)
e ad - eas oa
a ‘ 1
=
7 ~ x ,
7 ioe 4
. & *
7
~
7 ia n ‘
¥ Sd
ay A .
: i” : t =
| » - ,
‘ a 7
7 PY - , ,
a fo
7 —e }
: i es ‘
~— h
> ® Ms _ Ll
“ KACOMELD IOI. 5. oh oe tar ee ete ee a eae ie alle so ae pele age
Dea ICOM LSS Ol CLITUS.. 5 se <5 5-2 Sn n'a sw dee ee ee ees a
Ripa ARE ACh OMMMAUPOS <0 '2 coc icles swale shee eta oe end Poe eae cenees
PaligaMur apainshOranuee tHTIpS,-.....- 1. ~-2..2-..00---baseee nected sees -
Grain thrips. (See Euthrips tritici.)
Grape, European. (See Vitis vinifera.) ”
Grapefruit. (See Citrus decumana.)
Greenhouse thrips. (See Heliothrips hemorrhoidalis.)
Guava. (See Psidium guajava.)
Guava, wild. (See Anacardium occidentale.)
Heliothrips fasciatus—
MEGILVS CUAIACLET. 5. ccs =. 2 MC ec lo eles es even Lays 62) ) eae
SEPM TNS CNSTMOEUS 202 25s .222- a0 soe tees yee} sts + se ae em
Heliothrips hemorrhoidalis on mango and avocado..........-----++---++++++-
Heliothrips (Physopus) rubrocincta, bibliographic reference...........--....--
Heliothrips rubrocincta, bibliographic reference...........--.------+-----+--+--
55513—16——2 31
m SEP 261910 ¢
N,,., w/
“tional muses
19
28
19
29
29
oe INSECTS INJURIOUS TO SUBTROPICAL FRUITS.
Heliothrips rubrocinectus— Page.
adult, description... 2.5 ees . 2. oss pacts se oe > eee 21
bibliography... £2- i625 .22 2 ek goss Ses eb ene 2 ee eee 28
classification........ ~ fae Soe ea Bec\ds oseh te ee ee See eee eee en 21
control, artificial... 02k. . fs 2 - oes go eee eee is ee See ee 28
control “natural... 202 Sees ees Pode. ees oe ee eee cS
GOSCHIp TOM sree. aed ares m3 cl: mee = grab swine ale aa aoe in
eps, description... 2.0.5 sos 4e + cee s on ble od 0 Oe alee See 21
food: plants... 2.2. ¢3255..54 Se taen gens ces es Sees ee 25
habits‘of/adult, .. 0 2 acres a = -C cee piste eee oe ee eee ae 23-24
habitsof laryas.. 5. e Sele ele A ee Alene Sy cl 24
habits.of prepupa ahd pupa. ... : --%-/2mis~ 22 nos same sige el eel ee vie 25
Ratehine yor eee sc. css. tan Se et ascaeraaieewen (nawstetls Weseok ee cee 24
WIStOLy 25 Fe se oe Sea ee seh ee eee 2 26 Re eee Seen aoe, a 17-19
myjury, nature and extent:2 22. s. . -/sqestkue ose deaeneesina > ae eee 19-20
larva; first-stage, description..\....'... s. « ¢.dssneue ioeeeae eee ee 21
larva, second-stage, description).-< <5 4). nih <2 ac Ake Dy - ae eens 22
THES CY Che po05 soe Sas oe ong om ani ore aie ae in eae 25-27
nymph, full-grown, or pupa, description... 2scis<.0 442 ase eae 22
nymph, young, or prepupa, ‘description... . -.-\jcs.i\jsn-cse en see 22
origin-and distributions 2 j2)5?tls ysis ae vioe ee Sees feces See 20
recent records. 2222 cies 2s «do pen’ tp E SE ee 2 eee 19
Horton, J. R., Jones, P. R., and, paper, ‘‘The Orange Thrips: A Report of
Progress for the Years. 1909 and 1910” . ..2..42. 2-62 qacieaus sesh see 1-16
Hydrocyanic-acid gas. (See Fumigation.)
Jones, P. R., and Horton, J. R., paper, ‘‘The Orange Thrips: A Report of
Progress for the. Years 1909 and 1910”... .....a082 ee. ben see lke 1-16
Kola (see also Sterculia acuminata)—
food plant_of Heltothrips rubrocinctus . . ...12:6c-aseses eee eee eee 18
Kumquat. (See Citrus japonica.)
Lemon. (See Citrus medica var. limon.)
Lime. (See Citrus medica var. acida.)
Lime-sulphur and tobacco extract against orange thrips. .....--.------------ 10-15
Mangifera indica, food plant of Heliothrips rubrocinctus........+-----++-+-++-- 25
Mango (see also Mangifera indica)— f
food plant of Heliothrips hemorrhoidalis . oka eit kee eee 19
food plant of pes TUDTOCINCLUS... 2. <2 oe e's oe os on Se 17, 18, 19
Mesothrips ficorum Onicacad's:: 2 \-/2 22. 2s se nin 2.) tye 5 ote ep 17
Olea europea, food plant of orange thrips: .=.:--.----=~:=1-. des-ush eee 3
Olive. (See Olea europea.)
Orange—
Australian Navel. (See Citrus auwrantium*var. sinensis.)
food plant of Huthrips tritict.........----- ee es 2
Homosassa. (See Citrus aurantium var sinensis.)
Mediterranean Sweet. (See Citrus aurantium var sinensis.)
Parson Brown. (See Citrus aurantium var sinensis.)
Ruby Blood. (See Citrus aurantium var sinensis.)
St. Michael. (See Citrus awrantium var sinensis.)
Satsuma. (See Citrus nobilis.) :
tangerine. (See Citrus nobilis.)
Thompson improved. (See Citrus aurantium var. sinensis.)
Valencia Late. (See Citrus aurantium var. sinensis.)
Washington Navel. (See Citrus aurantium var. sinensis.)
INDEX. 33
Orange thrips— Page.
abundance and food plants, interrelation. ........---.......22--0eeeeee i
Reena, SSIS wine Sica lnc om. ts d DOE WOM ee ok SSistee as ae Malo ee a 8
SUOMrmcuigas, Oxperimente,. Hus iielagds cb lseni us Ses eul. sabns Pion Joes 9-13
Re eerror. MRC Lig DISHORY 55 Jere cian Sete so « ob de o's ba win ces cabin wasie cuae 4-6
Re PRCRACENNSTIOND cro) or8, oo iuett’s, «vic. aise! a es wan oe aed rea Salo eo a Mee 5
Perea, SOTIOU w «ug ns cui he walneal yaekne = exe cu etadh aan ealev oases alee 8
SETA 5c Sh Ste a ce. «teats MRE HR La Oh aged soe cE tee wae 2-3
BERS Ric cen etn dn wlliig Sie tn aie Mee aa bY Saks be Hite hates» SED 9
mare Sharaoier and. Extent ) tors: sites. insects.
1906.
DUNG esc eeee Neca Schiciek- eeigctte 4, 621 3, 831 73. 80 46. 90 23. 80 3.10 26. 90
Wl yest oht a Se sete hetonseeese 11, 120 5,111 61. 67 34. 29 21.83 5.53 27. 36
MUGS Sco ceaek Soleo wee oe oe 55, 686 19,173 54. 64 21.19 29. 32 3. 61 32. 93
Sentemberti ect usccss seeseceese 23,175 9, 832 50. 40 20. 80 24.14 5. 43 29.57
Octoberiet 22 552 sa seco seso eee 6, 042 2,126 44.12 19. 56 19.75 4.79 24.54
Totals and averages for 1906} 100,644 40,073 55.81 25.15 26. 31 4.31 30. 62
1907
MAING Se cromce aterm niceties 2, 274 1, 354 48. 67 27.03 14.99 6. 64 21.63
Sty 5s oben siete 6, 658 4,166 36.55 20.11 10.77 5. 66 16. 43
RUSS S eee ceed Boe n sees eee as 12, 898 7, 792 64.19 33. 39 20. 67 10.12 30.79
INGVeMIpeL Seon eee boe one osm 150 93 97.7 96.7 0 1.00 1.00
Totals and averages for1907} 21,980 13, 405 54. 27 29. 06 16. 88 8. 32 25.20
1908.
Hebruarys. 2o.sssilesaeseses Pest 12, 451 515 92. 81 82. 33 0 10. 48 10. 48
IMarehisee S28 steed eniae te tekenee 1, 329 22 100. 00 95.50 0 4.50 4.50
Maye onan ces co toces sess cata 100 56 10. 70 7.20 0 3.50 8.50
DUNC Eis Seeks cconewececcsseseee 10, 035 5,523 43.81 15.78 15.78 6. 24 22. 02
SUL eee ae cee axe oabtcene 16, 974 7, 764 45. 63 20. 99 14.73 9. 90 24. 63
AUIBUSTS ELE Sea esioceeae 5,177 2,441 61.53 29.79 16. 87 14.91 31.78
September so... ..-.<=- Boe eee 12, 708 6, 415 42.29 16. 66 17.06 8.55 25. 61
October. so See. aes ae 11, 302 6, 157 33. 92 15.57 5.73 12.61 18. 34
INovember2est) 2. eRe se teeeme 2, 248 653 50.53 35. 52 3. 06 14.70 17.76
Totals and averages for 1908 72, 234 29, 546 44. 34 21.21 13.12 10. 00 23.12
1909.
VANMALY see packers Geese ee. 5, 687 1, 285 45.52 36. 42 4.90 4.20 9.10
MebruUany sees. ce ceescaceceonecee 1,146 150 58. 00 16. 66 40.00 1. 33 41.33
Marchisea st oe) doc eee 1, 261 137 43.06 21.89 20. 43 ale 21.15
MUL Yoo cece soe Aas ce eek 8, 307 4,717 45. 36 28.70 11-19 5. 25 16. 34
IATIPUIST Se ogee on stances 7, 162 3, 764 37. 32 20. 64 13. 33 3. 34 16. 67
Seplembenseceneces tec cesccees 1,495 860 21.25 9. 30 3. 02 8.95 11.97
INovemiber:2.-2525.-- 26 Senate 136 52 100. 00 32. 00 0 68. 00 68. 00
December. $2. Nee se ae as 2, 663 688 52. 32 38. 37 2.03 11.91 13. 94
Totals and averages for 1909 27, 857 11, 653 41.73 25. 84 10.56 5. 32 15. 88
4. A GEOGRAPHIC STUDY OF THE STATISTICS OF INSECT CONTROL.
A study of these same statistics, when arranged to show the insect
control by States, has given much interesting light upon the subject
of the control of the weevil.
In fallen squares we find an average for total insect control of 26.8
per cent in Oklahoma, 25.9 per cent in Mississippi, 24.5 per cent in
Texas, 20.6 per cent in Louisiana, and 12.5 per cent in Arkansas.
Analyzing these figures from another standpoint, we find that the
State of Mississippi leads in parasite control with 14.27 per cent,
Oklahoma standing next with 4.71 per cent, Texas with 3.9 per cent,
Louisiana with 2.52 per cent, and Arkansas with 0.71 per cent. The
relative rank of the States for predatory control is quite different.
Oklahoma leads with 22.16 per cent, Texas comes next with 20.6 per
cent, Louisiana with 18.1 per cent, Arkansas with 11.82 per cent,
and Mississippi with 11.63 per cent. In climatic control Texas leads
GEOGRAPHIC STUDY OF STATISTICS. 21
with 37.9 per cent, Oklahoma comes next with 30.8 per cent, Arkan-
sas with 25.65 per cent, Louisiana with 12.5 per cent, and Mississippi
with 11.7 per cent. Thus it may be seen that the dry, prairie States
of Texas and Oklahoma lead in the climatic and predatory contro!
of the weevil and also in the total amount of control, and that the
climatic control in each of these States is greater than the total insect
control. This latter fact is also true of Arkansas. In Louisiana
and Mississippi, States which are naturally more humid, the climate
has less influence and the greater proportion of the control is by the
insect enemies.
In hanging squares the conditions are entirely reversed. It is
noticeable that Oklahoma leads in parasitism with an average of 31.74
per cent, Texas averages 26.6 per cent, Arkansas 24.16 per cent, Mis-
sissipi 21.2 per cent, and Louisiana 12.07 per cent. In predatory
control Louisiana leads with 12.9 per cent, Texas comes next with 10.9
PER aA MT
aes ‘oe ie
12.07 me
LOUISIANA i 5 Ee a La x — 22 | || 40.86
30
4 eee 8/2
MISSISSIPPI $e mei as
ae aoe Sia
ARKANSAS
TEXAS we abe es Gali
| mem
OKLAHOMA :
Fic. 2.—Diagram illustrating the average climatic and insect control of the immature boll weevils
during 1906, 1907, 1908, and 1909, in hanging squares. (Original.)
per cent, Mississippi with 6.98 per cent, and Arkansas with 2.53 per
cent. We have no record of predatory control in Oklahoma. In all
five States insect control in hanging squares is greater than climatic
control. With regard to climatic control Arkansas leads with 26.69
per cent, Texas has 16.8 per cent, Louisiana 15.89 per cent, Oklahoma
9.53 per cent, and Mississippi 8.12 per cent. These statistics are
graphically shown in figures 2 and 3.
A brief comparison of the condition in hanging and fallen squares will
show that the States of Texas and Oklahoma have a higher average
percentage of control from all factors in fallen squares than in the
hanging squares; the States of Louisiana and Arkansas have a higher
average percentage of control from all factors in hanging squares than
in fallen squares, and in the State of Mississippi the difference is very
slight, although in favor of the fallen squares. This illustrates the
22 INSECT ENEMIES OF THE BOLL WEEVIL.
difficulty of giving any single recommendation for the control of the
boll weevil which would apply to all regions. This point will be
brought out more fully in other sections of this bulletin.
5. A STUDY OF THE SHARE OF INSECT CONTROL IN THE MORTALITY OF
IMMATURE BOLL WEEVILS.
The condensed tables which have been presented are likely to give
the impression that the parasite control of the weevil is on an average
very low, but it must be remembered that the examinations have
been made in all parts of the infested region whether the weevil has
been present 17 years or only a few months, and whether the weevil
damage amounts to less than 1 per cent of the crop or to almost 100
ae gee
neal
O77
2565
ARKANSAS WLLL —— 8./8
(ae ES. =e
LOUISIANA GY TIE. —s
aes See
TEXAS & ee rj —
ABT eee. /6
OKLAHOMA Wht mo i Lie fie amend
M1SSISS/PP]
Fie. 3.—Diagram | __ the average climatic and insect control of the immature boll weevils
during 1906, 1907, 1908, and 1909, in fallen squares. (Original.)
per cent. This great difference in the sources of the material exam-
ined has necessarily lowered the average mortality to its minimum.
The following records show some of the cases of very high mortality
due to parasites:
Highest records of parasitism of the boll weevil.
IN FALLEN SQUARES.
ea greed
ae umber] ageo
Locality. Date. of stages. | parasit-
ism.
IRODSOM Ma erence says cisiectoson toon ee eos ae ne ae eS NOV./53 1907 2.50.2 eet 53 77.36
Corpus Christi, AVEO S © She a. SORE Sue cet ee ee emn re ane ae June 20, NGO 1 55,.hse 92 36. 95
Natchez, Miss............... they Sate hei). S22 EERE Oct. 23, PIDOB oct Sh aee 157 28.6
Dallas, 1 ies EN Oe Soe Re eta das Ce Beak se a ae ee Aug. 1S 19085 poo pee 18 27.78
GOHRGS Mem. iis2 282/62 sees S Aaa te eae ae es. 4 tae oe July 28, 1908 114 26. 63
INSGEHOZs MISSES £282 555% : [i Sie iy eee ee ee ie sae Oct.16 908s ess 230 PASC
Cuero, Rex Testes. icon tee: ee BS eee te take Aug. 12, 1OOsSo-£2te ee 105 19. 04
Natchez, MASSE, S202 a5 c 32 See eee eee eta aoe July, 1900 ese 200 18.5
Shreveport, | eee eee eee Soe eee. a ee A ayaa care oe Oct 29 IMB 2222-228 624 15.8
Wietoria, Pex 20) ooo aa nan eek eee = eae teas June 19, HOO Rao ae ae 513 14.5
Roosevelt, POs fee Fool i Se Se eee ieee eee Sept. 24, 1906.......... 69 14.4
Arlington, OAS IS oe Ne Oe Ree Oe oe Sie BIRD ee ae July 17, "1908. eee 382 13.35
BROWS vilies TOK; ./5.51:5.-n1cs Aeiepeonl aes Oo. ee ae Sept. 5, 1900..c26. 200 1,147 12.4
Bbuisan, Pak cls. aso cs sone July, ae a A 494 8.5
Misia AOA TT 2050 etiam Sept. 2, 1908......... i 100 8.0
SHARE OF INSECT CONTROL IN WEEVIL MORTALITY. 23
Highest records of parasitism of the boll weevil—Continued.
IN HANGING SQUARES.
een hs
: umber | age o
5 Locality. Date. of stages. | parasit-
ism.
WAR AOR ee SEER Sas cols «ok Swe DORR n «os Se aes wee July 23, 1909..........-. 39 66.6
PP MBENIANES CRE s. cc scp ctel a aox cine: 2 << ce male eateahisrets piece Sine ae cin’ WU) LOUGS omen sen 55 63. 63
Victoria, Tex.......... Sy ae eget Gh Tier ae Ceo PSO LOU (ace eee ao 26 61.5
(LE TRS LECCE SARIS Iaialitle ia: Bo deta le eo Ape Ie TOS ak 82 59.7
cet Ep TI SU 62s RS a ei eae Seat SF es, eae eee ee eee July 17, Ss. Se 51 56. 86
Dallas, 1). <2 ARLE aa rCk Ag le tay Gao tats July, ONG rs 57 52. 63
VE LOR Msn cot cadet. saben’ cememan cecuancceaeeees July 25, 1906-7.) se. =o 99 52.6
of ELST ay: REE EE le aie ter AERO gE Aug. 17, 1QUB Seco A scans 29 51.75
Natchez, Mae dln iodo dese ce ervcte Se tenen SDS Oct. 23, LODS eos scesset 82 51.3
SINT YG Ter RA Ne, A SR pay Seep ee ee aenree ra aa Jtliy 2419082 <2 veces 29 48.27
IGHBTISVINe yy hOxe. 2 oe ae emo et wwe caee oe eecacacsmsaccenae July 1, 1007. Me. 19 47.3
elias: Mem se oes ae ee es ee sh a ss Seow seas ctaades Aug. 10, 1907....-- see 193 47.15
SAI CONS Gps Sone oa ein ee see ee gee oo oe ce calcemede Aug. 6, aS. 260 46. 92
ke CNS OS So Soin fet Cale ily ae Read Ss aes ee July 29, TG0S. coer sac se 140 45.71
Foster, Ret Ae Seen STEN Pew N Sie Sirs. Ce Sept. 7; 190722. 2-< 2-24 - 22 45.47
Tallulah, rE Ren nied, REN EIS Tel a 5 abe ae cr Cll Bel tera nee Dee 20,1900! | ences 85 44.7
Forbing, TO ates 3 8 SE Oe ma eas aa rh i oe Meera meee Aue §29 1007 Sao scs oe 41 43.9
act esi HPS 5 LE ARS AEs aes eae ae ee Sa e Oxt.28; 1908 35235 50crn 37 37.84
IG HO eA Tee ee acs ce ge Coun pS esa ca mar ecaetecsasccse et pets 16, 1908-5. 22s 69 33.33
JAG 9011) ER aS SR Eee ee ee ee ene ae eee Ts ept. 4, DRG a. acer oc 63 31.74
Fouke, PAT ae cee ete cle onto fo nat cc imag | gis} ge | € |88| 2 188) eo |f81818"| &
o Sys } Oe Se visien |) ese aiveea | oes }
oy Za 1m a me |e im \pa mm | R 7 |e A
Hanging bolls........ 0. 75) 75) 6.30 4.7| 70.310.98 7. 7|16. 52 11.6) 5.90) 4.1) 37.4) 28.1
Hanging squares......| 4.25] 425)13.50) 57.4) 367.6/20.30) 74.6/20.50) 75. 413.00) 47.8] 60. 0} 255.2
Total hanging..| 5.00) 500)..... 62.1] 437.9]... 82.3]..... RTOs. re 283.3
Ballen bolls... s:..<... 14. 25) 1,425) 6.30) 90.0/1,335.0)13.34) 178.1)19.01) 253.8) .90) 12.0) 37. 4) 533.9
Fallen squares........ 80. 75] 8, 075/13. 50/1, 090. 1/6, 984. 9/31. 20/2, 179. 3/30. 70/2, 144. 4) 3. 30/230. 5} 69.8 5,644.3
Total fallen. ....| 95.00] 9,500!....- 1,180. 1/8,319.9|..... 9, 357.4). .2.. 2,398.2)..... 242, 5|..... 6,178.2
Totals and aver-| i |
BEES chase. < le . 00)10, 12. 42/1, 242.1]....... pea gee Res ee DS = 2. 94/294. 4/64. 61/6, 461.5
J
1 Given 10,000 weevil stages.
1907.—The mortality during 1907 was 54.27 per cent when figured
from the total number of stages and total mortality, thus showing a
decrease of 1.54 per cent from the mortality of 1906 figured in the
same manner. The parasitism showed an increase of 4.01 per cent.
Taste 1X.—Boll-weevil mortality in 1907.
Percentage of stages killed by—
Number of | Percentage Total per-
Class of forms. weevil of stages centage of
stages. alive. Climate. | Predators. | Parasites. mortality.
Happs ed... so Wek os oc ke 431 76.80 8.58 3. 02 11.60 23.20
Hanging squares.............. 2,612 51. 40 14. 50 7.50 26. 60 48.60
id UcreGi te) i re 342 49. 42 31. 28 14. 91 1. 46 50. 58
Wallensquares <2 --..2 22.5220. 10,020 42.90 33. 50 19. 90 3.70 57.10
26 INSECT ENEMIES OF THE BOLL WEEVIL.
Following the plan adopted for the 1906 records these figures ©
may be weighted for comparison with the earlier records.
TaBLe X.—The hypothetical or weighted average mortality of the boll weevil in 1907.4
5 1907—Mortality from —
=|
Es
Prolifer- : a ; Mot:
3 z ation: Climate. | Predators. | Parasites. Total.
S| 3
S 3 4 e . . —
Class of forms. st 2 3 * 3 a 5 = ‘3 |g is a
ao a © S wi © 5 S oo = » & = © =
Pople (Ba Sle Re) ee eee ee
~_ (3) Sota eed o § ~~ ma oO ~ 3 o ~ ue oO rL oO
a Perey =/Sy (ess en {Nis a |g 2a |g 2 |88|] «
ae Te ee Pee Bose) oe ee ae ee
5 5 5 3 ® Be ‘=| Se 3 Be| 3 |3 5
Ay Z Ay vA fae Ay vA oy GZ a Zim a
Hanging bolls. ....-.-- 0. 75 75) 6.30 4.7| 70.3] 8.58 6.0} 3.02 2.1/11.60) 8.1/29.70) 20.9
Hanging squares......| 4.25) 425)13.50} 57.4) 367.6)14.50) 53.3) 7.50) 27. 7/26.60) 97.8)55.50) 236.2
Total hanging..} 5.00) 500)..... 62.1) 437. 9]....- DONalaeeee 295.8 ke eee 10539 | 2s Pay psil
Fallen bolls..........-| 14.25) 1,425) 6.30 90. 01,335. 0.31.28] 417.6/14.91) 199.0) 1.46] 19.5)50.90) 726.1
Fallen squares......-- 80. 75) 8, 075/13. 50/1, 090. 1/6, 984. 9,33. 50/2, 339. 6/19. 90/1, 389.8) 3. 70/258. 4/62. 80/5,077.9
Total fallen.....} 95. 00) Or 500|2=a5- 1,180. 1/8, 319. oe PBI Y Br] Sass 1,588. 8)... -. P7i¢ A ee 5,804.0
Totals and aver- |
ALCS eee 100. 00:10, 000)12. 42/1, 242.1).....-. lew 16)2, 816. 5/16. 18/1, 618. 6) 3. 83/383. 8)60. 61)6, 061. 1
1 Given 10,000 weevil stages.
This table shows a weighted increase of 0.89 per cent for parasites
and a weighted decrease of 4 per cent for all agencies due to the
falling off in control by predators.
1908.—The mortality during 1908 was 44.34 per cent when figured
from the total number of stages, the total mortality thus showing
a decrease of 9.93 per cent from 1907. The parasitism showed an
increase of 1.68 per cent.
Taste XI.—Boll-weevil mortality in 1908.
Percentage of stages killed by—
Number of | Percentage
Class of forms. t weevil of stages
stages. alive. Climate. | Predators. | Parasites. aerens
Franvinm pols 2i2cee seems = 1,839 49. 40 38. 48 3. 97 8.15 50. 60
Hanging squares. ....-....---- 5, 922 49. OL 19. 24 9. 80 21.70 50. 99
Mallen*bollss=. 272.2222. 3.85. 941 70. 25 20. 08 5.95 3.71 29. 75
Wallen'squares: 25-22. 2-0-1 22 20, 844 57. 28 20. 30 15.18 7.15 42.72
SHARE OF INSECT CONTROL IN WEEVIL MORTALITY. 27
Following the plan adopted for the 1906 and 1907 records these
figures may be weighted for comparison with the earlier records.
TaBLe XII.—The hypothetical or weighted average mortality of the boll weevil in 1908.
5 1908—Mortality from —
F E
a Prolifer-
a. ation: Climate. | Predators. | Parasites. Total.
os :
Class of forms “3 g aa : a a a aa
: a oe 2 i) ue] Om a) 3 O72) os 3 3 19 Zz
Ae be ry = wi oo = o 9 ae © I = 2 =
° = o Ks] us) 42) ct =
2.) e4ga) oy) Steel y lgal '. 128| 4 ise) s
a 2 |8s!| 3 3 AS| 3 aS} 3 SIU erie t= nen | ek
> | 8-18 | 8 | g 18s| 8 [88] 8 188i (8°) &
5 3 15 A 2 |oH| 5 15H!| 5S |SR| 51S 5
a 4 |e vA mA za |e a |e Za \o Z
Hanging bolls. ...--.- 0.75 75, 6.30 4.7| 70.3)38.48) 27.1) 3.97 1.4) 8.15) 5.7/51.80) 38.9
Hanging squares......} 4.25 425 13. 50} 57.4) 367.6/19.24) 70.7) 9.80) 36. 0)21. 70| 79. 8)57. 30) 243.9
Total hanging. .| 5.00) 500)..... G2lp CARTE - Ate] eae | Bi Arle Sore Sosa eeeee 282.8
Fallen bolls...........| 14.25] 1,425) 6.30] 90. 01,335. 0/20 os 268. 1] 5.95| 79. 443. 71| 49. 5/34. 10 487.0
Fallen squares......-- 80.75) 8,075 13. 50/1, 090. 1/6, 984. 9/20. 30/1, 417. 9)15. 18/1, 060. 3] 7. 15 499. 4/50. 30/4, 067. 7
Total fallen.....| 95.00] 9,500 ..... 1,180. 1/8, 319. 9]... 11, 686. 0|..... ee | Pee 548.9}... 4,554.7
Totals and aver- | | | | |
OPES S = esc en <3: |100. 00/10, 000,12. ae yy | ee Wie al 783. 8)11. Hilt 177.1) 6. 34 634. 4/48. 37/4, 837.5
| |
1 Given 10,000 weevil stages.
This table shows a weighted increase of 2.51 per cent for parasites
and a weighted decrease of 12.24 per cent for all agencies, due to
the falling off in control by both climate and predators.
1909.—The mortality during 1909 was 41.73 per cent when figured
from the total number of stages, the total mortality thus showing
a decrease of 2.61 per cent from 1908. The parasitism showed
also a decrease amounting to 4.68 per cent.
TasLE XIII.—Boll-weevil mortality in 1909.
Percentage of stages killed by—
Number of | Percentage
Class of forms. weevil of stages
Stages. alive. Climate. | Predators. | Parasites. ae
Elanging polises 2. ..-.2.4ee~. 2 1,534 53. 33 37. 94 5. 21 3. 52 46. 67
Hanging squares.........-.... 1,959 61.16 12. 96 6. 38 19. 49 38. 84
Malem BOs. aoc chacewcc tees 573 54. 82 27.74 15. 00 2. 44 45.18
Pallen'squares. :.-.-..-.--..-- 7,587 58. 79 26. 58 12. 39 2. 24 41. 21
Totals and averages... -. 11,653 58. 27 25, 84 10. 56
28 INSECT ENEMIES OF THE BOLL WEEVIL.
Following the plan adopted for the three preceding years these
figures may be weighted for comparison with the earlier records:
Taste XIV.—The hypothetical or weighted average mortality of the boll weevil in 1909.1
5 1909—Mortality from—
5
F Prolifer- :
ah Gana Climate. | Predators. | Parasites.| Total.
2H| g
Class of ferms. ws $ sf s 3 s 3 S 3 s - s N
aye = o, = e o 3 S © s r= © 5 Este ove =
a ml cre wes a'| a eel) eeenl tee aioe I Fe let Me
~ 3) i oO § i o ~~ 3 o ~ 3 3) rr 3)
q 2 8/23) 2 = AS) io a 2 a doy NGS) )) ee!
SO B12) ee ee] BSE) See ee ee
5 5 13 S o |oe!| 3 |GH SA 5 5
Ay ZA |p v4 ae |e A 1m A | ZA la A
Hanging bolls. -..-.-.- 0. 75 75) 6.30 4.7| 70.3/37.94| 26.7) 5. 21 3.7) 3.52) 2.5/50.13) 37.6
Hanging squares....--| 4.25} 425)18.50| 57.4) 367.6)12.96) 47.6) 6.38) 23. 4/19. 49) 71. 6/4 29) 200. 0
Total hanging..} 5.00) 500)....- 6271 SAs7e9|bee VERS Baas 7 asl ee (CRN eo aee 237.6
Fallen bolls......-...-| 14.25] 1,425) 6.30) 90. 0/1, 335. 0/27. 74] 370. 3/15.00} 200. 2} 2. 44) 32. 6/48. 63 693. 1
Fallen squares... ----- 80. 75] 8, 075]138. 50/1, 090. 1/6, 984. 9126. 58/1, 856. 6/12. 39} 865. 4) 2. 24/156. 5/49. 14/3, 968. 6
Total fallen.....] 95.00) 9,500}... .- 1,180. 1/8, 319. 9}..... 25226. 922 ee 1065.6). =. - ete eee 4,661.7
Totals and aver-
QOS I eee ee se 100. 00/10, 000)12. 42/1, 242. 2)....... 23. 01/2, 301. 2}10.992)1,092. 7) 2. 63/263. 2/48. 99/4, 899. 3
1 Given 10,000 weevil stages.
This table shows a weighted decrease of 3.71 per cent for parasites
and a weighted increase of 0.62 per cent for all agencies due to an
increase in climatic control.
In the following table is given a comparison of the weighted aver-
age control by all agencies for the four years.
TasLe XV.—Weighted average mortality of the boll weevil, 1906-1909.
Weighted average mortality due to—
Years. :
Prolifera- . ee . All agen-
face Climate. | Predation. |} Parasites. aise
12. 42 24. 39 24. 85 2.94 64. 61
12. 42 28.16 16.18 3.83 60. 61
12. 42 17.83 it 6.34 48. 37
12. 42 23.01 10. 92 2.63 48.99
12. 42 24. 45 15.93 3.93 56. 73
In view of the fact that certain cotton varieties retain the infested
squares more than others, it is interesting to make another hypothesis
on the basis that 50 per cent of the infested forms are hanging. The
year 1908 is chosen to illustrate this phase of the subject.
SHARE OF INSECT CONTROL IN WEEVIL MORTALITY. 29
Taste XVI.—A hypothetical average mortality of the boll weevil in square-retaining
varieties .!
is] .
3 1908. Mortality from—
ie Prolifera- Climate Preda- | Parasites Total
= B gi tion. ‘ ; tors Mies °
Class of forms. Sah @ — —— |= =
on] a IS H ‘ Cin |\ ahs ey 5 |e ie | ae. =) Lal
o's - i) o tl oh o oh | o oh o ry o
BS lias) acl cee Lid reg) otf Met? ceed | Pret. | ao| og |g] og
=| 5 |e8! gs A le8| gS ledlsSiss! eS |as!| gS
® a |30 a 6 |os8 BR |os|F&a\aa = eR) ai
2 A jem] oe | 8 188) 4 (ee ios )o8| a4 je”) o
vo
ey micnlaa. hele eee ia le lee | | le ly
Hanging bolls........ 7.50 750) 6.3 47.2| 702.8/38.48) 270.4) 3.97) 27.9] 8.15 57.3] 53.7| 402.8
Hanging squares..... 42. 50| 4, 250} 13.5) 573. 7/3, 676. 3/19. 24) 707.3) 9.80)/360. 3/21. 70) 797.8] 57. 3/2, 439.1
Total hanging. .| 50.00) 5,000)... .. 620. 9/4, 379. 1]..... OT Tei saden bi] 855.1]..... 2,841.9
Fallen bolls.......... 7.50) 750) 6.3 47.2) 702.8)/20.08} 141.1) 5.95} 41.8] 3.71 26.1) 34.1] 256.2
Fallen squares. ....... 42.50} 4, 250) 13.5) 573. 7/3, 676. 3/20. 30] 746. 3)15.18)558.1] 7.15) 262.8] 50.3/2,140.9
Total fallen. .... 50. 00) 5,000)... -- 620. 9/4, 379. 1]..... 887. 4|..... §99.9)..... 288; 9] .262 2,397.1
—_——S=|—_ ——SS O_O, Sa ——_——$|$ =———_— |_| —<;
Totals and aver-
ages.......... 100. 00/10, 000)... . 1 249, Sl ac 18. 65/1, 865. 1] 9. 88/988. 1]11. 44/1, 144. 0/52. 39|5, 239.0
1 Given 10,000 weevil stages.
This series of tables, wherein the mortality of the weevil is given
an accurate basis for comparison, brings to light some very important
points. This is especially the case in Table XVI, which is based
upon the hypothesis that 50 per cent of the infested forms are hang-
ing. By comparing this hypothesis for the year 1908 with the
table of the same year in which it is considered that only 5 per cent
of the forms are hanging, it will be noticed that under the condition
of the greatest proportion of hanging squares the total control of the
weevil would be 52.39 per cent and the number of parasites to 10,000
weevil stages would be 1,154; whereas, with the smaller proportion
of hanging forms, the total control of the weevil would be 48.37 per
cent and the total number of parasites 634 to 10,000 weevil stages.
Now this shows a gain of 4 per cent in the actual control of the
weevil and almost double the number of parasites to 10,000 weevil
stages. Naturally, under such conditions it would follow that the
parasitic control would be even higher than that which has been used
as a basis for the estimate and would increase in rapid proportion.
In view of this showing of the fact that the larger the proportion of
hanging squares to the entire amount of infested forms, the larger
the insect control becomes, we recommend that those who are inter-
ested in the breeding of cotton varieties attempt to secure varieties
of cotton which will combine the necessary qualities of productive-
ness, length of lint, and early maturing with the square-retaining
tendency. It may be pointed out that the varieties known as Rublee
and Cook’s Improved are not only conspicuous for the square-retain-
ing qualities but also for their desirability under boll-weevil condi-
30 INSECT ENEMIES OF THE BOLL WEEVIL. =
tions. Several other varieties have been noticed to have this
same tendency, but they have not the other characteristics to reeom-
mend them. In this connection we refer the reader to section 4
(p. 21), in which it has been shown that at least two States have had
-a higher average control of the boll weevil in hanging squares than in
fallen squares when all of the records available are considered. It
will also be noticed in section 5, under Table XI, giving the actual
control of the boll weevil in 1908, that hanging squares and hanging
bolls were decidedly in the lead in the total control over either fallen
squares or fallen bolls. While this has not been the case in the other
years under consideration, we nevertheless consider that the pres- -
ence of a nursery for the parasites in the field is most desirable.
Undoubtedly these hanging squares constitute such a nursery.
6. A STUDY OF HOW AGRICULTURE MODIFIES INSECT CONTROL.
From studies made during 1907 the following comparisons may
be made to show the number of factors that it is actually necessary
to consider in order that differences in parasitism may be understood.
At Arlington, Tex., records were kept on a field in the red loam
post-oak country or ‘“‘cross timbers,’”’ another in the Trinity River
bottoms, and a third on the black waxy prairie. The first was
planted March 12, the second April 1, the third April 5. On August
28 the weevil infestation of squares in the timbers was 80.5 per cent,
in the bottoms 94.3 per cent, and on the prairie 21.4 per cent. At
the same time the parasitism in fallen squares on the timbers was 3.12
per cent, in the bottoms 1.9 per cent, and on the prairie 2.56 per cent.
In the timbers the parasitism of hanging squares was 39 per cent and
in the bottoms 24.78 per cent. The variable factors are soil, flora,
time of planting, variety of cotton, and weevil abundance. Hang-
ing squares were found in 1906 to be more highly parasitized in
timber land than on the prairie, and fallen squares inversely. There
appears to be an indication of the value of early planting. This
first field was the earliest field known in the vicinity and it showed
a high parasitism in hanging forms throughout the season.
At Calvert, Tex., were two fields on the prairie, one planted March
11 and 12, the other April 1. On June 21 the weevil infestation of the
first was 18 per cent and of the second 21 per cent. On July 5 the
parasitism in the first was 2 per cent and in the second nothing.
At Denison, Tex., were two fields, one in the red clay, the other on
sandy loam, neither surrounded by timber. On the first the stalks
were burned February 28, on the second March 15. Both were
planted March 30. On August 27 the weevil infestation on the
first was 88.3 per cent, on the second 87.6 per cent; the parasitism in
fallen squares on the first was 6.31 per cent, on the second 2.85 per
HOW AGRICULTURE MODIFIES INSECT CONTROL. 81
cent; the parasitism in hanging. squares on the first was 5.79 per
cent, on the second 11.53 per cent. Here the only variable condi-
tions were soil, possibly weeds, and time of plant destruction. The
parasitism in the two classes of forms was diametrically reversed.
At Terrell, Tex., were two fields on the sandy prairie, both planted
in March, but having different weeds present. The weevil infesta-
tion August 26 on one was 65.2 per cent, on the other 97.5 per cent,
while the parasitism in hanging squares on the first was 29.5 per cent
and on the second 25.6 per cent. The variables were field surround-
ings and weevil abundance.
The unknown influence which entered most of these examples was
very probably the relative abundance of the different species of para-
sites. This may best be illustrated by the hanging squares from the
timbers and bottoms at Arlington, which are quoted above. In the
timbers the determinable parasites proved to be 16 Hurytoma tyloder-
matis, 10 Microbracon mellitor, 6 Cerambycobius cyaniceps, 5 Micro-
dontomerus anthonomi, and 3 Catolaccus spp. In the bottoms there
were 17 Cerambycobius cyaniceps, 13 Microdontomerus anthonomi, 10
Eurytoma tylodermatis, 8 Catolaccus spp., and 7 Microbracon mellitor.
The rank of the species was almost-entirely reversed.
Probably the most important point in the entire set of examples
is that the earliest crop had the most parasites. To show this in
another way we may refer to the conditions on the experimental farm
at Dallas. The first part of the field to put on squares was the first
part to show parasites. On July 8 infested squares were to be found
in six plats, but only on this earliest plat was there any parasitism—
5.7 per cent. On July 19 it and the adjacent plat were still consid-
erably in the lead.
That the earliest field should show the highest parasitism was
expected by the writers in view of the early spring observations.
The parasites in hibernation, whether on the boll weevil or on winter
cohosts, all reached maturity in the latter half of March at Dallas.
It was reasoned that cotton, squaring and attacked by April 15,
would get the hibernated parasites in any part of the State; that
cotton squaring and attacked by May 15 would get the first genera-
tion of parasites from the cohosts, and so on. It is reasonable to
expect that cotton with squares infested in season to attract hiber-
nated parasites or a new brood from cohosts will fare better than
cotton that commences squaring when all the parasites are concen-
trated upon neighboring cohosts. This cotton must wait until the
period of the favored cohosts begins to wane before the parasites will
begin to seek new scenes of activity. Although it was so reasoned,
it was hardly expected that there would be sufficient proof to warrant
voicing the proposition.
32 INSECT ENEMIES OF THE BOLL WEEVIL.
A series of examinations was made in the vicinity of Victoria,
Tex., in 1907 and 1908. On October 9, 1907, Mr. Cushman noted
that fall destruction of the cotton was being carried on quite exten-
sively, but in different manners. On the east side of the river, south
and east of town, was an area in which practically all of the cotton
had been defoliated by the cotton leaf-worm. This area was sepa-
rated by the river and by a wide strip of huisache timber from
other cotton areas. In other directions were located fields stripped
by grazing, some that were plowed under, and one field only was
found which had received no treatment.
On June 17, 18, and 19, 1908, fallen squares from several of these
fields were examined, with the following results:
TaBLE XVII.—Boll-weevil mortality in various cotton fields, Victoria, Tex., 1908.
Percentage of mortality, 1908.
Treatment, 1907. Total | Total.
stages. A Preda- P
Climate. ens Parasites.
Destroyed. stalks sep tembere.--— qa ee tee eee 314 | 18.18 5. 43 4.14 9. 23
Plo wed WO CLODOr. seca se ae 296 13.80 7.70 3.00 3.00
(PlOweG: DW OCenT DOE aa ete ame ee lane eee 354 | 60.70 14. 40 41.20 5. 08
Crazed HOCtGPebas aera eae ie Bet Oye sor 144 44. 40 24.30 15. 97 4.16
SSIS SS See SC Re Se deer pace seta Ssen mae aot oor 290 37.50 25.50 7.20 4.80
Derolinteds vysec eae 2 SLE eee = nase ao eee eee 480 | 29.30 20. 60 225 6. 20
NE) Ore mterwiniate are cia eictete wie o eike eee ites erste sine ate ile gms ore edeiete 513 52.80 27.00 11.10 14. 40
ID Os Bete oe se eels Sewn gSocieeten ase seep a masa nisee 375) |p 238480 16. 50 3.10 4.50
These striking differences in the percentage of control can not be
attributed to the differences of treatment in 1907, although that
may have had a bearing. The different fields had different weeds
and plants surrounding them, they received different treatment in
the spring of 1908, and there are many other reasons why no one
basis of comparison can be chosen. The table is offered to illustrate
how wide a difference in natural control can be found in fields only a
few miles apart and proves conclusively the value of individual effort
in the fight against the weevil.
Numerous other instances are contained in the notes that are quite
as striking as the one to which reference has been made. There is
every reason why each planter should follow out as complete a pro-
gram against the weevil as he can, because each effort reduces the
total infestation of his neighborhood.
7. CLIMATIC CONSIDERATIONS.
The climate of the hibernating season of 1906-7 was very unusual,
so much so that the boll weevil hardly became quiescent, and the
emergence was largely during March, whereas normally it is in
April. The boll-weevil parasites mature simultaneously with the
CLIMATIC CONSIDERATIONS. 33
great wave of boll-weevil emergence. A glance at the accompanying
diagrams (figs. 4, 5) will show that in Louisiana the monthly mean
temperature was from 3° Fahrenheit (November) to 10° (January)
higher than the normal, and in Texas it varied from normal
(November) to 10° above normal (March) during the entire winter.
On the other hand, the accumulated moisture from November 1,
1906, to March 1, 1907, in Louisiana was 5 inches below normal and
in Texas 1 inch below normal.
Cotton was planted in March and April (1907) and normally would
have squared in May and June, but it was retarded a month by the
low temperature in April and May, during which months the monthly
mean temperature was 2° to 3° below normal in Louisiana and
3° to 6° below normal in Texas. In addition to the cold of the
spring, the precipitation in Louisiana from March 1 to July 1
was 7 inches above the normal and in Texas 2 inches above. This
cold and the presence of volunteer cotton tided the boll weevil over
until the planted cotton was up. The parasites were obliged to seek
cohosts from March 15 until late in May orinJune. The cold, damp
weather undoubtedly retarded their development so that the first
generation was ready to attack such boll weevils as were breeding
late in May and early in June. As only a few fields held this advan-
tage to the parasites, these fields naturally became much better
stocked with parasites, as has been pointed out in another paragraph.
The summer and early fall months showed a slight deficiency in
rainfall and a slightly higher mean temperature—to such an extent,
however, that the season was considered dry, for the cotton did not
put on a very luxuriant foliage, and thus gave the sun plenty of play
on the fallen squares. The result is evidenced by the high percentage
of mortality from heat shown in the mortality tables. The increase
in parasitism may be ascribed to the same cause,
The mean temperature of October, 1907, was normal in Texas, but
10° above normal in Louisiana. This warm season was followed by
a very sudden drop in temperature on November 11, the ‘‘norther”’
lasting until the 15th. This caused the November mean in both
States to be 3° below normal (Texas 53° F., Louisiana 56° F.). In
both States during this one month the precipitation was 3 inches
above the normal. In northern Texas about 30 per cent of the adult
weevils were killed by cold. The temperature at Dallas‘! reached
14° on November 13, which was 11° colder than was experienced in
1906 and 21° lower than at any time in November, 1905. The boll
weevils were not prepared for this cold, as they were still in great
1 The record was made both by the minimum thermometer and the self-registering thermograph at the
laboratory in East Dallas, and is a few degrees lower than the official record at Oak Cliff, about 5 miles
to the west and across the Trinity River.
16844°—Bull. 100—12
3
84 : INSECT ENEMIES OF THE BOLL: WEEVIL.
numbers on the plants and many immature stages were developing
in green squares and bolls.
Table XVIII gives the results of the examinations made immedi-
ately after the freeze.
TasLe XVIII. — Mortality of the boil weevil in Texas, November, 1907.
Mortality due to—
Place. Date. Form. | Location. ee Stages. Mortal
; Ye Para- | Other
Cold. f
sites. | causes.
1907 Perct. | Perct.| Perct.| Per ct
Weallassaeeesnssce Nov. 14 | Squares...| Fallen. .} Green 93 Ward 96.7 1200) See
ease eee eee Gosseea Hs. GOz=e se (ooh TA eee 151 47.0 36. 4 5.9 4.6
Brownwood...-- Novy. 25) |52-dote2- Plant...| Green 10050}! S10050) | 24a... | See
Navasota.....-..- Nov. 19 |..-do... -do.. Osd-2 1) 10050: )}\- 100; 082 aes eee
@alvert 2222-5252 Nov. 20 |...do... edoz doz: @) 100..0:)}| SLOOSO" Sao eee
Dallases ss nee Nov. 14 } Bolis...-.- Fallen Drys-ess 13 30.7 7.6 7.6 15.3
fos eae | ee Goren do... Plant ..do 8 STO eee aa ene 37.5
Brownwood..... Nov. 15 |..-do. Bots oa Green 7 100! Oi] S005 0) (2222525 beens
Navasota. .---.-- Nov. 19 |...do. Golrss Mixed 56 96.3 Bint 35) 30.7
Calvert:s: ---=: INOW 20a oe dO seat a 3 |e 2d Onecns|peedOvere 21 95. 2 S80). a cee 57.2
Waco. sesetee INOVa oleae dOmeoe3. Seto Rea seeGOsenee 16 100.0 DONOY Seas 50.0
PMS OLO Resets GOs cc oeedOneee ce | peedOurceatencdOseses 27 100.0 6380" fee eee 37.0
Totals and \ Squares sas|e- eo esees | aaeeeeeeee 246 66.3 59.8 4.0 2.8
averages. |f-"-"""""~ {pulls ie Saw sleee ates |seeeaeeee= 148 88.5 49.3 2-0°) 23741
Totals and
BVETAPCSs | Sack os cee oleae | Seeeeseeen lecnecine ee 394 74.3 55.3 3.2 15.8
1 Several.
2 Most of the death from “other causes”’ in bolls was due to proliferation, which seems to be stimulated
by frosts.
From this small number of stages no general statement can be made.
Of the 394 stages 55.3 per cent were killed by cold. Of the stages
in green squares or bolls, 98 per cent were killed by the cold.
The most interesting point is that although 98 out of 100 weevil
stages in green forms were killed, a parasite larva was found to have
just hatched from its egg on a weevil larva killed by cold. Three
other similar cases were found in dry forms. Seventeen cases of
parasitism were found on the 394 stages. Among these were two
living eggs of which one was an entirely new type and also two pupe
which proved to be Habrocytus piercei.
The remainder of the winter of 1907-8—that is, from December to
March 1—had a mean temperature a few degrees above the normal,
but with several severe cold spells. During the four winter months
the precipitation in both States was above the normal. The short
cold spells with warmer intervening weather and heavier rainfall
were disastrous to the boll weevil. The February examination to
ascertain the mortality of the weevil indicated about 98 per cent
mortality. Asa result of the extreme scarcity of weevils in the spring
and summer in most parts of Texas, there was a great reduction in
the number of parasites. In fact, in the northern portion of the
Texas black prairie the parasites were forced to seek other hosts. A
killing freeze in November, 1908, again killed many boll weevils.
HOW INSECT CONTROL FOLLOWS WEEVIL. 35
Following the cold of November, 1908, the winter was unusually
warm, being at least 5° F. above the normal in both Louisiana and
Texas. From March 15 to July 15, in both States, the temperature
was almost normal. However, by this time there was an accumulated
deficiency of precipitation in each State of several inches. The
months of July and August in Texas were extremely warm and many
places recorded the maximum temperatures for their entire period
of records. While the heat was less excessive in Louisiana, it never-
theless reached very high points. This extreme weather during these
two months had a tremendous effect upon the boll weevil and upon
its parasites, although records taken after some of the hottest days
showed that the mortality of the boll weevil from the heat was con-
siderably higher than the mortality of the parasites of the boll weevil.
After the middle of August a period of renewed growth of the cotton
plant gave the boll weevil an opportunity for increased development
and consequently permitted a large number of weevils to mature
before the hibernation season. Incidentally with this fall brood of
weevils, we find that there was a very great increase in the parasites,
especially in Louisiana. The following two diagrams (figs. 4, 5)
illustrate the temperature of the years under consideration.
8. HOW INSECT CONTROL FOLLOWS THE DISPERSION OF THE BOLL
WEEVIL.
From an economic standpoint it is very important to know what
kind of natural control of the boll weevil can be expected in newly
invaded country. Since 1904 it has been noticed that maximum
infestation is generally reached by August 1, and that simultaneously
an extensive dispersion of the boll weevil takes place. At this period
the boll weevils fly to fields many miles beyond the parasites. The
climatic conditions during the dispersion period are such as will not
seriously interfere with prolific breeding of the weevils in the newly
infested territory. The extent of the dispersion is limited only by
the number of weevils flying and the amount of food supply available.
In the fall of 1909 the sparse production of cotton in southern Missis-
sippi brought about a dispersion of 120 miles into new territory.
Our knowledge of the insects which attack the boll weevil shows
that most of them are derived from the parasites of similar weevils
that are native to the region infested. Therefore, if parasites and
predators are present in the invaded region, it is reasonable to expect
that they will immediately begin attacking the boll weevil. This
assumption has been proven in many definite cases. At Mmden, La.,
in 1906, a parasite larva was found in a green square infested by the
first generation. At Roxie, Miss., where the weevils had been present
only a few weeks in September, 1908, ant work and parasite work
INSECT ENEMIES OF THE BOLL WEEVIL.
36
(‘TeUIS1IIO) *GO6T PUP ‘SOGT “LOG UT SUOTYVIIVA O]}CUTI[O SBXOT, SUT} VIYSNI]I Weisel —'F “O1q
2 mae
ne
LOQV-906/ “¥
BOEY-LOE/ "FYMLLYT A:
Ni fan sane
Later in the season of 1908, an isolated infestation
was found at Roadside, in Yazoo County, Miss., about 40 miles beyond
Ni
é LMous ae a
were easily found.
the regular line of infestation, but it was noticeable that the weevil
was parasitized in this particular field.
37
STATUS OF WEEVIL AND CONTROL BY INSECTS.
9. THE STATUS OF THE BOLL WEEVIL AND ITS CONTROL BY INSECTS.
During the seasons of 1908 and 1909 the examinations of the boll
weevil to determine its status demonstrated that there had been a
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tremendous falling off of the weevil in all western and northern Texas.
In August, 1909, there was less than 10 per cent infestation in half of
88 INSECT ENEMIES OF THE BOLL WEEVIL.
Texas and in all of Oklahoma. At the same time a maximum infesta-
tion was found in all of that part of Louisiana lying south of the Red
River and in Mississippi for about 20 miles east of Natchez. An analy-
sis of the parasite records for this same season shows that the parasite
control of the weevil in these sparsely infested regions of Texas was
very light, whereas the control in the heavily infested regions of south-
ern Louisiana and Mississippi was correspondingly very high. The
inference drawn from this observation is either that the boll weevil
had ceased to be the predominating weevil species for parasitic
attack in the lightly infested region, or that the parasites had been
destroyed by the heat. That the parasites were not all destroyed
by the heat is demonstrated by many records of the same parasites
on other species of weevils during the fall and winter of 1909.
10. A BRIEF STATEMENT OF THE VARIOUS CLASSES OF CONTROL EXER-
CISED UPON THE BOLL WEEVIL.
Before passing from this part of the report, which deals with the
general conditions obtaining, it is necessary to say a few words con-
cerning the classes of control which are of importance in repressing the
boll weevil. The first agency which is responsible for mortality of the
weevils is the resistance of the cotton plant to attack, evidenced either
by the toughness of the plant tissues which must be punctured, or by
the proliferation of the tissues, which destroys the weevil eggs and
larvee by crushing. When the infested form falls to the ground or
withers on the plant it becomes immediately a subject for numerous
other factors of control. Intense heat kills many stages. A large
number of parasite species seek out infested squares for their prog-
eny; myriads of ants, beetles, and mites find nourishing food by
merely cutting their way into the infested forms and devouring the
weevil stages. In addition to these, sudden cold freezes countless
numbers of developing weevils. Neither are adults free from adverse
conditions. Many are killed by heat, or cold, or drowning; many are
picked up by birds and lizards or preyed upon by other insects; and
finally multitudes are starved on account of the ravages of other
insects upon their food supply. In this report we are able to deal
only with the three factors which are determinable in the control of
immature weevils, namely, climate, parasites, and predators.
11. PRACTICAL CONCLUSIONS DERIVED FROM STATISTICAL STUDIES.
The following conclusions of economic importance have been
reached from a study of this large series of statistics:
I. The month of August is the most important month for the con-
trol of the weevil by insect enemies. As this month is also the most
BIOLOGICAL COMPLEX. 39
important in the control affected by climate, it should be considered
as one of the most critical times of the year for controlling the boll
weevil. When a sudden drop in the temperature below freezing
occurs in the month of November before a large proportion of the
weevils has entered hibernation, and while many are still immature,
an excellent control of the species can be obtained. As, however,
this is only an occasional occurrence, it can not be relied upon and
every measure possible should have been carried out to prevent the
weevils from going into hibernation at all.
II. Hanging squares are the most important infested parts for the
work of parasites, and fallen squares in a similar degree for the work
of the predatory enemies. It has been demonstrated also that in
certain years the total control by all agencies is greater in hanging
squares than in fallen squares, and furthermore that in the more
humid States this condition is the prevalent one.
III. It has been shown by examples that the total mortality of
the weevil can be increased in proportion as the number of hanging
squares in a given area is increased and likewise that the pro-
portion of parasites to weevils is increased. It is therefore recom-
mended that plant breeders attempt to develop varieties of cotton
which will retain the squares, but will also have the other desirable
varietal characteristics necessary for the production of an early
cotton crop.
IV. The insect control of the boll weevil is dependent in a large
measure upon the operations of the farm and for this reason all those
field practices which have been included in the system of cultural
control of the boll weevil are further recommended as tending to
increase the insect control.
PART II. BIOLOGICAL COMPLEX.
In Part I of this bulletin one set of facts, composed of statistics,
was dealt with, and it was merely hinted that the causes of these con-
ditions were very complex. In this part is presented another series
of facts, even more significant than the first, but much more difficult
to present in a tangible manner. The study of these biological
factors received its first impetus when at Clarendon, Tex., in 1905,
Mr. C. R. Jones and the senior author were fortunate enough to learn
the biologies of three species of weevils and to find that all these were
parasitized more or less abundantly by the same parasites as is the
boll weevil. It was already known that some of the parasites of the
boll weevil attacked other weevils, but the significance of this fact
had not been realized.
-
40 INSECT ENEMIES OF THE BOLL WEEVIL.
With this simple beginning the search for other hosts of the boll-
weevil parasites was started and we have now built up the knowledge
of the following complex:
Owing to the complicated nature of the data to be presented in
this part, these have also been arranged in the following sections:
1. A list of the insect enemies of the boll weevil.
. The hosts of boll-weevil parasites.
Mites which attack the boll weevil.
. Flies which parasitize the boll weevil.
. The hymenopterous parasites of the boll weevil.
. Biological notes upon the parasites of the boll weevil.
The development of the parasites.
The distribution of the parasites.
9. The parasite seasons.
10. Adjustment to new hosts.
11. Beetles which prey upon the boll weevil.
12. Lepidopterous larvee which are incidentally predatory upon
the boll weevil. ;
13. Ants which prey upon the boll weevil.
14. Biology of the cohosts of the boll-weevil parasites.
15. A list of the host plants of the cohost weevils.
16. A summary of the most important biological facts.
1. A LIST OF THE INSECT ENEMIES OF THE COTTON BOLL WEEVIL.
The boll weevil is known to be attacked by 29 species of parasites,
while 20 species of predators attack the immature stages and 6
species of predators attack the adults. These species are listed as
follows:
Arachnida.
Acarina. Sarcoptoidea.
Tarsonemide. Pediculoidine.
Pediculoides ventricosus Newport (parasite on larva), Mexico.
Pediculoides sp. (parasite on larva), Louisiana, Texas.
Tyroglyphide.
Tyroglyphus breviceps Banks (parasite on larva), Texas.
Insecta.
Orthoptera. Mantoidea.
Mantide.
Stagmomantis limbata Hahn (predator on adult), Texas.
Hemiptera-Heteroptera.
Reduviide.
Apiomerus spissipes Say (predator on adult), Texas.
Coleoptera. Adephaga.
Carabidee.
Evarthrus sodalis Le Conte (predator on adult), Louisiana, Texas.
Evarthrus sp. (predator on adult), Louisiana.
A LIST OF THE INSECT ENEMIES. 41
Insecta—Continued.
Coleoptera. Polyphaga. Diversicornia.
Cantharide.
Chauliognathus spp. (predators on larva), Louisiana, Mississippi.
Cleride.
Hydnocera pallipennis Say (predator on larva), Texas.
Hydnocera pubescens Le Conte (predator on larva), Texas.
Cucujide.
Cathartus cassie Reiche (predator on larva), Texas.
Lepidoptera. Bombycoidea.
Noctuide.
Alabama argillacea Hiibner (defoliator, cuts off food supply).
Hymenoptera. Formicoidea.!
Dorylide.
Eciton (Acamatus) commutatum Emery (predator on larva), Texas.
Poneride.
Ectatomma tuberculatum Olivier (predator on adult) Guatemala.
Myrmicidze. Cremastogasterinz. F
Cremastogaster lineolata (Say) var. clara Mayr (predator on larva) Texas.
Myrmicidz. Solenopsidine.
Solenopsis geminata (Fabricius) var. diabola Wheeler (predator on larva),
Louisiana, Mississippi, Texas.
Solenopsis molesta Say (=debilis Mayr) (predator on larva), Oklahoma.
Solenopsis tecana Emery (predator on larva), Louisiana, Texas.
Myrmicide. Myrmicine.
Monomorium minimum Buckley (predator on larva), Louisiana, Mississippi,
Texas.
Monomorium pharaonis Linnzeus (predator on larva), Arkansas, Louisiana,
Oklahoma, Texas.
Pheidole sp. near flavens (predator on larva), Texas.
Pheidole crassicornis Emery (predator on larva), Texas.
Dolichoderide.
Forelius maccooki Forel (predator on larva), Texas.
Dorymyrmex pyramicus Roger (predator), Cuba.
_ Dorymyrmex pyramicus (Roger) var. flavus McCook (predator on larva), Texas.
Iridomyrmex analis André (predator on larva), Texas.
Formicidee.
Formica fusca subpolita perpilosa Wheeler (predator on adult), Mexico.
Formica pallidi-fulva Latreille (predator on larva), Arkansas.
Prenolepis imparis Say (predator on larva), Arkansas.
Hymenoptera. Chalcidoidea.
Chalcidide. Chalcidinze. Smicrini.
Spilochalcis sp. (parasite), Texas.
Torymide. Monodontomerine.
Microdontomerus anthonomi Crawford (parasite), Louisiana, Texas.
Eurytomide.
Eurytoma tylodermatis Ashmead (parasite), Arkansas, Louisiana, Mexico, Okla-
homa, Texas.
Bruchophagus herrere Ashmead (parasite), Mexico.
Eurytoma sp. (parasite), Texas.
1 All of these ants have been determined by Prof. William Morton Wheeler.
492 INSECT ENEMIES OF THE BOLL WEEVIL.»
Insecta—Continued.
Hymenoptera. Chalcidoidea—Continued.
Perilampide.
Perilampus sp.' (parasite), Louisiana.
Encyrtide. Eupelmine.
Cerambycobius cyaniceps Ashmead (parasite), Arkansas, Louisiana, Mississippi,
Oklahoma, Texas.
Cerambycobius cushmani Crawford (parasite), Texas.
Cerambycobius sp. (parasite), Mississippi.
Pteromalide. Pteromaline.
Catolaccus incertus Ashmead (parasite), United States.
Catolaccus hunteri Crawford (parasite), Louisiana, Mississippi, Mexico, Texas.
Habrocytus piercet Crawford, Louisiana, Texas.
Lariophagus tecanus Crawford (parasite), Texas.
Eulophide. Tetrastichine.
Tetrastichus hunteri Crawford (parasite), Louisiana, Mississippi, Texas.
Hymenoptera. Ichneumonoidea.
Ichneumonidz. Pimplinze. Pimplini.
Pimpla sp. (parasite), Texas.
Braconide. Sigalphine.
Sigalphus curculionis Fitch (parasite), Louisiana, Mississippi, Texas.
Urosigalphus anthonomi Crawford (parasite), Texas.
Urosigalphus schwarzi Crawford (parasite), Guatemala.
Urosigalphus sp. (parasite), Texas.
Braconide. Braconine. Braconini.
Microbracon mellitor Say (parasite), Mexico, United States.
Braconide.
Unknown species (parasite), Texas.
Diptera. Cyclorrhapha.
Phoride.
Aphiochxta nigriceps Loew (parasite), Texas.
Aphiochxta fasciata Fallen (parasite), Texas.
Aphiochxta pygmxa Zetterstedt (parasite), Texas.
Tachinide.
Myiophasia xnea Wiedemann (determined by Coquillett) (parasite), Texas.
Ennyomma globosa Townsend (parasite), Louisiana, Texas.
HYPERPARASITES.
Diptera.
Plastophora (Pseudacteon) crawfordi Coquillett on Solenopsis geminata Fabricius.
2. THE HOSTS OF BOLL-WEEVIL PARASITES.
As has just been stated, the boll weevil has 55 species of insects,
which are known to attack it. Among the parasites are to be found
7 which are occasionally accidentally hyperparasitic. At least 1 par-
asite is known to attack one of the predators. The accidental preda-
tor (Alabama argillacea) is attacked by 12 parasites, 46 predators,
1 This species may be a parasite of a Chrysopa larva or of some lepidopteron which had entered a weevil
cell.
2 The enemies of Alabama argillacea Hiibner afford some interesting sidelights on the complexity of the
biological relations of cotton insects.
MITES WHICH ATTACK THE WEEVIL. 43
and 1 hyperparasite. Among these 46 predators are 6 which also
prey upon the boll weevil. At least 1 very common predatory
insect is known to prey upon many of the boll-weevil predators.
Fifty-five species of weevils are known to be attacked as cohosts of
26 species of parasites and of the 19 species of predators which attack
the boll weevil. These 55 species of weevils are known to breed
upon 91 species of plants, most of which are to be found in the vicinity
of the cotton fields. Three of these weevils sometimes breed upon the
cotton plant. Among the great number of parasites which attack
the 55 cohost weevils, 44 species are definitely known to science and
at least 6 species of hymenopterous parasites are known to attack
these 44 species of parasites. This complexity could be carried still
further, but probably enough has been stated to show how the many
influences of nature are dependent upon one another. The state-
ments are illustrated graphically in the accompanying diagram (fig. 6).
The principal point of importance in all of these facts is that the
boll weevil has been deriving its parasites from these 51 species of
weevils and from other weevils which are not known to us, and
there is every reason to believe that some of these other 44 species
of parasites, or still additional ones to be discovered, may be drawn
over to the boll weevil as parasites in the future. The weevils serv-
ing as cohosts and the parasites are listed in the accompanying table
(fig. 7) in such manner as to show the nature of the interrelationships.
It will be noticed from this table that 6 weevils, namely, Laria
sallzi, Laria exigua, Smicraulax tuberculatus, Anthonomus albopilosus,
Tyloderma foveolatum, and Trichobaris texana each have 4 of the
boll-weevil parasites; 4 weevils are attacked by 3 of the parasites,
15 of the weevils by 2 parasites each, and the remaining 37 by only 1
parasite each.
Of the parasites, Cerambycobius cyaniceps attacks 18 hosts, Hury-
toma tylodermatis attacks 16 hosts, Catolaccus incertus 14, Catolaccus
hunteri 13, and Microbracon mellitor 12. These 5 parasites are also
regarded as the most important parasites attacking the boll weevil
itself. Perhaps this importance is due to the fact that they have
a larger number of native hosts and are hence in greater abundance
around the cotton fields than the parasites having fewer native
hosts.
3. MITES WHICH ATTACK THE BOLL WEEVIL.
ACARINA. TARSONEMID.
The mites of the genus Pediculoides are assuming an important
réle among insect parasites, two species being accredited to the
boll weevil.
44 INSECT ENEMIES OF THE BOLL WEEVIL.
Pediculoides ventricosus Newport (fig. 8). This mite has been
somewhat prominent in the study of the boll weevil since its first
notice in 1901 (Rangel, 1901) under the name of Pediculoides ven-
THE BOLL WEEVIL COMPLEX.
THE COTTON PLANT
/
THESE MUMEROUS ENEMIES A,
ARE KNOWN TO ATTACK AT LEAST. WEEVILS
WHICH ATTACK
o/
OTHER
SPECIES
OF
PLANTS
HVPER-
PARASITES
WITH
OTHER
FARASITES|
Fic. 6.—Diagram illustrating the boll-weevil complex. (Original.)
triculosus. Mr. Banks has stated that it may possibly be different
from the European species, but as it is known throughout this
country under the above name it is so quoted here. Mr. Rangel
45
PARASITES OF WEEVIL AND OTHER HOSTS.
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. 2222 2-2- 168 rosigalphus anthonomi.............-.-- 1
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Sigalphusicurciwlionis.~ 2.22 2o--22- Sani S7sll| Perilgmpus Sep. teod-2- 254 - o- ese o nae 1
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A study of the value of these parasites by years has shown that
the majority of the species had not occupied the same rank in two
successive years. The accompanying diagram (fig. 13), giving the
yearly rank of the boll-weevil parasites from 1906 through 1909,
shows that in each year new parasites were recorded and that in some
cases these parasites continued to attack the weevil. Microbracon
mellitor appears to vary but little in importance in different seasons,
while Catolaccus hunteri shows increasing importance year by year.
Some of the other parasites of considerable importance appear extremely
variable in their relative rank. It will be noticed that Habrocytus
piercei has occupied the ninth place three years in succession and
is now in eighth place. This parasite occurs in small numbers, but
may at any time become a leading parasite in Louisiana and Missis-
sippi. In addition to giving the yearly rank of the species this
diagram also shows the proportion of the sexes observed each year.
62 INSECT ENEMIES OF THE BOLL WEEVIL.
In order to show the regions in which the various species are of
greatest importance, the accompanying map (fig. 14) is presented.
This shows that while Microbracon mellitor has yielded more individuals
than the other species, it is the predominating parasite in by far the
larger proportion of the infested territory. It can also be seen that
much more can be expected from the other parasites as the weevil
moves eastward into their territory. Microdontomerus anthonomi is
quite important throughout the central black-prairie region of Texas.
Eurytoma tylodermatis is more important in north-central Texas and
also in the coast region of Texas. Cerambycobius cushmani is charac-
1906 1907 1908 1909
BRACON MELLITOR ESRACON MELLITOR BRACON MELLITOR CATOLACCUS HUNTER!
eal > ST PE < SE A Be
CERAMBYCOBIUS CYANICEPS EURYTOMA TYLODERMATIS CATOLACCUS INCERTUS CERAMBYCOBIUS CYANICEPS
| & [> <(2e9 se s> << a OR FE ie
CATOLACCUS HUNTER! \ MICRODONTOMERUS ANTHONONS CERAITBYCOBIUS CYANICEPS TETRASTIOWUS HUNTER]
erie [> <( ss ae
LURYTONMA TYLODERMAT/S \ censncs arvners \ TETRASTICHUS HUNTER! CATOLACCUS INCERTUS
ist’ AKL? Le DV >
CERAMBYCOBIUS CUSHMANT CATOLACCUS INCERTUS EURYTOMA TYLODERITATIS MICRODONTOMIERUS ANTHONOLA
ei | «[>
UROSIGALPHUS ANTHONOM, EURYTOMA SP \) UCRODONTOMERUS ANTHONOIY PIMPLA SP.
J
ENNYOMMA GLOBOSA CERAMEBEYCOGIS CUSHIMANS UROSIGALFHUS SP.
PERILAMPUS SP. MYIOPHASIA _AENEA CERAMBYCOBIUS SP
ci
SPHOCHALCIS SR.
c
LARIOPHAGUS TEXANUS
Fic. 13.—Diagram illustrating yearly rank of the boll weevil parasites, 1906, 1907, 1908, and 1909.
(Original.)
teristic of the counties grouped around Victoria County, Tex., but a
few specimens have been reared from the boll weevil at Alexandria,
La., by Messrs. Cushman and Jones.
9. THE PARASITE SEASONS.
For the convenience of this work on parasites of the boll weevil,
the year has been divided into definite parasite seasons correspond-
ing with certain groups of conditions. The year opens with the
hibernation period well underway. In so far as the parasites are
concerned those which hibernate as immature insects mature gen-
erally about the middle of March. This marks the end of the hiber-
THE PARASITE SEASONS. 63
nation period or winter season and the opening of the spring season.
From March until the middle of June or sometimes July there are no
cotton squares for the weevils to breed in. Consequently the para-
sites are obliged to seek other hosts. The swmmer season is defined
as beginning with the production of squares in which the weevils and
their parasites may breed. Thus this season continues until squar-
ing ceases—that is, until late in the fall when cotton is killed by frost
and is succeeded by the winter season. However, we frequently dis-
tinguished a fall or postmigration season, which begins with the first
Petlanerea av,
yO pre Pn
teaterettdtaterss 7ianne
g va \ z
elena
ti
:
aa
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be TONY
i
OF
l= CATOLACCUS /NCERTUS..
2=JETRASTICHUS HUNTER.
Fic. 14.—Map showing the distribution of the more important parasites of the boll weevil. (Original.)
attack of weevils upon the bolls in August and ends with the heavy
frosts in October or November. The fall season is also character-
ized by a renewed growth of squares.
I. THE HIBERNATION OR WINTER SEASON.
The most important parasites which winter as immature stages
upon the boll weevil are Microbracon mellitor, Catolaccus hunteri, Ceram-
bycobius cyaniceps, EHurytoma tylodermatis, Tetrastichus hunteri, and
Habrocytus piercer. The last two species are characteristic of
Winter examinations in Louisiana and Mississippi. The predatory
64 INSECT ENEMIES OF THE BOLL WEEVIL.
coleopterous larvee Hydnocera pubescens LeConte and H. pallipennis
Say are very frequently found hibernating as larve in the boll-
weevil cells or in the cocoons of Microbracon mellitor. The stage in
which these various parasites pass the winter is given very concisely
in the table of the developmental periods (Table XX) in section 7.
During January, 1910, Mr. Hood repeatedly found Eurytoma tylo-
dermatis and Catolaccus huntera hibernating in dry cotton squares
and bolls and especially in hanging moss at Mansura, La.
II. THE SPRING SEASON.
It has been demonstrated that there is a definite period between
the hibernation season and the first infestation of squares, extending
from the middle of March to the middle of June. What happens to
the parasites during this period is of considerable importance and a
great amount of work has been done in the search for intermediate
hosts.
In the case of Catolaccus hunteri the question was very satisfac-
torily answered. At Richmond, Tex., a large number of dewberry
buds infested by Anthonomus signatus was gathered March 21, 1907,
and this species of parasite was reared continuously between March
28 and Aprill. At Victoria, Tex., Mr. J. D. Mitchell collected, on April
23, 1907, a lot of haws (Cratxgus mollis), infested by Tachypterellus
quadrigibbus, and on May 7 he reared this species of parasite. In-
vestigations as to the distribution of these weevils added to the
formerly known records of Anthonomus signatus in dewberry buds:
Natchitoches and Shreveport, La.; Texarkana, Ark.; Muskogee and
Ardmore, Okla.; and Trinity, Richmond, Waco, Dallas, and Mar-
shall, Tex. Tachypterellus quadrigibbus was found breeding at
Shreveport and Natchitoches, La., and Victoria, Tex.
At Dallas, Tex., the buds of Galpinsia hartwegi were found to be
infested by Auleutes tenuipes as early as April 24. This species is a
host of several species of Catolaccus. The buds of Callirrhoe involu-
crata were found at Dallas to be infested by Anthonomus fulvus as
early as April 1, and on the same date Anthonomus zneolus was first
observed to be breeding in the buds of Solanum torreyi. Solanum
elzagnifolium, with Anthonomus xneolus both in its buds and in the
fungus leaf-galls, and Solanum rostratum with this weevil in the buds,
appeared early in April. All of these plants continued susceptible to
weevil work up to the end of the spring period, or until cotton began
to square. Numerous specimens of Catolaccus were reared from the
Solanum-infesting species of Anthonomus.
Myiophasia «nea was reared April 11, 1907, from Conotrachelus
elegans in galls of Phyllozera devastatriz on the petioles of Hicoria
THE PARASITE SEASONS. 65
pecan, collected April 2, 1907, at Victoria, Tex., and was reared June
5, 1907, from material collected May 4 at Dallas.
Sigalphus curculionis was reared in considerable numbers between
April 28 and May 7, 1907, from Conotrachelus nenuphar in plums
gathered at Texarkana, Ark., March 26; and between April 29 and
May 17, 1907, from Conotrachelus elegans in galls of Phylloxera devas-
tatrix on pecan, collected at Victoria, Tex., April 2; also between June
5 and 14, 1907, from the same species in material collected at Dallas,
Tex., May 4.
Cerambycobius cyaniceps was studied very carefully at Victoria,
Tex., by Mr. J. D. Mitchell during the winter of 1909-10 as an
enemy of T'richobaris texana in stems of Solanum rostratum, and of
Lizus scrobicollis in stems of Ambrosia trifida. Mr. T. T. Holloway
conducted experiments in longevity by feeding sugared water to the
parasites. Emergence began, in the lots of Trichobaris, on February
1 and continued until April 8. The last parasite lived until May 31.
The total period of activity was 119 days and the average period
lasted from March 11 to April 1. The longest record of longevity
was 71 days and the average 21 days. Emergence began from the
lots of Lixus on March 2 and continued until March 24. The last
parasite lived until May 11. The total period of activity was 70
days and the average period was between March 13 and April 4.
The longest record of longevity was 67 days and the average 22.
Eurytoma tylodermatis was reared from the same lots and treated
in the same manner. Emergence began from the lots of Trichobaris
on February 3 and continued until March 21. The last parasite
lived until April 30. The total period of activity was 86 days and
the average period was between March 10 and March 30. The longest
record of longevity was 42 days, and the average 20 days. Emergence
began from the lots of Lixus on February 22 and lasted until April 17.
The last parasite lived until June 1. The total period of activity
was 99 days and the average period lasted from March 16 to April 11.
The longest record of longevity was 79 days and the average 26 days.
Ill. THE SUMMER SEASON.
The first boll-weevil parasites of the year are reared late in May or
early in June in southern Texas, but in a very short time squares are
forming all over the entire cotton belt and parasites may be found
everywhere in small numbers as the summer progresses. The per-
centage of parasitism increases rapidly and generally becomes very
high after August 1. Most of the important parasites may also be
found on their normal summer hosts.
16844°—Bull. 100—12——5
66 INSECT ENEMIES OF THE BOLL WEEVIL.
About the middle of August squares commence to fail, and few
squares are to be found by September 1. This condition may be
said to begin the fall season, when the parasites are largely obliged
to seek other hosts or to attack the boll weevil in bolls.
IV. THE FALL OR DISPERSION SEASON.
Coincident with the decline in square production is the beginning
of the boll-weevil dispersion which extends into new territory around
the entire periphery of the infested region. In the fall there is a new
growth of squares which furnishes food for the weevils before entering
hibernation and also furnishes an opportunity for very high parasitism
just preceding hibernation. It is during this season that parasite
swarms are recorded and hence this is a very critical time for obtaining
and transferring desirable parasites to new regions. During this early
fall season there are several very important ways of propagating the
parasites already present in the vicinity, as will be shown later. The
fall season of the year closes abruptly with the first killing frost, for
this crisis precipitates the hibernation period.
10. ADJUSTMENT TO NEW HOSTS.
It is a very striking fact that the continuously breeding boll
weevil is attacked by parasites which in many instances attack nor-
mally weevils having but a single generation annually. Some of these
parasites attack one host after another throughout the entire breeding
season and may be found in activity at all periods except during
hibernation. This condition is well illustrated by the accompanying
diagram (fig. 15) giving the seasonal rotation of Catolaccus huntert
“ay Cerambycobwus ¢ yanceps. Whether these parasites were origi-
nally single-generation species like their hosts is a question we can not
now decide, but we now know that they have become adapted to
many species. This fact can be most easily proven by reference to
the list of hosts of the boll-weevil parasites given in the second section
of this part (p. 42): It appears possible that the constantly changing
factors of nature cause the various species to be continually adjusting
their habits to new environments and new hosts. In other words, the
groups of parasites from which the most available enemies of a new or
introduced species may be obtained are those groups in which the
parasitic habits are the most variable. A parasitic species that is as
readily at home on a stem weevil as on a bud or seed weevil is probably
able to attack many different species.
The most striking example of the adjustment of new parasites was
furnished in 1907. A lot of hanging squares collected by Mr. J. D.
Mitchell on August 5, 1907, at Victoria, Tex., on a field known as the
Haskell field gave a percentage of 61.5. There was something so
ADJUSTMENT TO NEW HOSTS. 67
striking about the nature of the record that Mr. Cushman was sent
immediately to Victoria to study the surroundings of this field and
report upon the possible reasons for the high percentage of parasitism.
Mr. Cushman reported after considerable study that there were
only two factors which, it seemed to him, might have an influence
upon the parasites of the boll weevil. The first factor was the com-
plete lack of fruit upon the huisache trees (Vachellia farnesiana)
which is the normal food of Laria sallxi. The second factor noticed
was the absence of flowers on the Callirrhoe involucrata, the host of
Anthonomus fulvus. Mr. Cushman reasoned that the point would be
proven if we should rear from the boll weevil some of the character-
istic parasites of either this or the other species. As a result of
rearings from the material collected in this field, the principal par-
asite was Microbracon mellitor, the typical boll weevil parasite, but a
SEASONAL ROTATION OF HOSTS BY CATOLACCUS. HUNTER! CRAWFORD.
[WANGARY FEBRUARY] MARCH | APRIL | May | JUNE | JULY | AUGUST |SEPTEMBER| OCTOBER WOVEMBER DECEMBER
cle
Aw7HONOMUS AENEOLUS BO, EM AN
HERELLUS_QUADRIGIEB | cen
: er arn | Bons, Av
se iS Is ateorilosus lasus Die
as eae PIERCE
| S04 PAULAX TU PERCULATUS p PIERCE
feerdesne a co a cal pal
Fan? Vrwonvont bes iS rien ae
Aan ar
hei ee EXANVA Bide bos
* [axus sdeosicouils Bovendy
eee
aS ee Zee Sled ET ES
Fic. 15.—Diagram illustrating the seasonal rotation of hosts of ai hunteri and Cerambycobius
cyaniceps. (Original.)
species which 1s also a typical parasite of Anthonomus fulvus. It
is probable that the latter species furnished some of the Micro-
bracons for this infestation. The next most important species was
Cerambycobius cushmam, a typical parasite of Laria sallei and of
Arezcerus fasciculatus which breeds in the fruit of the chinaberry tree
(Melia azederach). In addition to this species, this same field yielded
3 other new parasites of the boll weevil, 2 of which are known to
be parasites of the Laria. These were Lurytoma sp., Spilochalcis sp.,
and Lariophagus texanus.
To illustrate the divergence of habits among parasites the host
relations of Catolaccus incertus may be cited. This parasite attacks
several species of Laria (Bruchus) which are internal seed eaters and
pupate in their feeding cells; such weevils as Zygobaris xanthoryli and
Auleutes tenuipes, which are seed or bud feeders and pupate in the
68 INSECT ENEMIES OF THE BOLL WEEVIL.
ground; and Anthonomines, which dwell in buds (Anthonomus gran-
dis), in flowers (A. aphanostephi), and in hard seed (A. albopilosus).
But it draws the line apparently at stem dwellers and is replaced by
Neocatolaccus tyloderme on Lixus, Tyloderma, and Ampeloglypter.
Cerambycobius cyaniceps is as much at home in a stem as in a bud,
and so also are Eurytoma tylodermatis and Microdontomerus anthonomt.
The Braconide appear to be more particular as to food but the most
noted of all, Microbracon mellitor, has no preferences between stem
dwellers and bud dwellers.
Thirteen miles southeast of Yazoo City, Miss., on November 1, 1909,
the senior author found an isolated artificial focus of infestation by
the boll weevil over 30 miles from any infestation of the same age
and 20 miles beyond the regularly infested region. Out of 8 squares
picked, containing 5 stages, 1 parastized stage was found.
11. BEETLES WHICH PREY UPON THE BOLL WEEVIL.
The attack of the insects predatory on the adult boll weevil is purely
accidental. They maybe very numerous, but the only ones recorded
and verified are Evarthrus sodalis Le Conte and another species of the
same genus. There are, however, several insects which have an actual
value through their established habit of either breeding in the square
upon the boll-weevil stages or of entering the square and consuming
the weevil. We shall refer to four of them.
Hydnocera pallipennis Say. A single beetle of this species was
reared April 6, 1907, after 183 days in its cocoon, and over 214 days
isolation in the rearing tube. It was collected in a boll-weevil cell at
Waco, Tex., August 28, 1906. The cocoon is very finely threaded,
loosely woven, and only single layered. The stage of the beetle can
easily be observed at any time.
Hydnocera pubescens Le Conte. This clerid is a very common
breeder in the weevil cells. Its larve have been found not only
feeding upon the various weevil stages but have been taken frequently
from Microbracon cocoons which they have entered at a much
younger stage.
Cathartus gemellatus Duval. This cucujid beetle is both a predator
and a scavenger, its larve being frequently found, however, feeding
upon boll-weevil stages which they must have killed.
Chauliognathus spp. The larve of these lampyrid beetles are very
common in the squares and bolls of cotton in Louisiana and Missis-
sippi. In one instance undoubted proof of the attack of such a larva
upon one boll-weeyil larva was recorded. Many other very sus-
picious observations were made but no definite proofs found.
ANTS WHICH PREY UPON THE WEEVIL. 69
12. LEPIDOPTEROUS LARV WHICH ARE INCIDENTALLY PREDATORY
UPON THE BOLL WEEVIL.
Alabama argillacea Hiibner. The cotton leaf caterpillar is distinctly
an enemy of the boll weevil and of considerable importance. When
it defoliates a cotton field a month or more before the frosts it often
destroys immature weevils in the cotton squares and cuts off the entire
food supply of the adult weevils remaining. These weevils may be
able to suspend their activities and begin hibernation but it is well
known that weevils entering hibernation early in the fall can seldom
survive a long hard winter, or live until cotton is up in the spring.
Those that can not hibernate either die of starvation or rise in flight
to seek cotton elsewhere and may perish in the effort. It is presumed
that a very high percentage of flying weevils fails to find cotton.
The leaf worm is attacked by 18 predatory bugs, 16 predatory
beetles, 6 predatory wasps, and the following ants: Dorymyrmex
pyramicus flavus McCook, Forélius maccooki Emery, Solenopsis
geminata Fabricius (these three ants are enemies of the boll weevil)
and Monomorium carbonarium Smith. Ten hymenopterous parasites
and one hyperparasite are known, and in addition the leaf worm is
attacked by a predatory fly and by two parasitic flies.
13. ANTS WHICH PREY UPON THE BOLL WEEVIL.
HYMENOPTERA. DORYLIDA.
Eciton (Acamatus) commutatum Emery. This ant was taken by
Mr. C. R. Jones at Beeville, Tex., attacking the boll-weevil larve in
squares. Dr. W. M. Wheeler states that it is commonly parasitized
by a round worm of the genus Mermis.
PONERIDZX.
Ectatomma tuberculatum Olivier. The ‘‘kelep,” or so-called Guate-
malan ant, is a native of Mexico and Central America.” Like all other
ponerids it is slow in action. The winters have proven too severe
for any of the imported colonies. The rate of development is so
slow and the movements of the adults are so sluggish that little
could be hoped for from this species even if it could become accli-
mated in this country.
MYRMICIDA.
Cremastogaster lineolata (Say) var. clara Mayr. This ant is also an
enemy of the boll weevil, having been recorded attacking immature
stages at Dallas, Tex., by Dr. W. E. Hinds. It has frequently been
seen in the rearing cage carrying off insect prey. The species lives
70 INSECT ENEMIES OF THE BOLL WEEVIL.
in hollow stems, sticks, and galls and is commonly seen at the necta-
ries of cotton or attending aphides, membracids, etc. Prof. F. E.
Brooks has recorded this ant as an enemy of Heliothis obsoleta, the
cotton bollworm.
Solenopsis geminata Fabricius. The “fire ant” (fig. 16) is very
common in Texas cotton fields, where it is always an enemy of the
boll weevil, as well as of the cotton bollworm (Heliothis obsoleta)
and the cotton leaf worm (Alabama argillacea). In Louisiana,
Arkansas, and Mississippi it is very seldom seen in cotton fields,
except in southern Louisiana, where unfortunately it is in danger of
extermination by the Argentine ant, Iridomyrmex humilis Mayr.
This species divides credit for the greater part of the ant control of
the boll weevil with the other species of Solenopsis, two species of
Monomorium, and with the various spe-
cies of Pheidole. Its nests are placed in
the cotton fields, generally near the base
of the plants, and from these the foragers
go out in all directions in search of food.
The workers have learned to detect the
presence of the boll weevil in the squares
and in a short time can effect an entrance
into the weevil cell from which they either
draw the weevil bodily or convey it in
parts to their nests. This ant is some-
times found on the plant, but most com-
monly it does its work on the ground.
The species is parasitized by (Pseudac-
Fic. 16.—The “fire ant” (Solenopsis eon) Plastophora crawfordi Coquillett at
geminata), an enemy of the boll Dallas, ex.
LA hata all Meal rere Solenopsis molesta Say (debilis Mayr).
3 This minute ant was taken in the act of
attacking a boll-weevil larva by Mr. Cushman at McAlester, Okla.
This species and the next are so similar in appearance that they
may be easily confused. Prof. F. E. Brooks has recorded it as an
enemy of Craponius inequalis.
Solenopsis texcana Emery. This minute ant is a common enemy
of the boll weevil in Texas, Louisiana, and Mississippi. The entrance
holes are very minute, but sometimes the ants enter the squares in
great numbers. On October 31, 1907, at Thornton, Tex., Mr.
Cushman found 85 individuals attacking a weevil larva in a single
square. It is mentioned in the investigation records as attacking
the weevil at Alexandria and Monroe, La., and Cuero, Lampasas, and
Llano, Tex. It is also recorded as an enemy of Heliothis obsoleta.
Monomorium minimum Buckley. This common house ant (fig. 17)
is a very valuable enemy of the boll weevil and is common in cotton
ANTS WHICH PREY UPON THE WEEVIL. VL
fields. It is recorded in the Dallas collection as attacking the boll
weevil at Llano, Lampasas, Albany, Henrietta, Arlington, and Dallas,
Tex., Ruston, La., and Roxie and Port Gibson, Miss. The species
has been taken attacking the immature stages of T’richobaris com-
pacta, Anthonomus albopilosus, and Anthonomus fulvus. It generally
attacks these weevils as well as the boll weevil on the plant, entering
the infested bud or square in search of its food.
Monomorium pharaonis L. This cosmopolitan house ant (fig. 18)
is another of the most important boll-weevil enemies, being very
Fic. 17.—The little black ant (Monomorium minimum), an enemy of the boll weevil: a, Fe-
male; 6,same with wings; c, male; d, workers; e, pupa; jf, larva; g, egg of worker.
Enlarged. (From Marlatt.)
abundant in the cotton fields of certain sections. It is represented
in the Dallas collection as attacking the boll weevil at Victoria, Tex.;
Fosters, Ruston, and Monroe, La., and Camden, Ark. It also
attacks the weevil on the plant. In southern Louisiana it is being
exterminated by the Argentine ant (/ridomyrmex humilis).
Pheidole sp., near flavens. At Arlington, Tex., August 31, 1908,
Mr. Cushman found abundant evidence of the control of the boll
weevil by this species. It attacks the weevil larve both on the
plant and on the ground.
72 INSECT ENEMIES OF THE BOLL WEEVIL.
Pheidole crassicornis Emery. At Lampasas, Tex., September 23,
1908, Mr. Cushman found this ant a very abundant enemy of the
boll weevil.
DOLICHODERIDA,
Forelius maccooki Forel. At Beeville, Tex., August 13, 1906, Mr.
C. R. Jones found a high mortality of the boll weevil due to this
species. Dr. Wheeler has recorded the fact that this ant prefers
bare, dry ground for its nests. The species also attacks Alabama
argillacea and Heliothis obsoleta. On September 7, 1908, at Dallas,
Tex., Mr. F. C. Bishopp took specimens in the act of attack, and
September 21, 1908, Mr. Cushman took others at Llano, Tex., attack-
ing the weevil.
Dorymyrmex pyramicus Roger, the ‘‘lion ant,” protects solitary
tree cotton from the boll weevil in Cuba (Schwarz, 1905).
Fig. 18.—The little red ant (Monomorium pharaonis), an enemy of the boll weevil:
a, Female; b, worker. Enlarged. (From Riley.)
Dorymyrmexz pyramicus (Roger) var. flavus McCook. This com-
mon ant of the cotton fields has only once been taken as an enemy
of the boll weevil, namely at Texarkana, Tex., by Mr. R. C. Howell,
but its abundance would make it a very important species if it
should develop a fondness for weevil larve. It is an enemy of
Alabama argillacea and Heliothis obsoleta.
Iridomyrmex analis André. Specimens of this ant were found
attacking the boll weevil by Dr. W. E. Hinds. This species is nor-
mally a honey ant, but occasionally takes insect food. It is very
common in cotton fields, especially in Louisiana.
Iridomyrmex humilis Mayr. The much-feared Argentine ant has
been taken attacking the boll weevil. It is, however, a friend to
the weevil because it exterminates Solenopsis geminata, Monomorvum
pharaonis, and Iridomyrmex analis (Foster, 1908).
BIOLOGY OF THE COHOSTS. 73
FORMICID,
Formica fusca (Linneeus) subpolita (Mayr) perpilosa Wheeler. This
species of ant is normally a honey feeder, but it is recorded by Rangel
(Rangel, 1901c) as a predator on adult boll weevils in Mexico.
Formica pallidi-fulva Latreille. A single instance of this species
cutting its way into a square infested by a boll weevil was: observed
by Mr. Hood at Ashdown, Ark., September 2, 1908.
Prenolepis imparis Say. A single instance of this species cutting
its way into a square infested by a boll weevil was observed by Mr.
Hood at Ashdown, Ark., September 2, 1908.
14. BIOLOGY OF THE COHOSTS OF THE BOLL-WEEVIL PARASITES.
The biologies of the parasites concerned in the boll-weevil complex
have already been discussed. It now remains to consider the native
weevils which have already or may later enter into the complex of
cohosts of the boll-weevil parasites. Many of these weevils are
native to the territory already occupied by the weevil, while others
will become important as new territory is added. Other families of
Coleoptera and even other orders of insects may later be found to be
of more or less importance as cohosts of boll-weevil parasites. The
late Dr. William H. Ashmead stated that Microbracon mellitor had
been reared from many Coleoptera, while Cerambycobius cyaniceps
bred in cerambycids and other beetles. It is important also to note
the record of Cerambycobius cyaniceps from Languria. Our own
observations have been confined to the Coleoptera of the families
Larude, Anthribide, and Curculionide.
PHYTOPHAGA. LARIIDA.
(Bruchus)' Laria sallei Sharp. This bruchid is characteristic of
the Gulf Coast prairie of Texas. It breeds in the pods of huisache
( Vachellia farnesiana), is a continuous breeder, and is generally highly
parasitized by Urosigalphus bruchi, Cerambycobius bruchivorus, Crr-
AMBYCOBIUS CYANICEPS”; CERAMBYCOBIUS CUSHMANI, LARIOPHAGUS
TEXANUS, EuRYTOMA TYLODERMATIS, Horismenus sp., and several
other undetermined parasites.
Laria exigua Horn. This bruchid is apparently Austroriparian and
Carolinian. Its principal food plant is Amorpha fruticosa, in the seed
1 The generic name Bruchus was first used by Geofiroy in 1762. Only one species is admissible in our
code of nomenclature and this is CerambyxfurLinneus, which is also the type of Ptinus Linnzus 1767,
The genus Laria was described by Scopoli in 1763 and the type thereof has been designated as salicis
Scopoli, a synonym of Dermestes pisotum (pisi) Linnzeus.
Linnzeus’s conception of Bruchus dates from 1767 and the type thereof was designated by Latreille
(1810) as Dermestes pisorum Linneus. Hence we see that Bruchus Linnzeus (1758) is preoccupied by
Geoffroy (1752) and an isogenotypic synonym of Laria Scopoli (1763).
Although the genus has been subdivided into several genera, our American species have not been
studied with regard to such subdivision and it is hence best to consider all as in the genus Laria,
sensu latiore.
2 The names of boll-weevil parasites are printed in small capitals; others in italics.
74. INSECT ENEMIES OF THE BOLL WEEVIL.
pods of which it breeds prolifically. It is a continuous breeder and
is highly parasitized by Cerambycobius brevicaudus, CERAMBYCOBIUS
cYANIcEPS, Horismenus sp., Heterospilus prosopidis, Eurytoma sp.,
MICRODONTOMERUS ANTHONOMI, CATOLACCUS INCERTUS, and several
other species.
Laria obtecta Say. 'The common bean weevil is known to be para-
sitized by CERAMBYCOBIUS CYANICEPS and Bruchobius laticollis.
Laria compressicornis Schaeffer. This bruchid, which breeds in
the pods of Acuan illinoensis, is parasitized by CERAMBYCOBIUS CY-
ANICEPS and Heterospilus prosopidis.
Laria ochracea Schaeffer. This bruchid, which breeds in the pods
of Vicia sp., is parasitized by CERAMBYCOBIUS CYANICEPS, C. CUSH-
MANI, Eurytoma sp., and Heterospilus prosopidis.
Spermophagus robinize Schaeffer. This bruchid is very common in
the pods of the honey locust (Gleditsia triacanthos), and the water
locust (Gleditsia aquatica), both of which are trees belonging to the
humid Austral zones. It is parasitized by Heterospilus bruchi, Crr-
AMBYCOBIUS CYANICEPS, HURYTOMA TYLODERMATIS, and Urosigalphus
bruchi.
RHYNCHOPHORA. ANTHRIBIDZ.
Brachytarsus alternatus Say. This beetle probably breeds under
many different circumstances. The only records are from a fungus
gall on Ipomea pandurata, and from the stems of Elymus virginicus
and Sideranthus rubiginosus. It apparently belongs to the humid
Austral zones. It is parasitized by MicRoDONTOMERUS ANTHONOMI
and a Bracon.
Arexcerus fasciculatus DeGeer. This very widely distributed
Lower Austral insect (see fig. 19), known commonly as the coffee-
bean weevil,
breeds in stored
vegetable prod-
ucts, in the seed
of Theobroma
cacao, in the
berry of the coffee
tree (Coffea ara-
boca), in diseased
cotton bolls, in
seed pods of
Cassia _ occident-
Fia. 19.—The coffee-bean weevil (Arzcerus fasciculatus), a cohost of boll- :
weevil parasites: a, Larva; b, adult; c, pupa. Enlarged. (From Chit qlig and C. ob-
hi ae ate:
enden.) tusifolia, in seeds
of Indigofera tinctoria, in green and decaying fruit of Melia azedarach,
in green and dry cornstalks, and in dry acarian galls on Jpomea
BIOLOGY OF THE COHOSTS. 75
lacunosa. In the Melia berries it is parasitized by CeramBycosius
CUSHMANI, EURYTOMA TYLODERMATIS, and PEDICULOIDES sp.
CURCULIONIDA. APIONINAS.
Apion segnipes Say in Cracca virginiana is parasitized by Eury-
TOMA TYLODERMATIS.
Apion decoloratum Smith. Dr. Chittenden records this weevil as
breeding in Meibomia paniculata and parasitized by CaroLaccus
INCERTUS.
Apion griseum Smith. Dr. Chittenden records this weevil as
breeding in Phaseolus retusus, P. wrightti, P. polystachyus, and
Strophostyles pauciflora, and parasitized by CATOLACCUS INCERTUS.
Apion nigrum Smith. Breeds in buds of Robinia pseudacacia and
is parasitized by CaTOLACCUS INCERTUS.
Apion rostrum Say in pods of Baptisia is parasitized by CERAMBY-
COBIUS CYANICEPS.
CLEONIN:.
Tizus musculus Say. This weevil is known both from the Lower
Sonoran and Austroriparian zones. It breeds in the stems of Poly-
gonum pennsylvanicum, P. portoricense, and P.
punctatum, making an oblong gall or swelling.
It is parasitized by EuRYTOMA TYLODERMATIS,
CERAMBYCOBIUS CYANICEPS, Neocatolaccus
tyloderme, Glyptomorpha rugator, G: novitus,
and Horismenus lixworus.
Lizus scrobicollis Boheman. This weevil (fig.
20) is probably confined mainly to the moist
Austral zones. It breeds abundantly in the
stems of Ambrosia trifida, A. artemisizfolia,
A. psilostachya, and Helianthus spp. It is
quite highly parasitized by Ptinobius magnijicus,
rs hn acral EURYTOMA TYLODERMATIS, CERAMBYCOBIUS
cohost of boll-weevil para- CYANICEPS, Glyptomorpha rugator, G.mavaritus,
ea ee (From G. lixi, Vipio belfragei, Microdus simillimus,
and Horismenus lixivorus. Mr. Townsend has
described Lizophaga parva from a specimen reared from this weevil
at Dallas, Tex., August 15, 1907.
ERIRRHININ&.
' Smicronyzx tychoides LeConte. This weevil breeds in stem galls of
various species of Cuscuta. It is parasitized by MicROBRACON MEL-
LitoR and Lutrichosoma albipes.
76 INSECT ENEMIES OF THE BOLL WEEVIL.
Desmoris scapalis LeConte. This weevil (fig. 21) occurs mainly
on the black prairie in Texas and breeds in the heads of Sideranthus
rubiginosus. It is parasitized by MicROBRACON MELLITOR.
ANTHONOMINA.
Macrorhoptus spheralciz Pierce. This weevil was found breeding
in stems of Spheralcea angustifolia. It is the host of Kuryroma
TYLODERMATIS.
Tachypterellus quadrigibbus Say. This fruit weevil breeds in the
seed of apple, pear, Crategus oxyacantha, and Crategus mollis. It is
known to us to be parasitized by CrERAMBYCOBIUS CYANICEPS and
CaTOLACCUS HUNTERI.
Smicraulax tuberculatus Pierce. This species breeds in the stems
of mistletoe (Phoradendron flavescens) throughout Texas, and evi-
dence of its work has been observed in Louisiana and Mississippi. It
is parasitized by EURYTOMA TYLO-
DERMATIS, CERAMBYCOBIUS CYANI-
CEPS, CATOLACCUS HUNTERI, and
MICROBRACON MELLITOR.
Anthonomus fulvus LeConte.
This weevil breeds in the larger
buds of Callirrhoe involucrata and
C. digitata. It is a characteristic
woodland and meadow insect in
Oklahomaand Texas. Theknown
parasites are CATOLACCUS INCER-
Fig. 21.—The ironweed weevil (Desmoris sca. TUS and MICROBRACON MELLITOR.
palis), a cohost of boll-weevil parasites. .En- i
larged. (From Hunter and Hinds.) Anthonom us signatus Say. The
strawberry weevil is mainly char-
acteristic of the humid A abel zones, and it breeds in the buds of
strawberry, blackberry, dewberry, raspberry, Rubus villosus, Poten-
tilla canadensis, and Cercis canadensis. It is parasitized by Micro-
bracon anthonomi, Calyptus tibiator, CATOLACCUS HUNTERI, C. INCER-
Tus, and C. anthonomi. The two latter species were described from
this weevil.
Anthonomus albopilosus Dietz. This little Texas weevil breeds in
the capsules of Croton capitatus, C. engelmanni, and C. texense. It
is known to us to be parasitized by MicRoBRACON MELLITOR, CaATO-
LACCUS HUNTERI, C. INCERTUS, and CERAMBYCOBIUS CYANICEPS.
Anthonomus nigrinus Boheman. ‘This species is eastern in habitat
and breeds in the buds of Solanum carolinense, and the potato (S.
tuberosum). It is the host of Entedon lithocolletidis, Eriglyptus
robustus, CATOLACCUS INCERTUS, and C. anthonomi.
BIOLOGY OF THE COHOSTS. 77
Anthonomus xneolus Dietz. This Texas weevil breeds commonly
in fungus galls on the leaves and in the buds of Solanum eleagnifolium
and S. torreyi and also in the buds of S. rostratum. It is parasitized
by CaToLacous HUNTERI and a Eurytoma.
Anthonomus eugenii Cano (xneotinctus Champion). The pepper
weevil (fig. 22) breeds in most of the cultivated and wild peppers
and may be considered a serious pest. It is parasitized by CaToLac-
CUS HUNTERI, MICROBRACON MELLITOR, and PEDICULOIDES VENTRI-
COSUS.
Anthonomus squamosus LeConte. This is a weevil typical of the
gypsum prairie of the Lower Sonoran Zone, although occurring less
abundantly in the western edge of the moist Austral zones. It
breeds in the flower heads of Grindelia squarrosa nuda, G. inuloides,
and perhaps also on other Grindelias and Helianthi. It is known
to us to be parasitized by MicroBracon
MELLITOR, CATOLACCUS HUNTERI, and EKury-
TOMA TYLODERMATIS.
Anthonomus nebulosus LeConte. This wee-
vil breeds in the buds of Cratzgus in Louisi-
ana and Arkansas. It is parasitized by Cato-
LACCUS HUNTERI and Sigalphus sp.
Anthonomus heterothece Pierce. This small
weevil breeds in the flower heads of Hetero-
theca subaxillaris and probably other asteroid
flowers. It is parasitized by CatToLaccus
HUNTERI and HKURYTOMA TYLODERMATIS. Fic. 22.—The pepper weevil
Previous records by the senior author on ee ee eee toe Bm
Anthonomus disjunctus LeConte all refer to larged. (From Hunter and
this weevil. ee
Anthonomus aphanostephi Pierce. This weevil breeds in the heads
of Aphanostephus skirrobasis, and is parasitized by CaToLaccus
INCERTUS.
TYCHIINA.
Tychius sordidus LeConte. This Austroriparian weevil breeds in
the pods of Baptisia bracteata and B. leucantha. It is parasitized
by CERAMBYCOBIUS CYANICEPS.
CRYPTORHYNCHIN.
Chalcodermus zneus Boheman, the common cowpea weevil (fig. 23),
is abundantly parasitized by ENNyomMMA GLogosa, and is likewise a
host of Ennyomma clistoides and SIGALPHUS CURCULIONIS.
Conotrachelus affinis Boheman. This weevil breeds in hickory nuts
and is parasitized by My1opHasiA NEA and SIGALPHUS CURCULIONIS.
78 INSECT ENEMIES OF THE BOLL WEEVIL.
Contrachelus juglandis LeConte. This is the walnut weevil, which
is also parasitized by My1lopHasia #NEA, Cholomyia 4 saa Meta-
dexia basalis, and SIGALPHUS CURCULIONIS.
Coates elegans Say. This weevil breeds abundantly in
the petioles of hickory, the galls of Phyllozera devastatriz on pecan,
in pecan nuts, in leaf
rolls on hickory, and
finally in the roots
of Amaranthus retro-
flecus. It is fre-
quently parasitized
by MYIoPHASIA ENEA
and SIGALPHUS CUR-
CULIONIS, and occa-
sionally by Cholomyia
imequipes.
Conotrachelus nen-
uphar Herbst. The
common plum curculio (fig. 24) breeds in the pulp of drupes and
pomes. The larve are parasitized by Cholomyiva inzquipes, SIGAL-
PHUS CURCULIONIS, MICROBRACON MELLITOR, and Porizon conotracheli,
and the eggs by Anaphes conotracheli.
Conotrachelus naso Le-
Conte. The common
acorn weevil is para-
sitized by SIGALPHUS
CURCULIONIS.
Tyloderma foveolatum
Say. Thiscommon wee-
vil breeds prolifically in
the stems of Onagra bien-
mis and Epilobium. It
is highly parasitized by
Neocatolaccus tyloderme, Fic. 24.—The plum curculio (Conotrachelus nenuphar), a cohost
CERAMBYCOBIUS CYAN- of boll-weevil parasites: a, Larva; 6, adult; ec, pupa. Much
enlarged. (From Chittenden.)
ICEPS, EURYTOMA Ty-
LODERMATIS, MIcROBRACON MELLITOR, SIGALPHUS CURCULIONIS, and
Urosigalphus sp. nov.
Gersteckeria nobilis LeConte (Acalles). The common prickly-pear
weevil is parasitized by CaTOLAccUS HUNTERI and by several other
species.
Fic. 23.—The cowpea weevil (Chalcodermus xneus), a cohost of
boll-weevil parasites. Enlarged. (From Chittenden.)
BIOLOGY OF THE COHOSTS. 79
CEUTORHYNCHIN 4.
Auleutes tenuipes LeConte. This weevil breeds in the anthers of
buds of Galpinsia hartwegi on the Texas black prairie at least. It is
attacked by CaroLaccus rncEerTus, Microbracon sp., Eutrichosoma
albipes, and possibly by Catolaccus nigroxnea.
Craponius inxqualis Say. This weevil breeds in the fruit of the
grape. It is parasitized by Micropracon MELLITOR and Stiboscopus
brooks.
Rhinoncus pyrrhopus Boheman. This weevil breeds in the stems
of Polygonum and is parasitized by CERAMBYCOBIUS CYANICEPS.
Ceutorhynchus n. sp. This weevil breeds in the crown of Selena
aurea and is parasitized by CATOLACCUS INCERTUS.
BARIN 45.
Baris cuneipennis Casey. This weevil breeds in the roots of
Helenium tenuifolium and is parasitized by CaTOLACcUS INCERTUS.
Orthoris crotchii LeConte. This
Lower Sonoran weevil breeds in the
seed pods of Mentzelia nuda. It is
parasitized very highly by Microbracon
nuperus, EURYTOMA TYLODERMATIS,
and a species of Tetrastichus.
Trichobaris texana LeConte. This
species breeds very abundantly in
stems of Solanum rostratum, and is
hence more or less a Lower Austral
insect. Its parasites are CERAMBYCO-
BIUS CYANICEPS, EURYTOMA TYLODER-
MATIS, MICROBRACON sp., and SIGAL-
PHUS CURCULIONIS. Fic. 25.—The potato-stalk weevil ( Tricho-
Trichobaris trinotata Say. The po- baris trinotata), a cohost of boll-weevil
x é parasites: a, Beetle; b, larva from side;
tato stalk weevil (fig. 25) breeds in c, pupa; d, section of potato stalk opened
the stems of many Solanacex, includ- _—_ te show Jarva and pupa in situ. a, 2, ¢,
ita ii g ] Five times natural size; d, natural size.
ing Solanum carolinense, S. melongena (rom chittenden.)
(egg plant), S. rostratum, S. tuberosum
(potato), Datura stramonium, D. tatula, Physalis longifolia, P. philadel-
phica, P. lanceolata, P. heterophylla, and P. virginiana ambigua. It is
known to be parasitized by SiGALPHUS CURCULIONIS and EuRyYToMA
TYLODERMATIS.
Trichobaris compacta Casey. This weevil breeds in the pods of
Datura stramonium and is also recorded as breeding in Datura mete-
loides. It is parasitized by CeRAMBYCOBIUS CYANICEPS, MYIOPHASIA
ZNEA, and PEDICULOIDES VENTRICOSUS.
80 INSECT ENEMIES OF THE BOLL WEEVIL.
Ampeloglypter sesostris LeConte. The grapevine gall weevil is para-
sitized by MyropHasiA NEA, Neocatolaccus tylodermx, and Calyptus
tibiator.
Zygobaris xanthoryli Pierce. ‘This weevil is abundant in the berries
of Xanthoxylum clava-herculis. It is parasitized by CaToLaccus
HUNTERI and SIGALPHUS CURCULIONIS.
BALANININA.
Balaninus nasicus Say. This weevil breeds in acorns. It is para-
sitized by Myropuasrta “NEA and possibly by Trichacis rufipes.
CALANDRIN ZS.
Calandra oryza Linneus. The cosmopolitan rice and corn
weevil (fig. 26) breeds in acorns of several species of oak, in galls of
Phylloxera devastatrix on Hicoria pecan, in
old cotton bolls, and in all kinds of stand-
ing and stored grain. It is parasitized by
Meraporus calandre, M. vandinei, M. uti-
bilis, M. requisitus, and CaTOLACCUS IN-
cERTUS. Other parasites have been re-
ported abroad.
nee). A Gohet of bee. 1D» A LIST. OF THE HOST, PLANTS some
parasites. Enlarged. (From COHOST WEEVILS.
omen In order to show more plainly the num-_
ber and variety of plants whose presence around the cotton field,
if infested by their typical weevils, would influence the parasite
control of the boll weevil, the following list is presented, using the
classification of Britton (1901):
Plant. Infested by—
ELC SOLUOUATUR GWG) uate ee Calandra oryza J..
PEIAITTULLS RDN WILUGLUS eee ee ay ange ee Anthribus alternatus Say.
Zea mais (corn): {agers Jasciculatus DeG.
Ti: stated al abe ap =--"""|\ Calandra oryza L.
OPY2G SAUTE (TICE) 3, ageless saan 2 -| Calandra oryza. :
UL GTUSC TUG NG (nella eee ee Conotrachelus juglandis Lec. ~
EGON IG: SI. UICKOR) Se og2) es eae Sore ee Conotrachelus affinis Boh.
Hnconaialba (hiGkory)ersece ssh ase ae eee Conotrachelus elegans Say.
iceria pecan Mpecan ae 88 on ee oe Conotrachelus elegans.
Balaninus spp.
Onercus appa Lice eer es bees eee Conotrachelus naso Lec.
Calandra oryza L.
Phoradendrow flavescens=.-.---2---2--+4-+ 45 Smicraulax tuberculatus Pierce.
Polygonum pennsylvanicum.....--.-.------- Lixvus musculus Say.
IPO GOMUM A pOntoiiCenseene 2.68 a 4 eee Livus musculus.
Polygonum punctatum ES ere rer a.
Yd P RECN PCY SP aT eee Rhinoncus pyrrhopus Boh.
Amaranthus retroflexus. » 202 22 3-2 ~ see nse Conotrachelus elegans Say.
HOST PLANTS OF COHOST WEEVILS.
Plant. Infested by—
81
OT ORE EES OE ee ae ey te eae Ceutorhynchus sp.
Rubus villosus (blackberry)...............- Anthonomus signatus Say.
Rubus trivialis (dewberry)..........------- Anthonomus signatus.
Rubus occidentalis (raspberry). ....-.-.--.---- Anthonomus signatus.
Fragaria virginiana (strawberry)....-..----- Anthonomus signatus.
Potentilla canadensis... -+-+-+--2+---+ Anthonomus signatus.
EUS COMIRUNAS: (DORE) nn sierns nanan ingen lea =o Tachypterellus quadrigibbus Say.
Malus malus (apple) ...-.--- oS aga ees s 3 Tachy piereiiva HORTA RUG.
é . “ Tachypterellus quadrigibbus.
Crategus mollis (haw).......-.--+--++++++- (aac nebLIONe Lec.
Crateqts oryacantin. 2 .2-~-.5-<6 =2 5-5-4 > Tachypterellus quadrigibbus Say.
el Ae LT Et) ES ae Conotrachelus nenuphar Ubst.
Amygdalis persica (peach).......----------- Conotrachelus nenuphar.
Amygdalis persica (nectarine)......--..--.-- Conotrachelus nenuphar.
Amygdalis armeniaca (apricot)........-..-..- Conotrachelus nenuphar.
Vachellia farnesiana (huisache) .....--...-. (Bruchus) Laria salle Sharp.
Acuan illinoensts...........-..-.-----------| Larta bisignata Horn.
Strombocarpus (screw-bean)........------- Laria prosopis Lec.
Prosopis glandulosa (mesquite). ......----- Laria prosopis.
Cercis canadensis (redbud).......-.--.------- Anthonomus signatus Say.
Cassia obtusifolia.........-.-.------1-------| Arecerus fasciculatus DeG.
ANGE DCOUTETUES a a ain = Wawa ST ofc,» = Arexcerus fasciculatus.
Gleditsia aquatica (water locust)...........- Spermophagus robinix Schon.
Gleditsia triacanthos (locust).......---.----- Spermophagus robiniz.
Vigna unguiculata (cowpea). ....-.-------- Chalcodermus xneus Boh.
PPL OTECEUME s © Oo Ewa StS Se Tychius sordidus Lec.
PE CMCON Eo 2 a ca oe eatin 25 = Tychins sordidus.
RNS CITE on te a ue Ra 2c Apion rostrum Say.
FAUT DUG TRAED SE. 8a ras ae wim eee So Laria exigua Horn.
Tndiqgoleng HACIA. Sse ee see 2s =' - Arexcerus fasciculatus DeG.
Es 7 a ae a a a a Apion segnipes Say.
ALODUIUL PRCUMAOROA: <2 ~ em nese eee- Apion nigrum Sm.
A i a aie itis ae aels.< 5 ies Laria ochracea Schaeft.
Mabomia paniculata. ~ ....2. 202000252 -- Apion decoloratum Sm.
Phaseolus polystachyus.......-....=-..----- Apion griseum Sm.
PE ABPOLIERTOVUBUE 0 205 2 BEE 2 iS ee Apion griseum.
Pe IPCORIET WITGRING coals ee ae sks Se Apion griseum.
Phaseolus vulgaris (bean).........--.------- Chalcodermus xneus Boh.
PPMEITS WUGULIS ot = owe ee oe Se Laria obtecta Say.
Strophostylus pauciflora. ...-..------------ Apion griseum Sm.
Xanthorylum clava-hereulis.........---.----- Zygobaris xanthoxyli Pierce.
Melia azedarach (China tree)........-------- Arexcerus fasciculatus Dietz.
PNPM PRUNEUR Ss a2 oc nae cane a toe nga Anthonomus albopilosus Dietz.
Croton engeliniiitite: J 2.025) ns. cece Anthonomus albopilosus.
RE ae wig he Et iate ond See Sa Anthonomus albo plows.
“8 Ampeloglypter sesostris Lec.
Vatis spp. (grape)... ----<.-------+---s0r2se- facet Spiga Say.
OU ea eM Ly 0) 1: a. cn a a a ee Anthonomus fulvus Lec.
Callirrhoe involucraja......-.--.-----2------ Anthonomus fulvus.
Sphexralcea angustifolia..............-------- Macrorhoptus sphxralcix Pierce.
Anthonomus grandis Boh.
Arexcerus fasciculatus DeG.
Chaleodermus xneus Boh.
| Calandra oryza L.
Gossypium hirsutum (cotton)... ......-----
METRE TIN = enn we en ee eae Orthoris crotchii Lec.
Onuniea (prickly peat)? 2 2220022 22. A te Gerstxeckeria nobilis Lec.
Openten engel Wann so. = = yes dos 5 - Gerstxckeria nobilis.
LIS OO) era, Tine menes Tyloderma foveolatum Say.
PRAM Rae eles et Rak cus Seda k'o oy) Languria sp.
nO OE Ee ee ae Tyloderma foveolatum Say.
16844°—Bull. 100—12——6
82 INSECT ENEMIES OF
Plant.
Galpinsia harttweod.c.- 2. scnceese eet eee
Tpomed lacunesa-2 222) see eee ee eee
pond, pomdurate oS ee eos eee ecm re
Phusatis heteropnyllar.. Ss 2.62 oe ee
Rhysalislancedlattea neater eee a
Physalisilongijolig’ 222" snes ee etna ues
PHYS DRUM CL BCE e ee A ee ee
Physalis virginiana ambigua....---2..----.-
SOLON CANO lINe USC ee een
Solanum eleagnifoltum............--.------
Solari heterodorini-< 2202 a ee ete
Solanum melongena (egg plant)..-.-.--.--.--
OMAN FOSTATINUsa ee oo en ee ER
MOMMY ROSETOLUI nos soe See etree
SSOLATO A LOTT C8 ia ac) atte DU chore uty SGM Go ks a Ay <2
Capsicum annuum (pepper) ----------------
DO OSU GRCOnitss st 555-5. ae ee
Metita Lavine ete nee eee se ee eee
Ambrosta.artemisi@yolid.. -- 229i eee. ea
Ambrosia psilostachya.. += 245-2 se eee
AIROTOSUA UTINGG soc cee woe
Grindelia tnilowdes 22 oe ete ee
Grindelva squarrosa nuda... 2. 2 222 a2. ee
HEICIErOUICCE SLOALULLaNIs 1) ase see eee eee ee
Asice saliCijOlUUs enc. saAne eee ee eee
ISUGETANENUS TUDIGINOSUS -.. Aceon. ce ae eee
Sideranthus Tubvgyinosus 2-222. cee ee
Aphanostephus skiurrobass..2.~.-<--Uses-. ses
Helianthus spp. (sunflower)...-.......---.-
Felon tenurpornumn 2. ace ene oases
THE BOLL WEEVIL.
Infested by—
Auleutes tenuipes Lec.
Arexcerus fasciculatus DeG.
Brachytarsus alternatus Say.
Trichobaris trinotata Say.
Trichobaris trinotata.
Trichobaris trinotata.
Trichobaris trinotata.
Trichobaris trinotata.
{ Trichobaris trinotata.
\Anthonomus nigrinus Boh.
Anthonomus xneolus Dietz.
Trichobaris texana Lec.
Trichobaris trinotata Say.
Trichobaris texana Lec.
Anthonomus xneolus Dietz.
(Ae zneolus.
Trichobaris texana Lec.
Titenes nigrinus Boh.
| Trichobaris trinotata Say.
Anthonomus eugenit Cano.
eae trinotata Say.
\\ Trichobaris compacta Casey.
Trichobaris trinotata Say.
Lizus scrobicollis Boh.
Lixus scrobicollis.
Lizus scrobicollis.
Anthonomus squamosus Lec.
Anthonomus squamosus.
Anthonomus heterothecx Pierce.
Desmoris scapalis Lec.
Brachytarsus alternatus Say.
Lizxus scrobicollis Boh.
Baris cuneipennis Casey.
16. A SUMMARY OF THE MORE IMPORTANT BIOLOGICAL FACTS.
Anthonomus aphanostephi Pierce.
Anthonomus aphanostephi Pierce.
1. The boll weevil has 54 enemies, including parasites and predators.
2. These enemies are native to other insects which are to be found
in the vicinity of cotton fields.
3. The interrelationships of the boll weevil and its parasites with
surrounding insects are very complicated.
4, The parasites are sometimes found in great numbers.
5. The cotton plant, by its production of nectar, furnishes a very
powerful attraction for parasites and predatory insects.
6. The development of the boll-weevil parasites is as rapid as that
of the boll weevil.
7. Most of the parasite species are well distributed.
8. The parasite species attack other hosts in the spring and have
a generation before the boll weevil is ready for them.
9. New species of parasites are becoming adapted to the weevil
each year.
ECONOMIC PRINCIPLES INVOLVED. 83
10. Other cotton insects, by their ravages upon the food of the
weevil, sometimes reduce the numbers of the boll weevil itself.
11. Much valuable work is done by the ants, which are present in
many fields.
PART III. THE ECONOMIC APPLICATION.
The economic application of parasitic control to the boll-weevil
problem is dependent upon accurate knowledge of a multitude of
conditions. The preceding two parts of this bulletin have been
devoted to a statement of the many phases of the parasite situation.
It must be understood at the beginning of this part that we consider
the utilization of parasites and other insects inimical to the boll
weevil as intimately connected with good agriculture. The boll-
weevil problem, from a parasite standpoint, is entirely different
from any other parasite problem ever studied. In other cases such
means as introductions from foreign countries may be utilized. In
the present case the main problem is to devise such agricultural
practices as will increase the effectiveness of the parasites already
present.
In order to facilitate the treatment of the economic methods to be
_ suggested, this part is also divided into sections, which are as follows:
1. The economic principles involved.
2. Interpretation of parasite statistics.
3. Interpretation of the biological complex.
4. How to profit by existing conditions.
5. How to plan for the greatest possible control.
6. Propagation and artificial introductions.
7. Objectionable practices.
8. The economic significance of the investigation.
1. THE ECONOMIC PRINCIPLES INVOLVED.
The attempt at utilization of insect enemies in economic ento-
mology is now receiving so much attention that the authors will
set down the principles which appear to have been the foundation of
the work they have done.
1. Insects in a state of nature are more or less completely held in
check by natural agencies, in which other insects frequently figure
as of direct or indirect importance. Many insects are controlled
almost entirely by their insect enemies. No insect is without its
natural checks.
2. The relationships between an insect and its enemies can not
be expressed by a simple ratio, nor are they in any way invariable.
The agencies operating for and against the welfare of a given species
are so many and of such inconstant magnitude, due to the activities
84 INSECT ENEMIES OF THE BOLL WEEVIL.
of other agencies, that the effects of one or two agencies of control
with known strength can not be estimated, because of the many
other agencies either unknown or of unknown strength.
3. When an injurious insect escapes from its natural surroundings
to a region where conditions are favorable for enormous reproduction,
it may become a pest, but it is never absolutely free of natural checks.
Anthonomus grandis has never been free of its checks although it
escaped those of its native home. These agencies of insect control
are inherent to all countries. An insect parasite is as likely to escape
its original surroundings as a phytophagous insect.
4. When an insect finds in its vicinity a variety of food closely
related to its native host, and that food is more succulent or more
abundant, there is a cone hte that sooner or later the more inviting
food will become the normal food. This possibility becomes stronger
when the original food supply fails, if the species is to be oe
Not only phytophagous but entomophagous insects have frequently
been proven to have thus changed their food habits—whether from
preference or necessity it is not known. Leptinotarsa decemlineata
(the Colorado potato beetle) is an excellent example of this change of
habit among phytophagous insects. All of the boll-weevil parasites
are examples of parasites which have adjusted their habits in the
presence of their original hosts.
5. A crisis in the history of a species occurs whenever the food
supply fails. The species may either disperse in search of food, as
the boll weevil does each autumn, or it may hibernate or estivate,
or it may select a new host, or the species may perish. All these
results occur in nature. All of these alternatives may be chosen by
different individuals of the same species. It is safe to assume that
when a species is found to have many hosts that it has undergone
many crises and that the resultant species is a highly developed and
adaptable form. A species most limited in food habit is most lable
to restriction or extinction and consequently of a lower type than
one able to meet any emergency.
6. When a desirable parasite species is known to be adaptable to
various hosts, a crisis may be artificially superinduced by the timely
elimination of the favorite hosts, thus forcing the species to attack
the most predominant near-by related host in the vicinity, or it may
be taken to an entirely remote or foreign locality and placed near a
field containing many insects closely related to its original host,
which it may learn to thrive upon.
7. The species most available for utilization are those most adapt-
able to changing environments, or those having the most hosts in
the given locality. These other hosts will serve as nurseries for
parasites,
INTERPRETATION OF PARASITE STATISTICS. 85
8. Certain parasites with more or less established habits’ require
that their hosts be in certain habitual locations (for example, Neocato-
laccus requires stem-dwelling hosts), and in like manner there are
conditions which can be made more favorable for parasite attack
through cultivation or through plant selection. Furthermore, since
parasites require different conditions, it is desirable to alter the
existing conditions so as to make them favorable for as many species
as possible. In the case of insects extending their range over many
different climates it should be the aim to introduce parasites best
adapted to the prevalent conditions.
2. INTERPRETATION OF PARASITE STATISTICS.
From the great mass of parasite statistics given in Part I a number
of important facts need to be considered.
Parasitic and predatory attack is strongest from August until frost
time. Hence it may be presumed that whatever artificial propaga-
tion is to be done will be most profitable when conducted during this
period, provided it does not interfere with early fall destruction of
stalks, the fundamental cultural remedy against the boll weevil.
The greatest control of the boll weevil by insects and also by
all agencies is in hanging squares. As has been stated in Part I
(sec. 3), the hanging squares are a result of a diagonal absciss layer,
which causes the drying square to fail in separating itself completely
from the plant. These squares die on the plant and afford a very
favorable position for parasitic attacks upon the weevils within.
The statistics show that insect control in fallen squares is greatest in
the moist States of Louisiana and Mississippi. This is undoubtedly
due to some of the new parasites which are accustomed to attacking
woodland weevils and other insects characteristic of this humid
region. The insect control in hanging squares is the greatest in the
comparatively dry States of Texas and Oklahoma. These dry States
also have a higher combined natural control in the fallen squares
than in the hanging squares, largely because the climatic conditions
cause a higher mortality of weevil stages in squares lying on the
heated surface of the ground. On the contrary, the humid States
have a higher mortality from both climatic and insect agencies in
hanging squares than in fallen. Furthermore, it has been proven, in
Part I (sec. 4), that an increase in the amount of hanging squares
will increase the total control. Having these facts in mind, the
obvious conclusion is that it will be desirable to have varieties of
cotton which have this tendency best developed. Among the varie-
ties which are now known to retain their squares are the cluster
varieties, including the Rublee.
86 INSECT ENEMIES OF THE BOLL WEEVIL.
The figures show that parasitism becomes very high under favor-
able conditions and also that agriculture modifies the insect control.
Obviously therefore those agricultural methods which will favor the
highest insect control must be sought. These methods, as now
known, will be dealt with more fully in a following section.
It was feared for a long time that the parasites of the weevil would
be held in control by the warm climatic conditions which affect the
boll weevil. This is not so. We have found abundant proofs of the
fact that a temperature which will kill the boll-weevil larva will not
kill the egg or small parasite larva in the same cell, and that the
parasites can develop to maturity on the dried remains of the weevil.
The temperature fatal to the boll weevil is 123° F., a temperature
frequently reached on a hot burning soil. We have found in several
years that a low temperature which will kill the boll-weevil larva is
also not fatal to the parasites, for in November, 1907, when 97 per
cent of all the boll-weevil stages were frozen, no evidence whatever
could be found of mortality among the parasites. The minimum
fatal temperature of the boll weevil is 12° F.
3. INTERPRETATION OF THE BIOLOGICAL COMPLEX.
The complicated biological factors which have been noted in Part II
have been summarized briefly in section 16 of that part (p. 82).
The interpretation of these facts has been suggested in a number of
places throughout the second part. Hence only a few words are
necessary at this point.
The fact that surrounding each cotton field there are numerous
plants harboring weevils and their parasites is of extreme importance
in this problem. ‘These parasites are generally capable of attacking
the boll weevil under conditions of necessity or alternative choice.
The aim is therefore to find all the methods by which these parasites
may be forced to leave their native hosts and attack the boll weevil.
In fact, the entire second part has been devoted to giving these facts
in order to bring out this single point.
4. HOW TO PROFIT BY EXISTING CONDITIONS.
COLLECTION OF COTTON SQUARES IN SCREENED CAGES,
As has just been pointed out, there are conditions around the cotton
fields which are potential of a considerable increase in the parasitic
control of the boll weevil. Probably no other method will yield
better results than the gathering of the cotton squares which are
infested and placing them in wire-screen cages of 16 or 18 mesh to
the inch and placing these cages in selected parts of the cotton
fields. This method is not new in entomological practice. It has
HOW TO PROFIT BY EXISTING CONDITIONS. 87
been used with great value in the freeing of apple orchards in Europe
from the apple-bud weevil (Anthonomus pomorum). The boll weevils
can not pass through a 16-mesh or 18-mesh wire screen, while the
parasites can do so, and therefore the release of these enemies will
be constantly increasing the proportion of parasites against the
weevils. Even if a 14-mesh wire screen is used, only a small pro-
portion of the weevils can escape through it and some gain is effected
by the release of the parasites. In order to demonstrate numerically
just how this would happen, three hypotheses are presented. In the
first case squares are collected and put in a 16-mesh wire cage, and
in the second case squares are collected and put in a 14-mesh wire
cage, and in the third case no squares are collected. The average per-
centage of control which follows as a result easily demonstrates the
advantage which will be almost immediately gained.
It has been contended and proven that many weevils escape
through the ordinary wire screen.
I.—Given 10,000 developing stages in a 1-acre field.
(A) Collect squares containing 50 per cent of the stages and place in 16-mesh
Beep ermeoR eer Mie SoA Skettis So Ue 2 hs ae LE ho! 5, 000
Nowmat parasiinan Iso Per Cenbs.%2 o2.22s5 2-32 ole. fas naan es weer 250
Peereiiiel beta! 4) PEE COMt (5). 550.6 So. o4 shah oe ley eae ee 2, 000
RIRnERaMLaG rmeaa hd Wee Pee Fie Rte 2 SE SNE sD eae ee 2, 250
LE Se Suey hs 2g SSS A oy Te ge oe eae Ey A en Se Ne Se 2,750
There escape through 16-mesh screen—
#6 percent weevils... +0. 5... ..2<-5.-:- EES E SOE Tee Me EE OT SEP ns OE SEI 275
wo [LSIR IE CO AUG Ta STG an 2 car a eee ne see 225
(B) There remain in the field squares containing 50 per cent.......-.-.------ 5, 000
Normal mortality as.above, 45 per cent... -..----5-.+ 4--<---p-<2--+-<2s-2- 2, 250
Perce ae aes te Me Pe a ee Ce tl te nd OS 2, 750
pome.weevilsexcaped from). cageds. of oes oo ik 4-2 eee see RSE AeSe 275
Total wees at\end of generations... 5. 23)L. S20. 2. 0 2 3, 025
omer CRO yaah otitis ote Seeley ot Mee che se shis 250
Panes CECANOG JTOID PAROS a8 oa c J oda8s Aeteees se dt Lae ben 2 oe 225
PenieeR peodene in Held 2226. 8202 2 je eee ace. 475
There is 1 parasite to every 6.3 weevils.
IT.—Given conditions as above, squares in 14-mesh screened cage.
Peay erent Conlerbod. Byuares DICOG. 6. = 55 snes op see in wee ee ee eo aeee 2, 750
There escape through 14-mesh screen—
RIG MORAISSE eres. ose ree ee Sees. Leo. to Sk 1, 100
RESP eee Se mL A Ss De ee Seen. bd 250
(3) Breed infield... -..55-.- We Perle Seeth, ie oed Uy Mt Oe 4S de 2 no LE Eye see 2, 750
LEDS ES ETN hs OE Se Ee a ag ee a a en eRe ee a 1, 100
Total weevil at end of generation... . 2... 2 22225 5.5---0-- ace een eke 3, 850
88 INSECT ENEMIES OF THE BOLL WEEVIL.
Parasites reared 3.24225. 35a ee SR ee ce erwin 250
Parasites escaped. 2..)..... 422 See UT eet et eae 250
(IPATHSILCS TM HELIS oa ecco ee eee eae ert er oe 500
There is 1 parasite to every 7.7 weevils.
IIT. —Given 10,000 develo ping stages tn a 1-acre field.
No squares:are. collected. fss22.25 J25s50 2. DEAE, ee ee eee eee 10, 000
Normal parasitism, per,cent-...2/- sas Pae-2- s- hed dig ee 500
Anis and heat lall 40 per cent...../15.. cesaS-uson2 = ese sh eee ee 4, 000
Montalittyer: S22: foes. es ee OR a ee 4, 500
IBLeE dees asec seis fee ear a eee ot tete cao eels ceere see Serer eee ene 5, 500
Parasites reared, 500.
There is | parasite to every 11 weevils.
SUMMARY.
Squares collected and
placed in—
Squares not
collected.
14-mesh 16-mesh
wire cage. | wire cage.
Weevilsremain. jo2c2 2 kee base oleae 5, 500 8, 850 3, 025
iParasiiessremaiiie cn as ascr fe ae ee ee eee te Ce 500 500 475
Ratio of parasites to weevils... 1.0... +--..--..04<0 cee a ens 1:6.3
ELIMINATION OF COHOSTS.
Another practice of undoubted value in bringing about a higher
percentage of parasitism upon the boll weevil is the elimination of
the cohosts of the boll-weevil parasites at proper times. To show
what has been done in this line, the case of the Dallas farm in 1907
may be cited. On July 19 of that year a very large hedge of weeds,
Ambrosia trifida, infested by Lixus scrobicollis was cut. These weeds
were along the fence adjoining a part of the cotton field which had
been under close observation for parasites throughout 1906 and the
spring of 1907. In 1906 there was not found in any plat on this
farm a higher parasitism than 2 per cent by Hurytoma tylodermatis in
hanging squares. Kurytoma was very numerous in the Ambrosia
weeds next to this field, but did not appear to attack the weevil in
large numbers. Before the weeds were cut in 1907 the two plats
nearest these weeds averaged 26.76 per cent and 16.79 per cent
parasitism by Eurytoma. On August 17, about a month after these
weeds were cut, the two plats just mentioned had, respectively, 37.50
per cent and 26.66 per cent parasitism by Eurytoma. This striking
gain adjoining the weeds was not reflected by parts of the field farther
removed.
HOW TO PROFIT BY EXISTING: CONDITIONS, 89
EARLY DESTRUCTION OF THE COTTON STALKS.
There can be little doubt that the early destruction of the cotton
stalks, in addition to depriving the boll weevil of its food plant, will
also cause the parasites to seek a series of hosts which can carry them
through the winter period. In order to prove that fall destruction
does not have an injurious effect upon parasite control, we would cite
the discussion of the Victoria fields, in which various methods of fall
destruction were carried out, as discussed in Part I, section 6. As a
further proof the famous Olivia fall-destruction experiments may be
considered.
On October 1 to 10, 1906, all of the cotton plants in over 400 acres,
constituting the entire Olivia cotton community in Calhoun County,
Tex., were cut and burned under the direction of Mr. J. D. Mitchell.
According to the rearing records in our possession, the parasites
developing in this cotton would all be mature before November 10,
and if they hibernated, would have to do so as adults. Noother
cotton existed within 12 miles, as the community is completely iso-
lated by water and marshland.
Cotton was planted about March 15, 1907. On April 15 no boll-
weevil work could be found, but on May 7 a single weevil was found
after a careful examination of eight fields. On the same date at Six
Mile settlement, across the bay near Port Lavaca, there was consider-
able infestation. If the parasites hibernated as adults they would be
dead long before the middle of June. If they could have hibernated
as immature stages they would have matured by March 15, and under
normal conditions three generations would have passed by June 15.
The infestation was still very sight in July. It must be argued,
therefore, that any boll-weevil parasites must be breeding on some
other weevil, if they did not perish.
On August 22, 1907, Mr. Mitchell found parasites with weevil-
infested squares on a field in the opposite part of the community to
that in which he first found the weevil infestation. The obvious
inference is that a rotation of hosts occurred during the period of the
boll weevil’s absence.
Having planned the cropping system, it is also best to prepare the
fields early for cotton and plant as early as possible. Of course, most
of the reasons for early planting of cotton are well known and the
practice is very common, but in this connection it must be said that
such early planting has the actual advantage of enabling the para-
sites to start early.
Care must be given to the choice of the cotton variety which is to
be used. Frequent recommendations have been made of varieties
with light foliage, early maturing fruit, short nodes, and determinate
growth. All of these qualities are favorable to parasite control,
90 INSECT ENEMIES OF THE BOLL WEEVIL.
especially since such plants afford much more sunlight on the ground.
The ants and also the parasites prefer much more to attack the
squares which are dried out than moist squares. It seems that they
can more readily penetrate the linings of the square. In addition to
these qualities of the cotton variety, the use of a variety with at
least a moderate amount of nectar is also advised. The reason for
this has been explained in preceding paragraphs. Finally, the tend-
ency of plants to retain the squares must be again mentioned. If a
variety can furnish the desired qualities of early producing, produc-
tiveness, and quality of lint, as well as a diagonal absciss layer on the
square, that variety should be chosen above others.
If at all possible, it is advisable to plant the rows far apart or on
the check-row system, in order to give the necessary amount of sun-
light. The cultivations to follow this should be with the purpose
of obtaining a dust mulch, for with such a mulch the surface of the
soil may be heated to a much higher degree than by deep and lumpy
cultivation, and the control of the boll weevil will thus be greatly
increased, through the drying effect upon fallen squares.
5. HOW TO PLAN FOR THE GREATEST POSSIBLE CONTROL.
As it has been proven that many agricultural processes are favor-
able to the development and attack of parasites and enemies, there
can be no question but that it is desirable to plan to obtain the great-
est amount of this beneficial aid.
There are a few plants which have no objectionable qualities in
themselves which might with good reason be planted adjacent to the
cotton fields in order to induce the attack of weevils which act as
hosts of the boll-weevil parasites. For instance, the presence of a
hedge of blackberries or dewberries along the fence means the pre-
sence of Anthonomus signatus, the blackberry bud weevil, with its
numerous parasites, all of which attack the boll weevil. The para-
sites would be able to carry on a generation in the spring before the
boll weevils were breeding and would mature in plenty of time to
attack the first developing stages of the boll weevils.
It would seem advisable to plant a hedge of the flowering shrub
Amorpha fruticosa, which is the host plant of Laria exigua. This
little wevil is very abundantly parasitized.
In planning the cropping system there can be no possible harm
in arranging to have a forage or hay crop adjacent to the cotton
field. In case a forage crop is used, cowpeas with the ever-present
cowpea pod weevil would undoubtedly bring about the presence
of several important parasites. The early removal of the cowpeas
for fodder would force the parasites to attack the boll weevil. In
the case of a hay field, the process of haying and subsequent curing
PROPAGATION AND ARTIFICIAL INTRODUCTIONS. 91
would enable the parasites present in the various weeds to escape
and attack the most abundant host, namely, the boll weevil.
If, with all these precautions, the boll weevils are very numerous
in the field, and the expense is not too great, much can be gained by
picking the squares and placing them in cages, as has been described
in a previous section.
Finally, at the proper season for haying, the actual methods of
cutting and preparing the hay will without doubt furnish still greater
control to the weevil. Some time in September, if not before, whether
haying is carried on or not, there should be a thorough cutting of all
weeds around the cotton field in order to force the parasites to the
boll weevil and also to get rid of favorable hibernation quarters for
the boll weevil.
6. PROPAGATION AND ARTIFICIAL INTRODUCTIONS.
The propagation of parasites under artificial conditions and their
introduction are attended with a great amount of labor and expense
and have many technical difficulties. The simplest form of propaga-
tion is the collection of infested squares at one locality and the ship-
ment of them to another locality, where they are placed in the field
to await results. There are good reasons for attempting thus to
introduce parasites. It has been found by very close observations
that the parasites are not evenly distributed, but that each species
has a more or less definitely defined geographical region. This is
no doubt due to the distribution of the normal host weevils. The
purposes of introduction are to take these parasites from their native
localities and place them in geographical regions in which they do
not at present exist. Definite proofs that results can be obtained
in this manner were to be had at Dallas on the experimental farm in
1906 and also in 1907. The 1906 experiment has been fully described
in the first report on the parasites of the boll weevil (Pierce, 1908a).
In 1907 a similar experiment was tried by the release of large numbers
of adult parasites. These parasites were carried to a field in small
screen cages containing foliage, so that the parasites might not become
overheated. The cages were opened in the shade, and the parasites
allowed to fly out in any direction which they pleased. While many
species of parasites were released in this manner, they did not all
show the results that were expected, but the release of Catolaccus
incertus in a given part of the field accomplished an increase in the
control in hanging squares by this species. In two other parts of the
field Microbracon mellitor was released, and it also showed good gains.
As Microbracon was released on this farm both in 1906 and 1907,it may
be useful to compare the percentages of parasitism at various periods.
In August, 1906, this species furnished 8.5 per cent parasitism in hang-
92 INSECT ENEMIES OF THE BOLL WEEVIL,
ing squares; in September, 1906, this had risen to 10.2 per cent; in
July, 1907, the parasitism by this species was 35.2 per cent, and in
August, 1907, it had risen to 39.8 per cent.
At Shreveport, La., in 1908, many specimens of Catolaccus incertus
and Microbracon mellitor were released. Table XXII gives an idea of
the results and shows the expected increase by Catolaccus in both
hanging and fallen squares and by Microbracon in hanging squares.
TaBLeE XXII.—Experiment in artificial introduction of Catoloccus incertus and
Microbracon mellitor, Shreveport, La., 1908.
Percentage of mortality. Gain in mortality.
Class of forms. Plat. Date. Total
Total. | Para- | Cato- | Micro- aoe
* | sites. | laccus. |bracon. an ne
Cato- Micro-
laccus. | bracon.
Per cent.|Per cent.|Per cent.
Fallen squares... . - Release...} Oct. 5 | 36.44 5.93 4,23 1.70! 32 9eea eee eee
DOLE erases peed Osceates Oct. 28 | 37.96} 15.74] 10.80 2.16 165 150 33
WON ce ooee Checks 32 Oct. 5] 40.00] 10.50 5. 55 S270! [Lt sai eos he ch ease (See eenees
DONA es. eee ..-d0...-.-.-] Oct. 28 | 42.33] 16.00 8.00 5.00 52 44 35
Hanging squares...| Release - - | Oct. 5 | 47.15 9.90 4.39 35290 but ods becesaes apace see
DOM acct Se 0.81 | 18:91 282 148 477
RELEASE CAGES.
In order to obtain satisfactory results from the release of infested
material, it is necessary to place the material in cages from which
the injurious weevils can not escape but which will still allow the
parasites egress. This principle has been explained in other sections.
There is also another important consideration in the construction of
the cages. When a large amount of material such as this is collected
in a small space it furnishes great inducements to attack by colonies
of ants. The only way that the material can be protected from total
destruction by ants is the isolation of the cage on legs by the use of
“inverted cups”? containing oil, or by greasing the legs in some
manner.
TRANSFER OF ANT COLONIES.
Since the work of ants is always very favorable to control, means
should be devised of increasing their numbers in the cotton field.
The dust-mulch method of cultivation is very favorable to the ants
in that it does not disturb their colonies after they have commenced
breeding. This is a very important matter to consider. The late
Mr. F. C. Pratt, in working with the horn fly (Lyperosia «rritans
L.) discovered that fresh manure containing numerous fly larvee
is very attractive to Solenopsis, and that these ants seem to trans-
fer their whole colony at times to the manure. Mr. Wilmon Newell,
in connection with the Argentine ant investigations, at a later
date, found that he could trap immense colonies of the Argentine
OBJECTIONABLE PRACTICES. 93
ant Uiridomyrmex humilis) by means of boxes containing manure.
These observations are very suggestive, for they point out the possi-
bility that colonies of ants can be obtained by placing fresh manure
in boxes near ant colonies. When sufficient numbers have entered,
they may be boxed up for removal to a place desired. In this manner
great colonies could be transferred bodily for considerable distances.
7. OBJECTIONABLE PRACTICES.
There are several practices which are quite objectionable from the
standpoint of encouraging the parasites and most of which have
also been found objectionable from purely cultural standpoints.
When the cotton is planted closely on moist soil its growth is mainly
vegetative and consequently immense stalks may have very little
fruit. Agriculturists have always pointed out that large cotton
plants need plenty of room in order to produce fruit. Field examina-
tions to determing the mortality of the boll weevil from various causes
have always shown that the parasitism is greatest in the portions of a
field where the foliage is lightest. A notable example was found at
Natchez, Miss., where in a single field the growth was very irregular.
One spot seems to have been used for feeding cattle and was very
fertile. On this spot the cotton grew 6 or 8 feet tall and the ground
was densely shaded. Here the mortality of the weevil was very low,
and there was scarcely any control by insects. One hundred feet
from this was a thin piece of ground where the cotton plants were
barely 2 feet high, but they were loaded with bolls and showed a
much higher percentage of mortality, especially by insect enemies.
An actual count of the number of bolls in the two parts of the field was
greatly in favor of the smaller plants.
Late planting has been proven objectionable from almost every
standpoint from which it has been viewed. Under existing circum-
stances there are no valid arguments for late planting. From the
standpoint of control by parasites late planting simply delays the
attack of parasitic enemies and reduces the amount of control in the
fall at a critical time.
It is believed that the use of varieties which always tend to drop
their squares is objectionable if varieties with the opposite tendency
can be found with the same qualities of production.
The practice of picking squares and then burning them can not be
condemned too strongly. The planters are by this practice almost
nullifying the good work that they do by picking the squares. They
are doing nothing more or less than destroying their best friends
when they burn these squares. This may be proven by an hypothesis
similar to those presented (p. 87) in demonstrating the value of collect-
ing the infested squares.
94 INSECT ENEMIES OF THE BOLL WEEVIL.
Given 10,000 developing stages of the boll weevil in a 1-acre field.
(A) Collect and burn squares containing 50 per cent of the stages. .....-...-.- 5, 000
This destroys all parasites as well as weevils.
(B) There remain in the field squares containing 50 per cent of the stages
DIGHON Geos os a-ha kee eo Sh ee
Experiments in feeding Calosoma larvie with diseased gipsy
HIGinRCAbOL Paras. o.e te ek aes AG ooo oe emp aes Sheryl s wer ee
Results of feeding to Calosoma larvie caterpillars from sprayed
REA IDOULOG ROBE. ancien oe ace he ee oe se a ee
Experiments in feeding gipsy moth pup to Calosoma larvee. . -
Experiment in feeding earthworms to larvee of Calosoma....
Starvation experiment applied to larvee of Calosoma sycophanta.. .
Experiment to determine whether Calosoma larvee will hibernate
CIDE TIES fA gy 0) f ct le eae ae ae ene Ag RRB ec Ane
Placing Calosoma larvze in cold storage to determine ability to
eR nEMOCONh 64 see sash ye Sod kL oui a» wen Seo
Methods used in rearing’ Calosoma larvee....................-----
The distance Calosoma larvie penetrate the ground to pupate. . - -
tte Tore dh a Ooo eo x vines om es we Mona te radeeeee
Seam aREAD ELS 2 em Sob san arn mm 2 wel 3. Spee mae
Bee TPECETO DRA fo Soo ows. we nw sx = oe a wea 5 oe
“Io Oo
~I
bo bo bo bb bo bd bb Pb
io) ~I
oo
a
CALOSOMA SYCOPHANTA.
Investigational work on Calosoma sycophanta—Continued.
Investigation of the life history of Calosoma sycophanta—Continued.
The pupa—Continued.
Experiments with the pupze of Calosoma sycophanta............-.--
Experiments in wintering Calosoma pup in galvanized-iron
CAQCS W..Jcc shee ct S22 oot ce ee ee
Experiments in wintering Calosoma pupz in wire-netting
Cages... est Leis ek eee ee
Experiments in wintering Calosoma pupz in a cool cellar... .
Length of time spent by Calosoma sycophanta in the pupal stage. -
The adult.or beetle: .. 220. Jie. Se es ee ee
Emergence of Calosoma beetles in the spring. -...----..--------
Hibernation of Calosoma sycophania.=-- 4022-22 262 ee eee
Mortality of Calosoma beetles during hibernation. ............--
Experiments in wintering Calosoma beetles in galvanized-iron
CIGOS. sss Jno Si? de poe Se es Bae Ne a ee
Experiments in wintering Calosoma beetles in wire-screen cages. -
Experiments in wintering Calosoma beetles in box cages. .....-.--
Effect of removing Calosoma beetles from hibernation early in the
SPH fe see 32 Ud. c ao ames sees eet ee ee oe er
Feeding habits of the adultk= = 2. tae eee ae ee
Length of feeding period of the aduliss... .:2.22- 2+ 2s: esseaee sae
Food ‘of the adults. . [sicze. t2asce ose ee oe oe eee
Effect of feeding diseased gipsy moth caterpHlars to Calosoma
beetles: avea.ce ovis Sneha ae ee
Experiment in feeding Calosoma beetles with gipsy moth cater-
pillars from sprayed or poisoned foliage..........---...-------
Experiment in feeding Calosoma beetles on beefsteak.........--
Starvation experiments with Calosoma beetles. .......---......-
Assembling experiments. ._..20ah. J. (Seen ee ee
Gopulation:. 2. s0cn6 cue, ae ee ee
».- Reproduction 2.2 5 sesso we oe en ee oe ee
Polygannyis si ac 22 dt See a ee ee ee
The effect on egg deposition of removing beetles from hibernation.
Effect of cold storage on egg deposition. ..-..--.-..5---=--------
Relation of size of beetles to reproduction. .........-------------
Sexes of beetles reared ..:.. 2 .).'s: te shi0. soot eek eee eee
Experiments in crossbreeding Calosoma sycophanta and C. scru-
KO arsine mente Heron eee CGS sa OS Meteor se Guest easedtoss
Habits of flight. 2.0. Sisters. 22k 129 ee
Attraction of the adults to light?... 2-202) tee 20 eee eee
Drowning experiments with beetles? .--- ie) ..2 eee
Length. of life of beetles... 2.3.5. 252 50 22s see eeeee eee
Relation of Calosoma sycophanta to native species of the same genus. . -
Colonies of Calosoma liberated in Massachusetts ...---...----------------
Colonies’of Calosoma liberated tmasicnne eee i eee rae
Colony of Calosoma liberated in New Hampshire. .........---------------
Economic importance of Calosoma sycophaiiale. + 4-6-2. 22 2 oe eee
Index
Page.
45
46
46
46
47
48
48
48
50
51
51
51
52
52
52
53
55
55
56
56
57
59
59
61
62
62
62
63
64
64
65
65
67
69
70
71
76
77
78
88
89
89
91
ILLUSTRATIONS.
PLATES.
Page.
Prare I. Different stages of Calosoma sycophanta.................---- Frontispiece.
II. Out-door insectaries ‘‘A’’ and ‘‘B”’ for beetle rearing. ..........----- 20
Diiesiataner wiewonmsectary. Al (PL, IT). 72.22.0025 e.e cesses. 20
veelntentonviewrouilmeectary:--b\(PlLD)s. 22) 32 ohne as foe eee 20
V. Box cages used for rearing beetle larvee late in the summer........-. 24
VI. Larvee of Calosoma sycophanta feeding on gipsy moth caterpillars
under burlap, at Pine Banks Park, Malden, Mass., 1910..........- 32
VII. Gipsy moth pup that have been destroyed by the larvee of Calosoma
GSS UNE A OS SI OR SIO 9 Ee Ree Ee 36
RiiPieen cemiling Care im ‘a. pine ICC. 55-1 5 = wins oe ooo aco. wisieere eines 60
IX. Map of eastern Massachusetts, showing dispersion of Calosoma syco-
PMA eRe eee ee as Se eee = Alves Bieinin ws Sele BSS aime sore 80
TEXT FIGURES.
Fie. 1. Front leg of female and of male Calosoma sycophanta, showing differ-
ences im simeture of tront tarsal jommts:. 2... 2. s.2.---2.2- +256. 7
2. One of the tin boxes used for making the first shipments of Calosoma
Mee tleswemet ean aes wos eek uc teen aeee cae su alaste eeenees 10
3. One of the wooden boxes used for shipping Calosoma beetles from
Oui) Oe eee ee ae tee aaa ae 10
4, Same box as in figure 3, with cover removed, showing method of packing. 11
5. Wooden boxes from Japan, showing method of packing Calosoma bee-
(CLUS) Saag SH nt ayaa) ee eee te Ror ey ahd Ae oe A ae eS a 12
SpE MOE NAPe ONES rt rs ee ese cio wa ek male oo Sait SS epee ee aed 15
7. Small wire-screen cages, set in ground in insectary, for rearing Calo-
RONUMMAT Neto aac ece a pote dose tee a weiss es oleae es ececus. 16
Sa box cares for hibemation of beetles-.°... 202.2246. 2-2- 1 oe. ce ence 17
9. Galvanized-iron wire cages used for wintering pairs of beetles......... 18
10. One of the cages shown in figure 9, that has been removed from the earth. 19
11. Out-door insectary used for beetle-rearing work ..........-------.---- 20
"12. Jars of earth containing eggs of Calosoma sycophanta..........-.------- 21
13. Diagram showing temperature record during summer of 1909, the total
egg-laying record, and mortality of female beetles for the same period. 24
14. Method of securing data on the distance traveled by larvee of Calosoma
SE REEMUMG PE EEE ry i 82 operate ta wc ae as cw oe a ee 31
15. Roll of paper showing record of distance traveled by larva of Calo-
HOTS LNCAP Be - SR SO SS CERO ae OSA a TOES ERISA to oe 32
16. Larva of Calosoma sycophanta feeding on gipsy moth pup on tree
mum noeen Saurus, Mass: July, 1907-...................i2c8e -20s 34
17. A ‘‘Fiske”’ tray for feeding gipsy moth caterpillars...................- 42
6
Fie. 18.
CALOSOMA SYCOPHANTA.
Wire-screen hibernation cylinder where larvee of Calosoma were fed in
Anusust, D9LQE. oe snes es aie ee eee
. Pupa of Calosoma sycophanta in cavity in the earth. .......---.....-
. Assembling cage... 2.0.52. 222 5e- saee ee ee eee
. Two hundred tubes, each containing a larva of Calosoma sycophanta
ready for colonization 22:
&
Fic, 12.—Jars of earth containing eggs of Calosoma sycophanta. They have been placed in the sun
to hasten hatching. (Original.)
The result of the work for the year was the rearing for colonization
of 2,300 larvee. During the following year this line of work was con-
tinued and 6,100 additional larvee were placed in field colonies, and
in 1910 6,380 were reared and liberated. When larve are being
reared for liberation in field colonies it is desirable to hasten their
development as much as possible. They are given an abundance of
food and the jars containing eggs (fig. 12) are placed in the sun on
cool days to accelerate hatching. The method of liberating larval
colonies enables the species to become established over a much wider
range and also gives it a better chance of surviving, owing to the vary-
ing conditions and locations in which it can be placed.
99° CALOSOMA SYCOPHANTA.
The beetles can be reared with fair success after some experience
has been obtamed in properly handling them. The food supply is
one of the problems that causes considerable difficulty, especially
early in the spring and late in the summer. Before gipsy moth larve
are large enough to satisfy the ravenous appetites of the beetles, tent
caterpillars have been used when it was possible to find them in suffi-
cient numbers, while after the middle of July larve of the white-
marked tussock moth, fall webworm, or any other caterpillars that
could be collected have been used.
Each season the continuous services of one man have been required
to collect caterpillars for beetle food, and at some times each year he
has usually found it impossible to bring to the laboratory enough
specimens to supply the demand. The amount of food consumed by
beetles or larvee is noted daily when the jars are examined, so that the
feeding and rearing records can be observed at one time.
Owing to the carnivorous habits of the larve it is usually necessary
to isolate them. This is especially true if detailed records are to
be kept, or if they have become nearly full-grown. Hot weather
stimulates their activity and appetite, and it is seldom possible to
keep several large larvee in the same jar during hot weather unless an
abundance of food is supplied, and even then some of them usually
succumb to the attacks of their comrades. The small larve do not
attack each other so ferociously, but when some are practically
helpless at the time of molting they fall an easy prey to the others.
During the summer of 1909 and 1910, when large numbers were
being reared for field colonies, it was impossible to isolate each indi-
vidual, and as soon as hatching took place 10 to 15 were placed in a
large battery jar containing earth and an abundance of food. If
they were not allowed to remain more than three or four days before
removal, the mortality was relatively low. Later in the season,
after all the gipsy moth larve and pup had transformed in the field,
as many as 200 larvee were reared in box cages (PI. V) having a sur-
face area of 2 by 34 feet. The weather was cooler at that time, and
although a considerable number was killed, it did not render this
method of rearing impracticable for use in late summer.
INVESTIGATION OF THE LIFE HISTORY OF CALOSOMA
SYCOPHANTA.
One of the factors which renders this investigation somewhat
difficult is the length of life of the adults. Only a small amount of
data is available, because it is necessary to rear beetles in the labora-
tory in order to get the initial information. Many species of insects
die as soon as the females have deposited eggs, or the males have fer-
tilized the opposite sex, but this species, as well as others in the same
genus, have an entirely different habit of life.
INVESTIGATION OF LIFE HISTORY. 23
One female beetle received from Europe in July, 1907, was kept
under observation at the laboratory for two years, so that the length
of life may normally be considerably longer.
Nearly one-half of the beetles reared from eggs in 1907 that emerged
from the earth in the spring of 1908 survived the summers of 1908 and
1909, and went into hibernation in the fall. This servestoilustrate
the prolonged period throughout which accurate records must be
kept, and the care with which the work must be conducted in order to
secure correct data.
During the summer of 1910 measurements were made of 12 freshly-
laid eggs and the same number of larve on entering each stage, and
these notes are included in the descriptions of stages which follow.
THE EGG.
Twelve fresh eggs gave the followmg average measurements:
Length, 5.2 mm., width, 2.4 mm. They are somewhat elliptical in
form, with a slight taper toward one end. The color is white, with
a famt yellowish tinge. They vary somewhat in size and form and
before hatching often become somewhat kidney-shaped.
The time spent in the egg stage is from 3 to 10 days, and depends
largely on the temperature. Careful observations on 2,000 eggs that
were laid from May 15 to August 18, 1908, are summarized as follows:
TaBLe II].—Duration of the egg stage in Calosoma sycophanta.
Number of eggs in—
Egg stage.
May. June. | July. August. | Total.
LET ic pla te al ee te A le ee 75 13 | 88
EL CADSR cote rie BS Eat Mee ne ee ene eee eee 78 444 i 529
TAGE gente 25 6s es Pee Se De SAC Ae See es Ceres 605 451 3 1, 059
GEN S55 eee a Sie re RE a ey ele ee er ae ee an 23 164 36 3 226
MORSE ace Sains Con tn ase eo ee eee SSE ea oee 39 PM [Ee See eee ce (epee 71
ei SVs Sas ge SA IRS Sap ee See Sears ais See eee ee 9 Gite Su eRe |e cha ae 17
CAs EN Sp el 3 a hn a ee ae PE a OR eee 6: | Sere eee ee |e AS Fae ee ee 6
UMS each te aie Se = Seco oie oe ene peace ne er eS 1 Sl Meee ee Stee AONE dS 4
E. ia ate es
Average time in egg stage: Days.
IE ee teas Sas een Sete ce ects Stk hacare oe ee MISS eae Tae te aa ae eck ak a Eee 7
Afiobel st Ae Sh UN Sa Se Sep PRA iro ne eee eae eee Oe eee es Pe ne a eee EEN aes 5.2
EL ierstencs rele OC fats ee Sern ts NECN 2 oe ep Se eee Ss Do eee 4.4
DANTE TR Sa GOBER: - Ga Re Sa Se ee eter en el ae ae ee ee Sond 4
The eggs recorded as hatching in May were secured from females
that were taken from hibernation in March, April, and May and fed
in the laboratory. Oviposition seldom takes place under natural
conditions in the month of May.
The average length of time spent in the egg stage, based on the
hatching each month during the summer, was: May, 7 days; June,
5.2 days; July, 4.4 days; and August, 4 days.
The table also shows that 4.4 per cent of the eggs laid in 1908
hatched in 3 days, 26.4 per cent in 4, 53 per cent in 5, 11.3 per cent
94 CALOSOMA SYCOPHANTA.
in 6, 3.6 per cent in 7, 0.8 per cent in 8, 0.3 per cent in 9, and 0.2
per cent in 10 days.
That temperature has a predominant influence on the hatching
of the eggs can not be doubted, and in this connection the following
TEMPERATURE Recorp-1909.
| [nll a
Seenie..
BGK:
CO
CO
marae
300
200
700
Fie. 13.—Diagram showing temperature record during the summer of 1909, the total egg-laying record,
and the mortality of female Calosoma beetles for the same period. (Original.)
data, secured from the United States Weather Bureau at Boston,
are of special interest.
The accompanying diagram (fig. 13) shows that during each
period of high temperature there was an increase in the number of
Bul. 101, Bureau of Entomology, U. S. Dept. of Agriculture,
PLATE V.
Box CAGES USED FOR REARING CALOSOMA LARV/z LATE IN THE SUMMER
A, showing coarse-mesh sereen top, used after the larvee have gone into the ground to
(Original. )
transform and hibernate.
B, cover with fine-mesh screen, used in summer;
INVESTIGATION OF LIFE HISTORY. 95
eggs, as is indicated a few days later by the hatching record. This
held true until the food supply began to fail late in July.
It will also be noted that the greatest mortality of females occurred
about the last of July and indicates the relation between tempera-
ture, egg laying, food supply, and mortality.
Nores on HaAtcHIna.
As the eggs are deposited in the earth by the female Calosoma
beetles, it is difficult to secure exact data on the superficial changes
that take place. The following note is of interest.
On August 2, 1907, two eggs laid that day were placed in earth
in a jar, to observe the changes that take place previous to hatching.
They were placed 1 inch below the surface of the earth and against
the side of the glass, so that they could be easily seen. August 6,
they were somewhat darker in color and had become slightly kidney-
shaped. At 8 a. m., August 7, a larva had hatched from one egg
and the other was dark gray in color, the segmentation of the body
being plainly visible. At 2 p. m. the egg had hatched and the larva
had moved away from the cavity. At 8 a. m., August 8, the larvs
which hatched first had made a tunnel to the surface of the
ground, but had returned and was occupying the egg cavity. The
other larva was not in sight. At 2 p.m. both larve were crawling
on the earth in the jar in search of food.
Usually the eggs do not begin to assume a darker color until
about 24 hours before hatching, although the change in outline and
indications of segmentation are apparent before that time.
Infertile eggs sometimes become kidney-shaped, but usually the
outline is more or less irregular and segmentation of the contents
has never been observed. Such eggs usually contract to some
extent in a few days. In most cases they become dark in color and
eradually shrivel up and disappear in the earth.
To illustrate the care which must be taken in transferring the eggs
of this insect, if it is necessary to do so, the following case is cited.
On July 23, 1908, a Riley cage, having a galvanized iron base con-
taining earth, was examined for eggs. It contained a supply of
Calosoma beetles which had been received from Europe some time
previous. The insects- were transferred to another cage and the
earth was found to contain 253 eggs, which were placed in jars to
observe hatching. One hundred and eighty-five larve developed
from these eggs, or 73 per cent of the total number. Probably some
of them were infertile, but allowing that this was the case, at least
20 per cent of the eggs must have been injured during the transfer,
26 CALOSOMA SYCOPHANTA.
EFFrect oF CoLp on EGGs.
As eggs are sometimes laid in August, it seemed desirable to
test in a limited way their resistance to cold. Accordingly, on
August 8, 1907, a jar containing a single egg in a quantity of earth
was placed in cold storage, where the temperature was maintained
at 26° F. This jar was packed in a box with several others, asmall
quantity of excelsior being used between them to prevent breakage
and also to permit the contents to cool slowly. On August 22, two
weeks later, the jar was removed to the laboratory, but the egg in
question did not hatch.
Another jar, containing earth and two eggs, was placed in cold
storage on the same date (August 8), but it was not removed until
June 4, 1908, nearly 10 months later. An examination showed
that the earth was very dry and the eggs had shriveled up.
Although few eggs were used in these experiments, the results
seem to show that they will not hatch after being subjected to freezing
temperatures.
THE LARVA.
The larve on hatching are nearly white, although slightly darker
than the eggs. They remain in the chamber in which the egg reposed,
and gradually grow darker until they become jet-black. About this
time, if the weather is warm, they become active and make their way
to the surface of the ground in search of food. The following descrip-
tion is made from a comparison of several larvee after they had become
fully colored and fed slightly. They molt twice and a brief descrip-
tion of each stage is given.
First-STaGE LARVA.
Average length of 12 newly-hatched specimens, from base of mandibles to posterior
end of last abdominal segment (not including anal proleg or caudal appendages), 9.3
mm. Average width at mesothoracic segment 2 mm.
The anal proleg is usually 1 mm. in length and the caudal appendages are about
twice as long and taper gradually to the tips.
Color jet-black above; legs, antennse, and mouth parts dark mahogany brown. If
placed under a lens the body appears very dark brown, and the legs and mouth parts
are of a somewhat lighter shade. Joints of antenne, palpi, legs, and underside of body
of a pearly color, except chitinous markings, which are jet-black. General outline
of body fusiform. Antennz longer than mandibles; maxillary palpi nearly as long
as antennee, tapering to tip of last joint; labial palpi stout, last segment cylindrical,
truncate; prothorax wider than long. Second abdominal segment as wide as the first,
body tapering quite abruptly beyond the fifth abdominal segment. Body provided
with rows of lateral and ventral spines. Legs spiny. Caudal appendages bearing a
few spines.
SECOND-STAGE LARVA.
Average length 15.5 mm. Average width 3.4mm. Much stouter than first-stage
larva. Body shining jet-black, mandibles and legs mahogany-brown, mouth parts
lighter, nearly honey-yellow, dorsum of last abdominal segment and tip of proleg light
INVESTIGATION OF LIFE HISTORY. OT
brown. Caudal appendages relatively shorter than in preceding stage, each provided
dorsally with a stout but short protuberance on its inner third, which bears a stout
bristle.
Tairp-STaGe LARVA.
More robust than in previous stage. Average length 25.8 mm. Average width
5.7 mm. Body shining black in color, mandibles, legs, mouth parts, antenne, and
lateral and ventral abdominal markings dark brown. Prothorax much wider than
long, wider behind. Dorsum of last abdominal segment and anal proleg chestnut-brown.
Dorsal abdominal plates nearly truncate behind, lateral margins of each raised and
thickened. These margins more prominent on the last three segments. On the
penultimate segment, each dorso-lateral margin forms a stout, blunt, overhanging
fold, while on the last segment each margin is drawn out into a stout tooth, pointing
backward.
Median dorsal line prominent on all segments except the last. Caudal appendages
short, quite erect, with a large, stout dorsal tooth, and a small lateral tooth, both of
which are provided with spines.
THe Process or Motrtina.
The larvee are active and feed voraciously; during this time their
bodies are greatly distended and the white portions of the integument
render the insect quite conspicuous. Just before the molting begins
they become sluggish and do not move about unless disturbed. The
body shortens and becomes thicker than normal. By moving the
head and posterior end of the body downward and toward each other
at regular intervals the integument is ruptured along the dorsal line
of all the thoracic segments. The head, mouth parts, and legs are
gradually withdrawn and a pure white larva crawls from the old skin.
Usually the sutures on the top of the head are broken as the larva
makes its escape. The molting process requires but a few hours, and
this is fortunate, as the larva is practically helpless while the trans-
formation is being accomplished.
In nature the larve often molt under litter on the ground, but
when they are feeding on caterpillars on the trees molting takes place
in holes or cavities in the trees, among masses of gipsy moth pups, or
even in crevices of the bark. It is probably true that many of the
larvee pass through the two molts without descending to the ground.
LenerH or TIME IN LARVAL STAGES.
The duration of time between the molts is influenced greatly by
high temperatures and food supply. In the spring of 1908, careful
records were kept of a number of larve which hatched from eggs
deposited by beetles that were removed from hibernation in March
and early April. One of the objects of the experiment was to deter-
mine the length of time required by larve that hatched early in spring
to pass through their transformations, and further, to determine the
possibility of such larve developing a brood of beetles which would
become active and reproduce during the summer. A considerable
28 CALOSOMA SYCOPHANTA.
number of individuals in the experiment died owing to a scarcity of
food and other causes, but the following nine records give the length
of time which was spent in each larval stage and this may be con-
sidered as approximately correct for larve that hatch early in the
season when the weather is cool and the food supply is somewhat
restricted.
From the foregoing experiments data were secured regarding
the length of time in each larval stage.
TaBLe 1V.—Record of time passed in different stages by larve of Calosoma sycophanta
hatched from eggs laid by beetles taken out of hibernation in March and April.
4 E 4 Third
, irst- econd-| stage
No. hepa’ stage stage (until
*) larvee. larve. | finished
feeding).
1908. Days. Days. Days.
LAY We foe a ote aig SE ee one ei ees See SS 2 May 23 6 5 18
TODAS © 2 Se soe, «bide ais maine a stow ters BES EO OO Oe duos pee cee ae May 24 8 2 19
ODAC: Ser Sees ee oaks tee St eet eee eee eer eee May 25 7 4 15
TGA: tae Os fe ADE EISey Coane’ Satie eens ae ies he nck May 26 6 9 13
FOE ee Re Ne SO SS ie ey i re a ee ea May 27 6 8 15
TOS ATL. 202 Sted ate eo eee eae eee ee ee ee ee G0:eee 5 7 16
CNM oy 250 hoe Sania ep Ne Pr ke ee a 2 ator soe 5 8 14
NOGA Msne a SNS 52 Mom tdon eee eek Ee ee ee ee | May 28 | 4 8 14
TG AS PES oS age ct ee NE OOS Serer ae re |..-do a 4 8 15
Average length of time in each stage: Days.
Wirstianvalstage <2 .5- sseco.- saeee a eee 53
Second larval stage 63
Mhirdionfeeding Saves. s— se snes ee eee 14}
Total time larve fed 264
In order to check up this experiment and to determine the differ-
ence in time required for larvee to develop during hot summer weather
when food is abundant, another set of experiments was carried on
with larve that hatched on June 20 and the results are tabulated as
follows:
TaBLE V.—Length of time passed in different stages by larve of Calosoma sycophanta
developed from eggs laid by beetles that emerged normally.
z Third
First- econd- stage
No. . oes stage stage (until
‘i ‘}) larvee. larve. | finished
feeding).
1908. Days. Days. Days.
GAL a oho oe eas oe ee ct Se oot Ei a ee eee oe ee June 20 2 3 9
(fil ne ee ee eee eee Caen ae. Mee ay ie Oese a= 2 3 9
iif Aikl eee eens Gore ete ee kes 2a RCE ests ge Meee) OC al LID. oe © (ols Naoe 2 3 9
FUL Cah a eled ES og ee eS ee Oe re Be Se dos" 2 33 7
TULELER, oe eet Bt AS eR een hays eh ep Ol ee eee do: .i*: 2 3 9
Wee oe SP Le BESS chin tee, Mee eee meanere® en a Oa ot ae aa dora 2, 3 9
7 ict er ere eee pene pss ae et A SF eee Sen i ck ob Goze 2 3 9
Cif CR eee eee ae nS Se: ey SY ol ee yee ee Sassy sce (ones 3 2 9
Tis 22) Se Bm Sele oe ee ene aoe Soe ee eae dose 2 3 9
17h) oe eee Seem 82 ae ee eee Se eos doles. 2 3 9
CULO 2 3 Pa? ie ete Be ee > te ee ee See a ee ae do 2 3 9
TINO sons co Scie s Sew Bea Se SEE Lary Aa ee dois | 2 3 9
Average length of life in feeding stages: Days.
First larval/stage.oco sesh on dhatcs Beet oe eels Oe ee ee ae 2) ae ee 2
Second larvallstage-:. 22-2... 8255 Se eee Se ee Se ee eee Seen eee 3
Third: larval stage... ic 2232662 s.5 os ie orc ee ee 9
INVESTIGATION OF LIFE HISTORY. 29
An examination of this table shows that larve hatching late in
June transformed much more rapidly than those noted in Table
IV, the difference in the total average length of time being 124 days.
Similar records based on a few experiments have been secured from
larve that hatched at the laboratory late in July or during the first
few days in August. The length of time spent in the larval stages
was longer than the time required for the larve hatching in June.
This is partly due to the difficulty of furnishing an ample food supply
in August.
Time or APPEARANCE OF THE LARVA.
The date of the first appearance of the larva of this species in the
field, of course, differs from year to year, depending on the season,
and in colonies that have been liberated larve are seldom found
as soon as the first ones hatch and begin feeding. The records of
this investigation are rather fragmentary because of the relatively
small number of adults that have been liberated in field colonies
since the work began, and owing to the difficulty of making frequent
examinations of any given colony and searching thoroughly enough
to find the small larve. The earliest field records, however, are as
follows: 1907, July 17; 1908, June 29; 1909, July 7; 1910, June 27.
It should be stated that the first larvee found in 1907 were nearly
full grown, which explains partially the reason for their being found
so late in July, although the season was not so early as that of the
two following years. The latest records which we have of finding
larve in the field are as follows: 1907, August 7; 1908, July 8; 1909,
August 3; 1910, August 2. In the laboratory, where food was more
abundant in early June and during the month of August than in the
field, it has been possible to rear larve over a longer period of time.
Aside from the food problem it has been possible to control to some
extent temperature and moisture conditions, so that the time during
which feeding experiments have been carried on has been prolonged.
HABITS OF THE LARVA.
Larve of this species secure food by searching for the caterpillars
and pupz of various lepidopterous insects. Undoubtedly some of
those attacked are found on the surface of the ground or beneath
leaves or litter, where they have sought shelter either for protection or
pupation. The larvee of this species, however, in addition to feeding
in such situations are able to climb trees and devour their prey upon
the trunks or branches. To this extent they may be considered
arboreal in habit, although they are seldom found in any great
quantities on trees which have smooth bark, as it is quite necessary
for them to travel over uneven surfaces in order to secure a sure
30 CALOSOMA SYCOPHANTA.
footing. Not only do the larve secure a part of their prey in the
trees, but they molt in crevices of the trunks and branches to a con-
siderable extent. This habit is so general that it has been possible
to determine quite accurately the dispersion of the species by exam-
ining trees for molted skins outside the areas where colonies have
been liberated. This work can be done even after all larve have
entered the ground for pupation, so that the time when satisfactory
investigations can be made extends over the greater part of the
summer. Trees in the gipsy moth infested sections which have
been burlapped are favorite resorts for the Calosoma larve, as they
find plenty of food available and are protected in a large measure
from enemies that might destroy them. (See Pl. VI.) To determine
the distance that larve of this species will climb, the following
observation was made at West Gloucester, Mass. July 30, 1908,
a number of larvee was liberated in woodland and several were
placed at the base of a red oak tree about 10 inches in diameter.
Two of these larve immediately commenced climbing the tree.
One ascended to a distance of about 10 feet and as no food was present
it retraced its steps and returned safely to the ground. The other
continued its journey up the tree. At a distance of 15 feet from the
ground the bark became very smooth and offered little opportunity
for the insect to obtain a safe footing. It continued to climb, how-
ever, until it reached a point about 25 feet from the ground, where
it lost its hold on the bark and fell. There is no doubt that
these larve often climb nearly to the tops of rough-barked trees,
particularly white oak, in search of food. Several cases havé been
noted where molted skins were found at least 20 feet from the ground,
and they have been observed in masses of pupee on the underside of
branches near the tree trunk. The climbing habit of the larve is of
great importance, as it increases the opportunity for the development
and usefulness of the species.
DisTaNceE TRAVELED BY THE LARVA.
Inasmuch as young larvee of this species must be able to find suit-
able food in order to develop, the question of their ability to travel is
one of great importance. It seemed desirable to test this matter and
plans were made and apparatus constructed for the purpose. |oj
| Number. Eggs a Gtoannt
Large females......... Sich Sots Aaa EO bic ack Se Pe Ak ete SO oe | 15 | 3,848 | 256. 5
Shag EN AUT Grrr ks LCE eS el ee EET 0 ARAM ETERS SS AR Ie | IL | 1,846 168
This indicates that more eggs are normally developed by large
females than by small ones.
It was desirable to determine, however, if the size of the males had
any relation to the number of eges produced, for if this were true the
reliability of the data above given might be open to question.
Accordingly, typical data were secured from 9 males and 9 females
which had been mated according to size, and are as follows:
| | aa
} | Average
Eggs de-|} m4. :
| ; e
Tuy nurse Lave ns (IU Eeren (ohn to Lg ee pe eB de a { an \ 704 352
| onn |
miele esos mre nerinle@s =e bee ot ee ee co eat. ow uns temees { an \ 542 271
Siegel! rest vete yeaa UM (2) ert (ee ae a ee { td \ 364 182
134
Large male and small female.............-........-- Ser ok oe Sine Rack et 207 426 142
85
This indicates conclusively that the size of the males is not an
important factor relative to the number of eggs that the females will
produce, and although there is quite a wide variation in the number
of eggs laid by either large or small females, it demonstrates that
large females will lay more eggs even when mated with a small male.
Sexes or Beertes REARED.
In order to determine the proportion of the different sexes of
C. sycophanta reared from eggs laid, a careful record was kept of the
sexes of the beetles that emerged in the spring of 1909 and 1910.
Of 71 beetles that were secured 39 were males and 32 were females
(1909).
Of 512 beetles that were secured 261 were males and 251 were
females (1910).
This indicates that under laboratory conditions practically the same
number of each sex is reared.
64 CALOSOMA SYCOPHANTA.
EXPERIMENTS IN CROSSBREEDING CALOSOMA SYCOPHANTA AND C. SCRUTATOR.
During the summer of 1910, Mr. Collins conducted several experi-
ments to determine whether these two species would interbreed.
The beetles are of nearly the same size and it seemed worth while
to determine whether this would occur in the field.
June 20, 1910, one male C. sycophanta, received from Europe in
1909, was placed in a jar with a female C. scrutator which was col-
lected in Washington, D. C.,in 1909, and hibernated here the following
winter. The male emerged from hibernation June 1 and the female
June 5. June 21, 8.30 a. m., Mr. Culver noted that the pair had been
attempting copulation for the last half hour. At 8.40 a. m. the male
succeeded in his attempt at copulation and remained in coitu until
8.43. June 22, 2.48 p. m., Mr. Culver again observed the pair in
copulation, and watched them for 7 minutes before they parted.
June 23, 1 small egg was found, and on June 25 several eges were
noted in the jar. July 12, none of the eggs had hatched. Jar cleaned
out. July 25, the male sycophanta was removed from the jar, and
a male scrutator added instead. July 29, female scrutator died. No
egos were laid after the male scrutator was added.
Another experiment was Conducted as follows: June 16, 1910, a
female sycophanta emerged from hibernation. The cage was dug up
on June 23, but no male was found. The pair were pupe in the
fall of 1908 and the female did not reproduce in 1909. June 23,
a male scrutator was added which was collected at Onset, Mass.,
August 3, 1909, and brought to the laboratory. This male was kept
in a jar with one female which produced 22 larve that year. Infertile
eggs were seen in the jar containing the female sycophanta on the
date the male was added, but the latter paid no attention to the
female. June 27, infertile eggs in jar; jarchanged. June 28, infertile
eggs in jar; jar not changed. June 29, infertile eggs in jar; jar
changed. June 30, 2 p. m., the male attempted copulation with
female sycophanta three times but was unsuccessful, although the
latter stood quietly and attempted to facilitate the operation as much
as possible. July 1, 2, 3, 4, and 8, eggs on surface; jar changed.
July 9, male scrutator died. Male sycophanta added, copulation took
place immediately, and on July 14 larve hatched from the eggs
deposited in the jar.
In the above experiments with the two species, copulation was
attempted and unions effected apparently with difficulty, but all of,
the eggs were infertile.
Hasits or Fuieur.
Few notes have been secured on the flying ability of this species.
In the colonies the beetles have been frequently seen running about
or climbing the trees, and they often drop from the branches to the
ground without making any effort to fly.
INVESTIGATION OF LIFE HISTORY. 65
Specimens confined in cages or jars have been observed to vibrate
the wings rapidly. This is usually done soon after the beetles emerge
from hibernation or toward evening.
A large cage of the native species, C. scrutator, was kept under
observation one evening in June, and after twilight the beetles flew
about the cage freely. This habit is well developed in this species,
as the beetles are frequently taken at electric lights at night, in
localities where they are abundant.
Apparently sycophanta must have the ability to fly, or the disper-
sion of the species in the field could not have been so rapid as is
shown later in this report.'
ATTRACTION OF THE ADULTS TO LIGHT.
As has been already noted, C. scrutator is frequently captured at
electric lights. This does not often happen in New England, as the
species is comparatively rare, but at Washington, D. C., and farther
south, specimens can be commonly secured at are lights durmg May
and June.
Calosoma frigidum has this habit to some extent, as 2 males were
captured at light traps at Reading, Mass., June 22, 1910.
Several observations have been made at electric are lights located
near colonies of C. sycophanta, but thus far no evidence has been
secured which indicates that the beetles are subject to this attraction.
Lights near a’strong field colony at Oak Island, Revere, Mass., have
been under observation when time permitted. No reports have been
received from any of the field men that the beetles have been found
at lights.
DrRowNING EXPERIMENTS WiTH BEETLES.
March 17, 1910, cages containing frozen earth were dug up, and 2
male beetles were removed from their cavities and put in a jar of
water. At 11 a.m. the jar was placed in the laboratory ice chest
and kept at a temperature of 39 degrees F. Some pieces of cloth
and two small blocks of wood were put in the jar with the intention
of keeping the beetles submerged, but at 5.58 p. m., when an exami-
nation was made, both beetles were found swimming about in the
water. They were again submerged by placing a quantity of blot-
ting paper inside of the jar, but on the following morning they had
succeeded in making their way to the surface. A wooden float was
then constructed which was placed in the jar in such a manner as to
keep the insects under water. They were kept in this position 4
days , although every 12 hours they were taken out and examined
1 During the last few days of May and the first part of ioe 1911, both sexes of wocurtaenta: were
observed to fly freely in the field. This was shortly after emergence from hibernation and the beetles
probably do not fly freely later in the season.
100834°—Bul. 101—11——5
66 _ CALOSOMA SYCOPHANTA.
to see if they showed signs of life. At the end of this period, as they
were apparently dead, they were removed, but in less than an hour
they revived sufficiently to begin feeding on cutworms.
This experiment shows that beetles of this species can live for at
least 4 days and probably longer, if submerged in water a few degrees
above the freezing point.
March 17, 1910, several small wire cages, used for feeding larve,
each of which contained a newly formed beetle, were dug up and
submerged in a tub of water to see if the insects would survive this
treatment. There were several inches of frost on the top of each cage,
and the temperature of the water was about 39° F. March 18, at
8 a.m., 1 female had emerged and was clinging to the wire just above
the water. An examination of the earth in this cage showed that
the hibernation cavity was about 6 inches deep and as soon as it
thawed out the insect made its way to the surface of the water.
Another cage was examined after it had been submerged 24 hours
and a living beetle was found 34 inches below the surface of the earth.
The cage was replaced and removed later in the day and it was found
that the beetle had worked its way to a point a half inch below the
surface of the earth. It appeared dead but on removal soon revived.
At the end of 48 hours another cage was examined, and a live beetle
found 34 inches below the surface of the earth. This cage was re-
placed and on the following morning after it had been submerged for
24 days the beetle was found on the surface of the water.
The last cage was opened at the end of 4 days, and an active female
was found in the earth which was now very compact. The beetle
was replaced in the mud and the cage submerged, but at 3.10 p. m.
came to the surface of the water after having remained beneath it
4 days and 2 hours.
These experiments indicate that this species is able to withstand
excessive amounts of moisture and that in the spring when lowlands
are flooded the majority of the insects will survive, apparently with-
out serious inconvenience.
On March 21 a female Calosoma beetle that had been submerged
for 4 days and 2 hours was placed in a tub of water and floated about
on the surface. It seemed desirable to ascertain how long the insect
would remain alive and float when the water was maintained at about
39° F., and also whether it was able to make any progress in swim-
ming. During the first hour and fifteen minutes the insect swam
a distance of 22 inches. It rested on the water very easily, less than
one-half of the body being submerged. The legs were moved con-
tinually, but its progress was very slow. This beetle remained in
the tub of water 15 days and at the end of that period was removed
for dead. In a few hours it revived and began feeding, and was used
later in the summer in rearing experiments. This shows that in the
INVESTIGATION OF LIFE HISTORY. 67
spring beetles of this species might survive several days if they should
fall into ponds, and that they would probably float with the currents
and might be distributed quite a long distance in this way, especially
if they fell into streams or rivers.
Leneru or Lire or BEETLES.
Unlike most species of insects, such beetles of the genus Calosoma
as there has been an opportunity to study are, as a rule, able to sur-
vive two winters and carry on active warfare against caterpillar life
during two summers.
With species whose length of life extends over such a long period
it is difficult to secure normal data if they are closely confined, and
although the laboratory experiments show that Calosoma sycophanta
usually hibernates two winters and sometimes more, it is probable
that under normal field conditions even greater length of life could be
reasonably expected. An abundant food supply naturally stimu-
lates the activities and reproductive capacity of the species, and
where such conditions prevail, the insects exhaust themselves more
rapidly, and the length of life of the adult is therefore somewhat
curtailed. Such evidence as is at hand seems to show that if for
any reason the food supply is scanty the majority of the beetles are
able to survive, although their activities and rate of reproduction
are materially decreased.
This bears out the observations which have been made at different
times on native species of Calosoma which have been found very
abundant during local caterpillar outbreaks, although previously
they were considered somewhat rare.
The tables which follow give a summary of the data secured on
the leneth of life of adults fed in captivity at the laboratory. Speci-
mens received from Europe enter into this computation to some
extent, but of course it is impossible to determine with any degree
of accuracy the length of life of such insects, as their previous history
is unknown.
A record is given of the length of life of seven examples, 3 males
and 4 females. These, with several others, pupated in the fall of
1907, but the others died, chiefly because unsuitable hibernation
quarters were furnished during the first winter.
Of the 4 females noted above, all of which were supplied with males
during the summer of 1908 and 1909, 1 fed during the summer of
1908, laid no eggs, and died in hibernation during the winter of
1908-9; 2 fed during the summers of 1908 and 1909, laid eggs the
latter summer, and died August 10 and 26, 1909. The remaining
female fed during the summers of 1908, 1909, and 1910, laid eggs the
first and third summers, hibernated three winters, and died August
1, 1910. Of the 3 males, all of which were placed in jars with
68 CALOSOMA SYCOPHANTA.
females each summer, 1 fed during the summer of 1908 and died in
hibernation during the winter, while the other 2 fed in 1908 and 1909
and died in hibernation cages during the winter of 1999-10.
To summarize, 1 male and 1 female lived one summer and died in
hibernation; 2 females died at the end of the second summer; 2 males
lived two summers and died in hibernation the third winter; and 1
female lived three summers and hibernated three winters. |
The record of a female received from Europe in July, 1907, is of
interest as it shows what may happen im nature if the conditions
are favorable. This female was kept in a jar with a male after
receipt, but laid no eggs and went into hibernation in the fall. Dur-
ing the following summer she was isolated in a jar contamimeg earth
and supplied with food. The beetle survived hibernation and many
infertile eggs were deposited during the winter of 1908-9. A male
was supplied during the summer of 1909, durmg which time 106
fertile eggs were deposited, and the female died July 20.
From the time of receipt until the date of death 2 years and 11
months elapsed, and this insect must have spent one winter in
hibernation in Europe and perhaps more before being collected for
shipment. In other words, the insect must have lived at least three
summers and passed three winters in hibernation.
Among the beetles received from Europe in the summer of 1908
were 3 pairs from which were secured the followmg imteresting
records concerning length of life.
TasLe XVIL.—Longevity of 3 pairs of Calosoma sycophanta received from Europe during
the summer of 1908.
==
| Eggs laid in—
No. | Mate.| Fe
No. les ales! yale.| sae — — Remarks.
| 1908 | 1909 | 1910
Sen |) el 0 0| 2388 | Female died Aug. 8, 1910.
1592H 2 2 0) 0 | 392 | Females died July 25 and Aug. 13, 1910.
The females in this table failed to lay eggs until the second summer
after receipt, and as soon as this was done they died. The length of
life in each case was at least 3 full years. The imported males did
not live so long, but their age at the time of receipt was unknown.
The table which follows gives data on the length of life of beetles
which were reared in the summer of 1908. Each experiment was
closed as soon as the female died, and in case the male died another
specimen of the same age was added; hence more males than females
are accounted for in the table.
INVESTIGATION OF LIFE HISTORY. 69
TasBLE XVIII.—Longevity of 10 pairs of Calosoma sycophanta reared during the summer
of 1908.
Eggs laid
Fe- in—
No. | Male.) note,|_ Hibernation, 1910-11. Remarks.
1909 1910 | 1911
1735 1 1 Os U79! |e] Maleentered Aug. 26,1910, died.| Female died Aug. 16, 1910.
1736 1 1 0 18 26 | Male and female entered July | Male died in hibernation in 1909,
28, 1910. replaced; beetles died Aug.,
1911.
1743 1 1 38 | 0 53 | Male and female entered July | Female died July 31, 1911; male
26, 1910. died Aug. 12, 1911.
1771 1 1 0! 0 mp leur “skates. Sear oy eRe = Female died July 6, 1911; male
died July 31, 1911.
1775 1 1 0 Lo] et) Des CLO afar ern ss en he Se Male died July 5, 1911; female
| died July 11, 1911.
2705 | 1 1 Ov Peo lOn eee eee el foes em ee oat Female died Aug. 3, 1910; male
died Sept. 2, 1910.
2728 1 1 QU eee les. cA Wootters ia. Bae eek eae oe st Male died June 21, 1909, replaced;
female died Aug. 14, 1910.
2729 |..... 2 0 0 | 332) 1 male and 2 females entered | Two males added in 1909; one
| July 28, 1910; male died. died July 8, 1910; one female
died Aug., 1911.2
12775 | 1 Pale lo Gul eae |= 2. scelee tere ne = on crce Seo si at ser Female died July 10, 1910.
1 Age of aS this ecient ae econied
2 Second female deposited eggs August 12, 1911.
Of the females listed in the table, 3 lived two summers, 5 died at the
end of the third summer, and one is still living and ovipositing (Aug.
12, 1911). None of them laid eggs more than two seasons and some
of them only one.
Of 10 males 4 died at the end of the first year or during the hiber-
nation period following it, 2 died the second summer, and 4 the third
summer.
These experiments indicate that, on the average, there is little dif-
ference in the length of life of the males and females. The latter com-
monly live two summers, and if the full number of eggs has not been
deposited at the end of that time they continue to live until this
result is accomplished, provided a sufficient food supply is available.
RELATION OF CALOSOMA SYCOPHANTA TO NATIVE SPECIES OF THE SAME
GENUS.
The native species most closely resembling Calosoma sycophanta are
C. scrutator Fab. and C. willcoxi Lec.
C. scrutator is more common in the central and southern part of the
United States, and occurs somewhat rarely in the latitude of Boston,
Mass., and farther north. It is a larger species than C. sycophanta;
the green elytra are margined with a purplish band, and the thorax
has a shiny copper-colored margin on all sides. These color markings
distinguish it from C. sycophanta.
C. willcovi is also a southern species but is occasionally found in
Massachusetts and might be mistaken for a small specimen of C.
sycophanta. It differs, however, in having color markings on the
thorax and elytra similar to C. scrutator.
70 CALOSOMA SYCOPHANTA.
NATURAL ENEMIES OF CALOSOMA SYCOPHANTA.
During the summer of 1906 the remains of several dead Calosoma
beetles were found under conditions which would indicate that the
insects had been killed by some predatory enemy. In fact, one
report reached the laboratory that a hairy woodpecker had been
observed feeding on C. sycophanta. The locality where this observa-
tion was made was visited by Messrs. Titus and Mosher, and wing
covers and fragments of legs and bodies of the species were found under
a pine tree. Nearby was a nest of young crows, and it is probable that
they were responsible for the trouble.
Tt is a well-known fact that crows feed on various species of carabid
beetles, and specimens of native Calosoma have been found in the
crops of these birds by various investigators, so that it would not be
strange if they destroyed some of the imported ones.
In the fall of 1909 a report was received that birds, presumably
crows, were destroying the beetles, as a number of fragments of the
latter had been found on the ground in woodland near North Saugus,
Mass. No absolute evidence was secured to prove that this was the
case.
During the summer of 1910 Mr. H. 8. Barber observed that several
crows seemed to be loitering about in a locality where the larvee of
C. sycophanta were common under burlaps. None of the birds was
seen in the act of feeding but the persistence which they exhibited in
frequenting the locality aroused the suspicion that their mission was
not a friendly one.
During the summer of 1907 all the dead Calosoma beetles that
arrived in the shipments were isolated to determine whether parasites
of any kind would develop, and of 584 beetles which were treated in
this way, not one showed evidence of parasitic attack and no parasites
were secured.
In rearing Calosoma beetles it is always necessary to guard against
the accumulation of dead or decaying material. If such matter is
permitted to accumulate in the rearing jars, the earth soon becomes
infested with mites, which later attack the larve, or even the adult
beetles. Probably in nature these insect enemies of the beetles do
them no harm, as the conditions are not favorable for the increase of
the mites.
During the summer of 1908 several jars became badly infested with
a species of mite which was determined by Mr. Nathan Banks, of this
bureau, as Tyroglyphus armipes Bks. The beetles were treated with
carbon bisulphid, a small amount being applied with a brush to the
underside of the thorax and abdomen, where the mites attach them-
selves most frequently.
The beetles survived the treatment perfectly, and after it had been
repeated once or twice all the mites were destroyed. Several beetles
COLONIZATION. 71
were freed of the mites by repeatedly scraping them with a small
knife and brushing them with a small stiff brush.
Larve are more seriously injured by mites, and if attacked to any
ereat extent will die either before or after pupating. This happened
in several instances, and shows the necessity of keeping the jars as
clean as possible.
In the spring of 1910 several young Calosoma beetles emerged from
hibernation cages but died in a few days. An examination showed
that the insides of the bodies were badly decomposed, and a large num-
ber of nematode worms was present. These beetles had been reared
from larvee late in the summer of 1909, and some of the lot were fed
on gipsy moth pup that had been kept in cold storage and when
removed were partially decomposed.
There was a considerable number of these pupx in the cages late
‘in the summer, and whether the nematode worms are able to feed
upon them is not known. The death of the beetles may have been
due to entirely different causes, and it is doubtful, judging from our
experience, whether these insects are seriously injured by nematodes
under field conditions.
A larva of Carabus monilis Fab. which was attacked, apparently, by
the same trouble was sent to the Bureau of Plant Industry for determi-
nation, and on careful examination Dr. N. A. Cobb reported that two.
new species of nematode worms were present, viz, Rhabdites calo-
somitis and R. diplopunctata. He is inclined to believe that these
worms were introduced from Europe with the beetles, and that they
may be injurious. Inasmuch as the specimen attacked was one that
was reared from eggs deposited at the laboratory, the chance of the
parasite having been introduced from Europe is somewhat remote.
COLONIZATION OF CALOSOMA SYCOPHANTA.
As has been previously stated, the first importations of this beetle
that arrived in good condition reached Massachusetts in the spring of
1906, and from the number of specimens received it was possibie tor
Mr. Titus and Mr. Mosher to liberate several colonies that spring. The
method followed was to put out from 30 to 50 Calosoma beetles in a
locality where gipsy moth caterpillars were plentiful, and during the
season six colonies were liberated, and 389 beetles were used for this
purpose. No attempt was made to determine the sexes of the beetles
liberated, and the colonies were placed in the towns of Saugus, Malden,
Winchester, Burlington, and Lynnfield, Mass.
In the early summer of 1907 the beetle importations were cared for
by Mr. Mosher, and one large colony of 331 specimens was liberated
early in July in a badly infested woodland directly north of the old
parasite laboratory at North Saugus. Later in the season, after the
beetle work had been taken up by the writer and Mr. Collins, a few
79 CALOSOMA SYCOPHANTA.
other colonies were released. A stock of beetles was added to one of
the Lynnfield colonies that had been liberated the previous year, and
new colonies were put out at North Woburn and Peabody. The first
lot of beetles placed in the North Woburn colony was on July 31,
which was late in the season for effective work, and on August 2 more
beetles were added to the colony, making a total of 50 males and 50
females for this liberation. The colony in Peabody consisted of 25
males and 25 females, which were released August 28, 1907.
Tn 1908 less than 700 live beetles were receed oo Europe; hence
only a small number of adult colonies could be liberated. Experi-
ments were carried on, however, in rearing the larve of this species
at the laboratory, and as a result of this work it was possible to liberate
2,300 larve in field colonies during the breeding season. The gen-
eral plan of liberation was to place all the colonies in badly infested
sections, where plenty of food was available, and where the insects
would be disturbed as little as possible by hand methods of suppressing
the gipsy moth. Several colonies were liberated on estates, and in
some cases active hand suppression methods were carried on in order to
prevent defoliation by the gipsy moth caterpillars. In a few imstances
the trees were heavily sprayed, and, although this was not in accord
with the intention when the plantings were made, it gave an oppor-
tunity for securing data on the ability of the insects to survive in case
they were handicapped by spraying or other control measures. A
few small colonies were also liberated in York County, Me.
In 1909 the work was continued along the same lines, but a larger
number of larve was planted in field colonies. It might be added
that a single colony was liberated in the fall of 1909 at Sandwich,
N. H., the reason for this being that while no gipsy moths had been
found in this town, the maple, beech, and other forest trees were suffer-
ing from a severe outbreak of Heterocampa guttivitta Walk., and it
was thought advisable to release a colony for the purpose of deter-
mining whether the insects would be able to survive at that northern
latitude and do any considerable amount of good in reducing the num-
ber of these caterpillars.
In 1910 this work was carried on in much the same way, but an
effort was made to liberate colonies in towns where none had been pre-
viously placed, providing, of course, that suitable localities which were
badly infested could be secured for the purpose. The result of this
policy has been that practically all the towns in Essex, Middlesex, and
Suffolk Counties, and a few in Norfolk, and a single one in Plymouth
County, Mass., have been supplied with one or more colonies of the
Calosoma beetle.
In the first larval colonies from 75 to 150 or 200 specimens were re-
leased, but since that year it has been the practice to put out not less
than 200 specimens in a colony, unless some of the adult beetles are
COLONIZATION. TD
liberated at the same time, and in this case the number of larvee lib-
erated is often reduced one-half.
The method of liberating field colonies of Calosoma beetles has de-
pended on whether adults or larvee were to be planted. When adults
were used, they were taken to the area selected and scattered about
among the badly infested trees.
More care was required in distributing larval colonies as it was neces-
sary to pack the larve separately so that they would not injure each
other before they were turned loose.
In 1909 the larve were placed separately in glass tubes, both ends
of which were plugged with cotton. Before inserting the last plug, a
Fic. 21.—Two hundred tubes, cach containing a larva of Culosoma sycophanta, ready for coloniza-
tion. (Original.)
small amount of earth and sometimes a caterpillar or pupa was added
with the beetle larva: These tubes were packed in a basket and taken
to the place where the colony was to be liberated. (See fig. 21.) On
arrival the contents were dumped at the base of infested trees and the
tubes returned for refilling. Frequently the tubes became broken an
handling and transit, and occasionally some of the larve made their
way through the cotton plugs and escaped.
In 1910, a better device was used (fig. 22), which consisted of sev-
eral units of wood in which was bored a double row of 10 holes, so that
each block would accommodate 20 larve. The bottom of the block
74 CALOSOMA SYCOPHANTA.
was covered with fine-mesh copper wire to provide air, while on the
top a sliding cover was arranged so that the holes could be closed as
they were filled. Ten of these units were strapped together and were
convenient to carry, and the colony (200 larvee) which they contained
could be liberated very rapidly by withdrawing the cover, inverting
the unit, and giving it a sharp rap to shake out the insects.
Table XIX “Shame the number of living beetles imported and the
number of beetles and larve colonized since the work began. —
Taste XIX.—Number of living Calosoma sycophanta imported: and number of beetles
and larve of Calosoma sycophanta colonized.
Col- Reared and col-
: oe onized onized.
“ear. oe from
ceived. | importa-
tions. Adults. | Larvee.
MO ee wae Stare ate ar esc fm Canes eee eS RTE ere Se eee et 693 369 te al eee eee
1S Fc Se Rae OR ony oe g iy ooh cee Petit MEL SIS ORC RE RC Biel See my Res 5 967 O78 eee aes eee
HOUR 8 oes a hes Chics awe Se Rt ys ite I ce te Se ere ene ee ee 675 430) heite eee 2,300
AGO he at POS Eee SSeS Se ee eee eee eee 405 250) se nee 6, 100
LOL O Se ee oe cea Bae an eee eee Bene a eee Ele 1,305 1,064 452 6,380
Notal i222 Sse es oa DiS Rese eee gee ce ee ere aes 4,045 ,7ll 452 14,780
Fig. 22.Three ‘‘sets,”’ each containing 10 units, each unit holding 20 Calosoma lary in separate
cells, so that each set contains 200 Calosoma laryee or enough fora colony. (Original.)
During 1906 and 1907 the number of Calosoma beetles liberated
was comparatively small and the following two years only a moderate
number was colonized. It should be borne in mind that the present
condition as regards the abundance and dispersion of this species in
the field is due to the colonies liberated during the first two or three
years rather than to those which have been planted since that time.
Attention should be called to the fact that nearly as many beetles
METHODS OF SECURING DATA FROM COLONIES. 75
were liberated during the summer of 1910 as had been released in all
the previous years. This does not hold true in regard to the number
of larvee liberated.
Two years or more will be required before any accurate figures on
increase in the colonies planted in 1910, or spread from them, can
reasonably be expected. The information already given concerning
the reproduction of new and old beetles bears directly on the condi-
tions which exist in field colonies. If the beetles liberated in 1906
and 1907 reproduced at the normal rate, the progeny from these col-
onies should show far greater increase and dispersion than the beetles
more recently liberated, and that this is the case will be brought out
in the following pages. On the other hand, colonies consisting of
larve, or beetles reared from larve, can not be expected to show any
great increase for the first year or so, because young beetles ordinarily
oviposit sparingly.
_ Owing to the fact that Calosoma sycophanta has been able to sur-
vive for a number of years under field conditions and that reproduc-
tion and dispersion have been going on at a satisfactory rate, as deter-
mined by observations made during the past four summers, it has been
considered inadvisable to make further importations of this species,
for the reason that if it is necessary to liberate more colonies aside
from those that can be supplied from the material now being held at
the laboratory, it should be possible to collect sufficient quantities
in the field for the purpose.
METHODS OF SECURING DATA FROM FIELD COLONIES.
Since the work began it has been of the utmost importance to
determine actual conditions in the field and to find out whether each
introduced species was surviving and reproducing. During 1907
numerous visits were made to the colonies which had been liberated,
but little of importance was found until about the middle of July,
when Mr. L. S. Winchester, who had been employed for a few weeks to
take up this particular work, fourid Calosoma beetle larvee under the
burlaps on trees where a colony had been planted in Burlington, Mass.
This, of course, showed that the beetles had successfully hibernated
during the winter and reproduced, and was a very encouraging sign.
Later in the month several larve were found in the Saugus (Mass.)
colony and a single larva was found in one of the colonies at Lynnfield,
Mass., so that at the end of the season it was known definitely that
three of the six colonies liberated in 1906 were well established in the
field.
During the examination of the colony liberated by Mr. Mosher at
North Saugus, Mass., in July, 1907, it was discovered, contrary to
expectations, that the larve of this species climb the trees and feed
upon the caterpillars and pupe of the gipsy moth found on the trunks.
76 CALOSOMA SYCOPHANTA.
It also became apparent that many of the larve passed through the
molting process on the trunks of trees, under burlaps, or among
masses of caterpillars or pup of the gipsy moth. Later observations
showed that this was a quite constant habit and in the years which
followed it was made use of repeatedly as a means for determining the
dispersion of this insect.
In 1908 plans were made to follow up the colonies more closely than
had been done the previous year, and as the larvee of this species had
showed an inclination to secrete themselves under burlap bands
where caterpillars were more or less abundant, 1t seemed advisable
to burlap a number of trees in the center of each colony, so that con-
ditions could be easily determined by occasional examinations of the
burlaps during the summer. The plan was adopted of burlapping
from 50 to 100 trees in each colony. The field work in these colonies
was carried on by Mr. John V. Schaffner, jr., and Mr. F. V. Learoyd,
and during the summer beetles or larvee were found in all of the col-
onies except the one planted at Winchester. As it seemed desirable
to continue this work after the larve had descended into the ground
to pupate, and as very accurate results can be secured by searching
for molted skins on the tree trunks, several weeks were devoted to
this work. About the middle of July Mr. Learoyd was detailed to
other work and Mr. Emory A. Proctor took up the field work in his
place. As a result of these examinations it was also possible to trace
the dispersion of the species in a limited way.
In 1909 the field examinations were carried on in the same manner
by Messrs. Schaffner and Proctor, and late in the summer they were
assisted by several other men employed at. the laboratory. The
results of the early summer inspection showed that the beetles
existed in all of the colonies released in 1906, with the exception of
one at Winchester. Of the total number of colonies placed in the
field, 75 per cent were found to be reproducing. ‘The results of the
late summer inspection—that is, where the distribution of a species
was determined by the presence of molted skins on the trees—is
shown on the accompanying map (Pl. [X). This indicated a very
encouraging increase and spread of the insect. The method of
carrying on this work was to examine areas immediately outside of
the beetle colonies which were badly infested with the gipsy moth,
and if the molted skins were found, more territory was scouted until
the outside limit of spread was reached.
During 1910 this work was continued, the same men having charge
of the investigations in the field colonies. At the close of the work
80 per cent of all the colonies planted showed reproduction and much
gratification was felt. Molted skins were found near the colony
p:anted in Winchester in 1906, which indicates in all probability that
some of the insects in that colony reproduced. The results of the
RECORD OF TWO FIELD COLONIES OF BEETLES. i
late summer scouting, in which work it was necessary to employ
several assistants in order to cover the extensive territory which was
examined, indicated that the beetles had spread over a much larger
area than had been anticipated, and this is shown on the above-
mentioned map (PI. IX). In order to give an idea of the reproduc-
tion and dispersion under actual field conditions, a somewhat detailed
account will be given of two colonies, namely, Saugus and Wellesley,
Mass. ;
RECORD OF TWO FIELD COLONIES OF CALOSOMA BEETLES.
In July, 1907, Mr. Mosher liberated 331 beetles as soon as they were
received from Europe in badly infested woodland near the old para-
site laboratory at North Saugus, Mass. Larve of sycophanta were
found later in the month and during the following year they were
quite abundant. As there were plenty of gipsy moth caterpillars and
pupe for them to feed upon, it seemed desirable to determine the
extent of spread and the amount of increase of the Calosoma beetles
during the summer of 1908. In order to do this the woodland was
examined thoroughly in August, and counts made of all the molted
skins found. All the trees were climbed, and the rough bark, which
was likely to harbor molted skins, was inspected, as were the masses
of gipsy moth pupe and the burlaps. Ninety-three first-stage and
294 second-stage molted skins were found in an area of about six
acres, which seemed to represent the limit of spread of the species.
That this was not the limit of spread, however, was definitely shown
the next summer when larve and molted skins were found at inter-
vals for more than half a mile in every direction.
In the fall of 1910 the colony was examined in the same manner
as in 1908, and in the territory inspected the latter year 733 first-
stage and 848 second-stage molted skins were found. This indi-
cates that there had been an increase of the beetles in the center
of the colony as well as a general dispersion of the species. A small
block of trees adjoining this area was examined and molted skins
were found in about the same relative numbers. A record of the
dispersion from this colony could not be secured, because in 1909
it had merged with other colonies planted a mile or more distant.
In order to check up this data a careful scout was made, in the
fall of 1908, of a colony at Wellesley Farms, Wellesley, Mass. The
beetles that were placed in this colony, 105 males and 110 females,
were received from Europe late in June, 1908, and were liberated
July 1 of that year. The timber growth, which was chiefly oak,
with trees of from 4 to 10 inches in diameter, had been burlapped,
and two men were employed to destroy the gipsy moth caterpillars,
as the infestation was bad. The beetles were liberated in two spots
about 300 vards apart. The scouting in this colony consisted in
Vhs CALOSOMA SYCOPHANTA.
examining the burlaps and the trees as high up as a man could
reach, as well as inspecting some of the stones or other material on
the ground where the molted skins were likely to be found. Over an
area of about 5 acres, 292 first-stage and 465 second-stage molted
skins were found.
The following year no special inspection was made of the colony,
but a general examination of the territory showed that the beetles
had spread over about 2 square miles, chiefly to the westward.
In August, 1910, another careful examination was made similar
to that of 1908,andin the same area that was examined the latter
year 1,229 first-stage and 1,851 second-stage molted skins were found.
The area over which the species had dispersed had also increased,
so that evidences of the beetles were found over an area of 11.37
square miles. This colony was liberated in a region far away from
other colonies, so that the spread did not come from other sources.
A colony of larve was liberated in 1909 in Wayland and Weston, Mass.,
which area is now included, but it is improbable that these plantings
spread to any great extent.
It is interesting to note the amount of handwork that was done
in the colony. Although the trees had never been sprayed, the egg
clusters had been treated each year with creosote. In the center of
the colony the burlaps had not been turned, but in the remainder
of the woodland they had been turned twice a week during the
caterpillar season and the trees have never been defoliated.
COLONIES OF CALOSOMA LIBERATED IN MASSACHUSETTS.
The statement which follows gives a list of the towns and cities in
which colonies of Calosoma sycophanta have been liberated, the num-
ber released, and a summary of the data which have been collected
concerning the condition of the beetle colonies. This is given
somewhat in detail,so that it may be of value to owners of property
or residents in the several sections concerned.
Acton.—In West Acton, about 24 miles from the railroad station, 200 larve of
Calosoma sycophanta were liberated on July 15, 1910. The gipsy moth infestation
in this town was not serious at that time, and the Calosoma beetles were placed in a
woodland colony where the gipsy moth infestation was such that the beetles would
secure enough food to develop and reproduce the next season.
Amesbury.—Calosoma larvee to the number of 200 were liberated in the woodland
off Haverhill Street, in Amesbury, on July 11, 1910. The gipsy moth caterpillars
were present in sufficient numbers to furnish food for the development of these larve.
Andover.—At this point 50 male and 50 female Calosoma beetles that had just
emerged from hibernation cages at the laboratory were released on June 4, 1910, in
badly infested woodland off Rattlesnake Road. The colony was examined July 14,
1910, but no Calosoma beetles were found. Gipsy moth caterpillars and pupz were
very scarce, owing to the fact that the infestation was so bad earlier in the season
that most of those in the center of the colony died from starvation or disease.
COLONIES LIBERATED IN MASSACHUSETTS. 79
Arlington.—On July 13, 1910, 200 beetle larvee were liberated in woodland off
Appleton Street. The condition of infestation by the gipsy moth in this section
was favorable for the survival of the colony.
Bedford.—On June 9, 1910, 50 male and 50 female Calosoma beetles that emerged
from rearing cages at the laboratory were released in the woodland on Page Road,
near the Lexington town line. Gipsy moth caterpillars were common, and a liberal
food supply for the beetles was assured.
Beverly.—On July 17, 1909, 200 Calosoma larvee were liberated in woodland, which
had been partially stripped by the gipsy moth caterpillars, off Essex Avenue. Most
of the gipsy moth larvee were full grown at the time the planting was made, and
some pupz were present on the trees. This colony was examined July 18, 1910, and
several beetle larvee and molted skins were found on the trees. On August 29, this
colony was scouted by Mr. Proctor, who reported that molted skins of the beetle
larvee were found on trees to a distance of 500 yards from the center of the colony,
and, as he states that the number of ege-clusters present indicated that there would
be plenty of food for the Calosoma larve the following year, it is probable that this
colony will develop and spread rapidly.
Billerica.—On May 27, 1910, 50 male and 50 female beetles were liberated in badly
infested woodland near Ranlett’s Park, South Billerica. These beetles were reared
at the laboratory and had just emerged from hibernation cages. The gipsy moth
infestation was very serious in this section, although at this time the caterpillars were
rather small. July 29 the locality where the beetles were released was scouted by
Mr. Schafiner, but no molted skins of the Calosoma larvee were found. Many of the
gipsy moth caterpillars died from disease earlier in the summer.
On June 24 a planting was made in woodland off Sprague Street, North Billerica.
Fourteen males and 28 females, most of them being beetles that were reared at the
laboratory, were placed in this colony. Plenty of gipsy moth caterpillars were
present for food.
Boston.—No Calosoma beetles have been liberated within the city limits. One
of the Brookline colonies has spread over the line into Boston in the Forest Hills
district. ;
Boxford.—On June 27, 1910, 200 Calosoma larvee were liberated in badly infested
woodland about 1 mile north of the railroad station. Gipsy moth caterpillars were
present in large numbers, and the locality was favorable for the development and
increase of the beetles. ‘
Braintree—On July 19, 1909, 200 Calosoma larvee were liberated in infested wood-
land on Liberty Street, South Braintree. Gipsy moth caterpillars and pupz were
abundant, and conditions were favorable for the increase of the beetles. June 9,
1910, the colony was examined by Mr. Schaffner, and a single Calosoma beetle was
found. October 1, 1910, the colony was again scouted, and 1 first-stage molted skin
was found. The burlaps in and around this planting had been turned periodically
during the summer, and the gipsy moth larvee and pupz had been crushed, which
of course served to reduce the beetles’ food supply. While this was being done, it
is probable that the molted skins of the beetle, which are ordinarily found under
the burlap, may have been brushed to the ground, so that it was impossible to deter-
mine to what extent the beetles in the colony had reproduced.
Brookline.—Several colonies were planted in Brookline in the summer of 1908,
and in 1909 another colony was added.
On July 4, 1908, 100 beetle larvee were liberated in badly infested woodland off
Mammond Street. Another colony, containing 81 male and 64 female beetles, was
liberated in infested woodland off Newton Street, and on J uly 8, 100 beetle larve were
placed in badly infested woodland off South Street. The colony liberated in 1909
consisted of 200 beetle larvee, which were placed in badly infested woodland off Heath
Street.
80 CALOSOMA SYCOPHANTA.
Repeated examinations were made during the summer of 1909 of the al
liberated in 1908, and in each one, except the Hammond Street colony, a rec
definite and satisfactory reproduction was secured. Considerable spraying was
along Hammond Street, and as this colony was liberated near the road it is very prob
ble that the beetles migrated after they emerged from the ground. On August 31
several molted skins were found 500 yards from the center of the colony, which in
cates that the beetles had migrated. Some of the trees in and around this colony w
cut during the previous winter, and this may have had a tendency to induce the
insects to migrate to a more Roe hutied place. ;
In 1910 all the colonies liberated in 1908 were found in good condition, and the
Heath Street colony also showed satisfactory reproduction and spread.
It might be added that the conditions in this town were not ideal for the colonization
of Calosoma sycophanta, as a large amount of spraying had been done, which so reduced
the number of gipsy moth caterpillars that it is probable that in oe areas the beet
find it necessary to migrate after the effect of spraying becomes noticeable on the
eaterpillars. :
During the time that has elapsed since these colonies have been planted, the on
on Newton Street and South Street havé joined, spreading over the very considera
area indicated on the map. The Heath Street colony has also joined with a col
liberated in 1908 on Newton Street in the city of Newton, near the Brookline
The reproduction in the last mentioned colony will be considered under the colonies
in the city of Newton. F
Burlington.—On May 8, 1906, Mr. Titus released 40 beetles in badly infested woo d-
land about 1 mile west o Gephecietecy ilies in the town of Burlington. This colony
was visited several times during the year, but no beetles were found. On July
1907, Mr. L. S. Winchester began scouting operations in this colony, and continued
the work for about 10 days. On July 17 he found several Calosoma larvee, and
continued to observe specimens working under burlaps almost every day that he
visited the colony, but no beetles were seen. A total of about 50 larvee was found by
him.
In 1908 several examinations of the colony were made, and on July 17 a dead beet e
and 3 molted skins were found. The gipsy moth caterpillars were very scarce in
center of this colony, and undoubtedly migration from this locality had taken pk
On June 21, 1909, 3 Calosoma beetles were found under burlaps, but no molteds
were discovered later in the season. On October 16 the woodland surrounding
colony was examined by Messrs. Schafiner and Proctor, and a few molted skins we
found three-fourths of a mile from the colony. Later in the season more of the sur-
rounding territory was examined, but no more evidence of the beetles was found.
In 1910 only a few molted skins were found, and these were a considerable dist
from the center of the original colony. A inte amount of territory was examined in
this section of Burlington, without proving that the beetles were present. It m
be said, however, that large areas of woodland in this region have been practic:
killed by the gipsy moth, and hence the infestation is not so bad as in some other
sections where an abundance of foliage offers food for the caterpillars. 4
A colony that was liberated in North Woburn in 1907 had spread in 1909 to the
northeastern part of Burlington, and in 1910 some beetles were found in this area. —
Carlisle —On June 22, 1910, 50 male and 50 female Calosoma beetles that had been
received from Europe the previous day were liberated in badly infested woodland
about 1 mile east of the Carlisle station. }
Chelm sfor d.—On June 22, 1910, 50 male and 50 female beetles received from Europe
the previous day were faberaied in woodland where gipsy moth caterpillars were
abundant. This colony was located near Billerica Road, about 1 mile from Chel ms-
ford Center, 7"
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COLONIES LIBERATED IN MASSACHUSETTS. 81
Cohasset.—On July 12, 1909, 200 Calosoma larvee were released in badly infested
woodland near the Jerusalem Road, and on July 27, 200 additional larvee were liberated
in woodland off Forest Avenue, about one-half mile from the colony previously men-
tioned. During the summer of 1910 the trees near where the first planting was made
were badly defoliated. The colony was visited by Mr. Schaffner on July 1, but no
beetles or larvee were observed. Mr. Frank A. Bates, one of the agents employed by the
State forester, informed me that he found several specimens of this beetle during that
summer in this colony.
The colony off Forest Avenue was also visited by Mr. Schaffner on July 1. No
beetles or larvze were found, but the trees were not defoliated so badly as in the other
colony. Examinations later in the season failed to reveal any traces of the beetle in
this colony.
Concord.—On July 10, 1908, 25 male and 25 female beetles and 100 larvee were
released near Fairhaven Bay in infested wogdland. Only a moderate amount of
wooded area was infested, and most of the caterpillars had pupated at the time the
liberation was made. June 28, 1909, a colony of 200 larvee was liberated in the north-
western part of the town in badly infested woodland off Strawberry Hill Road. July
2, 1909, another colony of 200 larvee was liberated near Walden Pond, in a moderately
infested region. July 14, 1909, 200 larvee were liberated in infested woodland off
Sudbury Road.
During 1909 the Fairhaven colony was examined several times, and a few beetles and
molted skins were found during the season.
Examinations made in 1910 indicate that the Fairhaven and Walden Pond colonies
have survived, and that the beetles have spread a considerable distance from where the
liberations were made. Only a few visits were made to the other two colonies, but
no indications were found that the beetles had been working during the season.
Danvers.—On July 15, 1909, 300 Calosoma larvee were liberated in woodland off
Nichols Street, Danvers. The trees had been badly defoliated, and many of the
caterpillars were dying from disease. A considerable number of gipsy moth pup
was present. June 21, 1910, the colony was scouted by Mr. Proctor, and 2 male beetles
were found. On September 17 another examination was made, and molted larval
skins were found 200 yards from the center of the colony.
Dedham.—On July 9, 1910, 200 Calosoma larvee were liberated in woodland off Sandy
Valley Road.
Dover.—On July 2. 1910, 200 Calosoma larvee were liberated in woodland off Pleasant
Street, Dover. }
Dracut.—On June 24, 1910, 50 male and 50 female Calosoma beetles were liberated
in badly infested woodland near Lak2view Park.
Essex.—On July 7, 1909, 149 Calosoma larvee were liberated in infested woodland
near Wood Drive, near Chebacco Lake. July 22, 1909, 200 Calosoma larvee were
liberated in woodland near a bad gipsy moth infestation off Conomo Drive. July 24,
1909, 200 larvee were liberated in woodland off the Old Essex Road, near the town line
of Manchester and Essex. All of these colonies were examined during the summer of
1910. On June 14, 2 beetles were found in the last-mentioned colony, but in the
others no adults or larval skins were secured.
Framingham.—On July 16, 1910, 200 Calosoma larvee were liberated near Framing-
ham Junction, in infested woodland.
Georgetown.—On July 17, 1909, 200 Calosoma larvee were liberated in woodland
near Baldpate station. The infestation was moderate and conditions were favorable
for a colony. June 16, 1910, the colony was examined, but no beetles found. The
woodland had been sprayed, but many gipsy moth and brown-tail moth caterpillars
were present. July 5 examination was made in the territory immediately outside of
the colony and two Calosoma larvee were found. OnSeptember 19 another examination
100834°—Bul. 101—11——6
82 CALOSOMA SYCOPHANTA.
was made in and around the colony. A few molted skins were found under burlaps,
and also some 100 yards east of the original planting.
Gloucester.—On June 23, 1908, 75 Calosoma larvee were released in a moderately
infested woodland area about 1 mile east of the West Gloucester station. July 14,
100 larvee were liberated in an infested woodland area half a mile east of the West
Gloucester station, and on July 30, 100 more larvee were placed in the woods a short
distance from the point where the last-mentioned liberation was made.
These colonies were examined in 1909. Nothing was found in the first colony, but
in the second, beetle larvae were observed on July 10 and 16, and later in the year a
considerable number of molted skins was found.
July 20, 1909, 200 Calosoma larvee were liberated in woodland off the State Road in
Magnolia, and on July 22, 200 were placed in a badly infested wooded area near Has-
kell’s Pond.
In 1910 all these colonies were examined during the summer, and in the early fall
the surrounding region was carefully scouted for molted skins. No indications of
Calosoma beetles were found in or around the colony liberated 1 mile east of West
Gloucester station.
In the colony liberated near the West Gloucester station a few beetles were noted
during that summer. Later in the season molted skins were found 1 mile south and 1
mile west of the center of the colony.
Molted skins were also found in the colonies liberated near the State Road at Mag-
nolia and at Haskell’s Pond, which indicated that these plantings had survived and
the beetles were increasing.
Groveland.—On July 5, 1910, 200 Calosoma larvee were liberated in an infested
wooded area located on a hill near the center of the town of Groveland.
Hamilton.—On July 14, 1909, a colony containing 60 male and 44 female beetles
and 100 larvee was liberated in infested woodland off Farm Road. June 1, 1910, 1
male beetle was found in this colony. Later in the summer examination showed that
several molted skins were present in the colony and a few were also found 100 yards
distant.
Haverhill.—On July 5, 1910, 200 ancora larvee were liberated in badly infested
woodland about 1 mile north of the Groveland Bridge. On July 6, 200 larvee were
released in woodland in Bradford, near the electric car line from Haverhill to Andover.
Hopkinton.—On July 7, 1910, 50 male and 50 female Calosoma beetles received from
Europe were liberated in infested woodland in Hopkinton.
Hudson.—On July 7, 1910, 50 male and 50 female Calosoma beetles received from
Europe the previous dav were liberated in infested woodland on Priest’s Hill.
Hyde Park.—On July 19, 1910, 200 Calosoma larvee were liberated in woodland near
the corner of West and Austin Streets.
Ipswich —On July 17, 1909, 200 Calosoma larvee were released in woodland off
Rowley Road. July 16, 1910, a male beetle was found in this colony. Gipsy moth
caterpillars were very abundant, and the trees were being stripped of foliage. A
later examination, made on September 20, 1910, revealed the presence of a consid-
erable number of molted skins of the Calosoma larve in this colony.
Lawrence.—On July 18, 1910, 200 Calosoma larvee were liberated in woodland off
Beacon Street, South Lawrence.
Lerington.—On July 3, 1908, 100 Calosoma larvee were liberated in woodland near
the State Road in Lexington. The trees on the opposite side of the street had been
entirely defoliated by the gipsy moth caterpillars, and many of those in the area
where the liberation was made were badly stripped. Gipsy moth caterpillars were
very scarce, but some moth pupe were present on the trees where the Calosoma larvee
had been released. The colony was examined several times during the summer oi
1909. No trace of Calosoma beetles or their larvee could be found. Gipsy moth
caterpillars were rather scarce. Several examinations were also made during the
COLONIES LIBERATED IN MASSACHUSETTS. 83
summer of 1910 with the same result. Early in the season fire ran through the woods
and burned over the area where the liberation had been made.
July 16, 1909, 200 Calosoma larvee were liberated on the east side of the town, in
woodland, off Paint Mine Road. The colony was examined several times during the
summer of 1910, but no beetles were found. On October 4 several molted skins were
found 100 yards outside of the planting, and also a large number of gipsy moth pupee
that had been eaten by the Calosoma larvee.
Lincoln.—On July 18, 1908, 100 Calosoma larvee were liberated in infested woodland
about 1 mile northwest of the railroad station. The coleny was examined several
times during 1909, but few beetle larvee were found. Gipsy moth caterpillars were
very abundant in a part of this colony, and some of the trees were stripped, and this
caused the owners to have a portion of the area sprayed. The colony was inspected
several times in the summer of 1910 and a few Calosoma beetles were found. In the
fall a careful examination showed that the beetles had spread about three-fourths of a
mile north and one-half a mile east of the planting. A number of molted larval skins
was found throughout this area.
Littleton —On July 15, 1910, 200 Calosoma larvee were liberated in woodland about
one-fourth of a mile from the railroad station. Gipsy moth caterpillars were com-
mon, but none of the trees had been stripped.
Lowell—On July 18, 1910, 200 Calosoma iarvee were liberated in woodland near the
Lowell General Hospital.
LIynn.—No beetle colonies have been planted in this city, and up to and including
the year 1909 no evidence of the presence of this insect could be found, although
several days were spent in making careful examinations in various sections of the
Lynn woods. It was believed that the insects would make their first appearance in
that part of the city, owing to the fact that several colonies had been liberated in
Saugus and Lynnfield. In the summer of 1910, in several localities which had been
visited the previous summer, beetles and larvee were found. Later in the summer
examinations were conducted for molted skins, and in some parts of the Lynn woods
they were found abundantly. Molted skins were also found throughout the northern
part of the city and in the residential section nearest the woods.
Lynnfield —On July 7, 1906, 100 specimens of Calosoma sycophanta and 20 specimens
of Calosoma inquisitor were placed by Messrs. Titus and Mosher in woodland near
Broadway. This colony was visited several times during the summer of 1907, but no
beetles or larvze were found. In 1908 examinations on July 2 and July 8 resulted in
the discovery of several larve in the center of the colony. Several visits were made in
1909 and a considerable number of beetles and larvee was found during June and early
July. Later examinations were made and it was found that the Calosoma had spread
over a large area in the eastern part of the town. It had also spread north and west so
that this colony had fused with another, which will now be mentioned. June 20, 1906,
Mr. Titus liberated 118 beetles in a pine grove which was nearly surrounded by hard-
wood growth. The trees were badly infested by gipsy moth caterpillars, and although
several examinations were made later in the season no Calosoma beetles or larvee were
found. July 31, 1907, a single larva was found by Mr. Collins, and on the same date 50
pairs of beetles were liberated a short distance from the point where the previous
planting had been made. Several examinations were made during the summer of
1908, and 2 live Calosoma beetles were found on July 23. In 1909 the Calosoma beetles
were more numerous, and the examination of the surrounding territory showed that
this colony had fused with the one in Lynnfield, already mentioned, and specimens
were also found west of the colony in the town of Saugus. Subsequent scouting showed
that two colonies in Saugus, which are treated under that town, had spread to such an
extent that they had joined with the Lynnfield colonies. In 1910 examinations were
made late in the season and traces of the beetles were found throughout the southern
part of the town as well as in adjoining towns, which will be mentioned later,
84 CALOSOMA SYCOPHANTA.
*
Malden.—On May 8, 1906, Mr. Titus liberated 40 specimens of Calosoma sycophanta in
badly infested woodland in Malden near the Saugus-Melrose line. During June, on
visiting the colony, he was able to find 2 beetles. This colony was examined in 1907,
but no trace of the Calosoma beetles or larvee was found, and although several exam-
inations were made the next summer nothing was found until July 16. On that date
6 full-grown Calosoma larvee and about 25 molted skins were collected, some of them
being taken 100 feet from the point where the original liberation was made. In 1909,
Calosoma beetles and larvee were abundant in this colony and in the fall a careful
examination was made of the surrounding territory. It was found that the insect had
spread over a section of Malden known as the Maplewood district and as far south as
the Linden station. The beetles were also found over a considerable area in the
southeastern part of Melrose, and in Saugus in the vicinty of Cliftondale. Some speci-
mens were found in a section of Revere not far from the center of the colony, known as
Franklin Park. In 1910 examinations showed that this colony had spread over prac-
tically the whole northern half of the city of Malden and into the adjoining towns
and cities.
Manchester —On July 27, 1909, 150 Calosoma larvee were liberated in woodland on
School Street, about one-half mile from the Essex town line. July 24, 200 Calosoma
larvee were liberated in a badly infested area off School Street, one-half mile farther
north. Examinations of these colonies made in 1910 showed that in the latter a few
beetles were present, but none was found in the first colony. Infestation by the
gipsy moth was less severe than the previous year, as a large number of the moth cater-
pillars died from disease.
June 7, 1909, 39 male and 34 female Calosoma beetles were liberated off Crooked
Lane, in Manchester. July 10, 300 beetle larvee were liberated north of the area pre-
viously mentioned and not far from the Wenham line. Examinations made during
the summer of 1910 failed to indicate the presence of the beetles near the point where
the adult colony was liberated. Molted skins were found, however, near the larval
colony; some were in the town of Manchester, others in Hamilton, and still more in
Wenham. It is probable that some of these beetles spread from the colony located in
the eastern part of Wenham, which will be mentioned later.
Marblehead.—On July 9, 1908, 100 larvee of sycophanta were liberated in Marblehead
about one-half mile east of the Forest River station. On July 15 of the same year 100
more larvee were added to this same colony. Plenty of gipsy moth caterpillars were
present and the Calosoma colony appeared to be in a flourishing condition when it was
examined about a week later. During the summer of 1909 several visits were made to
the colony, but no Calosoma beetles or larvee were found. On June 30, 1910, the owner
of the property said that he had seen two ‘‘ green beetles ”’ in the woodland earlier in the
season, which were undoubtedly specimens of Calosoma sycophanta. Later in the sum-
mer molted skins were found near the Forest River station. Some beetles evidently
had survived in this colony, but many had either migrated to other places or else con-
ditions were not as favorable as might be wished for the rapid increase of the species.
Marshfield —On June 30, 1910, 200 Calosoma larvee were liberated in infested wood-
land near Marshfield Center.
Maynard.—On July 25, 1910, 200 Calosoma larvee were liberated in badly infested
woodland. Only a small number of gipsy moth caterpillars was present, but pupze
were more abundant.
Medfield.—On July 2, 1910, 50 male and 50 female Calosoma beetles were liberated in
infested woodland in Rocky Woods.
Medford.—No colonies of Calosoma beetles have been liberated in this town, but dur-
ing the summer of 1910 indications of the presence of the beetles have been found
throughout the northern part of the city.
Melrose —On June 25, 1909, 100 Calosoma larvee were liberated in the northeastern
part of the city not far from the Savgus-Wakefield line, June 30, 100 larvee were added
COLONIES LIBERATED IN MASSACHUSETTS, 85
to thiscolony. Practically every section of this city was examined in 1919and beetles
were found in small numbers throughout the entire area. It is probable that only a
few of these came from this colony. Large numbers must have migrated from the
colonies in Saugus and Malden. In the northeast section of the Melrose Highlands
district the beetles were quite common in the woodland during the summer, and it
was usually possible to find one or more of the beetles or larvee at work if careful search
was made.
Merrimac.—On July 11, 1910, 200 Calosoma larvee were liberated north of Main
Street, in Nichols Woods.
Methuen. —On July 6, 1910, 200 Calosoma larvee were liberated in infested woodland
in the eastern part of the town not far from the Haverhill line.
Middleton.—On June 23, 1910, 50 male and 50 female Calosoma beetles, which had
been received from Europe two days previous, were liberated in badly infested wood-
land off East Street.
Milton-Quincy.—On July 6, 1909, 200 Calosoma larvze were liberated in infested
woodland near Shawmut Spring in Cunningham Park. This colony was visited only
once during the summer of 1910, and no beetles or larvae were found. At the time of
the examination many of the gipsy moth caterpillars were dying as the result of spraying
or from disease.
Natick-Weston.—On July 22, 1910, 200 Calosoma larvae were liberated in badly
infested woodland on South Avenue near the Natick-Weston line. There were many
gipsy moth egg clusters and some moths present, but only a few gipsy moth pupz and
caterpillars.
Newbury.—On July 8, 1910, 42 male and 46 female Calosoma beetles, which had
been received from Europe two days previous, were liberated in badly infested wood-
land near the Byfield station.
Newburyport.—July 26, 1910, 200 Calosoma larvee were liberated in woodland near
the West Newbury line. Some gipsy moth larvee and pupz were present, but a
large number of the moths had laid their eggs.
Newton.—On July 4, 1908, 100 Calosoma larvze were liberated in woodland off
Newton Street, about one-fourth of a mile from the Brookline line. July 6, 1909, 1
female beetle and 9 larvze were found on trees in the center of this colony, and later
in the season when the surrounding territory was scouted a large number of gipsy
moth pup was found that had been destroyed by the beetles. June 24, 1910, an
examination was made and beetles found in the colony. The trees had already
been sprayed. Late in July the territory between this colony and the one of Heath
Street, Brookline, was visited and molted skins found in different localities between
the places where the original liberations were made.
June 30, 1909, 200 beetle larvee were liberated in woodland off Langley Road,
Newton Center, and on July 13, 200 more larvie were placed in the same woods about
one-half mile from the original colony. The territory where these liberations were
made was examined several times during the summer of 1910, and both beetles and
larvee were found.
North Andover.—On June 16, 1910, 50 male and 50 female beetles which emerged
from hibernation at the laboratory were liberated in badly infested woodland off
Osgood Street.
North Reading. —On July 6, 1910, 200 Calosoma larvze were liberated in woodland
about one-half mile from the State road.
Peabody.—On August 28, 1907, 25 male and 25 female Calosoma beetles that were
received from Europe in August were liberated in wooded area which was badly
infested. All the gipsy moth adults had emerged at this time, and but few cater-
pillars of any kind were present to serve as food for the Calosoma beetles. Several
examinations were made during the summer of 1908, and on July 8 a full-grown larva
of C. sycophanta was found under burlap. In 1909 several beetles were found in the
86 CALOSOMA SYCOPHANTA.
colony, although the gipsy moth infestation was rather light, and an examination of
the surrounding territory in August failed to show any indications of the Calosoma
beetles or their larvee.
July 2, 1909, 100 Calosoma larvee were liberated in woodland off Birch Street, West
Peabody. Several examinations were made during the summer of 1910, and a few
molted skins were found outside of the colony.
July 3, 1909, 200 Calosoma larvee were liberated off West Street near the West
Peabody station. In the summer of 1910 many larvee and molted skins were found.
June 23, 1910, 50 male and 50 female Calosoma beetles just received from Europe
were liberated in badly infested woodland near the Middleton Paper Mills.
Quincy.—July 19, 1909, 200 beetle larvee were liberated in a badly infested wooded
area off South Street. Several examinations were made during the summer of 1910,
and beetles and larvee were found in abundance in and around where the colony was
liberated.
Reading.—No colonies have been liberated in this town. Molted larval skins were
found in the summer of 1910 in the southeastern and central parts of the town, having
spread from the Saugus plantings.
Revere.—July 26, 1908, 100 Calosoma larvee were liberated on Oak Island, and on
July 27 100 additional larvee were placed in this colony. These were liberated on the
east side of the railroad track. On August 3 100 Calosoma larvee were liberated on the
extreme west edge of the wooded area. The colony has been visited each year, and
beetles and larvee have been found in moderate numbers.
Rowley.—On July 8, 1910, 200 Calosoma larvee were liberated in infested woodland
off the Newburyport Turnpike.
Rockport.—On July 138, 1910, 200 Calosoma larvee were liberated in woodland in the
rear of Manning Park.
Salem.—No colonies have been liberated in Salem, although a number of larvee
was released in Swampscott in 1908, not far from the Salem line. In 1910 an exami-
nation showed that the beetles had spread over the southern part of the city, the strip
where they were found being about one-half mile in width.
Salisbury.—On July 11, 1910, 200 Calosoma larvee were liberated in infested woodland
in this town.
Saugus.—On May 6, 1906, Mr. Titus liberated 24 Calosoma beetles in woodland in
North Saugus, and on June 26, 25 more were liberated in the same region. July,
1907, several larvee were found in this colony, and in 1908 a few beetles were found.
July 3, 1907, Mr. Mosher liberated 228 Calosoma beetles in badly infested woodland
directly north of the old gipsy moth laboratory at North Saugus, and on July 7, 103
more beetles were placed in this colony. Calosoma larvze were found late in July,
and in the summer of 1908 both beetles and larvee were common in the center of the
colony. This liberation was made about a mile from the one put out by Mr. Titus.
In the summer of 1909 a careful inspection of territory showed that beetles were
present in the area between the two colonies, and molted skins were found for a con-
siderable distance surrounding each. The colony planted by Mr. Mosher had spread
east and northward and fused with the Lynnfield colonies. It also had spread west-
ward, as molted skins were found in woodland in the eastern part of the town of
Wakefield. In 1910 the beetles were found in practically all parts of the town of
Saugus.
Sherborn.—On July 2, 1910, 200 Calosoma larvee were liberated in infested wood-
land off Main Street, Sherborn. ;
Stoneham.—On June 22, 1908, 75 Calosoma larvze were liberated in woodland off
Franklin Street, Stoneham. Examinations were made in this colony in 1909 and
a few beetles were found. Several were also found in 1910. Later in the season a
general inspection was made of the territory in Stoneham where gipsy moth cater-
pillars had been very abundant. Molted skins were found in the eastern and southern
parts of the town.
COLONIES LIBERATED IN MASSACHUSETTS. 87
Stow.—On July 7, 1910, 48 male and 38 female Calosoma beetles were liberated in
badly infested woodland.
Sudbury.—On July 25, 1910, 200 Calosoma larvie were liberated in badly infested
woodland in East Sudbury. On this date very few gipsy moth caterpillars or pupze
were present. Most of the moths had emerged and several had laid their eggs.
Swampscolt.—On June 26, 1908, 75 Calosoma larvze were liberated in infested
woodland off Danvers Street. On June 30 100 more larve were added to this colony.
Examinations were made in 1909, and a few beetles were found in the colony. In
1910 no beetles or larvee were seen in the center of the colony, but in the area outside
where gipsy moth caterpillars were at all abundant, molted skins were found.
July 1, 1908, 100 Calosoma larvee were liberated on high land north of the Ocean
House. On July 6, 100 more larvee were added to the colony. Examination was
made in 1909, but no beetles or larvee were found. During the summer of 1910 several
larvee and molted skins were found from one-half mile to a mile distant from the
colony.
Tewksbury.—On August 12, 1908, 100 Calosoma larve were liberated in woodland
where gipsy moth caterpillars had been present earlier in the season. At this date
all the moths had emerged and deposited their eggs. Brown-tail moth caterpillars
were hatching and feeding on foliage of some of the deciduous trees. This colony
was examined in 1909 and 1910, but no Calosoma beetles or larvee were found. The
colony was liberated principally as an experiment to determine whether it was possible
for any of the beetle larvee to survive and develop upon such a limited food supply.
July 2, 1910, 50 male and 50 female Calosoma beetles were liberated in badly infested
woodland off Shawsheen Avenue. July 14, 1910, 200 beetle larve were liberated
near Prospect Hill in infested woodland.
Topsfield—On July 8, 1910, 180 beetle larvze were liberated in badly infested
woodland off High Street.
Wakefield —N 0 beetles have been liberated in this town. In 1909 it was found that
a small area along the eastern border had been stocked with beetles from the Saugus
colonies, and in 1910 the beetles were found in various localities in practically every
part of the town visited.
' Waltham.—On August 7, 1908, 100 Calosoma larvee were liberated in wood and brush
land off Lake Street. At this date no gipsy moth caterpillars were present. A few
small brown-tail moth larvee were feeding and occasionally a native caterpillar would
be found. The Calosoma larve were nearly full grown, all having molted the second
time. This colony was examined in 1909, and no beetles or larvee were found during
the summer, but on September 2 a single molted skin was found under burlap near
the center of the colony. June 1, 1910, a beetle was found in the center of the colony,
and in July several larvee were noted. The territory surrounding was scouted in
August and September and a considerable number of molted skins was found in
Prospect Park, some of these at a distance of 2 miles south of the colony.
Wayland. —On July 12, 1909, 200 Calosoma larvee were liberated in infested wood-
land off Poor Farm Road. The colony was examined in 1910 and a few beetles and
larvee were found near where the original planting was made. In September molted
skins were found about 200 yards outside the planting.
Wellesley. On June 27, 1908, 36 male and 37 female Calosoma beetles were liberated
in infested woodland near Wellesley Farms station. July 2 69 males and 81 females,
taken from a shipment received from Europe June 29, were liberated in this same
colony. In the fall of 1908 an examination of the trees in this colony was made and
a large number of molted skins was found on the trunks and underneath the burlaps.
In 1909 and 1910 both beetles and larvee were found in the center of the colony. In
1909 the territory in the northern part of Wellesley and extending into the southern
part of Weston, about 2 miles in length and 1 mile in width, was inhabited by this
species. In 1910 this region was kept under observation, and late in the season areas
88 CALOSOMA SYCOPHANTA.
outside were thoroughly examined. It was found that the general direction of dis-
tribution had been toward the north and west, and territory shaped like an onion
embracing the northern part of the town of Wellesley and the southern part of the
town of Weston, and extending to a point beyond the Weston railroad station, showed
marked evidences of the presence of this insect.
Wenham.—On June 27, 1908, 6 male and 6 female Calosoma beetles and 75 larvee
were liberated in badly infested woodland off Cherry Street. In 1909 this colony was
examined and beetles and larvee were found. Late fall examinations showed that
they had dispersed over a relatively small area. In 1910 the entire western end of
the town was examined, and beetles were found over an area of about one-half
square mile.
July 14, 1909, 43 male and 30 female Calosoma beetles and 100 of their larvee were
liberated off Grapevine Road. The territory was examined in 1910, and beetles and
larvee were found outside the colony. Beetles and larvee were also found in the towns
of Hamilton and Manchester at a distance of one-half mile or more from where this
colony was liberated.
Westford.—On June 24, 1910, 100 Calosoma larvee were liberated in woodland in
the northern part of the town, and on June 28 100 more larvee were added to the colony.
Weston.—On June 24, 1909, 100 Calosoma larvee were liberated in woodland near
the railroad station, and on June 26 100 more larvee were added to the colony. Exam-
inations were made several times during the summer of 1910. No Calosoma larvee or
molted skins were found in the colony, but several were secured in the area surround-
ing it. In the southern part of the town the beetles have become well established,
having spread from the colony at Wellesley.
West Newbury.—On July 8, 1910, 200 Calosoma larvee were liberated in woodland
near the top of Pipe Stave Hill.
Westwood.—On July 9, 1910, 200 Calosoma larvee were liberated in badly infested
woodland.
Weymouth.—On July 19, 1909, 200 Calosoma larvee were liberated in woodland off
Commercial Street, Weymouth. The colony was visited several times in 1910, and
on July 6 a beetle and 33 larvee were found. Later in the season molted skins were
found to be very abundant in this colony.
Wilmington.—On June 25, 1910, 100 Calosoma larvee were liberated in woodland
about one-half mile from the railroad station. June 30, 100 more larvze were added
to thiscolony. In 1910 beetles were found in the southern part of the town that had
spread from a colony planted at North Woburn in 1907.
Winchester.—On May 8, 1906, Mr. Titus liberated 41 beetles in wood and brush land
off High Street. During the winter most of the woodland was cut off, and although
careful examinations were made during the summers of 1907, 1908, and 1909 no Calo-
soma beetles or larvee were found in the center of the colony, but in 1910 molted skins
were found about one half mile north of where the liberation was made.
Woburn.—On July 31, 1907, 23 male and 24 female beetles were liberated in the
piece of woodland which had been partially stripped by gipsy moth caterpillars near
North Woburn. On August 2, 25 pairs of beetles were added to this colony. Larvee
were found during the summer of 1908, and in 1909 a number of beetles was discovered
in the colony and molted skins of the larvee were found a mile distant. In 1910 the
colony had spread over a much larger area, extending throughout the northern part
of Woburn and into the towns of Wilmington and Burlington.
COLONIES OF CALOSOMA LIBERATED IN MAINE.
July 22, 1908, 100 Calosoma larvae were shipped by express to
Capt. E. EK. Philbrook, Portland, Me. They were packed separately
in glass tubes with earth and were liberated by him in Kittery and
ECONOMIC IMPORTANCE. 89
Wells. Subsequent examinations have shown that the places selected
for making liberations were not particularly suitable for the purpose,
as the infestations were so scattering that a sufficient quantity of
food was not available for the development of the larve.
Kittery.—On July 24, 1908, 15 Calosoma larvie were liberated near Thaxters Station,
under some oak trees upon which were some gipsy moth caterpillars. A wall near
the base of these trees had been burned out before the planting was made. Later
examinations during the year failed to reveal the presence of the Calosoma beetles
and very few gipsy moths remained.
No beetles have been recovered from this colony.
July 25, 1908, 25 Calosoma larvee were liberated on a large willow on the grounds of
the Portsmouth Navy Yard. This tree was not badly infested, so there evidently
was not sufficient food for the larve. No beetles have since been found in this
planting.
July 31, 1908, 100 Calosoma larvee were liberated on a small island of trees in the
salt marsh. Gipsy moth caterpillars and pup were scarce at this time. Several
examinations have been made since that time, but no Calosoma beetles have been
recovered.
Wells.—On July 25, 1908, 20 Calosoma larvee were liberated around fruit trees
infested with the gipsy moth. Caterpillars were scarce on account of the careful
handwork that was being done. No beetles have since been recovered. On examin-
ing the trees in the summer of 1910, it was not possible to find either the gipsy moth
caterpillars or pupee.
York.—On July 24, 1908, 30 Calosoma larvee were liberated in woodland slightly
infested with the gipsy moth. Although several examinations have since been made,
no Calosoma beetles have been found.
COLONY OF CALOSOMA LIBERATED IN NEW HAMPSHIRE.'
July 31, 1909, 100 Calosoma larve were liberated in woodland
near the Sandwich-Tamworth line, which was being defoliated by
Heterocampa guttivitta. The gipsy moth had not been found in this
region, but it was desired to see whether the Calosoma beetles would
feed on Heterocampa and survive the winter.
An examination was made August 24, 1910, but no Calosoma
beetles were found. Heterocampa larve were very scarce through-
out this section of the State.
ECONOMIC IMPORTANCE OF CALOSOMA SYCOPHANTA.
The preceding pages show conclusively that this beneficial species,
Calosoma sycophanta, is firmly established in eastern Massachusetts.
The data also show that although in most cases some traces of the
insect’s presence have been found the year following planting, it
takes three years or more before they are sufficiently abundant to
attract attention.
For this reason the beetles have not been found by many residents
of the district infested with the gipsy moth. The question of the
part which this insect is destined to play in controlling the gipsy
1 Molted skins of sycophanta larv were found in August, 1910, at Plaistow, N. H. The adults must
have migrated from some of the Massachusetts colonies.
90 CALOSOMA SYCOPHANTA.
moth is one which must be settled by future developments rather
than by prophecy or pure speculation.
The feeding period of the beetle and its larvee corresponds closely
with that of the larval and pupal stages of the gipsy moth, and there-
fore there seems to be no good reason why it will not take prominent
rank with the true parasites of this insect and assist and supplement
their work. |
Its ability to survive and reproduce in New England has been
clearly demonstrated when it is stated that as a result of the planting
of 13 adult and 14 larval colonies from 1906 to 1908, the presence of
the beetle was found over an area of about 94 square miles in the
summer of 1909. During that year 3 adult and 29 larval colonies
were liberated and in the summer of 1910 the insects were found
scattered over about 1064 square miles in Massachusetts.' The aggre-
gate rate of multiplication and dispersion increases with the age of
the colonies. Future observations will show the precise value of this
insect as an enemy of the gipsy moth.
1 Examinations in the early summer of 1911 of the regions where liberations have been made indicate
that the beetles have continued to increase nd spread at a very satisfactory rate.
Pi EX:
Page
Alypia octomaculata, prey of Calosoma sycophania.........--.-+------+-++++--- 34
Meech 1000 plant of crererocamma GULavILtd...- 2... 2s elec eee ete eee 72
Beefsteak, feeding to Calosoma beetles, results................-....--..----- 56
Beetles (see also Calosoma and Carabus).
Precareohe eq uupEient LOM TEATS <<... ea se Se ee dae eee ee 15-19
MCINOUROMeANUC Ne. 2 eae ee oes | oe DL Be 20-22
Paine rer SMIPMNeING I oc a eon ae reece ene ents 9-12
Boxes, kinds used for shipping Calosoma beetles................------------ 9-10
Brown-tail moth (Luproctis chrysorrhea), prey of Calosoma inquisitor......----- 7
Calosoma sycophanta.......--- 7,34
Burlapping trees, use in securing data on Calosoma beetles. ........--..-.-- eee ae 76
Cage for assembling experiments with Calosoma beetles............-.--.------ 57-58
Cages for hibernating Calosoma sycophanta beetles.........---.-...---------- 17-18
rearing Calosoma sycophanta larvee, 1907.....-...-.-.-.------ 16-17, 43-44
wintering Calosoma sycophanta beetles... .- EEE (et a Raia see 51
J O00 OF: Oe a St eR ae ee eee 46
Callosamia promethea, prey of Calosoma sycophanta..........-.--------+-+---- o4
Calosoma and allied genera, importations from Europe and Japan.....-...---- 8-9
beetles (see also Calosoma sycophanta).
1ia%9) 124 Bitip ay halla rg 100s hp gee ee 89; 10; 11, 12
Miruteteey MUURAC HONS UOMO ben See. So oc oie ok win wwe eh cwee SS 65
inquisitor, enemy of gipsy and brown-tail moths.....-...-....----- 7
A Periauiots MOG MUPGPC nso S50 2 sso snes ose - 2 ete 8-9
Aer SOM TO WONG os cyae a= Moa ain A= Sls Sus < 20 Siew aes «2 65
COMIPARISOUWItRNC,. dab
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rae
Cirrus AND SusrropicAL Fruit Insect INVESTIGATIONS.
C. L. Maruart, in charge.
A. W. Morrimt,! E. A. Bacx, R. 8. Woctum, W. W. Yoruers, E. R.
CHITTENDEN, in charge of truck crop and stored product insect investigations.
SASSCER,
J. R. Horron, Recainanp Wooupriper, P. H. Trwseriaxe, H. L. SANForp,
entomological assistants.
2 1 Resigned.
Gee eet COPIES of this publication
may be procured from the SUPERINTEND-
ENT OF DOCUMENTS, Government Printing
Office, Washington, D.C., at 20 cents per copy
LETTER OF TRANSMITTAL.
U.S. DEPARTMENT OF AGRICULTURE,
Bureau oF ENTOMOLOGY,
Washington, D. C., November 3, 1911.
Sm: I have the honor to transmit herewith for publication as
Bulletin 102 of the Bureau of Entomology a report on ‘‘Natural
Control of White Flies in Florida,’ by Drs. A. W. Morrill and E. A.
Back, both of whom were formerly employed as special field agents
in this bureau.
The control of the citrus white flies in Florida by natural means,
most important among which are the fungous diseases of these
insects and natural insect enemies, is a subject of much importance
to the Florida citrus grower. In connection with the investigation
of the white fly in Florida a good deal of time has been devoted to this
special subject, and the results are here summarized. This investi-
gation has been under the general direction of Mr. C. L. Marlatt,
assistant chief of this bureau, and has been carried out by the authors
named with the assistance and cooperation of Mr. E. L. Worsham,
now State entomologist of Georgia, and Mr. W. W. Yothers.
Respectfully,
L. O. Howarp,
Entomologist and Chief of Bureau.
Hon. JAMES WILSON,
Secretary of Agriculture.
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CONTENTS.
Page.
INSTR NO ere ec oP ress, caste ce PEER PS ons oi ates oat Liao a cpr Se soak woke 7
Parasitic and predatory enemies of white flies..................--.-------...- 8
Peer ieeat cea onrsooLy Mons. ls. thhe TTP 9
OS ST Ta LO ESIGN El ob Sad ok 2 SE SO ee ee 10
SERRE EMILE MA ORERALY™ Ae cock crys hang 3 0 AND CARLY! FP UREN Ne DU oe 5 11
PREPAC REITER CRE ee ae Se ee ee Tera SAMY APA EE hee S| eee 18
Emr ike TOrOVercrow dime: ¢. 2 ketch ee UO? BEL Oe et tas 18
Effect of curling and dropping of leaves from drought......-.....--- ee ee 19
Sy Pid ie isc 2 OS ud Ba A hed Ch a ole in a a 19
J PS Lehi St) 20 p. SMR cae hs BRA See he ob el ty Sse cn A oe 20
SR EPEMBRLSCL CREERNDTELLI Coe © oop ale Se I] Ec ec
% |n°| 3a | ba | ae [os 3 d@j)s|]é |a°3| #3 | gs
4 |o ag igs 33 25 B i) q ig | Sia 2 g
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Bele | eee lao ee SS etic a=a2| 8 | Ee
2s 5 Fa A 5 5 3 3 2 | &§ | $28) # 53
5 14 a 1) =) <3) <4 oa} al aa) Sy) Nis =) n
1 85 8,813 24.5 24.5 5.6 | 49.1 9.5 0.05 |14. 1 0.0 23.6 23.6 52.8
21 100 6, 541 24.1 34.0 nie 3.6 .0 41.2 .0 0 41.4 52.0 6.5
3 | 100 | 10,832 iL 72.6 | 2.0] 32.0 0 1.6 0 0 1.6 67.0 31.4
4 | 100 | 13, 257 19.2 89.9 3.4] 20.0 4.0 10.4 -0 uM 14.5 67.8 17.6
5 | 100 | 22,922 29.6 157.2 6.5 | 35.9 .38 12.5 a0 0 12.9 68.6 18.5
6 85 | 36,841 29.8 306 17.8 | 80.6 6.2 - 06 -08 6 6.9 70.5 22.6
7 | 100 | 11,944 16.4 91.8 1.9 9.3 .4 13.3 -0 0 13:7 76.8 9.5
8 | 100 | 59, 728 80.9 | 469.5] 16.4] 30.6] 12.5 -05]} .03 9 13.5 78.7 7.7
9] 100 | 28, 242 43.9} 228.5] 1.7] 8.4 5.8 US| ria) 2 15.5 80.9 3.6
10 | 170 | 46, 935 84.2] 380.6] 2.8] 1.7] 10.1 2.1 | 5.2 5 17.9 81.1 .95
11 | 109 | 14, 702 17.9 | 119.2] 2.4) 7.5 2.7 9.4 .0 1 12.2 81.1 6.5
12 85 | 19,540 9.7 210.8 itil! 8.3 “id 2.1 .6 9 4.2 91.7 4.1
1 Represented on leaves examined by empty pupa Cases,
UNEXPLAINED MORTALITY. 15
An examination of the data in the last three columns of the above
table shows a striking relationship between the unexplained mortality
and the insects which survived. In the case of the fungous parasites
however, there seems to be no striking relationship of this kind. In
order to make this point clear the six records (Nos. 1 to 6, inclu-
sive) with the lowest percentages of unexplained mortality and the
six records (Nos. 7 to 12, inclusive) with the highest percentages of
unexplained mortality are here summarized and compared with a
similar summary with regard to fungous parasitism rearranged from
the same data:
Unexplained mortality:
6 lowest percentages averaging 58.2 per cent, 24.9 per cent survived.
6 highest percentages averaging 81.7 per cent, 5.4 per cent survived.
Fungous parasitism:
6 lowest percentages averaging 8.5 per cent, 15.1 per cent survived.
6 highest percentages averaging 21.1 per cent, 15.2 per cent survived.
It appears from the above summary that a difference of about 24
per cent in unexplained mortality in two groups of groves was asso-
ciated with a difference of about 20 per cent in the insects which
survived. On the other hand, a difference of about 13 per cent in
the deaths due to fungous parasites was associated with no appreciable
difference in the proportion of insects which survived.
In December, 1910, Mr. S. S. Crossman, at the suggestion of the
junior author, made a series of records to correspond with 10 of the
12 included in Table IV. A summary of the 10 records for the two
years is given in Table III.
TaBLE II1.—Status of white flies in 10 groves at ends of seasons 1908 and 1909.
a,
E Leaf averages. Percentages of totals.
Total num-
ber white
s fly forms
Year. ee Per cent of| Per cent
examined | Kijed by | UCX- | Ative and | Per cent of | ““unex- | surviving;
on 1,000 i plained fungous ex Sey
leaves fungus. | J) ortalit matured. infection plained alive an
pad y- * | mortality. | matured.
ee 259, 054 34.0 203.1 33.5 12.4 73.7 13.9
Ul lor See ae 107, 191 16.3 76.5 14.5 15.4 71.0 13:7
In five groves a larger percentage of surviving insects was found in
1909 than in 1908, in four groves a smaller percentage of surviving
was found in 1909 than in 1908, and fn one grove there was no
appreciable difference in this percentage, as shown by the two exami-
nations. Unexplained mortality ranged from 23.6 to 91.7 per cent
in 1908 and from 61.8 to 78.8 per cent in 1909. The following is a
summary for 1910 based on arrangements of the data to show rela-
tion between unexplained mortality and fungous diseases to the
number of insects surviving.
16 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
Unexplained mortality:
5 lowest percentages averaging 66.1 per cent, 15.7 per cent survived.
5 highest percentages averaging 76.1 percent, 11.7 per cent survived.
Fungous parasitism:
5 lowest percentages averaging 10.2 per cent, 14.7 per cent survived.
5 highest percentages averaging 20.5 per cent, 12.6 per cent survived.
In the above summary the comparatively small difference between
the five highest and five lowest records in each case makes the results
less striking than are the results of the previous year. However, it
is noteworthy that a difference of 10 per cent in unexplained mor-
tality shows a corresponding difference of 4 per cent in the number
surviving, while a difference of 10 per cent in the fungous parasitism
shows a difference of 2.1 per cent in the number surviving.
A fair estimate of the results produced by either unexplained
mortality or fungous diseases must include a consideration of the
increased degree of benefit from each if it had been the only factor
concerned with the mortality of the larvze and pupz on the leaves.
This point has been discussed elsewhere as to fungous diseases.
Assuming that, in the 10 groves considered in Table III, the 12.4 per
cent recorded as infected by parasitic fungi in 1908 and the 15.4 per
cent in 1909 were actually destroyed by the fungi,' a large part of
those infected by fungi would have died from unexplained causes if
the fungi had not been present. EKighty-eight of every one hundred
larvee and pupz were not infected by fungi in 1908 and 85 of every
100 were not infected in 1909. Of these 84.1 per cent (73.7/87.6) and
83.8 per cent (71.0/84.7), respectively, died from unexplained causes.
It must therefore be assumed that if no fungous parasites had been
present 84 and 83.8 per cent of the 12.4 and 15.4 per cent recorded
in. Table III would have died from unexplained causes, giving a total
efficacy for unexplained mortality of 84.1 per cent and 83.9 per cent,
respectively, for the years 1908 and 1909. This efficacy, combined
with the effects of fungous diseases and overcrowding, did not result
in a condition of satisfactory control in the average grove in 1908,
with an average of about 24 live pupz per leaf, nor in 1909, with the
average reduced to 11 live pup per leaf. In each year there was a
satisfactory condition of control in two or three of the groves under
observation or a promise of such a condition the following season.
In the opinions of the authors the data here given, representing a
small selection of the large amount of similar data at hand, covering
all sections of the State of Florida, conclusively show that the fluctua-
tions from year to year in the proportion of white flies dying from
causes as yet unexplained are of first importance in the periodical
‘cleaning up’’ of infested citrus groves.
More attention should be given to a study of the cause or causes
contributing to the unexplained mortality herein discussed. Attempts
1As shown elsewhere, the brown fungus fs known to infect dead as well as live insects.
UNEXPLAINED MORTALITY. 17
to separate pathogenic bacteria from material sent to the Bureau of
Animal Industry have not thus far been successful. There is certain
evidence that some organism is directly concerned. As a rule
unexplained mortality is greater in heavily infested groves than in
lightly infested groves, although it is not dependent upon this point
to a great degree after the insects have once become well established.
The data in Table II, illustrating ordinary conditions in groves long
infested, are here summarized:
Average number of forms per leaf:
6 lowest, averaging 112.7, 61.3 per cent unexplained mortality.
6 highest, averaging 368.3, 78.5 per cent unexplained mortality.
It should be noted that unexplained mortality was from 2.3 to
12.5 per cent greater in the case of record number 11, averaging 147
forms per leaf, than in the case of either record numbers 5, 6, or 8,
averaging 229, 434, and 597 forms per leaf, respectively. Of the
twelve records the one showing the highest unexplained mortality
ranks seventh in point of average number of forms per leaf.
Tn newly infested groves or in groves where the white fly has been
temporarily greatly reduced from any cause, unexplained mortality
as a rule is comparatively low. Grove No. 1 in Table VI, that of
Hon. J. M. Cheney, previously referred to as to its condition in 1906
and 1907, shows a condition which may follow the reduction of the
white fly to a negligible quantity for a season. Table IV gives the
results of the examination of white flies in six newly infested groves,
no fungous diseases, so far as could be detected, being present in any
case:
TaBLE 1V.—Conditions with regard to unexplained mortality of white flies in newly-
infested groves.
| Average
Grove . “eaves, | Total num-| number | Fortnase®
; When examined. See ber of forms} white fly plained
ined. counted. sore Pet mortality.
fw 6C. 4; 1806 referee 25 = 2-225 27 5,503 20. 4 12.0
29 | Septerls, 1907s). 338 -225k. 5 100 15 1.5 15.3
3 Oc Fae LY Coa ete eee aes 10 2,094 20.9 30.5
AACA Gh IO0ges. SE Ot 100 1, 222 12.2 24.2
5 DGC) 8 MO08 «cree an sconces 41 233 5.7 12.4
6 DBGr at L OOD feracacteecee ke 25 12,801 51.2 10.9
Both species of white flies herein considered are affected by mor-
tality from unexplained causes, but the effect on the cloudy-winged
white fly (Aleyrodes nubifera Berger) seems to be more pronounced
as a matter of control, since the absence of food plants other than
citrus tends to prevent the rapid increase in infestation which results
in the case of the citrus white fly when its useless food plants are neg-
lected. In the foregoing records both species were present, the citrus
white fly greatly predominating.
21958°—Bull. 102—12——2
18 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
DROPPING FROM LEAVES.
Daily observations made on marked larve from date of settling
to emergence of adults, in connection with life-history studies, proved
that a small proportion of larve loses hold upon the leaves and drops,
especially at molting periods. Of 231 marked larve, 20 (or 8.6
per cent) dropped before reaching maturity. This dropping occurred
in nearly every case after the larve had passed several days in the
plump condition preceding molting and were in no way pressed for
room. While dropping is largely restricted to the earlier instars,
one pupa has been known to drop after having shown developed
eye-spots for nine days. Where infestation is excessive, dropping
is more frequent than noted above, but is then due more directly
to overcrowding, as shown under the following heading.
MORTALITY DUE TO OVERCROWDING.
The excessive overcrowding of leaves with eggs always results
in the death of practically all the larve that hatch, as it either becomes
a physical impossibility for them to find suitable places for attach-
ment, or, because of the closeness of the eggs, such spaces as they do
find are far too limited to permit development to the pupal stage.
TaBLeE V.—LE fect of overcrowding upon development of the citrus white fly.
Leaf Number Number Number Number Per cent
No. Geeta: live larve. | live pupz. |pupal cases.| _ alive.
1 13, 882 0 0 0.01
2 14, 000 0 0 4 -03
3 2,000 0 0 -0
The data in Table V illustrate the mevitable outcome of over-
deposition. The leaves on which these data are based were heavily
infested with eggs, No. 3 being a very small leaf. Unfortunately
this wholesale mortality is not so important a factor in the develop-
ment and spread of the citrus white fly as in the case of the cloudy-
winged white fly, since the habit of the female leads her to scatter her
eggs over the older as well as over the more tender growth. With
the former species on more than one occasion effective control has
been observed to follow certain favorable conditions as to the rela-
tive abundance of the adult insects and new citrus growth. It has
been computed that the larve hatching from the 13,882 eggs deposited
on Leaf No. 1, would require about 25 times the surface of that leaf
in order to reach the pupal stage should they settle with the view
of utilizing the least possible space. Since the larve do not show
such discrimination in locating themselves, an even larger amount of
leaf surface would be required.
BACTERIAL DISEASES. 19
Because of this lack of discrimination in settling, it will be readily
seen, death due to overcrowding is not, strictly speaking, always the
result of overdeposition, but frequently results from the overlapping
of larvee and pupe during growth on leaves only moderately infested.
Since, after settling, the immature stages do not change their loca-
tion, specimens having ample room during the early larval stages
become so large in the pupal stage, if not before, that they may over-
lap each other at the molting period, with disastrous results to the
individual beneath. Partial overlapping of the posterior portion of a
pupa does not always result in its death, but death invariably follows
the overlapping of the anterior or head end of the body.
EFFECT OF CURLING AND DROPPING OF LEAVES FROM DROUGHT.
Data collected durmg an unusual period of drought extending
throughout the fall and winter of 1906-7 show that curling of leaves
as an effect of drought has little effect on the vitality of the fly at
this season. In March, 1907, pupe of the citrus white fly were
observed on leaves which had been curled and dry from the effects
of droughts for more than three months. The leaves were so dry
that they felt and tore much like paper, but they soon regained their
normal texture after the. beginning of the rains. The emergence of
the adults on trees affected as here described was delayed for several
weeks as compared with unaffected trees, but aside from this there
was no apparent effect on the insects.
Although the curling of the leaves of citrus trees as a result of
drought has not, so far as observed, resulted in checking the white
flies, the dropping of the leaves may be decidedly effective in this
respect. When citrus trees suffer from the effects of drought to the
extent of shedding a considerable part of their foliage, the resulting
reduction in the numbers of white flies rarely proves of sufficient
advantage to offset the injury to the trees, and the insects as a rule
resume their normal status fully as rapidly as the trees recover.
BACTERIAL DISEASES.
While no bacterial disease has been recognized as such in produc-
ing the very high rate of mortality often occurring among the larve
and pupe of both species of white flies, there are indications that
bacteria play a more important réle in this connection than has been
suspected, and are at times more beneficial in holding the fly in
check than are the fungi. The fluctuating effectiveness of the
unexplained mortality heretofore discussed, without the visible
appearance of any fungous parasite which might be responsible,
seems to indicate that some parasitic organism is directly concerned.
°0 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
FUNGOUS DISEASES.
THE RED FUNGUS.
(Aschersonia aleyrodis Webber.)
HISTORY.
The red fungus was first discovered at Crescent City, Fla., in
August, 1893, in the grove of Mr. J. H. Harp, by Dr. H. J. Webber,
then of the Division of Vegetable Physiology and Pathology of the
United States Department of Agriculture, who, in a preliminary
notice * of its entomogenous nature, referred it to the closely allied
species Aschersonia tahitensis Mont. In 1896, under the same name,
he mentions it in the bulletin ‘‘The Principal Diseases of Citrus
Fruits in Florida.””? Upon further study, however, he found it to
be a distinct species, and in 1897, in his bulletin on the ‘‘Sooty
Mold of the Orange and its Treatment,’ ? described it as Aschersonia
aleyrodis, and illustrated it with 14 line drawings and 2 colored
figures. It is interesting to note that at the time Prof. Webber
first reported this species attacking white-fly larve and pup no
species of the genus Aschersonia had been known to attack insects,
although several entomogenous species have since been discovered.
In the last-mentioned bulletin the author, besides discussing at
length the development of the red fungus on the white fly, the
probable methods of spore dissemination, and methods of introduc-
tion into noninfested groves, states that he had found fungus only
at Crescent City, Citra, Gainesville, Panasoffkee, Bartow, Manatee,
and Fort Myers, Fla., while no fungus was seen in white-fly groves
at Ocala, Orlando, Evinston, and Ormond. He further states that
the fungus was very abundant in groves at Panasoffkee and that
while in 1893 no trace of it could be found in the grove at Citra, it
had been reported by growers as being quite abundant there in
certain localities at the time of the first freeze, which occurred
December 28, 1894. Since the publications mentioned above, the
yearly reports and numerous bulletins of the Florida Experiment
Station and the Transactions of the Florida Horticultural Society
have contained the principal contributions to the literature of this
species of fungous parasite. Special mention should be made of the
work of Dr. E. W. Berger and Prof. H. S. Fawcett. From a tech-
nical standpoint the most important contribution to our knowledge
of this fungus since Webber is contained in Prof. Fawcett’s paper on
“The Fungi Parasitic upon Aleyrodes citri,”’* in which the author gives
the description, history, methods of introduction, distribution, and
1 Journal of Mycology, vol. 6, no. 4, p. 363, 1894. i
2 Div. of Veg. Phys. and Path., Washington, D. C., Bul. 8, p. 27, 1896.
3 Div. of Veg. Phys. and Path., Washington, D. C., Bul. 13, p. 21, 1897.
4 University of the State of Florida, Special Studies, No. 1, pp. 10-17, 1907.
Bul. 102, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE III.
ORANGE TWIG INFESTED WITH CITRUS WHITE FLY, SHOWING A SUCCESSFUL INFECTION
OF RED FUNGUS.
{Hundreds of white flies may develop to maturity on a twig as well infected numerically as this one,
or the mortality may be complete. (Original.)]
Bul. 102, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE IV.
@
FUNGUS-INFECTED WHITE FLIES.
[Red Aschersonia developing on Aleyrodes inconspicua infesting sweet-potato leaves (top); red
Aschersonia infecting the cloudy-winged white fly (Aleyrodes nubifera) (lower left); red Ascher-
sonia pustules, enlarged, showing mycelium and pyenidia (lower right). (Original.)]
THE RED FUNGUS. 21
valuable data on cultural methods and on the introduction of arti-
ficially grown spores. Dr. George F. Atkinson, of Cornell Univer-
sity, was successful in growing cultures of this fungus during the
summer and fall of 1907 from material sent him by Mr. Worsham, at
that time an agent of this bureau, and under date of September 30,
1907, sent the authors at the Orlando Laboratory cultures from
which infections were secured in the grove.
DESCRIPTION.
A glance at Plate I, middle figure, would give one unfamiliar with
this fungus a sufficiently correct idea of its appearance and make
possible its identification in the grove. (See also Plates III and IV.)
Dr. Webber’s original technical description is as follows:!
Stroma hypophyllous, depressed hemispherical, pinkish buff or cream colored,
coriaceous, 1-24mm. in diameter; mycelial hypothallus grayish white, forming a thin
membrane closely adhering to the leaf and extending about 1 mm. beyond the stroma;
perithecia membranaceous, at first superficial, later becoming irregular, reniform or
orbicular in mature specimens, and opening by small, round, or elliptical pores or
slits; basidia crowded, filiform, slender, continuous, 28-40y long, 0.94-1.5 in diam-
eter; paraphyses abundant, slender, projecting beyond the basidia, 65-100. long,
#1» in diameter; sporules fusiform, continuous, mucilaginous, hyaline, sometimes
obscurely 3-4 guttulate, 9.4-14.1y long by 0.94-1.88» wide, very abundant and erum-
pent, forming conspicuous coral-red or rufous masses. (Parasitic on Aleyrodes citri
R. & H., infesting citrus leaves in Florida.)
Dr. Webber further states that peculiar darkened cells occur at
irregular intervals in the paraphyses which are quite characteristic of
this species of fungus.
DEVELOPMENT.
If in the process of dissemination the spores find a favorable resting
place and the weather conditions permit, they soon germinate or
grow by sending out rootlike processes known technically as hyphex
or mycelial threads. Should one of these succeed in finding a vul-
nerable spot in a white-fly larva or pupa, the growth of the fungus
becomes very rapid and the insect is soon killed. The following
description of the development of the fungus within the insect has
been taken, with slight changes, from that of Dr. H. J. Webber,
which in the main has been verified by the authors.
The first indication of the effect of the fungus on the larva of the
white fly is the appearance of slightly opaque, yellowish spots, usu-
ally near the edge of the larva. In the early stages of infection the
larva becomes noticeably swollen and appears to secrete a greater
abundance of honeydew than normally. As the fungus develops,
the internal organs of the larva appear to contract away from the
margin, leaving a narrow circle, which then becomes filled with the
1 Bul. 13, Div. Veg. Phys. and Path., U. 8. Dept. Agr., p. 21, 1897. 2Tdem, pp. 23-24, 1897.
22 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
hyphe or mycelium. This circle becomes opaque and whitish,
presenting a very characteristic appearance. Shortly after this
the hyphe burst out around the edge of the larva, forming a dense
marginal fringe. This may form all around the larva at about the
same time, or may develop at one portion of the margin sooner than
at the others. The body of the larva at this time is plainly visible,
but it is opaque and yellowish throughout. Death usually ensues,
it is believed, before the hyphz burst out. The fungus does not
spread over the leaf to any great extent, but grows upward in a mass,
gradually spreading over the larva. It is not uncommon to find the
perithecia, with their bright coral-red masses of sporules, formed in a
circle around the edge of the larva while it is yet visible. As the
Aschersonia develops, the hyphe spread over the larva, forming a
dense, compact stroma, which ultimately entirely envelops the
larva. The stroma in this stage is thin and disklike, the fructifica-
tions being usually borne in a circle near the edge. The hymenium
at this time is spread out on the surface of the stroma, or but slightly
sunken, the sporules projecting in a conical coral-red or rufous mass.
As the fungus develops the stroma becomes thickened and hemi-
spherical and the hymenium gradually becomes immersed. The
hyphz which make up the main mass of the stroma are from 3.5 to
7.5 micromillimeters in diameter. Within the body of the insect
and near the perithecia they are somewhat smaller.
Data collected in connection with experimental work in the field
have shown that well-developed pustules can mature within 15 days
after artificial spreading of the infection. Ten shoots on the outside
of a tree which were sprayed on June 25, 1909, had developed by
July 10 numerous well-developed pustules (red Aschersonia). Check
shoots produced no fungus growth. The range in temperature
during this period was from 70° to 95° F. (average daily mean, 80.5°
F.) and frequent showers fell. Fungus introduced by spraying on
July 27, 1907, had produced pustules by August 17, or 21 days later.
During this period the temperature ranged from 70° to 98° F.
(average daily mean for period 80.8° F.), with numerous showers.
In both of these instances no earlier examinations were made. In
another instance a larva of A. citri, noted to have died on October 15,
1908, began to develop a whitish appearance on October 23, or 8
days later, and while the fungous growth was daily observed the
characteristic reddish color of the spore masses of red Aschersonia
did not appear until November 4, or 12 days after the fungus first
began to be visible to the eye and 20 days after the larva was recorded
as having died. During the 20-day period the temperature ranged
from 45° to 85° F. (with an average daily mean of 70.4° F.) and there
was norain. The average daily mean humidity for the three periods
was 92.3, 89, and 90 per cent, respectively.
THE RED FUNGUS. 23
Prof. H. S. Fawcett! has found that this fungus requires from 30
to 40 days to mature a pustule and produce pycnidia when grown on
a 5 to 10 per cent glucose agar in the laboratory.
DISSEMINATION OF SPORES.
Various agencies, such as rains and dews, crawling and adult white
flies, and other insects, have been considered as probable means of
spreading fungous spores. ‘Notwithstanding the fact that its spores
have been described as mucilaginous, and therefore would not seem
to be subject to being blown about by winds, laboratory tests have
shown that after water solutions of spores have been dried on a hard
surface the spores can be loosened and blown away by the aid of an
electric fan or lung power. While complete success did not attend
these experiments, it was demonstrated that spores can be and doubt-
less are blown about by winds to a considerable extent after once
being freed from their mucilaginous matrix by rains and dews, and it
is believed by the authors that winds are the most valuable agents in
spreading the fungus from tree to tree and to the more isolated groves
in a fungus-infested district. However, when once the white flies
in a tree have become infected, rains and dews appear to be the most
valuable agents of distribution throughout the individual and closely
adjoining trees. The fact that the pustules are largely borne on the
underside of the leaves is no argument against this view. While the
pustules thus located are for the most part protected from the direct
wash of beating showers, examination of citrus trees, especially
oranges and tangerines, will show that many of the leaves are more
or less slightly curled so that their underside is easily wetted, either
entirely by direct rainfalls or in spots by splashing from closely
growing leaves, while the newer growth, upon which infestation is
usually very heavy, because of its more flexible nature is soon beaten
or weighted down by the rain so that the underside of its leaves
receive innumerable splashings and drippings from the pustule-
bearing leaves above.
After several showers of moderate duration and force, an exami-
nation of trees in the laboratory grove showed that about 90 per cent
of the leaves were either thoroughly or partly wetted on the lower
surface, and during the progress of ordinary showers drippings from
leaves above have been seen to bound off from lower leaves to which
they had fallen and strike the exposed underside of leaves 3 feet to
one side, or to splash obliquely upward as high as 1 foot. This
upward spattering accounts not a little for the upward spread of
fungus. It requires only a microscopic examination of drippings
from fungus-laden trees, caught during a heavy shower, to prove that
1 Special Studies, No. 1, Univ. of the State of Fla., p. 13, 1908.
94 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
spores are not only spread about by rain but that many are washed to
the ground.
It is probable that dews, and especially the heavy dews of fall, are
of greatest value in moistening the pustules, thus aiding in the dis-
solving out of the spores from their mucilaginous matrix, so that they
may be more readily transported by other agencies. After heavy
dews the matrix containing the spores is so soft that portions of it
will adhere to any body brought into contact with it, and not infre-
quently such a quantity of spores is dissolved out of the pycnidia that
they spread out over the leaf for one-fourth of an inch from the
pustule, as shown by the reddish coloring matter of the matrix,
Because of the adhesive nature of the matrix thus moistened, it is
possible, and even probable, that insects play a part in spore
dissemination ; yet the failure of this fungus to increase to any extent
during an unusually dry period in midsummer or after the summer
rains cease, even though the insects remain abundant, is regarded
by the authors as significant and leads them to conclude that insects,
in general, play a minor réle in spore dissemination.
Microscopic examination of washes from the bodies of adult white
flies collected on trees bearing much fungus has not disclosed the
presence of the spores. Of still greater importance as direct evidence
is the frequently repeated observation that leaves upon which adult
flies collected from similar places have been caged, and which have
been protected from rain drippings, have seldom developed fungus
pustules. In this connection it is also worthy of note that water-
shoots, even though more heavily crowded with adults than outside
new growth, develop only a slight amount of fungus as compared with
the outside growth if not so located as to be easily drenched with
rains. It has been generally observed by growers as well as by the
authors that rapid dissemination of spores is concurrent with summer
rains, and if these fail to fall the fungi are not spread rapidly, no
matter how abundant the adults may have been.
SPECIES OF WHITE FLIES ATTACKED.
While the red Aschersonia is most effective in its attack upon the
citrus white fly and is of economic importance largely in connection
with this species, it is frequently found growing upon several other
species of white flies. On numerous occasions it has been observed
at Orlando and other points in Orange County attacking the cloudy-
winged white fly, upon which it develops into unusually large pustules.
Thus far, however, attempts at introduction into groves infested
only with the cloudy-winged white fly have met with failure from an
economic standpoint, although in each instance an infection was se-
cured. During the summer and fall of 1907 such a luxuriant growth
of fungus upon Aleyrodes inconspicua Quaintance was discovered at
THE RED FUNGUS. 95
Orlando, on the underside of sweet potato leaves, that several bushels
of leaves of this plant were picked as the easiest way of procuring a
supply of fungus for experimental purposes. Mr. W. C. Temple, of
Winter Park, also noted a similar attack upon a sweet potato aley-
rodid, probably the species above mentioned, in July, 1909. The
senior author has several times seen pustules on Aleyrodes floridensis
Quaintance on guava at Orlando and Manatee, and on another, as
yet undetermined, aleyrodid attacking Spanish mulberry at Orlando,
while in 1908 Messrs. M. T. Cook and W. T. Horne reported it
attacking A. howardi Quaintance as well as A. citrd in Cuba.’ The
junior author has found a rank growth of this fungus on a white fly
(Aleyrodes abutilonea Hald.) at Orlando.
DISTRIBUTION.
In Florida the red Aschersonia occurs in all the leading orange-
growing sections infested with the citrus white fly. The fact that
Dr. Webber reported it from such widely separated places as Gaines-
ville, Bartow, and Fort Myers, is sufficient evidence to warrant the
conclusion that even then its distribution was wider than known.
It is being continually reported from or introduced into new localities,
and at present may be said to occur in greater or less abundance in
Florida in all sections infested by the citrus white fly. It is most
widely distributed in Manatee, Lee, and Orange Counties.
Outside of Florida the red Aschersonia now occurs in different
points in Louisiana, having been introduced by agents of the Louisiana
Crop Pest Commission. In 1905 Mr. F. S. Earle? reported this
fungus on A. citrd in Cuba. In 1906 Mr. J. Parkin * mentioned
finding in Ceylon an Aschersonia closely resembling aleyrodis on
several undetermined species of Aleyrodes. Dr. Berger has identified
this species of fungus on citrus leaves infested with Aleyrodes citri
from Japan,‘ and the junior author found it attacking A. howardi in
1910 in both Cuba and Mexico.
HYPERPARASITIC FUNGI.
Thus far the red Aschersonia has not been subjected to wide-
spread attack by hyperparasitic fungi. In sheltered places during
the late summer and in the fall the pustules sometimes become over-
grown by the species of Cladosporium mentioned more fully under
the hyperparasitic fungi of the yellow Aschersonia. In a grove at
McIntosh, Fla., examined in December, 1907, it was estimated that
fully 50 per cent of the red-fungus pustules were overgrown by this
hyperparasite. Old worn-out pustules are often entirely overrun late
1 Bulletin 9, Cuban Experiment Station, p. 31.
2 Primer Informe Annal de la Estacion Central Agronomica de Cuba, 1904 and 1905, p. 169, 1906.
3 Annals Roy. Bot. Gard. Peradeniya, vol. 3, pt. 1, p. 36, 1906.
4 Ann, Rept. Fla. Agr. Exp. Sta. for year ending June 30, 1909, p. xxxvi.
26 NATURAL CONTROL OF WHITE FLIES IN FLORIDA,
in the season by a rank growth of sooty mold ( Meliola sp.), but this
usually occurs after the fungus has ceased spreading rapidly and on
pustules the majority of which would fall from the leaves before
spring. On the whole these two fungi are of no practical importance
in checking the spread of the red Aschersonia or in reducing its
efficacy.
THE YELLOW FUNGUS.
(Aschersonia flavo-citrina P. Henn.)
HISTORY.
Specimens of a white-fly parasite from the grove of Mr. J. F.
Adams, of Winter Park, Fla., sent to Mrs. Flora W. Patterson,
Mycologist of the United States Department of Agriculture, in Sep-
tember, 1906, by Prof. P. H. Rolfs, director of the Florida Agricul-
tural Experiment Station, were identified by Mrs. Patterson as the
yellow fungus (Aschersonia flavo-citrina). Previously this had been
discovered occurring on leaves of the guava (Psidium) at Sao Paulo,
Brazil, in October, 1901, and described in 1902 by P. Hennigs. No
insect was mentioned associated with it on the guava leaves.
Since its discovery in Florida as a parasite of Aleyrodes nubifera
and A. citri it has been found in several new localities and has been
introduced into others. Reports and bulletins of the Florida Agri-
cultural Experiment Station and the Transactions of the Florida
Horticultural Society contain the only references to data concerning
the yellow fungus as a parasite of white flies. Prof. Fawcett has
published the most important contributions to our more technical
knowledge and has successfully grown artificial cultures on various
media. Prof. George F. Atkinson, of Cornell University, has also
successfully grown cultures from which infection has been secured
in the grove by the junior author in early October, 1907.
DESCRIPTION.
The yellow Aschersonia in general form closely resembles the red
Aschersonia, but is at once separated from it by the rich yellow
instead of pink or red color of its well-developed pustules. A suffi-
ciently clear idea of its appearance may be had by referring to Plate I,
upper figure. (See also Plates Vand VII.) During the early stages of
infection it is impossible to separate these two fungi by ordinary exami-
nation; it is only after the pycnidia, with their characteristically col-
ored spore masses, are formed that they can be readily distinguished.
Prof. H. S. Fawcett states! that the pustules of A. aleyrodis under
similar conditions average less in diameter, that the pycnidial cavities
1 Fungi parasitie upon Aleyrodes citri, University of State of Florida, Special Studies, No. 1.
THE YELLOW FUNGUS. Wf
are usually more sunken than in A. flavo-citrina, and that its spores
are smaller. The original description follows:
Aschersonia flavo-citrina P. Henn. Stromatibus carnosis, hypophyllis, sub-
discoideo-pulvinatis vel hemisphaerico-depressis, citrinis, 2-2.5 mm. diameter,
pruinosis, superne punctulato-pertusis, intus subaurantiis, subiculo membranaceo,
flavo; pycnidiis immersis oblongis, paraphysibus filiformibus, flexuosis, hyalinis,
140-180x1-1.5 micr., continuis; conidiis fusoideis, utrinque acutis, continuis, hyalinis,
12-18x2 micr.; conidiophoris brevibus, hyalinis, fasciculatis.
The manner of development of the yellow Aschersonia upon the
larve and pupe is so like that already described for the red Ascher-
sonia that no further mention of it need be made here.
The method of spore dissemination, so far as can be determined,
is also similar to that of the red fungus.
BIOLOGY.
The yellow Aschersonia, except when artificially introduced, has
never been found in groves infested only by the citrus white fly and so
far as observed thrives only on the cloudy-winged white fly. Dr.
Berger? reports having caused the infection of a few larve of citri,
but states that this fungus did not increase in his experiments. The
same experience has been had by the authors at Bradentown, Fla.
It has been noted by the senior author attacking a scale insect on the
leaf of sweet gum (Liquidambar styraciflua) at Winter Park, Fla.
DISTRIBUTION.
Up toJuly, 1909, this fungus has been found growing naturally at
Altamonte Springs, Maitland, Mims, Oneco, Orlando, Oviedo, Wild-
wood, and Winter Park, Fla., and has been introduced into Bucking-
ham, Gainesville, Lakeland, Lake City, Largo, Lemon City, Manatee,
Miami, New Smyrna, Sutherland, St. Petersburg, and in the vicinity
of Turkey Lake in the western portion of Orange County, Fla. Its
occurrence in Brazil has already been noted.
HYPERPARASITIC FUNGI.
The yellow Aschersonia is subject to widespread parasitism by a
ereenish-brown hyperparasitic fungus identified in March, 1907, by
Mrs. Patterson as Cladosporium sp. The attack of the latter upon
the yellow Aschersonia was first noticed by the senior author in the
summer of 1906. During the winter of 1906-7 it was estimated to have
overrun 95 per cent of the yellow pustules in certain groves at Winter
Park and Orlando, and has since been noted wherever the yellow
Aschersonia occurs. The destruction of more than 90 per cent of
the supply of yellow Aschersonia spores during the fall and winter
must necessarily have a retarding influence on the spread of the
fungus at the beginning of the next season for its normal spread.
Frequent observations and experiments at both Winter Park and
1 Bul. 97, Fla. Agr. Exp. Sta., p. 53.
28 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. ;
Orlando have demonstrated, however, that ordinarily the overrun-
ning of from 20 to 90 per cent of the pustules does not prevent the
fungus from spreading rapidly when the weather conditions are
favorable. The Cladosporium spreads most rapidly during dry
weather and upon leaves bearing many pustules of the Aschersonia.
The yellow Aschersonia pustules in all ages and conditions are
subject to the attack of the Cladosporium. (See Pl. VI.) The former
is frequently so closely followed by the latter that even when spread-
ing rapidly practically all of the Aschersonia pustules show the
beginning of the hyperparasitic attack before they reach more than
one-fourth of their normal size.
During 1907 and 1908 the Cladosporium was especially active in
August and October. In 1907 its spread was unusually rapid
between October 17 and 31, during very dry weather, and by Novem-
ber 15 of the same year had so overgrown the yellow fungus in one
nursery at Orlando that 92.6 per cent of the pustules were affected.
This estimate is based on the examination of 50 leaves upon which
there were 3,110 pustules of the yellow Aschersonia. Again, between
August 6 and 13, 1908, when no rain had fallen since July 28, it
spread with such rapidity as to render useless numerous experiments
started in July at Drennen. During the summer of 1909, when the
rain was more abundant than during 1907 or 1908, the Cladosporium
did not spread with such rapidity in any of the groves at Orlando.
THE BROWN FUNGUS. 6
(Aigerita webberi Fawcett.)
Dr. H. J. Webber, then of the United States Department of Agri-
culture, first discovered the brown fungus, parasitic upon the immature
stage of the citrus white fly, in March, 1896, in the grove of J. H.
Viser, Manatee, Fla. Dr. Webber states that while the spread of the
fungus was phenomenal from March to December of that year and
killed so many larve and pupe that the fruit was clean, he was
unable to discover it in any of the surrounding groves heavily infested
with the fly. Although a thorough study of the fungus was made by
its discoverer at several seasons of the year, no trace of fructification
was found; hence it was impossible to determine its relationship.
The fungus was, therefore, popularly named the brown mealywing
fungus, or, as it is now more commonly called, the brown fungus.
During the past three years the authors have noted the frequency
of the occurrence of patches of minute brownish spores on leaves
infected with this fungus, arising apparently from its ground mycelium
As these spore patches occurred only upon leaves infested with the
fungus and upon no other leaves no matter how heavily coated with
sooty mold, it was concluded that they must be the fruiting bodies of
the fungus. A specimen leaf was sent to Mrs. Patterson, the mycolo-
Bul, 102, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE V.
GRAPEFRUIT LEAF, SHOWING YELLOW ASCHERSONIA INFECTING THE CLOUDY-WINGED
WHITE FLY.
[The parasitic fungous pustules are overgrown in spots by sooty mold and sooty mold is also shown
developing around the edges of infected pupze. More, rather than less, sooty mold usually accom-
panies as extensive an infestation by the yellow fungus as that shown on this leaf. (Original. ) ]
Bul. 102, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VI.
RANK GROWTH OF CLADOSPORIUM ON YELLOW ASCHERSONIA.
[All pustules of the yellow Aschersonia are destroyed except the few lighter-colored ones. (Original.)]
THE BROWN FUNGUS. 29
gist, who, under date of November 2, 1907, wrote: ‘‘The specimen
has a fruiting stage connected with the brown fungus.” In a publi-
cation dated October 1, 1908, Prof. Fawcett! announced that he
had noted what appeared to be the spores of the brown fungus, and
that these spores were then germinating in hanging drop cultures of
sugar solutions, and were producing hyphz that seemed identical
with those of the brown fungus. Since then, however, Prof. Fawcett
has been most successful in not only growing the characteristic
brown-fungus mycelium from the spores, but infecting healthy white-
fly larvee with the mycelia thus grown and in securing the charac-
teristic pustules of this fungus, to which he has given the name
Aigerita webberr.?
DESCRIPTION,
The pustules of the brown fungus, which vary in size according to
the size of the larva or pupa infected, are seal-brown in color and
when fully developed entirely conceal the insect attacked. The
pustules are round or slightly elliptical, and, as compared with the
pustules of the red Aschersonia, are more flattened, thus resembling
the Florida red (or circular) scale (Chrysomphalus ficus) (see Pl. I,
lower figure; also Pl. VII.) Dr. Webber gives the following general
description: *
The mature stroma is compressed hemispherical, frequently having a slight depres-
sion in the apex over the center of the insect, where the hyphz come together as they
spread from the edges of the larva in their development. The size varies greatly
according to the stage of development of the insect attacked. In many young larve
it is from one-fourth to one-half a millimeter in diameter. The thickness or height
also varies in like manner, specimens on mature larve or pupz having usually from
175 to 260 microns while those on young larve are much thinner. * * * The
stroma is commonly seal brown, with a shade of chestnut, but becomes slightly darker
with age. It adheres closely to the leaf, but no indication has been found that the
hyphe penetrate the latter. The hyphz which make up the body of the stroma are
light brown, very tortuous, and but slightly branched.
Those in the body of the insect are of similar character, but a much darker brown.
From the base of the stroma a ground mycelium, or hypothallus, spreads out in all
directions on the surface of the leaf, forming a compact membrane near the stroma,
but becoming gradually dispersed into separate filaments. * * * The hyphe of
the hypothallus are colorless, sparingly branched, mostly continuous, having only an
occasional septa, and are from 5 to 7 microns in diameter. In some places in the
hypothallus, when the hyphe are apparently somewhat amassed and knotted, they
become light brown, similar in color to the isolated hyphz of the stroma.
When there are but a few pustules on a leaf, the threadlike myce-
lium spreads as separate strands on the underside of the leaf
for as far as 2 or 3 inches and may be seen with the aid of a
lens. The mycelium also often extends to the upper surface of the
leaf. When the pustules are abundant, however, the mycelial
1 Univ. of the State of Florida, Special Studies No. 1.
2 An important entomogenous fungus. Mycologia, vol. 2, no. 4, July, 1910.
8 Bul. 13, Div. Veg. Phys. and Path., U.S. Dept. Agr., pp. 28-30, 1897,
30 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
threads interlace to form a dense papery membrane covering the
lower surface of the leaf, and mycelial threads growing down the
petioles and along the branch to the next leaf are often so numer-
ous as to form a like coating on these. The authors have on many
occasions seen watershoots 5 feet long with the undersides and
petioles of the leaves, and the stems of the shoot, wholly coated with
this dense mycelial growth. In one instance there were brownish
sporelike bodies, abové mentioned, scattered over the entire mycelium
on the stem of the watershoot and along the edges and upper surface
of the leaves. (See Pl. VII.)
DEVELOPMENT.
The development of the brown fungus on the larve and pups
does not differ materially from that of the red and yellow Ascher-
sonias already described, with the exception that after the hyphee
have filled the insect body and have broken out around the edges,
the stroma which then forms does not produce fruiting bodies but
from them there grow out slender mycelial filaments which extend
iw, greater distance than those of the Aschersonias and partly take
the place of the spores of the latter in infecting other larve and
pupe. As with the other fungi, insects may be killed without the
formation of the characteristic complete stroma, or the stroma may
be restricted in its growth to the margin of the insect. Often when
several insects close together are infected, one large irregular stroma
will develop over them all.
The junior author has followed from day to day the growth of the
mycelium of the brown fungus toward dead pupx, and the subse-
quent development thereon of the characteristic stromas. This
fungus is therefore definitely known to be partially saprophytic.
This was previously suspected, since on leaves infected by it nearly
all specimens within reach of the mycelium are overgrown and the
usually large percentage of specimens dead from unknown causes is
not apparent. The stroma frequently does not develop normally
except around the margin, leaving the greater part of the body of
the insect and the segmentation easily distinguishable. This con-
dition is probably due in some cases to the effect of dry weather on
the growth of the fungus, but it is considered by the authors to be
due more often to the development of the fungus on the body of a
dead insect.
DISSEMINATION.
Although Dr. Webber was unable to discover any fruiting bodies
of the brown fungus, his observations led him to believe that the
mycelial filaments, spreading out over the surface of the leaf from
larve already infected, have the power to infect other larve and
pup with which they come into contact, and that it seemed probable ~
THE BROWN FUNGUS. 31
that the spread of fungus from tree to tree was effected through
fragments of the mycelium carried by wind or birds. It has been
conclusively demonstrated by means of a series of marked specimens
that Dr. Webber’s observations as to the power of infection possessed
by the mycelial filaments is correct. In several instances infection
was-noted to occur only so far as the mycelial growth extended. In
this respect the mycelia of the Aschersonias is different; living
pupx have frequently been noted to touch developing pustules of
both red and yellow Aschersonia without becoming infected.
While it is very likely that winds, birds, and insects do spread this
fungus by carrying small pieces of mycelium on their bodies, the
experiments of the authors and of Dr. Berger have fully demon-
strated that the fungus can be spread from grove to grove by means
of broken pieces of mycelium. It has been frequently observed that
the fungus appears on trees to which no attempt has been made to
introduce it. As yet no success has followed the attempt on the
part of the authors to spread the fungus by means of the spores
already mentioned, but considering the abuidance with which they
are developed, especially after the middle of July, it is consider u
probable that they play an important, though as yet unknown part
in its dissemination.1. Although it probably will be proved that tha
brown fungus is most widely disseminated through the agency of
the small spores, it is apparent that after becoming well established
on a branch its spread is due chiefly to infection started by the spread-
ing mycelium. As noted elsewhere, these mycelial filaments have
been traced from one leaf down its petiole, along the branch to the
next leaf, thence along its petiole to start an infection on its under-
side. It is not a rare occurrence to find all the leaves on a watershoot
or small branch thus connected by mycelial growths.
SPECIES OF WHITE FLIES ATTACKED.
The brown fungus thrives best on the citrus white fly and has never
been observed in any amount in a grove infested by any other species.
However, slight infections of the cloudy-winged white fly have been
noted in various places.
DISTRIBUTION.
The brown fungus has been introduced into or reported from the fol-
lowing places in Florida: Lake City, St. Augustine, Hawthorn,
McIntosh, Boardman, Leesburg, Orlando, Oviedo, Winter Park,
Bartow, Lakeland, Largo, St. Petersburg, Bradentown, Manatee,
Oneco, Palmetto, Sarasota, Alva, Buckingham, and Fort Myers.
spores, thus removing all doubt that they are a means of disseminating this fungus.
32 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
and Texas through the offices of the entomologists of the experiment
stations of those States. Its recent discovery in India by Mr. R. S.
Woglum, of the Bureau of Entomology, has been noted by Dr.
Howard.!
HYPERPARASITIC FUNGI.
A greenish hyperparasite of the brown fungus was noted by the
senior author in April, 1907, in Manatee, Fla., where an examination
of leaves shed by the cold of the previous winter in one grove showed
that fully 95 per cent of the pustules of the brown fungus had been
parasitized. Since then it has been observed at various times in
many of the groves in Manatee, Oneco, and Palmetto. In September;
1907, it was noted by the senior author at Lake Charles, La., where
its occurrence was directly traceable to importation of nursery trees
from Manatee County, Fla.
Prof. H. S. Fawcett has identified this hyperparasite as Con-
iothyrium sp. It forms a dense, dark-greenish, hard growth over the
pustule of the brown fungus and presents a surface roughened by
numerous pustular elevations as shown in Plate VII.
As only the stromata of the brown fungus appear to be affected,
it is doubtful if the Coniothyrium has any practical influence in
checking theespread of the mycelium of the brown fungus. In fact,
it has been repeatedly noted that even when its parasite was present
the brown fungus was spreading as rapidly and doing as effective
work in controlling the fly as when it was not parasitized. In Janu-
ary, 1909, the junior author noted that the Coniothyrium was rare
in groves in and about the Manatee hammocks, even where it was
observed to be most abundant in 1907, and in all these groves the
brown fungus was doing effective work in controlling the fly.
FUNGI OF LITTLE OR NO VALUE AS WHITE-FLY PARASITES.
THE WHITE-FRINGE FUNGUS.
( Microcera sp.)
The white-fringe fungus ( Microcera sp.) is so inconspicuous that it is
easily overlooked. It forms no distinct pustules as do yellow and
brown fungi. (See Plate [X, lower figure). Larve and pups infected —
turn whitish, then red, often pinkish, and from their margins bursts —
forth a delicate fringe of white mycelial growth from which the fungus
derives itsname. There subsequently appear at various points along
the margin and through the vasiform orifice the fruiting bodies, which
are pink in color and vary in number in different specimens infected.
After the specimens infected are dried or after the mycelium has been
long developed, the characteristic fringe dries up and disappears, so the
best lasting evidence of the presence of this fungus is its pink fruiting
1 Journ. Econ. Ent., vol. 4, p. 130, 1911.
PLATE VII.
LEAF SHOWING BROWN FUNGUS WHICH HAS DEVELOPED ON LARVA: AND PUPA OF THE
Citrus WHITE FLY; FILM OF MYCELIUM PARTLY TORN FROM LEAF AND STEM.
[Lower figure shows Coniothyrium on brown fungus. (Original.)]
THE WHITE-FRINGE FUNGUS. 33
bodies. Those desiring a fuller description are referred to Press
Bulletin 68, issued October 14, 1907, by the Florida Agricultural
Experiment Station, by Prof. H. S. Fawcett, in which appears the
original description. In June, 1908, Prof. Fawcett! published a
more technical description, together with data on successful cultural
methods and introductions secured in the field with artificially grown
cultures. The apparent effectiveness of this fungus and methods of
- introducing it are discussed by Dr. Berger? in a publication bearing
the date of February, 1909.
The authors’ experiences with this fungus date from the fall of 1906.
Under date of November 26 of that year the senior author noted the
presence at Orlando, in a grove infested with the cloudy-winged
white fly, of an ‘unknown pink fungus especially prevalent on pup
killed by a spray.’”’ While no data as to the relative abundance of
infected pup on the sprayed and unsprayed trees were collected, the
_ number of infected specimens on the sprayed trees was unmistakably
ereater. Examinations made showed that from November 26 to
December 10 there was no spread of fungus to previously marked
healthy pup from infected pup touching them. Later in the same
year this fungus was seen at Hawthorn developing upon the citrus
white fly. Under date of August 27, 1907, Mr. Worsham reported the
Microcera quite abundant in Manatee, Hillsboro, and Orange Counties,
saying that at that time it was present in greater abundance in every
grove visited in Manatee County than on July 19. Under the same
date Mr. Worsham reported it very abundant in the groves of Mr.
F. L. Wills and Mr. C. W. Hicks, at Sutherland, and in several groves
at Orlando. On November 1, 1907, an examination of leaves from
Mr. Hicks’s grove gave the following results: Flies reaching maturity
and emerging, 46.8 per cent; living larve and pup, 4.9 per cent;
dead larve and pupe, 4.2 per cent; dead larve and pup infected
with the white-fringe fungus, 44 per cent. Under date of Novem-
ber 11, 1907, a grower at Largo reported that this fungus had killed
95 per cent of the fly in his grove, but an actual count of the leaves
sent to the Orlando laboratory with this statement showed that 12.9
per cent had reached maturity and had emerged, 52.7 per cent were
still alive on the leaves, and 34.3 per cent were dead from fungus and
unexplained mortality, no attempt being made to find the percentage
of white-fringe fungus, which was noted as being very slight.
On October 3, 1907, many pupe of Aleyrodes nubifera were killed
by mechanical injuries in applying as a smear a culture of yellow
Aschersonia; on October 31 the junior author noted that many pupe
had been killed by the application of the culture, and on November
1 Fungi parasitic upon Aleyrodes citri. Univ. of State of Florida, Special Studies, No. 1.
2 Bul. 97, Fla. Agr. Exp. Sta., pp. 54-55.
21958°—Bull. 102—12 3
34 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
11 that these same dead pupe had developed the characteristic
growth known as white-fringe fungus. During 1908 and the summer
of 1909 the authors found the fungus in every grove visited in various
parts of the State.
Since the observations made on November 26, 1906, this fungus
has been regarded by the authors as entirely or largely saprophytic,
and all data and observations since obtained have strengthened this
belief. Three series of observations have been conducted in connec-
tion with fumigation experiments. The data obtained are presented
in Tables VII and VIII. Specimens of the fungus under observation
were submitted to Prof. H. S. Fawcett, who verified the authors’
determination of the species. The data in Table VI are based upon
the examination, by the senior author and Mr. W. W. Yothers, of
leaves picked promiscuously from adjoining fumigated and unfumi-
gated rows of nursery trees. The trees were fumigated on September
26, 1908, and the examination was made on October 8, 1908:
TasBLe VI.—Relative abundance of white-fringe fungus on fumigated and unfumigated
leaves.
Pupe infected with white-
Number | fringe fungus.
= ofleaves| Live Dead
Leaves. exam- pupe. pups. |
ined. | Average
| Total. | per leaf. Per cent.
Mintamisatedin. 5. nc om ac A-Gae- See mee Bone 20 2,154 | 1,03 29 1.4 0.9
Mamicatedss=. Ls see sos: seek Seem eee 20 19 | 4, 432 302 15.1 6.8
In Table VII are given data collected by Mr. Yothers showing the
development of the fungus over a period of one month on fumigated
leaves, as compared with the same on unfumigated leaves. Five
selected leaves were under observation in each case.
TaBLeE VII.—Development of white-fringe fungus on fumigated and unfumigated leaves.
Fumigated October 12, 1908.1 Unfumigated.2
Pup infected on— Pupz infected on—
Leaf
Leaf No. | = ————7 = No
| Oct. 13. | Oct. 26. | Nov. 9. Oct. 13. | Oct. 26. | Nov. 9.
LSS coat Dene eee aie aS ee 0 1 2 6 0 0 0
DEE ogee tele Pe ee be oo ee | 1 | 4 12 7 3 4 4
Sec One 2 URE EEE? Sete tenn 4 8 8. 8 1 3 3
ASAE. Aon sae aes ate 1 13 20 9 0 0 0
SS ee AOS SSS See eres SAD Eee, erate | 0 1 29 10 1 4 4
BAD cat 3 OS es ste! | 6 27 ie ae 5 11 |
1 Leaves 1 to 3 on one nursery tree with a total of 400 dead and 2living pup. ‘Leaf No. 4 on similar tree
and with same number dead and living pup. Leaf No. 5 on similar tree but with 1 living and 400 dead
pupe. 4 ;
2 Leaves 6 to 10 with average of about 40 living pup and numerous dead larve and pup per leaf.
SPOROTRICHUM. 35
In the third series of observations the junior author selected leaves
on which all living pup had been killed by fumigation. It is proba-
ble that fungus had already infected a few dead pupxe but had not
broken out around the margin previous to fumigation; yet, consider-
ing the comparatively few pupxe becoming infected on unfumigated
leaves as compared with the unusual number infected on fumigated
trees, there is no doubt that the fungus developed for the most part
after the pupx were killed by the gas.
Taste VIII.—Development of white-fringe fungus on leaves fumigated Sept. 26, 1906.
Pup infected with white-fringe fungus on—
Leaf No. Pupx Pups 4
alive. dead.
Sept. 30.| Oct.8. | Oct.14. | Oct. 21. | Oct. 28. | Nov. 5.
= z pa |
ER foes. ck cts aw as ls 0 200 0 10 32 07 57 57
tet By SE pain Sea ae 0 600 0 0 2 21 40 40
Ne ee he ee eee 0 200 0 0 8 21 48 48
ee ic aie Ne oi atte sia waive 0 400 0 0 l 10 22 22
MAE. Se eis So ante 0 100 0 0 i 6 6 6
otal. 3.820. 0 1,500 0 10 44 115 173 173
Concerning the reported practical results in reducing the white
flies, it may be said that the occurrence of a very high percentage
of the dead larve and pupe, especially of the cloudy-winged white
fly, as already noted in the grove of Mr. C. W. Hicks, where over 91
per cent of the dead insects were infected, has no bearing on the
parasitic nature of this fungus, since an equally high rate of mor-
tality occurs in groves infested with the same species where very
little white-fringe fungus can be found. Its prevalence is evidently
only an indication of the extent of the occurrence of unexplained
mortality. The data here presented are regarded by the authors
as satisfactory evidence that the Microcera develops almost entirely
or exclusively on larve and pupe already dead from other causes
and should be disregarded as a factor in the control of the white fly.
SPOROTRICHUM.
The Sporotrichum is either closely related to or identical with one of
the diseases of the chinch bug which attracted so much attention from
entomologists a number of years ago. As a white-fly parasite it
has been under observation since September 8, 1906, and is largely
limited in its spread to the fall of the year, when, under favorable
weather conditions, it spreads with astonishing rapidity among
adults of both the citrus and cloudy-winged white flies then crowding
the new growth. This fungus does not form pustules like the red
Aschersonia. Adults killed by it remain attached to the underside of
the leaf, their bodies become shriveled, and in a short time the grayish
mycelial threads of the fungus break through the body of the fly and
86 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
produce countless spores. To the casual observer the flies appear
merely to die and shrivel up on the leaf as shown in Plate IX, upper
figure. .
In connection with this fungus the authors’ observations have been
limited to the vicinity of Orlando, but Prof. Fawcett, to whom credit
is due for its determination, has seen it several times working in
different parts of the State since August, 1908. While it has been
reported by Dr. Berger! as attacking the larvee of the citrus white
fly, and has been seen by the authors attacking the eggs of the same
species, it must be regarded, so far as now known, as primarily a
parasite of the adult.
Notwithstanding the very large number of adults it is capable of
killing when spreading most rapidly during the fall, it can not be said
that it has proved itself of any value in checking the progress of fly
infestation for the reason that a sufficiently large number of adults
escape to deposit as many eggs as the new growth can well support.
During September and early October, 1908, when this fungus was
spreading very rapidly and there were in places from one to several
hundred dead flies per leaf and it appeared that much good was being
accomplished, careful examination of the leaves of the new growth
showed that they were heavily infested with eggs. In a grove near
Turkey Lake, 8 miles west of Orlando, where the Sporotrichum was
even more virulent in its attack upon the cloudy-winged white fly, the
surviving adults so overcrowded the leaves with eggs that on many
shoots not a larva was able to mature. These observations have been
mentioned to show that, if anything, the killing of an even compara-
tively large number of the fall brood of adults may act as a stimulus
rather than a check to the progress of infestation, inasmuch as it seeks
to prevent that overdeposition of eggs, which, in itself, as explained
elsewhere, is an important element of self-control with this species:
Thus far the authors have not been successful in attempts at spread-
ing the Sporotrichum artificially. During September, 1908, many
thousand infected flies were collected for experimental purposes. On
October 8, when the fungus was spreading less rapidly than during
September, two watershoots were rubbed with infected flies, and
although adults of both species fed on the leaves for two weeks none
became infected. One hundred adults caged on a leaf smeared with a
paste made of 100 infected flies and water did not become infected,
neither did adults confined on leaves sprayed with a solution of 100
infected flies in one-fourth of a cup of water. Experiments with the
same material on May 29 and August 17, 1909, gave equally negative
results, although adult citri were abundant on the treated leaves.
Leaves of china tree and orange were dipped and sprayed with a water
solution of infected flies, were rubbed with a paste made of flour and
1 Bul. 97, Fla. Agr. Exp. Sta., p. 56, 1909.
Bul. 102, Bureau of Entomology, U. S, Dept. of Agriculture. PLATE VIII.
CINNAMON FUNGUS, SHOWING PUSTULES AND THE DENSE WHITISH MYCELIUM FORM-
ING IN PLACES A FELTLIKE COVERING ON UNDERSIDE OF LEAF. (ORIGINAL.)
Bul. 102, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE IX.
UPPER FIGURE, SPOROTRICHUM FUNGUS INFECTING ADULT WHITE FLIES, CAUSING
THEM TO REMAIN ATTACHED TO UNDERSIDE OF LEAF, INSTEAD OF DROPPING AS IS
USUAL.
LOWER FIGURE, LARV4 AND PUP OF THE CITRUS AND CLOUDY-WINGED WHITE
FLIES KILLED BY FUMIGATION AND LATER DEVELOPING THE WHITE-FRINGE FUNGUS.
(ORIGINAL. )
THE CINNAMON FUNGUS. 37
infected flies, and, both wet and dry, were dusted with a mixture of
infected flies and flour applied with a blowgun. No fungus developed
on checks kept on these experiments.
THE CINNAMON FUNGUS.
( Verticillium heterocladum Penz.)
History.—The cinnamon fungus ( Verticillium heterocladum) was first
described by O. Penzig in 1882 attacking the soft scale (Lecanium)
Coceus hesperidum lL. on lemon leaves in Italy. In 1905 Dr. E. H.
Sellards, then entomologist of the Florida Experiment Station, found
it growing on Aleyrodes citri at Palmetto, Fla., on leaves also bearing
numerous pustules of the brown fungus. As no fruiting bodies of the
latter had ever been found, for several years it was thought possible
that it might be the spore-bearing stage of the brown fungus. How-
ever, it has since been proved distinct by Prof. H.S. Fawcett, who has
referred it to Penzig’s species, and in 1908 published the results of his
studies begun in 1905, giving an account of its history, its description,
and biological notes.
Description.—The pustules of this fungus are brownish-gray or
cinnamon colored and are surrounded by a whitish feltlike growth
spreading out over the leaf for a short distance ‘around the pustule.
In general appearance, when not growing luxuriantly, this Verticillium
superficially resembles the brown fungus. The following technical
description is quoted from Prof. Fawcett: +
The pustules, which are cinnamon colored, are powdery on the surface. Under
the hand lens they appear brushlike in form, bristling with hyphe. From the edge
of the pustules there grows out a creeping layer of white, delicate, interwoven hyphe.
From these colorless hyphee, as well as from the top of the pustules, there arise upright
conidiophores. These may have either a simple series of whorls, two to four branches
in each, or the branches of the whorls may again be whorled. The conidia are borne
on the ends of the ultimate branches. The conidiophores are quite delicate, slender,
hyaline, 150 to 240 microns by 3 to 4 microns, several times septate. The conidia
are oblong, hyaline, 4 to 6 micorns long by 1.5 to 2.5 thick. The main body of the
cinnamon-colored stroma when mature becomes powdery in appearance, and under
the microscope it is found that the hyphz have broken up into short pieces irreg-
ular in shape and length with rounded ends, some of them quite closely imi-
tating spores. These have thicker walls than the conidia, and probably act as repro-
ductive bodies in carrying the fungus through a period of dry weather.
The resemblance to the brown fungus mentioned above is most
striking when the pustules are very scattering and only partially
developed. However, when very abundant, as shown in Plate VIII,
the similarity between the two fungi disappears. Leaves have been
found in which the underside was entirely concealed beneath the
feltlike mycelial growth surrounding the pustules. This running
together of the mycelial growths of the several pustules is shown in
1 Special Studies No. 1, Univ. of Florida, p. 23, 1908.
88 NATURAL CONTROL OF WHITE FLIES IN FLORIDA,
places in Plate VIII. When weathered the pustules lose their powdery
appearance and their surface appears pitted. This fungus attacks
both the larval and pupal stages of both the citrus and cloudy-winged
white flies, and has been observed by the junior author to spread to
and develop pustules on larve and pupe known to be previously
dead. It is therefore saprophytic as well as parasitic.
Effectiveness —The authors have frequently observed this fungus
in various places in Lee, Manatee, Orange, and Marion counties since
1906, but in only one instance, on a few nursery trees in a very moist
spot at Orlando, did it appear to give promise of ever being of value
in holding the fly in check. The pustules are usually very scattered,
being most abundant in the lowest and most shaded portions of the
grove. Considering the almost negligible good accomplished by it,
it has not been the subject of serious study in the course of these
investigations except In noting its spread on certain trees to both
living and dead marked larve and pup. Prof. Fawcett has success-
fully grown cultures on various media, and both he and Dr. Berger
have secured infections in the grove with these cultures.
Distribution and insects attacked —The cinnamon fungus has been
reported as infecting Aleyrodes citri at Gainesville, Citra, McIntesh,
Orlando, Winter Park, Apopka, St. Petersburg, Palmetto, Braden-
town, Manatee, Oneco, Bartow, Fort Myers, Buckingham, and Alva.
Its attack is not restricted to the citrus white fly. Prof. Fawcett
states that it has been found in Florida on the following five scale
insects: Lepidosaphes gloveri Pack., Gainesville; Diaspis sp., on leaves
of Huonymus americanus, Gainesville; Lepidosaphes beckit Newm.,
Palmetto and Citra. In Italy it attacks soft scale (Coccus hesperidum)
on lemon leaves, and in Africa and the Antilles it has been reported
on unknown host insects.
THE REDHEADED SCALE FUNGUS.
(Spherostilbe coccophila Tul.)
The red-headed scale fungus (Spheerostilbe coccophila) is here recorded
among those fungi of minor importance attacking the white fly only
because it has been repeatedly associated with it in this connection.
It was first noted as a parasite on Aleyrodes citri at Orlando in 1903 by
Prof. H. A. Gossard. While it has a world-wide distribution and is
very effective at times as a parasite of scale insects, being reported on
no less than 15 species, its value as a parasite on the citrus and cloudy-
winged white flies is absolutely nil. Probably not more than one
white-fly larva or pupa in a million is killed by it. In not a few cases,
where it has been thought on casual observation to be attacking the
white-fly larva, careful examination with a lens has shown that its
bright red fruiting bodies originated not in the fly larva itself but in a
purple scale, Lepidosaphes beckit Newm., partially or completely con-
cealed by it,
NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 39
NATURAL EFFICACY OF FUNGOUS PARASITES.
Under this heading are discussed subjects relating to the actual
degree of control of which fungous parasites have shown themselves
capable, without regard for the possibilities of increasing that degree
of efficacy by artificial means. These two subjects are frequently
confused, although a clear distinction is necessary for a proper under-
standing of the economic value of the parasitic fungi.
CREDIBILITY OF COMMON REPORTS.
It is a well-recognized fact among economic entomologists that
wherever predaceous insects or parasites of any kind are conspicuous
enemies of an insect pest, popular reports are greatly exaggerated in
regard to the efficacy of the natural enemy. The amount of control
influence exerted by the natural enemy can not be approximated by
casual observation, by the record of parasitism of a comparatively
small number of specimens of the insect pests, or even by the seem-
ingly practical results as shown by the condition of the host plant. A
casual observation summarized by a statement that 50, 75, or 90 per
cent of the insects are destroyed by fungous parasites is usually
worthless and misleading. Even an experienced entomologist could
not make a statement of value in this respect without first making
extensive counts of specimens, recognizing the influence of unex-
plained mortality and the effect this has upon the apparent percentage
of parasitism. The experience of the authors in the course of the
investigations reported herein shows that thousands of insects rather
than hundreds, and these on leaves picked absolutely at random
without previously making any note of their condition, can be regarded
as the only satisfactory basis for approximate estimates of the efficacy
of fungous parasites. Even reports based on seemingly practical
results of fungous parasites, with the white flies greatly reduced and
with clean leaves and fruit, should not be credited without being
authoritatively confirmed.
Experience has shown such reports too frequently to be incorrect
for either of two reasons: The first is due to a misunderstanding of the
factors influencing fluctuations in numbers of the insects; the second
is the absolute lack of any actual foundation for the popular report of
the character referred to. These reports are traceable to a feature of
human nature which is found everywhere. One can not become well
acquainted with the white-fly situation without noting instances of
persistent and emphatic reports in regard to the complete efficacy of
fungous parasites in certain sections or in certain groves which upon
investigation are found to be entirely erroneous.
It is desirable that citrus growers become acquainted with all
important facts in regard to the white flies and the methods of their
40 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
control, but due weight should be given to the authoritativeness of
common reports. Otherwise the confusion which arises becomes a
decided hindrance to progress.
OLDER ESTIMATES OF THE NATURAL EFFICACY OF FUNGOUS PARASITES.
In some respects the subject of the natural efficacy of the fungous
parasites of white flies is the most important subject dealt with in this
bulletin. Common reports concerning this matter are so frequently
erroneous or misleading, as has just been explained, that in addition
to the specific observations and records to be given under another
heading it is considered advisable to present here quotations from
previous publications showing the status of the fungous parasites at
different periods since their discovery and the views expressed by
various writers concerning their efficacy.
In a publication previously referred to, submitted for publication
in March, 1897, Dr. H. J. Webber makes the following statement :!
The writer believes it may safely be assumed that the spread of Aschersonia aleyrodis
and the brown mealy wing fungus will ultimately materially check the ravages of the
mealy wing (white fly) and sooty mold.
According to the publication mentioned, Dr. Webber knew of two
instances of apparently satisfactory control resulttng from the red
Aschersonia and one such instance resulting from the brown fungus.
Owing to the comparatively brief period of his observations and to
the checking of both the white fly and its parasitic fungi by the
freezes of December, 1894, and February, 1895, the fact that the
parasites did not maintain a uniform state of control apparently
had not come under Dr. Webber’s observation at the time of writ-
ing the report from which the quotation is taken. However, as a
prediction his statement was doubtless fully warranted by the
circumstances.
The next investigator to give attention to the matter of the efficacy
of the fungous parasites was Prof. H. A. Gossard. After more than
four years of more or less continuous investigations and observations,
noting the fluctuations from year to year in the abundance of the
insects and of the parasites, he arrived (1903) at the following
conclusion: ?
I repeat emphatically that while I have no word of condemnation for the man who
with intelligence and skill directs nature’s agencies so that he secures results from most
insects equal to the best (and we have some such in Florida), I believe that white fly
is an insect that should be fought by everybody by insecticides from the day it is dis-
covered in a grove. J admit that there is no spray that will kill white fly and not at
the same time inflict injury to the trees, but I am satisfied that the injury is far less
than white fly causes, except during exceptional periods when fungous diseases are
unusually active. Infested trees that are properly sprayed through many years and
1 Bul. 13, Div. Veg. Phys. and Path., U.S. Dept. Agr., p. 34, 1897.
2 Bul. 67, Fla. Agr. Exp. Sta., p. 626, 1903.
NATURAL EFFICACY OF FUNGOUS PARASITES. 41
are correctly treated in other respects I believe will live longer, yield better, and
give much larger net profits than they will do if fungi alone are relied upon for
protection.
After three years largely devoted to investigations of the white
flies affecting citrus in Florida, giving particular attention to their
fungous diseases, Dr. Berger! (1909) summarized his observations
concerning natural efficacy of the fungous parasites as follows:
When left without assistance the fungi will practically destroy the white fly in a
grove, on the average, once every three years; thus reducing the injury due to the
white fly by at least one-third. The destruction is not complete, so that the insects
increase again during the two succeeding years; but this is accompanied by rapid
increase of the fungi, until the white fly is again overwhelmed. ‘This is the course
run by the white fly and the fungi when unassisted in those sections which have been
longest infested, such as Manatee County; ‘Fort Myers, and Orlando. At Orlando the
fungi were in the ascendency during the summer of 1906, and this resulted in so far
reducing the white fly that an fe aOR a large and clean crop of citrus fruit was
marketed in 1907. ?
Mr. C. L. Marlatt, assistant chief of this bureau, after visiting
various sections of Florida in the fall of 1907 and discussing the
white-fly situation with numerous well-informed citrus growers,
described the natural efficacy of the red and brown fungi as follows:
In Manatee County, where the fungi are fully established, they are able practically
to exterminate the white fly once in three years, so that every third year the fruit is
clean and requires no washing. The following year the insect again flourishes because
the white-fly fungi have disappeared, having during the clean year nothing on which
to develop. Toward the end of this year, however, the fungi again begin to operate,
but not sufficiently to prevent the complete blackening of the foliage and fruit during
the following or third year. Nevertheless, during this year the fly is again reduced to
practical extinction, so that the year following is a year of clean foliage and fruit.
The senior author of this bulletin, writing in the fall of 1907 * after
a little more than one year devoted exclusively to white-fly investiga-
tions, discussed the natural efficacy at some length, in part, as follows:
Data obtained from many orange growers and personal observation by the writer
and other entomologists connected with the Bureau of Entomology indicate that the
fungi, without artificial aid, reduce the injury from the white fly about one-third.
* * * One year in three, itis the experience of the growers in this county (Manatee),
the fungi have so thoroughly cleaned up the pest that the fruit is clean and requires
no washing. * * * Considering the county as a whole in 1906, fully three-fourths
of the groves were so free from sooty mold as to require no washing of the fruit. It
was generally considered that this condition had never before been equaled since the
white fly first obtained a foothold in this county. * * * Asa natural consequence
of the lack of abundant food for the fungous parasites in 1906, the situation in 1907
showed a complete reversal, with more than three-fourths of the groves thoroughly
blackened by sooty mold. It is not uncommon to find that individual groves vary
considerably from the average condition of the groves in the county as a whole.
1 Bul. 97, Fla. Agr. Exp. Sta., p. 50, 1909.
2 See explanation of this condition on p. 11.
3 Proce. Ent. Soc. Wash., vol. 9, nos. 1-4, p. 124, April, 1908.
4 Bul. 76, Bur. Ent., U. S. Dept. Agr., p. 64, issued October, 1908.
49 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
From the foregoing quotations it is seen that there is practical
agreement among the various writers as to the natural efficacy of the
fungous parasites.
OBSERVATIONS AND RECORDS CONCERNING NATURAL EFFICACY.
Under the subject of unexplained mortality it has been shown that
even where fungous diseases are most effective mortality from this
source is secondary in importance to that from unexplained causes.
The recognition of this fact does not in any way detract from the
actual value of the fungous parasites, but should be regarded as a
necessary step in the proper estimate of that value.
The theoretical efficacy of white-fly fungous parasites may be deter-
mined by a similar method of calculation as that employed on page
16, in estimating the efficacy of unexplained mortality. Instead of
12.4 and 15.4 per cent for the years 1908 and 1909, the efficacy would
become 47.6 and 53.2 per cent if there had been no unexplained mor-
tality. Considering the normal rate of increase of the white flies as
shown in a previous bulletin of this bureau, mortality among the
larve and pup to the extent of the foregoing calculations (47.6 per
cent and 53.2 per cent) obviously would be of no practical advantage
as an average condition. The insects could continually maintain
themselves at the maximum of injurious abundance even if the mor-
tality were 25 or 30 per cent higher. Theoretically considered, there-
fore, the fungous diseases were entirely ineffective in either 1908 or
1909 for the average of the 10 groves under observation.
There is another phase of the subject to be considered, however.
With unexplained mortality present in all groves it is not necessary
for fungous diseases or any other known cause of mortality to increase
to a point of independent efficacy in order to be of distinct value.
The most important question to be considered here, therefore, is: To
what extent do fungous parasites effectively supplement all other
causes of mortality to the direct and practical advantage of white-
fly infested citrus groves ?
For practical purposes in this bulletin, fungous parasites are said to
have worked effectively or to have cleaned up a grove when they
appeared to have worked effectively on the insects not succumbing
to unexplained causes of mortality, bearing in mind that the same
rapidity of spread and multiplication and the same percentages of
infection do not produce similar effects in different cases. This
absence of standards of efficacy is plainly shown in the data pre-
sented in Table II and also in the following table in which the rec-
ords concerning eight of the groves included in Table IT are extended
to show the status of the white flies and their fungous diseases at the
end of the season of 1909.
NATURAL EFFICACY OF FUNGOUS PARASITES. 43
TaBLeE IX.—Status of white flies and their fungous parasites in eight groves, December,
1908, to December, 1909.
Examination, December, 1908. Examination, December, 1909.
Examination, July, 1909, 100 Average
Average | Average | number
number | number forms
forms |live forms] killed
Grove Average | Average eee leaves picked at random from
Nol Seen are nun ber fats each grove; condition as to
z 4 ~ S yr
forms |live forms} killed sooty mold.
per leaf. | per leaf. |by fungus per leaf. | per leaf. |by fungus
per leaf. per leaf.
1 103.7 49.1 24.5 | All leaves thoroughly blackened. 170.0 0.5 56.6
3 108.3 32.0 1.7 | 79 per cent moderately blackened. 124.4 13.0 12.4
4 132.6 20.0 19.2 | 60 per cent moderately or slightly 106.2 6.8 14.0
blackened.
5 229.2 35.9 29.6 | 64 per cent thoroughly, 34 per 218.5 13.8 26.0
cent moderately blackened.
8 597.3 30.6 80.9. | None blackened................. 82.3 11.9 13.4
9 282. 4 8.4 43.9 | Traces of blackening............. 48.7 4.9 3.1
10 469.4 ie 84.2 | None blackened................. 56.8 3.9 11.6
12 229.9 8.3 9.7 | Sper cent moderately blackened, 27.8 2.5 3.6
remainder showing traces.
1 See Table IT.
As regards blackening of the fruit and foliage, which is the most
important element of injury by the white flies, groves 1, 3, 4, and 5
were not benefited by the work of the parasitic fungi during either
1908 or 1909. By the Ist of July, 1909, these groves were at least
as black as the average infested grove in which no fungous parasites
were established. Moreover, there were sufficient live insects present
to continue this condition regardless of any unusual climatic condi-
tions which might favor the multiplication of the fungous diseases.
As regards the reduction of the insects themselves, the fungous diseases
were decidedly effective in grove No. 1, promising a condition of
freedom from white-fly injury in 1909. The condition of groves Nos.
3 and 5 did not give promise of such condition, since any number of
live white flies (pups) above 10 per leaf in December is strong indi-
cation that the insects will multiply sufficiently the following spring
to cause a decidedly injurious blackening of the foliage and fruit
before climatic conditions will give the fungous parasites an opportu-
nity to check them. Without interference by adults migrating from
other groves, an average of 12 overwintering insects per leaf has been
noted to produce a general blackening (moderate) of new spring
growth of foliage by June 15, while an average of 2.6 live insects per
leaf in December was noted to result in a very heavy infestation one
year later with excessive blackening of the foliage. As is often the
case, in this latter instance the foliage appeared entirely clean up to
midsummer, most of the blackening appearing in September and
October.
On the July examination of No. 4 it was found that the average
number of forms per leaf representing the insects which produced
the condition noted consisted of 26 dead larvee and pupex, 8.8 live
larve and pup, and 1.9 pupa cases. No. 8 was in a satisfactory
44 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
condition in July, but in December the average number of dead
larve and pupe was found to be 61, live larvee and pup 11.9, and
pupa cases 5.1." This would indicate at least a slight blackening of
the leaves by the end of the year, judging from the effects of a lighter
infestation in the case of No. 4 as noted above. To a casual observer
this fairly satisfactory condition might appear to have resulted from
fungous diseases. As a matter of fact the fungous diseases had no
appreciable effect. A fairly high average number matured per leaf
in the spring of 1909, but very few eggs were deposited on the citrus
trees. This appeared to be due to the emergence of the insects
before the appearance of new growth on the citrus trees and as a
consequence the attraction of the adult white flies to other food
plants, persimmon and China trees, having new fohage. An examina-
tion of a persimmon tree growing in the midst of the citrus trees on
this property showed 8 times more larve and pupe per leaf than on
the leaves from surrounding citrus trees. If fungous diseases had been
concerned in the reduction of the infestation of the citrus trees the
July examjnation of the spring growth would have shown this. The
examination of 100 leaves picked at random showed that an average
of 0.37 white flies of the first generation had matured and that of
this generation an average of 0.15 per leaf showed infection by fungous
diseases. These, with a very small average of less than 1 per leaf
dying from unexplained causes, represented the entire first generation
as shown by the examination of the leaves.
The July examination of No. 9 showed that an average of 0.2 white
fly per-leaf of the first generation had matured and that 0.46 per
leaf was infected with fungous diseases. This low average of infec-
tion could not have had any appreciable effect on the normal increase
of the insects, and it is obvious that in this grove the comparative
freedom of the foliage from blackening was not due to the fungous
diseases.
The very excellent condition as to white-fly infestation of grove
No. 10 during the season of 1910 may be properly credited to the
effective work of the fungous diseases after midsumer in 1909. The
trees suffered so severely during 1909 from the excessive infestation
that their unthrifty condition was noted at the time of the examina-
tion in July, 1910.
In No. 12 it was found, on July 1, that an average of 0.2 per leaf
of the first generation had matured, while 0.74 forms of this generation
showed fungous infection. As shown by Table IT, the reduction in the
number of the insects in this grove in 1908 was due almost entirely
to an excessive rate of mortality from unexplained causes, fungous
diseases being comparatively insignificant. As regards the cause for
the failure of the live insects found in December, 1909, to multiply
normally, No. 12 must be classed with No. 9. In both these cases
the explanation is probably similar to that in the case of No. 8.
NATURAL EFFICACY OF FUNGOUS PARASITES. 45
When the data in Table IX are examined with due consideration
of circumstances known to the authors, it appears that the fungous
diseases in the eight groves were ineffective in 1908, but produced a
condition in that year resulting in satisfactory freedom from the
insects and blackening of the foliage in one grove in 1909 and with
prospects for such a condition in at least one grove in 1910. As the
investigation of fungous diseases was discontinued in 1909, there are
no records as to the condition of the groves the following season.
Since the actual cause of the temporary freedom from injurious
attack is often obscure, as the foregoing records show, it is evident
that less detailed observations, such as have formed the basis of the
estimates of the authors of previous publications (including the
senior author of the present publication), have favored the fungi
rather than otherwise in crediting them with complete efficacy to
the extent of one year in three.
During 1906, 1907, 1908, and 1909 a large number of records were
accumulated in regard to the efficacy of fungous diseases during those
years in about 25 citrus groves located in different sections of Florida,
mostly in Lee, Manatee, Hillsboro, and Orange counties. In several
instances authentic information has also been secured in regard to
the efficacy of the fungi in previous years, as shown by the necessity
for washing the fruit to remove sooty mold.
More than one-half of the total number of records are concerning
hammock groves and the list includes the majority of groves in
Florida where the fungous diseases have been exceptionally effective
during the period under observation. In two instances groves have
been noted or authentically reported as free from blackening for two
successive years after being well freed from the insects by fungous
diseases. These are offset, however, by several instances of groves
showing no benefit whatever for three or more years after the fungous
diseases have become well established. In the case of one grove in
Manatee County, unfavorably located with respect to a general
nursery with citrus, China trees, privets, and other food plants, it
had been necessary for the owner to wash the fruit every year for a
period of more than 10 years, except for less than one-half. of one
crop. Although the red and the brown fungi were always found
present in abundance at each of the several examinations made by
the authors, the trees were always found to be more or less blackened
and in one instance noted as being as thoroughly blackened as any
grove seen in Florida.
The hammock groves of Manatee and Lee counties have offered
the best opportunities for observations of the fungous diseases under
the most favorable conditions. During 1906 and 1909 the majority
of the Manatee hammock groves were practically free from blackening
by sooty mold, but the crop of 1907 in these same groves was as
46 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. —
thoroughly piackened as any to be found in the State and in 1908
was only slightly improved. In Lee County the hammock groves
located near the Caloosahatchee and Orange Rivers have been much
less uniform than hammock groves in Manatee County as regards the
efficacy of the fungous parasites. It has been more frequent to find
very effective work by the fungi in one section of a grove, while
another section of the same grove has been heavily infested and
thoroughly blackened. On the whole the average condition in these
groves in Manatee and Lee counties has conformed entirely to the
estimates given in previous publications; in effect, that the efficacy
of the fungi amounts to about one-third of a complete remedy.
In the interior of the State, in high pine land groves, the natural
eflicacy of the fungous parasites appears to be somewhat less than in
the hammock groves referred to. Prof. Gossard mentioned the
presence of the red and the brown fungi at Orlando in his annual
report for the year ending June, 1901.!. According to an authenti:
report, the grove of Hon. J. M. Cheney (grove No. 3 of Table I, and
No. 1 of Tables II and TX) at Orlando was one of the earliest in that
section to become infected with the red and the brown fungi. This
introduction was not later than 1901. In 1907 the grove was entirely
free from sooty mold, as noted in the discussion of unexplained mor-
tality. This was the first year that the fruit had not been generally
blackened since the introduction of the fungi, and the fungous diseases
in this case were not responsible. In 1908 and 1909 the trees and
fruit were very black, while by the end of the latter season the insects
had been reduced in an entirely satisfactory manner. While we
have no record concerning the condition of the crop for 1910 in this
grove, it may be said without hesitancy that if not clean it was due
to the interference with the efficacy of the fungi by adult white flies
migrating from other groves or from China and umbrella trees.
Without doubt China and umbrella trees have seriously interfered
with the natural efficacy of the fungous parasites in Orlando and other
cities and towns in Florida, but at the most the natural efficacy of
the fungous parasites at Orlando and at similar locations apparently
will not equal the natural efficacy in the hammock groves of Manatee
and Lee counties.
COMPARATIVE EFFICACY OF DIFFERENT SPECIES OF PARASITIC FUNGI.
In the preceding topics, under the general heading of natural effi-
cacy, the brown, red, and yellow parasitic fungi have been discussed
collectively. All other species so far reported as white-fly parasites
are of negligible value, as shown elsewhere. ‘The brown fungus has
long been considered as more effective than the red fungus against
the citrus white fly. This estimate is in accordance with our obser-
1 Rept. Fla. Agr. Exp. Sta., p. 65, 1901.
ARTIFICIALLY SPREADING FUNGOUS DISEASES. 47
vations. An examination of 100 leaves picked at random in 5 typical
groves in Manatee County and 5 in Lee County in January, 1909,
showed a ratio of 14 red-fungus pustules to 32 brown-fungus pustules
in groves which had all been infected with both species for several
years previous. In 9 of the 10 groves the total number of pustules
of brown fungus counted exceeded the total number of red-fungus
pustules. The single exception was a grove in which both species of
fungous parasites were present in almost negligible amounts. In
Orange County the brown fungus has also as a rule shown greater nat-
ural efficacy than the red wherever the two species have both been pres-
ent in the same grove and both have become well established. For
example, in grove No. 1 of Tables II and TX the average number of
red and brown fungus pustules per leaf was found to be 9.9 and 14.5,
respectively, in December, 1909, and 3.7 and 52.9 in December, 1910.
The natural efficacy of the yellow fungus against the cloudy-winged
white fly is about the same, according to the authors’ observations,
as the natural efficacy of the red fungus against the citrus white fly.
The fact that the red and brown fungi have shown very little adapta-
bility to the cloudy-winged species has been mentioned elsewhere.
HAVE THE FUNGOUS PARASITES INCREASED IN NATURAL EFFICACY SINCE THEIR FIRST
DISCOVERY?
The statement sometimes heard to the effect that the fungous dis-
eases are more effective now than formerly is unquestionably without
the slightest foundation, and it is unnecessary to devote any space
to a discussion of the subject.
ARTIFICIAL MEANS OF SPREADING FUNGOUS DISEASES.
HISTORY OF WORK IN THIS LINE.
Dr. H. J. Webber, who first discovered the red Aschersonia and
the brown white-fly fungus, was also the first to undertake experi-
ments with artificial methods of spread.t| The methods tested included
mixing the spores of the Aschersonia with water and spraying the
infested leaves with an atomizer, hanging branches with pustules of
the Aschersonia and brown white-fly fungus above branches in-
fested with the white fly in groves where the fungous parasites did
not occur, and transplanting young trees with parasitized white flies.
The first method is reported to have failed to give satisfactory results.
The second method was tested several times, but results were obtained
in only one instance in the case of the red Aschersonia and once in
the case of the brown fungus. The season of the year when these
tests were made is not stated. The transplanting of young trees
seemed the most reliable method, and this was recommended in estab-
1 Bul. 13, Div. Veg. Phys. and Path., U. S. Dept. Agr., pp. 26 and 30, 1897.
48 NATURAL CONTROL OF WHITE FLIES IN FLORIDA,
lishing the red Aschersonia and the brown fungus in groves where
these white-fly enemies did not occur.
Prof. H. A. Gossard! tested pinning fungus-infected leaves onto
leaves infested by the white fly, as also spraying with spores of the
fungus and fragments of its mycelium suspended in water. These
and certain other methods of less practical interest Prof. Gossard
states ‘have been tried by various experimenters, myself included,
without marked success.’”’ He adds: ‘‘ However, an infection is some-
times started by these methods.” With the knowledge concerning
the fungous parasites obtained up to the time of writing (1903) Prof.
Gossard recommended the transplanting of young trees as the most
reliable method of spreading the parasites.
At the beginning of the present investigations in July, 1906, spread-
ing the white-fly fungi by pinning the infected leaves onto uninfected
trees was the method commonly employed. This method was suc-
cessfully used, together with the so-called tree-planting method, in
introducing the red Aschersonia and the brown fungus into a grove in
Orlando as long ago as 1898 or 1899.
Dr. Berger has recorded experiments in pinning leaves infected with
red Aschersonia in June and July, 1906, and in spraying the spores
in a water solution in July and August, 1906. Results of pinning
leaves infected with brown fungus and of spraying water solutions
of brown-fungus mycelium incidental to experiments with red Ascher-
sonia have also been noted by the same author. Dr. Berger was the
first experimenter to obtain results in spraying water mixtures of the
spores, justifying the use of this method in preference to the tree-
planting method or leaf-pinning method. He was also the first to
recommend that the spraying method be used to spread red and
yellow Aschersonias in groves already infected in order to aid arti-
ficially in their multiplication and in the increasing of their efficacy.
EXPERIMENTAL METHODS.
In connection with the present investigations extensive experi-
mental work has been conducted to determine the best methods and
most favorable conditions for introducing the fungous parasites into
groves where they do not exist, as well as to determine to what extent
practical benefit can be derived through artificial methods of spread
and encouragement of the growth of these fungi in groves where they
already are present and well distributed. During 1906, 1907, and
1908 a total of about 3,500 trees was included in the experimental
work. In addition, fully as many trees sprayed with water mixture
of spores by citrus growers as independent experiments have been
carefully examined and extensive data concerning the results obtained.
1 Bul. 67, Fla. Agr. Exp. Sta., pp. 624-625, 1903.
ARTIFICIALLY SPREADING FUNGOUS DISEASES. 49
During 1909 about 2,000 trees were included in the experimental work
conducted.
Various methods have been employed in experimental work in the
artificial dissemination of the fungous diseases. The tree-planting
method recommended by Dr. Webber and Prof. Gossard and the
leaf-pinning method commonly employed previous to 1907 have both
been tested as checks on other methods. Spraying water mixtures
of spores of the red and yellow Aschersonias, which, as heretofore
stated, was first successfully used and recommended by Dr. Berger,
has been most extensively used, as this method has proved the most
satisfactory for use on a large scale. Preliminary tests of using water »
mixtures of spores in September, 1906, by the senior author seemed
to show that the spores were affected by pressure in passing through
an atomizer or spraying nozzle.!
Consequently, two other methods were used which, so far as known,
had not been previously tested. These methods, with their various
modifications, have been called the dipping and the brushing methods.
Aside from the tree-planting and leaf-pinning methods and the
methods mentioned in connection with the dissemination of fungous
infection by means of water mixtures of spores and mycelia, the
authors have tested and in correspondence recommended for use the
rubbing of the underside of infected leaves against the underside
of the leaves of uninfected trees. This has been done both with
single infected leaves and with twigs with several infected leaves
attached. It has also been tested with dry and wet leaves. The
rubbing method has been most extensively used in experiments in
the dissemination of the brown fungus.
PINNING AND RUBBING INFECTED LEAVES.
The pinning of infected leaves in introducing the Aschersonias,
being obviously an inferior method, has been used by the authors
principally in the form of checks on other methods tested. Infection
was not secured in more than 50 per cent of the experiments, and
when secured was a more local infection than those following spraying.
Better results followed when the upper surface of the fungous leaf was
brought into contact with the underside of the leaf to which it was
pinned, although good infections have followed when the fungus
pustules have been placed against the leaf. In all instances where
infection followed pinning, fungus developed either on the leaf to
which the fungous leaf was pinned, or more often on leaves immedi-
ately below, and occasionally on leaves so located that they might
have been brushed against the fungous leaf by winds. In view of the
greater abundance of infections occurring immediately below the
1 Later experience indicates that the unsatisfactory results obtained were due to lack of suitable weather
conditions.
21958°—Bull. 102—12——4
50 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
fungous leaf, the authors conclude that showers and abundance of
larve and pup are conditions most favorable to successful pinning.
Good infections have been secured at times when there were no adults
on the leaves.
While there are cases on record where very good results in intro-
ducing fungus have followed the pinning method, this must be
regarded as second in importance to the introduction of spores in
water mixtures, especially when Aschersonias are concerned. On the
other hand, infections with the brown fungus have been secured with
more certainty by pinning than by spraying, although with no more
certainty and in a less widespread manner than by the dipping of
infested shoots into ground brown-fungus leaves and water as de-
scribed elsewhere. Infections with brown fungus by pining have
been secured as late in season as November 6 (1908).
Infections secured by rubbing fungus-infected leaves, as described
under experimental methods, have proved of more value in connec-
tion with the brown fungus. Although success has attended the
introduction of the Aschersonias by this method, they are too easily
introduced by water mixtures to warrant attempts at mtroducing
them by rubbing. Under favorable weather conditions the rubbing
method is many times superior to the pinning. At most, rubbing,
even for brown fungus, is a very uncertain method, as only a very
small percentage of leaves rubbed become infected. In a hammock
grove at St. Augustine, Fla., in August, 1907, the senior author
rubbed about 1,200 leaves on four trees, the leaves averaging about 75
citri larve and pupex. Infection resulted only on about two twigs.
Later in the season slightly better results have been obtained. When
only a few brown-fungus-infected leaves are obtainable, they can best
be used for rubbing and then pinning. Frequently leaves that appear
to have been rendered worthless by rubbing have caused infections
when pinned. Fungous leaves should be kept wet or moist during
rubbing by frequently dipping in water. Good infections with
brown fungus have been secured as early as June 5, 1907, and as late
as October 31, 1908, although September and October have proved
more favorable months than the three preceding. While Prof. Faw-
cett reports + success in obtaining infections by means of the brown-
ish sporodochia, which are found dusted over the surfaces of the
infected leaves, several similar tests by the authors made at various
times since June, 1907, have all been without results.
WATER MIXTURES OF SPORES AND MYCELIA.
Preparation of miature—Whichever of the three most promising
methods of introducing the fungi in water mixtures is to be followed,
viz, spraying, dipping, or brushing, the initial steps in the preparation
of the mixture, with few exceptions, are the same. The ‘‘fungous
1 Science, vol. 31, no. 806, p. 913, 1910.
_
ARTIFICIALLY SPREADING FUNGOUS DISEASES. 51
leaves,” as leaves! bearing fly larvee and pup infected with fungi are
popularly called, are placed in water, allowed to soak a varying length
of time, and then shaken or stirred vigorously for from three to five
minutes in order that the spores may be washed from the pustules, or,
if brown fungus is used, that in addition small pieces of the mycelia
may be separated from the leaves. After the leaves have been
thoroughly agitated by shaking or stirring, the mixture is carefully
strained, if it is to be applied as a spray, like ordinary insecticides; or,
if the dipping or brushing methods are to be followed, merely poured
into the final receptacle, together with the leaves and fungus. This
stock mixture is then diluted to the desired strength.
In securing infections with the brown fungus, infections have been
secured by using ground fungous leaves. In preparing water mixtures
of the mycelia in this way, the leaves are first passed through an
ordinary meat grinder or similar instrument. During this process
the leaves are thoroughly ground into small particles. The ground
leaves may be shaken in a jar, then poured into a bucket, thoroughly
stirred, and the resulting mixture used for dipping the ends of white-
fly infected branches.
As the spores are very readily gotten into solution, no special appa-
ratus is necessary. The authors have found an ordinary 2-quart fruit
jar very convenient when no more than 3 or 4 gallons of solution are
desired at any one time. The fungous leaves are placed in the jar
previously half filled with water, the top screwed on, and the contents
shaken the desired length of time. In making larger amounts of
spray, an ordinary washtub is a convenient retainer; the leaves being
thrown into the tub half filled with water and vigorously stirred with
a stick or board. The solution is then strained through a wine
strainer into the spray pump and is ready for application.
Means and methods of applying water mixtures of spores.—For those
who have only a few trees into which they wish to introduce fungi and
do not care to go to the expense of purchasing spray pumps, very
satisfactory results will be obtained by the use of an ordinary wooden
bucket half filled with spore solution into which the badly infested
outer shoots of the tree are dipped. In using the brushing method an
ordinary whisk broom, or even a bunch of leafy twigs, in addition to
the bucket, is all that is necessary.
In spraying the spores into the trees, the authors have used ordi-
nary knapsack sprayers, compressed-air sprayers, and barrel pumps.
There is little choice between these sprayers from the standpoint of
infection secured, and the sprayer used has depended largely upon the
1 The danger of introducing by means of fungous leaves either the citrus or cloudy-winged white fly into
sections or groves where both do not occur is very great. When a grove is infested by only one species, the
danger of introducing the other by this means may be obviated by scraping the red and yellow Aschersonia
pustules from the leaves or by crushing the leaves, particularly those infected with brown fungus, in a meat
chopper.
52 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
preference of the grower and the amount of work to be done. The
compressed-air sprayer has a capacity of 3 gallons, and besides having
the advantage of being somewhat lighter has a valve by the use of
which the spray can be instantly cut off by the operator, thus pre-
venting loss of solution in passing from tree to tree. It has the dis-
advantage of requiring frequent pumping up, and having been in use
for some time, this feature is apt to become a serious drawback.
Knapsack sprayers and barrel pumps, new or thoroughly cleaned,
were found less likely to cause delays in work.
The method of procedure in the grove has differed but little from
that by which insecticides are applied, and is very simple. In using
knapsack or compressed-air sprayers it has been found very conven-
ient to have as many jars on hand as there are sprayers. After the
fungous leaves have been shaken the solution is strained directly into
the tank and then diluted to its capacity. The jars are then refilled
with another supply of leaves and water and allowed to stand until
the contents of the first tank have been sprayed out. After the first
shaking, the leaves have been used to advantage a second time when
the supply was limited, but when an abundance of fungous leaves
was available it was found to be a better policy either to throw them
away or add fresh leaves for reasons mentioned elsewhere. Where
three or four sprayers were in use it was found to be of advantage
to have an additional man to keep the water supply replenished,
shake the fungus, and change the base of supplies, so as to save time
in traveling back and forth.
When using a barrel pump, in view of the larger amounts of water
necessary, it is more essential that the tub or other retainer be placed
near a larger supply of water. After the spore solution had been
prepared and strained into the barrel, the latter was filled and the
solution sprayed. Meanwhile the tub was again partially filled and
more leaves added to soak and be stirred in readiness for the next
barrelful of solution.
In spraying with knapsack or compressed-air sprayers, or in brush-
ing, best results were obtained by directing the spray onto the under-
side of the leaves of the outer, more heavily infested, shoots.
Experiments have shown that better infections were obtained on the
outer portions of the tree than on water shoots. With a barrel
pump two leads of hose were used to advantage, the halves of two
rows being sprayed as the wagon passed between the rows.
The dipping method was first used as a check on experiments with
other methods, but as it has been found to have a practical usefulness
under some conditions, it has been frequently recommended by the
authors to citrus growers. The water mixture is prepared as already
described. A clean bucket half full of the unstrained mixture is
held with one hand and arm in such a manner that with the other
ARTIFICIALLY SPREADING FUNGOUS DISEASES, 53
hand the ends of the branches of the white-fly-infested tree can be
momentarily immersed. This method is especially desirable where
there are only a few trees to infect with the fungus and no satisfac-
tory spray pump is available; also when only a few fungus-infected
leaves can be obtained—as is frequently the case—and the greatest
economy in the use of the water mixture is needed. The branches
and twigs most heavily infested with the insects should be selected.
For the dissemination of the brown white-fly fungus this is probably
as satisfactory for general use as any method now known, the mixture
being prepared as hereafter described in a slightly different manner
than in the case of the mixtures of Aschersonia spores.
The brushing method consists in dipping a whisk broom or a sub-
stitute in the unstrained water mixture and brushing the under-
side of the leaves of the trees to be infected as far as within reach
and throwing the water by means of the brush against the under-
side of the leaves higher up in the trees. This method, like the
dipping method, can sometimes be employed with advantage in the
case of the red and yellow Aschersonias and is especially useful in
the case of the brown fungus, where unstrained solutions are naturally
more desirable.
MISCELLANEOUS EXPERIMENTS AND OBSERVATIONS.
As infection was almost invariably secured.in favorable seasons
with fresh fungus material when spores of either the red or yellow
Aschersonia were introduced by spraying, dipping, or brushing, it
became apparent that the problem to be solved in connection with
the introduction of fungi was not that of how to secure an infection,
but by what means the ordinary infection secured by haphazard
work could be increased by careful attention to the details. The
results, however, of over 500 experiments conducted by the authors,
together with those of growers, have been so variable that, at the
end of three years of experimentation, little has been added to our
practical knowledge of how to insure satisfactory infections. These
same statements apply to the brown fungus, although the securing
of an infection with this fungus is at no time so certain as with the
red or yellow Aschersonias.
Results of straining water mixtures of spores through cloth strainers.—
In straining the solution before spraying, the authors have found a
fine-wire strainer (about one-sixteenth-inch mesh) of most value.
Under no circumstances should cotton cloths be used as strainers,
for microscopic examination of strained and unstrained solutions
shows that a large percentage of spores fails to pass through the cloth.
Mr. E. L. Worsham found, as a result of 36 microscopic examinations
of solutions strained and unstrained, that about one-third of the
spores were lost when ordinary cheesecloth was used as a strainer.
54 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
Examinations by the junior author have shown that even a larger
percentage of spores may be lost. It was found that a closely
woven cheesecloth removed as high as 73.8 per cent to 92.8 per cent
of the spores, while an ordinary coarse towel removed 41 per cent.
In obtaining these results one-tenth cubic centimeter of solution of
red Aschersonia spores and water was placed on a glass slide marked
off into one-tenth millimeter squares, and the counts made beneath
a compound microscope. While the results thus obtained were
subject to much variation, they all demonstrate that cloths should
be avoided as strainers. Similar examinations of solutions strained
through fine-wire strainers showed that practically no spores are
lost.
Amount of fungus to use-—Experiments to determine the most
economical amounts of fungus to use per gallon of water have given
such varying results that no dependence can be placed upon the
data obtained. Even under identical and apparently most favorable
weather conditions, in experiments conducted at the same time and
on trees equally well infested and favorably located, frequently as
good infections have resulted from the use of 200 pustules as from
4,000 pustules per gallon of water. This is equally true of results
obtained when only a few or a larger number of trees were included
in the experiments. Within reasonable limits, the amount of pus-
tules to use, therefore, depends entirely upon the amount of fungus
obtainable. In all of the experiments herein reported, unless other-
wise stated, 200 or more pustules have been used to each gallon of
water.
Advantages of soaking fungous pustules before shaking or stirring.—
A series of experiments in which the fungus was allowed to soak for
different periods between 5 minutes and 48 hours showed that it is
immaterial how long the fungous pustules remain in the water before
shaking, provided, of course, that they are not left soaking an unrea-
sonable length of time. Experiments have furnished no data to even
warrant any soaking of the fungous leaves if they are comparatively
fresh, except such as takes place during shaking or stirrmg. As good
infections have been secured repeatedly when pustules were shaken
as soon as placed in the water as when soaked several hours.
Number of times fungous pustules can be used to advantage.—Several
experiments have been conducted to determine this point with definite
results. Twelve hundred and 1,800 pustules of red Aschersonia in
different experiments were shaken with a quart of water in a 2-quart
glass jar for a period of five minutes. After pouring off the water
used in the first shaking, fresh water was added and shaken as before,
repeating up to four times. The quart of water used in each succes-
sive shaking was diluted to make 4 gallons of spray and applied to
a given number of trees. In every test the third and fourth shakings
ARTIFICIALLY SPREADING FUNGOUS DISEASES. 5d
gave only the slightest trace of an infection or none at all, while the
second shaking in four different experiments gave 20, 70, 4, and
less than 1 per cent as much infection as the first shaking. The
second shaking is, therefore, very unreliable as compared with the
first. These field experiments have been supplemented by a micro-
scopic examination of spore solutions.
Two hundred red Aschersonia pustules freshly picked in January
were shaken five minutes in 1 quart of water, the solution poured into
a clean dish, and the same pustules shaken again in a similar way
three times. The solutions of the successive shakings were likewise
poured into separate dishes. Each solution, in turn, was thoroughly
stirred and the number of spores present in one-tenth cubic centi-
meter of solution (a very small drop) were counted by means of a
slide marked into one-tenth square millimeters. The count gave the
approximate numbers of spores in the successive solutions to be 9,188,
2,100, 274, and 19, respectively; or 79.3, 18.1, 2.4, and 0.2 per cent,
respectively.
Effect of copper sprayers on vitality of spores.—It is a well-estab-
lished fact that fungi are susceptible to the effects of solutions contain-
ing very small quantities of copper. Consequently, in purchasing
spray pumps or retainers of any kind for work with white-fly fungi,
it has been considered advisable on general principles to avoid
copper and brass parts as far as possible. Numerous experiments
have conclusively shown that equally good mfections can be secured
whether a copper or a galvanized-iron knapsack sprayer is used,
provided the spore solution is not permitted to remain in the tank
longer than is necessary to spray it into the trees. Throughout the
summer of 1908 the authors used a copper and a galvanized tank in
numerous duplicate experiments on different occasions, including
nearly a thousand trees, and in all these no difference in infection
secured could be detected. As good infections were secured when
the copper tank was used as when the spore mixture was applied by
means of a barrel pump, and as good as resulted in check experiments
using the dipping and brushing methods where the spore solution was
carried in a wooden bucket. Unsprayed trees developed no fungus
except where the natural spread was rapid.
Effect of nutrients added to water mixtures of spores.— Experiments
to determine what benefits, if any, accrue from the addition of nutri-
ents to the ordinary water solutions of spores were begun in 1906,
and were continued throughout 1907 and 1908. Agar, glucose-agar,
vlucose, and gelatin were used in varying amounts, and the solution
allowed to stand varying lengths of time before application. As
Prof. Fawcett has found a 5.10 per cent glucose-agar solution the best
medium for the germination of the spores of the red Aschersonia, and
that germination usually takes place in a little over 24 hours, field
56 NATURAL .CONTROL OF WHITE FLIES IN FLORIDA.
experiments were conducted with the view to showing the effect of
applying spores brought nearly to the point of germination in this
medium. In this and other series of experiments the solutions were
applied under favorable weather conditions, but no difference could
be observed between the infection secured with nutrient solution
and ordinary solutions used as checks. In some instances better
infections were secured where no nutrient was added. Similar
experiments with glucose as the nutrient have been reported by
Dr. EK. W. Berger t who also obtained negative results.
Effect of sulphur waters on spores—Experiments to determine
what effect sulphur water has upon securing infections with water
solutions of spores have been conducted only in the grove. Artesian
water from Manatee County was used. An equal number of red
Aschersonia pustules (400) were soaked in sulphur water and in lake
water for one-half hour, shaken thoroughly, and the solutions used for
dipping on June 25, 1909. By July 10, on the six shoots dipped in
sulphur-water solution, representing an aggregate of 54 leaves, 180
pustules had developed, while on the four shoots dipped in lake-
water solution with a total of 28 leaves, 89 pustules developed. For
each solution 3.3 and 3.2 pustules per leaf, respectively, were obtained.
Check shoots developed no fungus. The results obtained gave no
evidence of any injurious effect of the sulphur water on the spores of
the fungus.
LENGTH OF VITALITY OF SPORES.
Field tests only have been made by the authors in determining
the length of vitality of spores of white-fly fungi. No definite infec-
tions resulted from the use of fungi, either the Aschersonias or the
brown fungus, collected from September to December, 1907, and
applied in various ways during the following summer months. Infec-
tions were secured with fungus dropped by the cold in January,
1906, during the following June, although far better infections at the
same time followed the use from freshly picked fungus, as a check.
In all; the authors have used in their experiments about a barrel of
fungus-infected leaves, collected during the early winter months, with-
out success. In several instances a very minute infection, one or two
pustules, was detected, but under such conditions that it was more
than probable that the infection came from other sources. Special
attention has been given to these experiments in order to determine
the value of picking fungus-infected leaves in the fall so that much of
the fungus that falls from the leaves during the winter months might
be saved for spring infections. The results above mentioned would
indicate that such fungus pustules are valueless unless some more
successful method be devised for preserving the fungus-infected
1 Rept. Fla. Agr. Exp. Sta. for year ending June 30, 1908, p. 111.
RELATION OF WEATHER TO FUNGOUS INFECTIONS. Sy
leaves than the usual drying process followed by the authors. In
summer and fall, fungus left remaining on leaves, as well as when
scraped off and kept in bottles, has produced infections as long as
two months after picking.
RELATION OF WEATHER CONDITIONS TO FUNGOUS INFECTIONS.
While it is an established fact that good infections of the red and
yellow Aschersonias are occasionally secured as early as April and
May, and as late as early October, experiments have shown that
weather conditions during these months are too subject to variation
for even reasonably reliable results. Unless due regard be given to
existing conditions, more failures than successes follow introduction
at this season. Considering the difficulty with which fungus can be
secured so early in the season, the tendency toward unfavorable
weather conditions, and the better infections secured later in the sea-
son in return for the same expenditure of time and money, the au-
thors do not recommend the introduction of fungi before June or, at
least, until the summer rains begin. All experiments have shown
that it is useless to force nature; that fungi can not be successfully
introduced unless the weather conditions are such that the fungi are
spreading naturally in infected groves. At Orlando this did not
occur till June in 1907 and 1908, but in 1909 occurred by the middle
of May. While infections of red and yellow Aschersonias have been
secured as late as early October during the past three years, it is
recommended that introductions of these fungi be completed during
the summer rainy season. Our records show that numerous attempts
by various means to introduce the brown fungus earlier than the Ist
of September have frequently been failures, while previous to that
time the slight infections secured have spread very slowly.
During the rainy season itself, all experiments to determine just
what combination of humidity and temperature would give the best
infections have, as a whole, been thoroughly negative. No difference
in resulting infections has been observed whether the spore solutions
were applied on bright, sunny days or on cloudy, muggy days; on
ordinary days, days with frequent showers, or directly after such
showers; at various times in the day from 5 a. m. to 6 p. m., with the
temperature high and the humidity low, or vice versa.
It would appear that applications have been made under every
conceivable combination of weather conditions, and from the entire
mass of experiments nothing can be learned aside from the fact that
it apparently makes no practical difference at what time of the day
or under what conditions of humidity, temperature, prevalence of
showers, etc., the spores are applied, so long as typical Florida sum-
mer weather prevails.
58 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
RELATION BETWEEN ABUNDANCE OF WHITE FLIES AND RESULTS IN
SPREADING FUNGOUS INFECTIONS.
While theoretically introduction of fungi should begin as soon as
the presence of the white fly is discovered in a grove, the autlfors
have met with such poor success with all attempts at such introduc-
tions that they have recommended the waiting until the white fly
becomes abundant enough to cause a very slight blackening of foliage.
Attempted earlier introductions have proved practical failures. It
is contrary to natural laws governing the relation between host and
parasite to expect to keep the fungus abreast of the fly all the time,
and all experiments and observations during the past three years have
failed to bring out a single instance where the fungus has spread,
artifically or naturally, in a newly infested grove soon enough or fast
enough to prevent the blackening of foliage. One can reasonably
hope for success in holding down the fly in slightly infested groves
only by careful attention to the direct remedial measures.
SUSCEPTIBILITY OF DIFFERENT STAGES OF HOST INSECTS.
Experiments have shown that the presence of no one instar of
either species of white fly is essential to successful infections, or that
any one larval stage is more susceptible to fungous attack than
another, or than the pupal stage. Considering the large number of
larve that hatch and the high rate of mortality that greatly reduces
the number of forms in each successive instar, it is only natural that
such leaves sprayed with spore solutions when the larvee are very
young should develop a large percentage of pustules on young larvee.
It has been found equally true that a much larger percentage of
pustules develops on advanced larve and pupe when introductions
are made when the fly is largely in these later stages. A count of 40
leaves of various ages, picked promiscuously and with the citrus
white fly in all stages, gave the percentages of red and yellow Ascher-
sonia pustules developed on the first, second, and third larval, and
on the pupal stage as 33, 32.1, 22.2, and 12.7, respectively. Another
count following introduction of the fungus in experimental work gave
in percentages of the total number of pustules developed: Pupal stage
36.5 per cent, third larval stage 34.5 per cent, and first and second
larval stages 29 per cent. Examination showed that the various
stages of fly were present in about this proportion at the time of the
application of the fungous spores.
COST OF INTRODUCING AND SPREADING PARASITIC FUNGI.
The very low cost of introducing fungi into white-fly infested groves
has influenced many to resort to this method of control, hoping to
get much for little. Men who have taken up the matter in a commer-
cial way furnish the supply of fungus and spray trees with water
DEGREE OF INFECTION OBTAINABLE. 59
mixtures of spores for about 2 cents a tree. At this price there is, of
course, a fair margin of profit. The authors, with knapsack sprayers,
and with the assistance of laborers at $1.50 per day, have been able
to spray 3 trees for 1 cent. One grower, by using a barrel outfit,
with the aid of a boy at the pump, sprayed 100 trees with 50 gallons
of solution in one hour. If one has to purchase fungus-infected
leaves the cost is correspondingly higher. The very low cost of
spraying fungous solutions can not fairly be compared with that of
spraying insecticides or of fumigation if one considers the results
obtained. Certain expenditures for either of these last methods of
control may be expected to produce definite results that can be figured
in dollars and cents if the remedy is properly applied. The returns
for money spent in spraying fungus are never assured; if there is no
infection in the grove at the time of the first application, the spraying
may result in a temporary fungous control within three years, or it
may ultimately cost the grower, through failure of the fungi to spread
properly, much of his foliage and bearing wood as a result of secondary
scale attack, to say nothing of a sharp falling off in the bearing of his
trees, and other losses incident to white-fly infestation.
DEGREE OF INFECTION OBTAINABLE.
In field experiments it is impossible to distinguish the extent of
direct infections with certainty, since natural spread usually takes place
before the entire direct infection manifests itself. Hven under the
most favorable climatic conditions for fungous spread, only a very
small percentage of the immature white flies which are exposed to
spores from freshly matured pustules of red and yellow Aschersonias
becomes infected. Many field tests have been made on a small
scale, in which one or more branches heavily infested with white-fly
larve and pupx have been dipped or drench-sprayed with concen-
trated mixtures of Aschersonia spores.1 In no instance has the
resulting infection amounted to more than 5 per cent of the number
of insects alive at the time of the introduction, and the apparently
‘ direct infection has rarely exceeded 1 per cent. In ordinary spraying
on a large scale the direct infection on the parts of the tree reached
by the spray is usually but a very small part of 1 per cent.
The brown fungus has proved much more difficult of spread arti-
fically, as regards the degree of infection which it is possible to obtain
by the methods tested as described elsewhere. During September
and October, the most favorable season for brown fungus, introduc-
tion and infection are rarely secured on more than 1 per cent of white-
fly-infected leaves? which have been dipped in water mixtures of
1 Tests with red Aschersonia for the citrus white fly and with the yellow Aschersonia for the cloudy-
winged white fly are particularly referred to.
2 Since the brown fungus generally destroys all of the white flies on a leaf upon which it becomes estab-
lished, it appears-to the authors that the number of leaves infected is a better standard than is the actual
number of insects infested.
60 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
spores and mycelia. The best general infection by brown fungus
which has come under the observation of the authors was one
secured in a grove! of Mr. W. C. Temple at Winter Park, by Mr.
Frank Sterling of Deland. The ordinary method of spraying spores
was used. The spraying was done between October 2 and 16, 1908.
Doubtless there was more or less secondary spreading in the fall, but
there was no appreciable spread in 1909 before April 23, when the
records were made. At that time brown fungus was found to be
present on 7 per cent of the leaves, averaging 23 pustules per infected
leaf or 16 pustules for the entire lot of 100 leaves examined.
As regards the extent of infection attainable by methods herein
discussed, the authors consider the results far from satisfactory. The
dipping of white-fly infested branches in water mixtures of spores of
Aschersonia and ground-up leaves infected by brown fungus would
appear to represent a maximum of favorable influences so far as prac-
ticable methods of introduction or spread are concerned, and the fail-
ure to secure more than a slight infection, comparatively speaking,
under any conditions indicates the relative insignificance of human
efforts as compared with natural methods of spread.
PRACTICABILITY OF INCREASING THE EFFICACY OF FUNGOUS PARASITES.
The efficacy of the fungous parasites may be said to be increased, in
a broad sense, whenever they are introduced or even spread naturally
into white-fly-infested citrus groves in which they previously did not
exist. The subject to be considered here, however, relates to the ordi-
nary meaning of the expression oerepeon the ipfiesey after the
initial introduction has already been Sloane Apparently there
are only two opportunities for effort in this direction. The first con-
sists in producing conditions more favorable for the development of
the fungous parasites and the second consists in artificially spreading
the infection.
IMPROVEMENT OF CONDITIONS FAVORING THE DEVELOPMENT OF FUNGOUS PARASITES.
A line of work which naturally suggests itself in connection with an
investigation of this kind is the improvement of conditions favoring
the development of fungous parasites. Preliminary work in spraying
trees with clear water in the absence of regular rainfall gave no
promise of benefit. Common observations made in hammock groves
in Lee and Manatee counties are sufficient to prove the futility of
1 No examination of this grove was made prior to Dee. 8. 1908, but since no brown fungus was found in
several surrounding groves, since none was known to occur nearer than 5 miles, and since no previous
attempt had been made to introduce it, it was presumed that this fungus was introduced by Mr. Sterling.
On the other hand, yellow and red fungi sprayed at the same time were presumed net to have been suc-
cessfully introduced or spread by this application, since on the opposite side of the road a grove in which
no artificial introduction had been made was found to have an average of twice as many red-fungus pus-
tules and six times as many yellow-fungus pustules per leaf.
PRACTICABILITY OF INCREASING EFFICACY OF FUNGI. 61
attempting materially to increase the efficacy of fungous parasites by
artificially increasing the humidity. Even were it possible to secure
a high percentage of humidity on high pine land in the counties
mentioned and in the interior of the peninsula comparing favorably
with the humidity in the most humid hammock lands, the accom-
plishment would avail nothing of practical importance.' If the con-
ditions in these very hammock lands of Lee and Manatee counties
were improved so that the work of the fungous parasites were sufli-
cient to keep the crop of fruit free of sooty mold one year in two
instead of, as at present, one year in three, the injury from the
white fly would still be sufficient to demand more satisfactory means
of control than natural enemies afford. Notwithstanding the appar-
ently self-evident impracticability of efforts in this line, the careful
investigation of the subject would be of much interest and possibly
of usefulness in connection with the investigation of other fungous
parasites affecting insect pests. In a small investigation conducted
within reasonable time limit, however, the elimination of unpromis-
ing lines is necessary.
+ INCREASING THE EFFICACY BY SPREADING THE INFECTIONS.
The most important subject in connection with the investigation
of white-fly fungous parasites is that of increasing their efficacy by
artificially spreading the infection. At the time of this writing the
only published record of the results secured by an attempt to spread
infections where the fungous parasites already exist, and properly
classifiable as a result of this kind, has been made by Dr. Berger.’
The authors’ field investigations of this subject consist of person-
ally conducted or cooperative experimental work in six groves in
addition to more general observations in a few other groves where
work in this line was taken up commercially. Altogether more than
1,500 trees were included in the experimental blocks in these groves,
not including the untreated trees left as checks.
(1) Gettysburg ae near Orlando, Fla. Estimated 94.8 per cent
citrus white fly, 5.2 per cent cloud, aaa white fly—To determine
what effect one introduction of spores of the red Aschersonia might
have on the abundance of fungus in a grove already slightly infected,
1 Since the preparation of this report the investigation by Prof. H. S. Faweett, of the Fla. Agric.
Exp. Sta., of a new disease of citrus fruits, known as ‘‘stem and rot’’ (Fla. Exp. Sta. Bul. 107, 1911),
has shown that humid conditions in orange groves which are considered an advantage in favoring the
white fly parasitic fungi are a serious disadvantage in also favoring the destructive disease of the fruit.
2 Rept. Fla. Agr. Exp. Sta. for fiscal year ending June 30, 1909, p. xli. ‘‘On Aug. 17, 1909, red fungus
was reintroduced into six trees in the Heathevat grove in order to compare, at a later date, the amount of
fungus in these trees with those not treated again. On Mar. 2, 1909, these trees were estimated by Mr.
Jos. E. Kilgore and the Entomologist to have 10 times as much fungus in them as six trees in either
row next to them, showing clearly that fungus should be introduced frequently, if necessary to get the
best results.”
62 NATURAL €CONTROL OF WHITE FLIES IN FLORIDA.
blocks of trees in this grove (fig. 1) were sprayed as indicated with
a spore mixture made by using about 1,200 pustules of red Ascher-
sonia to each 4 gallons of water.'
On August 21, almost before the introduced fungous spores -had
had an opportunity to mature into pustules, 27.6 per cent of the 185
trees sprayed August 10 were visibly infected with red Aschersonia,
and 18.6 per cent of the 354 trees sprayed on August 11, while 15.5
per cent of 252 check trees showed the presence of fungi. A fungous
inventory of this grove made during the following December showed
the general infection represented in figure 1. A study of the distri-
bution and comparative abundance of the fungus as indicated shows
that it had no relation to the trees sprayed and that the spread from
the middle of August on was entirely independent of any practical
influence of the introduced spores. In fact some of the very best
infections were on trees that were not sprayed.
A count of leaves picked promiscuously from the trees on April 30,
1909, gave data included in Table X.?
TABLE X.—Red Aschersonia; averages per leaf on sprayed and unsprayed blocks.
Rows 1-3 4-11 12-14 | 15-20 | 21-23| 2427 28-30 | 31-33 | Cheek | Sprayed
5 check.| sprayed.) check.| sprayed.| check.| sprayed.| sprayed.| check.) rows. rows.
Live pupe.......- 0.7 0.5 0.4 0.1 0.4 (yal 0. 4 0.3 0.4 0.3
Pupa cases (adults
emerged spring
Of L909) occ cee: 7a 24.8 UPA 21.9 16.0 9.2 2.5 By 12:2 14.6
Spring mortality
among pupr....| 3.7 1.3 2.6 2:2 2.0 3.3 1.3 1.4 2.4 2.0
Red Aschersonia
infection. ..-..- 9.0 IW Kei 8.6 6.3 7.2 2.6 Q 1.0 6.4 6.9
In Table X the forms recorded, aside from fungous infections, rep-
resent the total number of white flies surviving the winter. The
spring mortality referred to is mostly the same as that discussed
under the head of climatic conditions. The predaceous thrips men-
tioned elsewhere was also concerned in this mortality to some extent.
It is evident from the data presented that absolutely no tangible
benefit resulted from the attempt to spread the infection. A grove
immediately south of the experimental grove, similarly infested
with red fungus but in which no attempt was made to spread the
infection, developed even more fungus than did the sprayed trees.
An examination of 100 leaves picked at random in this grove showed
1 Spraying began in the afternoon of Aug. 10, 1908. About 2 inches of rain fell during the morning and
the afternoon was cool; the temperature for afternoon and night ranged from 74 degrees to 71.5 degrees F.,
while the humidity ranged from 92 degrees to 82 degrees and up to 99 degrees, where it remained close
to 100 until 7a. m., Aug. 11, when it gradually dropped to 63 degrees by 1 p.m., then rose suddenly to
94 degrees by 4 p. m., remained between 94 and 95 degrees for about one hour, suddenly dropped to 90
degrees, and then rose to 99 degrees and remained at 100 during the night of Aug.11. The temperatureat
4a.m., Aug. 11, was 71.5 degrees F., gradually rose to 89 degrees F. by 12 m., and remained there until
2.30 p. m., then suddenly dropped to 74 degrees F. by 3.30 p. m., and then slowly dropped until 71
degrees F. was reached at 4.30 p.m. On Aug. 12 temperature rose to 92 degrees F. by 2 p.m. Subse-
quent conditions were very favorable for the spread of fungus.
2 One hundred leaves were picked from each block, or 800 in all. The leaf averages are proportionally
lower than in the records in Table II, since leaves were taken from all growths at random.
PRACTICABILITY OF INCREASING EFFICACY OF FUNGI. 63
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Fig. 1.—Diagram of Gettysburg Grove; experiment in spreading red-fungus infection in an attempt to increase its efficacy.
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64 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
an average of 29.8 red-fungus pustules per leaf, the degree of white-
fly infestation agreeing quite closely with rows 4 to 11 (Table X) of
the experimental grove.
(2) Swindley grove, near Orlando, Fla. More than 80 per cent
citrus white fly; less than 20 per cent cloudy-winged white fly—tn this
grove of 900 seedling oranges experiments were conducted during
the summer of 1908 to determine what advantage might follow two
introductions during the same season, and incidentally, one intro-
duction on each of two successive years. About one-fourth of the
trees were sprayed with no fresh red Aschersonia,! one-fourth with
fresh red-fungus mixtures varying to strength (300 to 625 pustules
per gallon) during July, and another fourth in a like manner during
July and August. The remaining fourth, which had been sprayed
during July, 1907, was again sprayed in August, 1908. The results
are given in Table XI.
TABLE XI.—Red Aschersonia: Results of experiments in spreading the infection.
ie Pupa nee As
‘ eaves : chersonia
Block Fungous introductions. exam- | C@S°S Pel | infection
No. A leaf, 2: »
ined. average, | 2verage
8°. | per leaf.
1.'|| Unsprayed chek... 2¢ 32.26 --Ssaee~ senate ee see eee eee 120 9.8 0.01
2 | Sprayed: once, July; 1908 5. 252222252 see sens eee ee eceeee ae eee 120 6.2 6.1
3.| Sprayed twice; July-and August, 1908 coo 825. . see oe acess ce mines 120 6.7 7.3
4 | Sprayed twice, July, 1907, and August, 1908.................--.--- 120 6.0 2.9
While the data presented show that more fungus developed on the
trees sprayed twice in one season, the spread of the fungus on all trees
during the season of 1909 was so rapid that it became impossible to
tell which trees had been sprayed once, twice, or not at all. All
developed an equally large amount of fungus which, supplementing
unexplained mortality, so held the fly in check that the fruit in the
grove was practically clean by the following fall. By the following
spring much of the fungus had fallen off and there were more specimens
of the fly in the grove during 1910 than the owner had noticed for
many years, and the trees became thoroughly sooted.
(3) Drennen estate grove, near Orlando, Fla. The citrus and
cloudy-winged white flies present, the latter comprising 0.8 per cent,
according to an estimate made in June, 1909.—In this experiment a
solid block of six rows of eight trees each was divided into two series,
one comprising the even and one comprising the odd numbered trees
of the six rows. Only a trace of red fungus (no yellow or brown) had
been found in this grove and none had been discovered near the
experimental block. After the first introduction, therefore, the
experiment is properly one of increasing the efficacy by spreading
the infection. An attempt was also made to introduce and spread
the yellow and brown fungi by including their spores and mycelial
1 This fourth was composed of trees either not sprayed or sprayed with dried pustules of the Ascher-
sonias later determined to be valueless.
PRACTICABILITY OF INCREASING EFFICACY OF FUNGI. 65
fragments with the red-fungus spores, but no results worth noting
were secured.
Series A was sprayed 11 times between May 7 and October 19,
using from 300 to 600 pustules per gallon of water.!| The applications
were made on the following dates: May 7, May 26, June 25, July 24,
August 27, September 11, September 18, September 25, October 2,
October 9, October 19.
Series B was sprayed only once, May 7.
Eight examinations, each based upon 300 leaves picked promis-
cuously from the trees of each series, gave the records shown in
Table XII.
TaBLeE XII.—Average number of red-fungus pustules per leaf at successive examinations.
| | |
When examined (1909). \June 10./June 30.| July 9. | July 24. Aug. Th eae 27. Sept.11., Oct. 26.
|
| == ears
Series A, sprayed 11 times..........-.- 0. 22 0.5 1.2 3.5 Liss 10.1 20.1 21.5
Series B, sprayed once.............-- aL -3 A) 8 2.4 6.0 8.8 9.5
A eheck lot of leaves picked promiscuously from unsprayed trees
within three rows of the experimental block showed an average of two
red-fungus pustules per leaf on October 26.
The rainfall and the comparative humidity’ for each week during
the six months covered by the sprayings are shown by the data in
Table XIII, being based upon the mean of the maximum and minimum
relative humidity records for each day by a Friez recording hygro-
graph located at the standard Weather Bureau shelter near the
Orlando laboratory.
TaBLe XIII.—Rainfall and relative humidity records, Orlando, Fla., May to October, 1909.
LDU ae eee || Daily rie
Week beginning— mean | ven Week beginning— mean ae
humidity. : humidity. a
| yj |
; |
Per cent.| Inches. |} Per cent.| Inches.
LOGOS «ee ee (hie “DBalwAUp URE 24224 wreck coast 78 9
U2 aa . sae 82 sor | Cs pea eat til RE PR 84 3.39
We nna aimee gion aie artis 78 1. 83 |} AGs. eceie e cena eee 91 », 2086
2 5 Se EEE ee 80 | .0 7 ROS SER RICE Sty 86 57
Me OOS Eee (ii 2.01 | BO Bc ernicita 6 tote ee | 83 73
Monthly mean........... Vic ee mee rae Monthly mean........- 84. Biles oe ae
see ee | WE SS eae
DRIBE AW see ee emo s wees 3 See &3 sUbel|pSeptembernG6! 5. .132524~ se Ss 84 | aa
1h cpa aa A 77 0 || ss ea a ah S27" 99
hig ire Se Ba aha nc wie ~'a'0'f 76 -99 |} 7. | eee ee ee 86 1.65
2 St ina 77 8.23 | [poe ake. Eps) 0
Monthly mean........... Toca eos seen Monthly mean........-.- S47 [once ee
| UD 91 Sage Oeteber 6.0.02. 22.0 81 | 0
UE eee | 86 2.34 i) ee Pee aes ae 78 .0
ie ce. 2a nen 81 .0 LI etn nyt, DEE ect 80 | . 38
PRN eS mani ale ote id wane 80 1.59 7 PE eee ene 2 eo 79 -92
Monthly mean........... Sis |e. ee Monthly mean.......... (HA EER,
| |
1 As inall experiments, unless otherwise stated, the freshest fungous pustules obtainable, according to the
season of the year, were used.
2 These humidity records are not comparable to U. S. Weather Bureau records, which in Florida are
taken at 7a.m.and7 p.m.
21958°—Bull. 102—12——5
66 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
It appears that the great humidity, after the introduction of Sep-
tember 11, was not a condition which would promote fungous develop-
ment. The increases in the average number of fungous pustules per
leaf are, as a rule, inconsistent, in series A and B, whether the data
be examined from the standpoint of the attempts made to spread the
infection or from that of climatic conditions. One exception is
found in the rapid increase between the examination of August 14
and that of September 11 for both series. This most important
increase of the year appéars to be entirely uninfluenced by the
attempts to spread the infection, since the fungous pustules in series B
increased at practically the same rate as in series A. The pustules
in series A increased about 200 per cent between July 9 and July 24,
when practically uninfluenced by artificial spreading of infection,
while the pustules in series B increased only about 60 per cent.
Between July 24 and August 14 the attempt to assist natural means of
spread was followed by a 46 per cent increase, while without any
effort in this direction the natural spread in series B amounted to a
200 per cent increase in the number of fungous pustules.
Notwithstanding the foregoing inconsistencies the records show
that after the initial introduction the fungous pustules multiplied
about 10 times (964 per cent increase) in series A and about 6 times
(623 per cent increase) in series B. It is not impossible that such a
difference as this in the rate of multiplication might be found in two
arbitrarily selected groups of trees treated identically as regards
fungous introductions. We may, however, fairly give the fungous
diseases the advantage of the presumption that the difference noted
is due to the artificial spreading of the infection. The question then
arises, Did this difference result in any practical benefit to the trees ?
On June 30 an examination showed an average of 59 live larvee
and pupx per leaf in the experimental block; on July 24, 21.5 per
leaf; on August 27, 43.7 per leaf on old mature growth and about 350
larvee per leaf on the newer summer growth, and on October 26 an
average of 27.8 live per leaf. The last estimate was based on 10
typical leaves which averaged 27.5 red-fungus pustules per leaf and
10.4 pupa cases. While this examination was not extensive enough
to compare with those the results of which are given in Table X, a
summary showing more live insects in the leaves showing the most
fungous infection is noteworthy.
Five leaves with greatest number of red-fungous pustules, averaging 47.6 per leaf,
36 live per leaf.
Five leaves with least number of fungous pustules, averaging 7.4 per leaf, 19.6 live
per leaf.
It is probable that more adults migrated from the surrounding
trees to the experimental block and from trees of series A to series
PRACTICABILITY OF INCREASING EFFICACY OF FUNGI. 67
than vice versa, thus giving more live insects to those trees upon which
the fungus spread best than they otherwise would have had. This,
however, was an advantage so far as the increase in the average number
of fungous pustules per leaf was concerned. On the other hand, the
experimental block, which was heavily infested at the beginning of the
season, began blackening by the 1st of June, and this heavy infestation
would unquestionably have continued and a general blackening have
resulted in spite of an increase in the number of fungous pustules to 21
or even 25 per leaf. From our data in this experiment and from our
general knowledge of white-fly and fungous conditions, we conclude
that no practical benefit to the orange trees resulted during 1909 from
the repeated attempts to spread the infection of red fungus, and that
from this standpoint the results would not have been affected if the
trees of series A had been isolated. The only accomplishment of
practical importance was in the introduction of the red fungus onto
trees not previously infected.
(4) Wills Grove, Sutherland, Fla. Grapefruit trees infested by cloudy-
winged white fly only—In cooperative experimental work, in 1909,
Mr. F. L. Wills, of Sutherland, Fla., sprayed 49 trees in the middle
of a block of 378 trees, all heavily infested with the cloudy-winged
white fly, and already slightly infected with yellow Aschersonia,
with mixture of yellow Aschersonia on May 18, June 11, July 8,
August 9, and after the 1st of September until October 18 one-half
of the sprayed trees every two weeks, the rest once a month. By
July 17 a count of 185 leaves, picked promiscuously, showed that
173 were infected, with an average of 41 pustules per leaf, or nearly
twice as many pustules as were present on leaves picked from check
trees. On August 18 Mr. Wills noted that the fungus was spreading
very rapidly and making its appearance over 20 acres of orange and
tangerine trees adjoining. At the time there was an average of 90.7
pustules per leaf on the sprayed trees as compared with 51.8 pus-
tules on the check trees. By September 22 a count of 200 leaves
from the sprayed and from the unsprayed check trees showed the
average abundance of pustules per leaf to be 118.4 and 137.5, re-
spectively; in other words, by the middle of September, the natural
spread in the entire block had been so rapid that there was more
fungus in the check than in the sprayed tree. By the middle of
November no difference could be noted on a general examination of the
grove, and both the owner and the authors concluded that had no
spraying been done the natural spread would have accomplished the
same results.
(5) Fairbanks Grove, Island Grove, F'la.—Orange trees infected with
citrus white fly only; cooperative experiments arranged with Rev:
J. J. Glass.—The trees were fairly heavily infested and there was a
68 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
trace of red fungus present in the experimental block of 26 orange
trees located in the midst of a 10-acre grove. An examination of 100
leaves of old growth picked at random from the experimental block
showed that an average of 12.6 had matured in the spring of 1909
or were still alive on the leaves as pupe. The new spring growth was
beginning to become blackened by May 21 and was generally moder-
ately blackened by June 15. The experimental block was sprayed by
the foreman, Mr. John Engle, on May 17, June 9, July 2, August 2,
September 2, and September 11, using about 2,000 pustules of red
fungus for the first and about 4,000 pustules of red fungus for each
later spraying. One hundred and fifty leaves picked at random on
June 15 had an average of 7 pustules of red fungus per leaf; on
August 21, 140 leaves had an average of 8.8 pustules, and on Sep-
tember 15, 50 leaves had an average of 19.6 pustules. On August 2
Mr. Engle wrote to the effect that the fungus seemed to be working as
well in other sections of the grove as in the experimental block. At
the end of the season no difference could be detected so far as showing
the slightest advantage from the repeated applications. An ex-
amination of two lots of leaves from surrounding unsprayed trees
on September 15 and October 18 showed an average of 41.3 and
14.3 red-fungus pustules, respectively, on lots of 50 and 100 leaves.
In regard to the record of October, a misunderstanding is involved
which in the opinion of the junior author renders the record valueless,
but even if it be accepted the data show that more fungus developed
on the check trees immediately surrounding the experimental block
than on the trees to which the spore mixture was applied.
(6) Keep Grove, Boardman, Fla. Orange trees infested with citrus
white Ny only; cooperative experiment with Mr. B. B. Keep.—The degree
of infestation in this grove was practically the same as in the Fair-
banks grove, but there was no fungous infection. A small block of
36 trees was sprayed. On May 3, a lot of 25 spring-growth leaves
picked at random from the experimental block showed an average
infestation of about 50 larve in the first three stages. Red-fungus
spores were sprayed as in the preceding experiments within the first
10 days of May, June, July, August, and September. On October 25
an examination of 125 leaves from the sprayed block showed an
average of 2.2 red-fungus pustules per leaf while from the surrounding |
unsprayed trees an average of 0.3 pustules was found on 134 leaves.
On September 25 it was noted by Mr. Yothers that 72 out of 143
leaves examined from the experimental block had considerable sooty
mold while the remainder were only slightly blackened.
NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 69
THE DISADVANTAGES ACCRUING TO CITRUS TREES THROUGH THE
USE OF PARASITIC FUNGI.
DIRECT INJURY TO FOLIAGE.
Dr. H. J. Webber gave the subject of direct injury to foliage
some consideration in connection with the brown fungus and reported
as follows:!
Old leaves on which the larvee have been dead for some time, and on which the
fungus has been exposed for an extended period to the action of rain, etc., clearly
show the slight damage to the leaf caused by this fungus. Leaves which were observed
in March, 1896, to be badly infested with the fungus were found in December of the
same year to show only the remains of the pustules, the hypothallus having been
entirely washed away. That the fungus does some damage to the tree can not be
denied, buf this is clearly a secondary effect.
The secondary injury referred to by Dr. Webber has been noted
by the authors. It may be considered as of slight importance. .-2-.245-222-4--2--+--2"=-enee 19
Coccinellid, undetermined small black species, enemy of citrus*white fly... . - 9
Coccus hesperidum, host of Verticillium heterocladum...........-------------- 37, 38
Coniothyrvum sp., parasite of Aigerita webbert..........--.2.2--2--+-----02-48 32
Cryptognatha flavescens, enemy of citrus white fly.......-...-..---.---.------- 9
Cycloneda sanguinea, enemy of citrus white fly. ........------..-------.----- 9
Duspis sp., host.of Veriieillium heterogladum £22. 2. 25/2. - = +n hele
on leavesiol Huonymais!amenicanis= 24 2255s. see ae ee 38
Dipping method for water mixtures of fungous spores and mycelia... ...-. 51, 52-53
Dropping from leaves in control of: white flies. ...=-~.-.-=-----=---5---s-sees 18
Drought in control of white flies. ....:...-..is2) el -eveee et ee ee oe 19
Eincarsia luteola, parasite of Aleyrodes fernaldt: 2.220220 22> 20 3aens -- - on eee 8
tested as to ability to parasitize citrus white fly. ...........- 8
variegata, parasite of Paraleyrodes persex......-----------2-+----+---- 8
tested as to ability to parasitize citrus white fly..........-- 8
Euonymus americanus, food plant of Diaspis sp.......--------+----------+-+- 38
Hungous diseases of white flies... .c.22-5.224-0e2 2 eee tae a ee 20-73
cost of introduction and spread.....-.-.-------- 58-59
degree of infection obtainable...............-.-- 59-60
disadvantages accruing to citrus trees through
their ses yc “eaeilels ete. 69-70
efficacy, comparative, of different species. ..... 46-47
credibility of common reports.......-- 39-40
increase by spreading infections. ....-. 61-68
natural’: SiS. eaenOs2)2) Coe ee 39-47
earlier estimates. .....----.--- 40-42
has it increased since their first
Giscoveryi 242! - See ee 47
observations and records. .-...- 42-46
practicability of increase. ......--.--- 60-68
improvement of conditions favoring their devel-
OpMent. 522) 2 eee ee ee eee 69-61
injury, indirect, from their use, through disuse
of needed fungicides .........----...- 69-70
to foliage through their use. ----.------- 69
mycelia, water mixtures, application..........- 51-53
preparation........... 50-51
pustules, advantages of soaking before shaking
orahirrine) 34) toe eee 54
number of times they can be used to
advantage: stesso eee 54-55
relation between abundance of white flies and
results in spreading infec-
tions st eas 2 ee 58
weather conditions and infec-
tlonss). 4s eee 228 eee 57
spores, vitality, effect of copper sprayers thereon 55
lengths Anare.i3c 4a 56-57
water mixtures, application. ...-.--.-..- 51-453
as Means of spread..--.- 50-53
effect of adding nutri-
@Nt82 os. eee 50-56
straining them
through cloth
strainers..... 53-54
sulphur waters
thereon!--...- 56
preparation. 22.2... 6222 50-5 L
spreading them. . ../ .@aeeSee saree: Boe. ees 47-56
by pinning and rubbing infected
Leaviess estas. 200... See 49-50
water mixtures of spores and
muyicelan mee’ ir: suns See 50-53
experimental methods. ........ 48-49
experiments and observations. .. 53-56
history ot work: 222 = see seer 47-48
INDEX, Th
Page.
Fungous diseases of white flies, spreading them, results in relation to abundance
gnominte fited sos. tht 57
to increase their efficacy... ..... 61-68
susceptibility of different stages of host insects
to Intoeitonrs.nd-enitt sald. ds «cl baa eae 58
Fungus, ee gunts to use in water mixtures for spread of infection among white
1S Se EOI EE Seer a2) oh la =. 2. an pees Same ea te 54
cinnamon. (See Verticillium heterocladum. )
brown (see also A’gerita webberi).
efficacy as parasite of citrus white fly compared with red
TU CN ect Cah). Scneeitietcd. 3 Ais Tere oe. se aiatsl ots Gee 46-47
on Aleyrodes citri and Aleyrodes nubifera.................----- 12
red (see also Aschersonia aleyrodis).
efficacy as parasite of citrus white fly compared with brown fungus. 46-47
on Aleyrodes citri. and Aleyrodes nubifera.............-.-.022---- 12
redheaded scale. (See Sphexrostilbe coccophila. )
white-fringe. (See Microcera sp.)
yellow (see also Ascher sonia flavo-citrina).
efficacy as parasite of cloudy-winged white fly................ 46-47
on Aleyrodes citri and Aleyrodes nubifera EN = A eee Se) MOR Be RP 12
Fungi of little or no value as white-fly parasites.................2.-2.22---. { 32-38
Gardenia gasminoides, food plant of citrus white fly.......2....2.-...--------- 10
Grapefruit (see also Citrus, Orange, and Tangerine).
food plant of Aleyrodes citriand Aleyrodes nubifera...........-.--- 12
iaaaga. toad ‘plant of Aleyrodes floridensis..cosccses lesvele wal so) Jen wted eee ene 25
Jessamine, Cape. (See Gardenia jasminoides.)
Lacewing flies, hosts of hymenopterous parasites...........---..-.-----.------ 9
two or three species enemies of citrus white fly..............- 9
Lecanium hesperidum. (See Coccus hesperidum.)
Lepidosaphes beckii, host of Verticillium heterocladum ........--..-.22222222+++- 38
gloveri, host of Verticillium heterocladum............---+-+------- 38
Ligustrum spp., food plants of citrus white My 1 ss242-4- nee ae ceess.-+.- = 10
Liquidambar styraciflua, food plant of scale insect attacked by Aschersonia flavo-
RUA s neste ert apt Rodentia baa owes ee UY<. ocs2ed See wae 27
Melia azedarach, food plant of citrus white fly.............-----.---2.-.--2-.- 13-14
umbraculifera, food plant of citrus white fly........-..----.--- 13-14
PeeeeL an. 1060 OL-DUhmulis dormant... .-2-<<26stIoe2 depen eeeele ss 2... 9-10
SRE MOL" Seekehgs or teh ets Oc Ue we eee ol ete 2, 9-10
GRLEIRERN Go soo). SOBRORES: ate MAG SHEE se oon ans ww oie 9-10
oyerrunning Agchersoniaaleyrodis.s.-~..-...0<-----..-%-.--+-+----- 26
Microcera sp., probably “mostly saphrophytic on white flies.................-.. 34,35
Mulberry, Spanish, food plant of undetermined aleyrodid...........-.....--- 25
Orange (see also Citrus, Grapefruit, and Tangerine).
food plant of Aleyrodes citri and PAVEUTOMES TOY ENG. sane selene aso 12
Cerrerrwaine in Control oF white filers ite cok. ec eee eke 18-19
Paraleyrodes persex, a citrus-infesting species.........-..-.:---------22--02- 8
hiost Gk Pineangia waragatas..... =<. =<. --- 2-22. 5----2--- 8
Potato, sweet, food plant of Aleyrodes inconspicua...........--.-------------- 24-25
Privets. (See Ligustrum spp.)
Prospaltella aurantii, parasite of Aleyrodes coronata.......-..---..2++---++++---
tested as to ability to parasitize citrus white fly .........
citrella, parasite of Aleyrodes coronata............---+.+.2-++ee2---
tested as to ability to parasitize citrus white fly. .........
iphorenms, parasite of citrus white fy..........--2--s6----.s0e6--
Rainfall and relative’ humidity records during experiments in spraying fun-
SRUIS DOLD EEL CHM ee fee =e oe eo eter pees op AOE SOE Slee cig See e ee 65-
Rains, beating, in control of citrus and cloudy-winged white flies...........-.
Scale insect on Liquidambar styraciflua, host of Aschersonia flavo-citrina........
soft. (See Coccus hesperidum.)
Snail, Manatee. (See Bulimulus dormani.)
Miami, feeding on sooty mold ( Meliola sp.).....-...------------+-+----- 10
Sooty mold. (See Meliola sp.)
Sphexrostilbe coccophila of little or no value as a white fly parasite..........--. 38
Piigcthamertener Clits WHILG fly... -.. =... 2.--- seen secw sense seeee 9
Sporotrichum of little value as a parasite of white flies.....................--- 36-37
Spraying water mixtures of fungous spores and mycelia............-.-..-.--- 51-52
NO o Cmnmnnm
Nike a
78 NATURAL CONTROL OF WHITE FLIES IN FLORIDA.
Page.
Sulphur waters, effect on spores of iimpi.205.29!)22995 ea ee ee 56
Sweet gum. (See Liquidambar styraciflua.)
Tangerine (see also Citrus, Grapefruit, and Orange).
food plant of Aleyrodes citri and Aleyrodes nubifera.......-.......+-- 12
Unexplained mortality of white flies in Plorida.................. Ee aya oh a 11-17
Verticlium heterocladum, descriptionss22222220522223 A See 37-38
Cistrib Ubon wise ee cet en 38
effectiveness2=.22200...2i422 202) 9a 38
history ee. 5 2 ssid 23 Se 37
insects attacked cs: 2..4: Sui). 5O ee eee 38
parasite of (Lecanium) Coccus hesperidum ......----- 37
Verania cardoni, enemy. of citrus*white fly 22-2... 5535 252 eee 9
Weather conditions in relation to fungous infections of white flies.............- 57
White flies in Florida, control by climatic conditions. ...............-......-- 10
curling and dropping of leaves from drought. 19
dropping from leayes: 2°... 053. eae 18
fungous diseasest-eo-2h.9855.. cons eee 20-73
overcrowding. Sse see eee 18-19
parasitic and predatory enemies............- 8-9
unexplained catises 42). 202 e hae eee 11-17
fungi of little or no value as parasites.................. 32-38
natural:control:t ius sees 2 3 ee eee 1-73
summary and conclusions.............. 70-73
fly, citrus (see also Aleyrodes citri).
control by: bacterial diseases.:.24.3-5.5. ©2202. eee 19
climatic conditionsss: S522 Sete 2 et eee 10
overcrowding ::610). 4.22 eee eee 18-19
host, of Aigenita avebbert: 33.8 ee eee ee eee 31
Aschersonia aleyrodisi=aaae te ee eee 24, 25
flavo-ciirina. 3. 22 ee ee ee 26, 27
Spherostilbecoceophila. sets te eS eS 38
infection-with. Microcerasp-2) An ee eee 33
Sporotrichwm 225 £232 RUS ee ee eee 35, 36
natural control, personnel engaged in investigations. ......... ii
on Ligustrum spp. and Gardenia jasminoides ...........------ 10
parasitic and’ predatory enemies. {222222 22 S2S2 Ae ee 8-9
unexplained, mortality........ 3.2 ea ee eee 11-17
cloudy-winged (see also Aleyrodes nubifera).
control by bacterial diseases.............--.......--- 19
climatierconditionssss+ee5 o eee ee eee 10
overcrowding. !7/9. YEAw. eee 18-19
host of Algerita: webbemia 42 AS eee 31
Aschersonia aleyrodish-cccssesee eee ee 24
flavo-citrind. 22 eee 26, 27
Spherostilbe coccophila: 2 25 es ae eee 38
infection. with Microcera sp2t-1L 8 eee 33
Sporotrichum’.2:d uss. ee 35, 36
parasitic and predatory enemies......-.--..-..- Meta go =)
unexplamed mortalitys:<:. 723. Ree ee 11-17
‘Winds, strong drying, in control of citrus and cloudy-winged white flies. ...... 10
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