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STATE document;
THE MONTANA STATE BOARD
OF ENTOMOLOGY

SECOND
BIENNIAL REPORT

1915-1916

■^DEPENDENT PUBLISHING I

Montana Slate Library

3 0864 1005 9470 7

THE MONTANA

STATE BOARD
OF ENTOMOLOGY

SECOND
BIENNIAL REPORT

1915-1916

MONTANA STATE BOARD OF ENTOMOLOGY

W. F. COGSWELL, M. D.. Secretary State Board of Health,

Chairman --------- Helena, Montana

W. J. BUTLER, D. V. S., State Veterinary Surgeon,

Member ---------- Helena, Montana

R. A. COOLEY, B. Sc. State Entomologist,

Secretary -------- Bozeman, Montana

R. R. Parker, Ph. D., Assistant Entomologist,

- - - - - - - - - - Bozeman, Montana

LETTER OF TRANSMITTAL

Bozeman, Montana, December 15. 1916.

To His Excellency,

Governor Samuel V. Stewart,
Helena, Montana.
My Dear Sir:

On behalf of the Montana State Board of Entomology I
have the honor to transmit to you herewith the Second
Biennial Report.

During- the two-year period now closing there has appear-
ed a widespread outbreak of Rocky Mountain Spotted Fever
in a mild form, similar to that found in Idaho, in the eastern
part of Montana. Roughly speaking this new infected area
occupies the whole southeast one-fourth of the State. Num-
erous cases of the fever have occurred and several deaths.
The Spotted Fever tick, which occurs in western Montana, is
also abundant in this infested region in the eastern part of
the State, and here, as in the Bitter Root Valley, is the
agent of man's infection.

We have given preliminary attention to the Spotted
Fever problem in Eastern Montana. A report of this work
is presented together with a report of the work in the Bitter
Root Valley and certain work on the housefly.

Very respectfully,

R. A. COOLEY,

Secretary.

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SECOND BIENNIAL REPORT

OF THE

Montana State Board of Entomology

By R. A. Cooley.

The activities of the Montana State Board of Entomology
during the past two years may be classified under three
heads, as follows:

1. Investigation and control of the Rocky Mountain

spotted fever tick in Montana.

2. Investigation and control of the housefly in relation

to human disease in Montana.

3. Miscellaneous preliminary studies of parasitic insects.

Control of the Rocky Mountain Spotted Fever Tick in Montana

Rocky Mountain spotted fever is, comparatively speak-
ing, a new and little known disease of human beings. It is
confined to America where it occurs, so far as at present
known, only in nine Rocky Mountain and Pacific Coast States,
as follows: California, Colorado, Idaho, Montana, Neveda,
Oregon, Utah, Washington and Wyoming. Its occurrence and
distribution have not been extensively studied in all of these
states but. because of the severity and the nwmDer of cases
in some of them, special attention has been compelled.
Spotted fever is undoubtedly of more importance in Montana,
Idaho, and Wyoming, than in other states, and of these three,
Montana is looked upon as being particularly the home of the
disease because of the fact that in this State, in the western
part, is a locality where spotted fever occurs in a particularly
fatal form.

During the past two years covered by this report the
fever-tick situation has changed materially. Up to 1915
interest in spotted fever centered, so far as this State is con-
cerned, almost entirely in the Bitter Root Valley and other
territory close by. A few cases of much milder form had
been reported from Carbon County and, although no official
mention had been made of it. there was some reason to

6 REPORT OF STATE BOARD OF ENTOMOLOGY

believe that the disease existed in a restricted locaHty in the
northern part of Gallatin County.

In the spring of 1915 suddenly, and without warning,
spotted fever in a mild form appeared in several of the large
counties in eastern Montana. This was the outstanding fea-
ture of the year and there were 22 cases in new territory in
eastern Montana. Two of the cases, one in Big Horn County,
and one in Fallon County, were fatal.

Human Cases of Rocky Mountain Spotted Fever in Montana
in the Years 1915 and 1916.

Counties— 1915 1916
Western Montana.

RavalH 3 5

Missoula 4 1

Granite .... 1

Eastern Montana.

Custer ,.._. 8 1

Dawson ..: 6 4

Rosebud 5 1

Big Horn 1

Fallon 2

Musselshell 2

Yellowstone .... 1

Fergus 1

Phillips 1

Scattering.

Carbon 3 1

Gallatin 2

Cascade 1*

Totals 35 19

* This case came in from Idaho and did not originate in
Cascade County.

In the course of the investigations conducted in 1916 it
developed that 1915 had been a particularly bad year for
ticks in Montana. An assistant spent some time in eastern
Montana in that year and the observations made as compared
with those made in 1916, as well as numerous statements
made by residents showed that ticks were much more abund-
ant the previous year. This probably accounts for the large
number of cases in that year and for the dropping off of the
number in 1916. However, it should be borne in mind that
the infection in eastern Montana is a new one and we canont

REPORT OF STATE BOARD OF ENTOMOLOGY 7

yet tell just how extensive it is and there is some reason
to fear that the number may rapidly increase during the
next few years. It is already clearly evident that the disease
is spreading. A detailed account of these studies is presented
in an article in this report by Assistant Entomologist, Dr.
R. R. Parker.

Progress in the Eradication of the Rocky Mountain Spotted
Fever Tick in Western Montana.

In the work of the spotted fever tick in the Bitter Root
Valley both investigational lines and practical control are
being pursued. As fast as information is obtained it is put
into practical use in the field.

We feel that good progress is being made but on account
of the long drawn out life cycle of the tick and the overlap-
ping of broods, considerable time is required. There are now
fewer ticks than formerly and fewer cases of fever. In
earlier years the cases of the disease were running from
nine to twenty-eight. Our work under the State Board of
Entomology began in the spring of 1913. Data regarding
the number of cases in that year are lacking, but in 1914
there were eleven, in 1915, seven, and in 1916, six cases.
These figures taken alone give only an inaccurate impression
of the progress that has been made for the disease has been
spreading up and down the valley during recent years and
has extended beyond where the control work has been taken
up. The work of control was first undertaken where the
situation was the most distressing, which was in the vicinity
of Florence, Stevensville, and Victor on the west side of the
valley. Here the work has been pursued with energy from
the first and here, where the majority of all the cases form-
erly came from, we are now having very few. At the same
time cases are springing up in the far upper part of the val-
ley and in the far lower part of the valley, which fact, to-
gether with the occurrence of some cases up Lo Lo creek,
where the work of control is not yet fully under way, ac-
counts for a considerable part of the number of cases now
occurring. Where the work is well under way, then, distinct
progress is shown.

It should be borne in mind that no two localities are just
alike with respect to the conditions which favor control of
the tick. In each new locality it is necessary to get new in-

8 REPORT OF STATE BOARD OF ENTOMOLOGY

formation and conduct the campaign in a different way.
The conditions up the Lo Lo creek are unlike those around
O'Brien creek, and both of these are very unlike those
around Florence, Stevensville and Victor.

It is clearly apparent that if no work of control had been
taken up we would now be haing, with the increased cases up
and down the valley, some 14 to 18 cases at least per year,
instead of some six or seven, and it therefore appears that
during the past four years some 20 to 35 lives have been
saved and perhaps more.

The saving of life is of course the principal item of bene-
fit derived from the control program, but this is not all.
There can be no doubt that the presence of spotted fever
disease in a locality has in past experiences worked out to
be a detriment. Residence in such localities has been con-
sidered to be less desirable and property values have suffered.
Towns to which infested localities are tributary have also
been hurt in a business way. It is already apparent that in
the parts of the Bitter Root valley where the work of eradi-
cation has been under way, there is a new confidence in
the land value and in the locality generally.

REPORT OF STATE BOARD OF ENTOMOLOGY 9

REGULATIONS OF THE MONTANA STATE BOARD OF

ENTOMOLOGY.

The complete regulations of the State Board of Ento-
mology, with respect to the control of the Rocky Mountain
Spotted Fever Tick in western Montana, are as follows:

Section 1.

The following tick-control districts are described and
declared :

(1) The Florence District. Bounded on the east by the
main channel of the Bitter Root river; on the north by the
boundary between the 2nd and 3rd tiers of sections north-
ward from the dividing line of Missoula and Ravalli counties,
and extending from the river westward to and into the
mountains as far as human habitations do or may go. or as
far as domestic animals may wander; on the west by an
imaginery line running north and south along the mountains
as far back from the valley as human habitations do or may
occur, or a 3 far as domestic animals do or may wander; and
on the south by the boundary line between townships nine
and ten north, known as the O'Hare lane, and extending
from above described imaginary line on the west, eastward
to the main channel of the Bitter Root river.

(2) The Stevensville District. Bounded on the east by
the main channel of the Bitter Root river; on the north by
the boundary line between townships nine and ten north,
extending from the main channel of the Bitter Root river
to and into the mountains as far as human habitations do or
may go or domestic animals do or may wander; on the west
by an imaginary line running north and south along the
mountains as far back from the valley as human habitations
do or may occur, and as far as domestic animals do or may
wander ; on the south by a certain stream of water commonly
known as Big Creek, extending from the mountains to the
Bitter Root river.

(3) The Victor District. Bounded on the east by the
main channel of the Bitter Root river, on the north by a
certain stream of water known as Big Creek, extending from
the Bitter Root river to and into the mountains ; on the west
by an imaginary line running north and south along the
mountains, as far back from the valley as human habitations
do or may go, or domestic animals do or may wander; on the

10 REPORT OF STATE BOARD OF ENTOMOLOGY

south by the highway locally known as the Bourne lane and
on the east and west extension of the same, extending from
the main channel of the Bitter Root river and into the
mountains.

(4) The Hamilton District. Bounded on the east by
the main channel of the Bitter Root river; on the north by
Bourne lane and on the east and west extension of the same ;
on the west by an imaginary line running north and south
along the mountains, as far from the valley as human habi-
tations do or may go and domestic animals do or may
wander; on the south by a certain stream of water commonly
known as Canyon Creek extending from the mountains to
the Bitter Root river.

(5) The Gold Creek District. Bounded on the east
by the main channel of the Bitter Root river; on the north
by a certain stream of water commonly known as Canyon
Creek, extending from the mountains to the Bitter Root
river; on the west by an imaginary line running north and
south along the mountains, as far from the valley as human
habitations do or may go and domestic animals do or may
wander; and on the south by Lost Horse Canyon and creek
and east and west extensions of the same.

Section II.

At a convenient point in each tick-control district shall
be constructed a dipping vat and yards, for use in dipping
domestic animals, and all cows, horses, mules, asses and dogs
shall be periodically dipped or otherwise freed and kept free
of ticks, by spraying, carding or hand-picking, at such times
and in such manner as the officers in charge of the work
liifxy prescribe.

Amendment to Section H. The rules and regulations of
the Montana State Board of Entomology, respecting the dip-
ping of domestic animals for the destruction of the Rocky
Mountain Spotted Fever tick are hereby amended; and on
and after May 20th, 1913, or until otherwise notified, dairy
cows which are giving milk are exempt from dipping, pro-
vided the owners keep them free of ticks by hand-picking
or spraying with an arsenic-pine-tar solution, containing .22
per cent of arsenic trioxide.

Section III.

Owners of domestic animals in tick-control districts
shall be allowed to dip their animals in the State dipping vats

REPORT OF STATE BOARD OF ENTOMOLOGY 11

without charge, but the responsibility of dehvering the ani-
mals for dipping and of passing them through the vats, or
otherwise freeing them of ticks, as prescribed by the men in
charge of the vats, is placed upon the owners.

Section IV.

A close quarantine of all domestic animals, including
driving horses, mules and oxen, shall be placed upon ani-
mals and premises of all persons who refuse or fail to bring
their animals to the vats for dipping.

Section V.

On and after April 1, 1914. domestic animals, including
cows, horses, asses, mules, sheep, goats and hogs, may be
removed from the tick-control districts between March first
and July fifteen of each year only on written permits of
the Secretary of the Board of Entomology or duly authorized
representatives of the United States Bureau of Entomology
or the United States Public Health Service.

Section VI.

On and after April 8th, 1916, domestic animals, includ-
ing cows, horses, asses, mules, sheep, goats and hogs, shall
be prohibited from entering any tick-control district as de-
signated by the Montana State Board of Entomology, for
grazing or feeding purposes between February first and
July fifteenth of each year, unless accompanied by a permit
issued by the Secretary of the State Board of Entomology
or a duly authorized representative of the United States
Bureau of Entomology or the United States PubUc Health
Service.

"Helena, Montana, April 5, 1914.

"TO WHOM IT MAY CONCERN:

"Notice is hereby given that Doctor L. D. Fricks,
Victor, of the U. S. Public Health Service and Mr. W. V.
King. Florence, of the U. S. Bureau of Entomology, are
authorized to issue permits for the removal of domestic
animals from tick-control districts.

"By authority of the Montana State Board of Ento-
mology.

"R. A. Cooley, Secretary."

12 REPORT OF STATE BOARD OF ENTOMOLOGY

The cooperative arrangement with the United States
Pubhc Health Service and the Bureau of Entomology of the
United States Department of Agriculture, as mentioned in
the First Biennial Report of the State Board of Entomology,
has been continued during the past two years with Dr. L. D.
Pricks representing the Public Health Service and Dr. W. V.
King representing the Bureau of Entomology as formerly.

The reports of Dr. King and Dr. Fricks to the Board of
Entomology are herewith presented;

We have been very much in need of information regard-
ing the germ or organism which is the specific cause of
spotted fever. The Public Health Service through Dr. Fricks
has been making a study of the virus and his results as first
published in the Public Health Reports is attached.

The Board of Entomology has also engaged the cooper-
ation of Dr. S. B. Wolbach, Associate Professor of Pathology
and Bacteriology, Harvard Medical School of Boston. The
results of Dr. Wolbach's studies are also presented.

Dr. Frick's and Dr. Wolbach's studies are not yet com-
pleted, but both are continuing the investigation. It is ex-
pected that Dr. Wolbach will also be in Montana next spring
for the purpose of carrying on his work on the virus.

REPORT OF STATE BOARD OF ENTOMOLOGY 13

REPORT ON THE INVESTIGATION AND CONTROL OF

THE ROCKY MOUNTAIN SPOTTED FEVER TICK

IN MONTANA DURING 1915-1916.

W. V. KING, Ph. D.

Bureau of Entomology,

U. S. Department of Agriculture.

Following the general plans of the work as outlined in a
previous report to the Montana State Board of Entomology %
experimental control operations against the spotted fever
tick (Dermacentor venustus) have been continued during the
spring seasons of 1915-1916. This work has been confined
to the northern half of the Bitter Root Valley in western
Montana and the area includes several typical endemic foci
of infection. Our efforts have been directed toward the
determination of a practical plan by which the tick might be
eradicated or at least reduced to the point of safety. The
peculiar habits and host relationship of the spotted fever
tick, combined with local conditions has made the problem
a particularly difficult one, and the extremely long duration
of the various stages in its life cycle has, as was to be ex-
pected, greatly delayed the demonstration of results of the
control work. During the 1916 season, however, a compari-
son of the abundance of ticks at present with the abundance
under normal conditions has shown a distinct improvement
and given encouragement to further efforts.

The control program is based upon the fact that the tick
must feed upon warm-blooded animals in order to develop
and reproduce. Domestic animals are the usual hosts of the
adult tick and the small native rodents are hosts of the im-
mature stages. In brief, the general plan of the work has
been; first, to prevent the engorgement of adult ticks on
domestic animals as the principal measure; and, second, to
supplement this with important secondary measures, prin-
cipally the destruction of small native animals an encour-
agement of the clearing and development of tick infested
lands. In organizing for the work, the principal foci of in-
fection as indicated by the occurrence of human cases were
selected. These have been divided into convenient units, the

1— King, W. v., 1st Bien. Rept. Mont. State Board of Ent. , Helena, 1919,
pp. 16-27.

14 REPORT OF STATE BOARD OF ENTOMOLOGY

size of each being determine! by local conditions. Three such
districts were in active operation during 1914-1915, but in
1916 the work was discontinued in one of them, owing to lack
of funds as well as unusual natural obstacles encountered.
Toward the latter part of 1916 preliminary steps were taken
to inaugurate the control work in a new district in which
infections have been occurring recently.

In the present report the discussion of methods and
results will be limited to the operations in the two districts
in which the work has been uninterrupted for the three
seasons. These are known as the Florence and Stevensville
districts. The area included lies in the main valley and con-
sists of about 28,000 acres of farming and timber lands ex-
clusive of the mountain sides where stock may be grazed in
many places. Approximately a half of this area is cleared
and under cultivation, the other half being for the most part
cut-over timber land and used as pasturage for domestic
animals. This cut-over timber land lying along the foot of
the mountain constitutes the area of tick infestation, as it is
here that conditions favorable for their development exist.

From a census made in 1914, the two districts contained
119 fa^ms with a total of 1.569 horses and 1,784 cattle. In
the control work, however, a good proportion of these are
eliminated from consideration as they are pastured outside
of the tick infested fields.

Starvation and Destruction of Adult Ticks.

In the measures directed against the adult tick, no
single method has been found which is practical under all
conditions. Periodic dipping of cattle and horses, supple-
mented with hand-picking of small herds, of dairy cattle and
work horses, and the removal of the stock from the tick
infested fields have been employed according to the circum-
stances. The difficulties of the dipping program due to the
necessity of short intervals between dippings, to the local
conditions of the range and the ultimate expense have oper-
ated against the success of this method. These difficulties
are being met by elimination of domestic animals from the
tick country in the spring.

The active period of the adult tick lasts from the opening
of spring, usually in March, until some time in June, The pas-
tures and range are not suitable for use until about the first

REPORT OF STATE BOARD OF ENTOMOLOGY 15

of May and prior to this time the stock are or may be kept
on the tick-free hay fields and meadows. The fact that the
period is so short during which the use of the pastures is
lost if the stock are kept out of them is favorable to the
starvation method of tick control and in 1916 most of the
stock owners were able, with our assistance, to secure other
pasturage during the tick season. Some of the owners were
able to provide tick-free fields large enough to accommodate
their herds for this period and where possible this is un-
doubtedly the best plan. One owner found it advisable to
reduce the number of his animals for this purpose. In one
locality a district herd was organized and herding expenses
paid jointly by the owners and the Bureau. This herd, con-
sisting of about two hundred animals, was kept outside the
control district and eliminated most of the animals which
could not otherwise have been provided for. In another
district a tick-free pasture near the river was secured to
accommodate several small herds which had been very
troublesome in previous seasons.

At a central point in each of four districts a dipping vat
of about twenty-five hundred gallons capacity is located.
One of these is of concrete and the other three of galvanized
iron, the latter being preferred because of the ease with
which they are kept in repair. If desired, they may be also
moved. The first of the season, usually in March, these are
filled with an arsenical dipping solution. If many animals
are dipped during the season a second filKng is necessary,
usually in May. Sodium arsenite and a weak kerosene emul-
sion are now used in the dipping formula to replace the white
arsenic-sodium-carbonate-pine tar formula in general use in

the Texas fever tick work.

The method of preparation of the dipping solution is as
follows: Sodium arsenite containing about 70% arsenic is
used and the solutions are prepared so as to contain between
.195 and .200% arsenic in the arsenious form. The capacity
of the vat is computed by the prismoidal formula' and the
amount of sodium arsenite needed to give the desired
strength is figured from the actual percentage of arsenic in
the sample, allowance being made for any variations apt to
occur in each vat as determined by previous experience in
mixing solutions in the different vats. The proper amount of

i_See U. S. Dept. Agri., Farmers' Bull., No. 498, p. 36.

16 REPORT OF STATE BOARD OF ENTOMOLOGY

sodium arsenite having been determined and weighed out. is
dissolved by heating in about 50 gallons of water. Arsenic in
this form is readily soluble and is usually dissolved by the
time the water has come to the boiling point. The solution
is then added to half a vat full of water. Ten gallons of
kerosene are emulsified, mixed with the solution in the vat
and the vat then filled to the proper depth with water.

A considerable improvement in the preparation of the
kerosene emulsion has been made as a result of tests made
for us by the Chemistry Department of the Montana State
Experiment Station. The details of the method are as fol-
lows : Potassium soap (green soap) is dissolved in warm water
in the proportion of 12 pounds of soap to 2 gallons of water.
This is allowed to cool and the emulsion is made in a cold
solution at the rate of 3 gallons of kerosene to 2 quarts of
soap solution. The emulsion is made in a hand spray pump,
one in which the nozzle can be turned back into the tank. The
soap is placed in the tank and pumped back until it begins
to foam. The kerosene is then added, slowly at first, with
forceful spraying of the mixture back upon itself. When the
emulsion is complete, as evidenced by a thick, creamy con-
sistency, it is diluted with water by mixing in a separate
tank. The entire ten gallons of kerosene are emulsified in
this way and the final mixture added to the arsenic solution
in the vat.

After thorough mixing of the ingredients of the vat,
an eight-ounce sample is taken and an anlysis made to deter-
mine the percentage of arsenic present as arsenious oxide
and total arsenic. (All of the analysis have been made by
the Chemical Department of the Montana State Experiment
Station, to whom I am greatly indebted.) No dipping is
done until the analysis has shown that the proper percentage
of arsenic is present. The strength of the arsenic is apt to
be raised by evaporation or lowered by dilution with rain or
oxidation of the arsenious oxide, so that frequent analyses
are made and the strength corrected as necessary. It is
sometimes advisable also to add more kerosene emulsion. The
amount of kerosene present is too small to be of any especial
value as a tick killing agent and is employed largely to give
added pentration to the arsenic solution. Any kerosene which
has not been completely emulsified and which may separate
from the solution should be removed by skimming as it

REPORT OF STATE BOARD OF ENTOMOLOGY 17

floats to the surface. Free kerosene has been found to be
injurious to the animals.

The tests under way to determine the exact effect of
the arsenic solution upon this species of tick have not been
completed.

Based upon the engorgement period of adult female ticks,
the interval between dippings has been set for ten days. To
be absolutely effective the interval should be even less, but
since a ten-day period has been difficult to enforce it has
seemed impractical to attempt to reduce the interval except
in experimental work. The dippings are supplemented with
hand picking.

The following numbers of animals were dipped and
examined in the Stevensville and Florence districts in 1915
and 1916.

No. Dipped No. Examined

t- to :;3.2>>?' " .2>>

^ £ 'J i^'^ s 3 ^'^

1915 142 1266 73 586 1267 109

1916 87 664 51 188 836 88

The reduction in number dipped and examined in 1916

is due largely to the removal of stock from the tick infested
fields this year.

Destruction of Columbian Ground Squirrels.

Since it appeared unlikely that the breeding of adult
ticks could be completely stopped, it was decided to reduce
the development of the immature stages as much as possible
by the destruction of their hosts, the small native rodents.
The Columbian ground squirrel (Citellus columbianus) is the
most important host of the larval and nymphal stages and is
also an injurious pest of crops. In 1914 preliminary tests
with poison grain were made and in 1915 and 1916 nearly
all of the tick infested area in the two districts were given
a treatment with the poison.

The poisoned grain formula which gave the best results

is;

Hulled oats (groats) 16 quarts

Water .._ 2i/^ pints

Salt - 1 pint

Saccharine 1 teaspoonful

Starch 1 pint

Strychnine alkaloid (powdered) ...- 2 ounces

18 REPORT OF STATE BOARD OF ENTOMOLOGY

The directions for preparation are as follows: Mix the
saccharine and salt and dissolve in the two and a half pints
of warm water. Add one pint of starch and heat (but not
cook), with constant stirring until it becomes quite thick.
Remove from stove and add the strychnine, which must be
thoroughly mixed with the starch solution with an egg
beater. Pour the mixture, now about the consistency of
stiff whipped cream, over the 16 quarts of hulled oats con-
tained in a tub and give thorough mixing by rubbing between
the hands. The alkaloid of strychnine is insoluble in water
and by this formula the grain is simply given a poisonous
coating.

This was freshly prepared at the beginning of the season
and its distribution begun as soon as the squirrels emerged
from hibernation, since this is the most effective period of
the year. In order to have the area covered as quickly as
possible after the squirrels appear, it was divided into five
parts and a crew of three men placed in each. In distrib-
uting the poison, a teaspoonful of the poisoned grain was
placed at the opening of each squirrel burrow and records
were kept of the number of baits placed and the amount of
land treated. These operations were carried out each year
during the first half of April.

The following tabulation is taken from records of the
squirrel poisoning work:

>> ■"-> °

_g 5" 5' .^d*^

u "3^ "cs— "dS rt— "d

® o<ti °m °^ go 03

1915 9535 83,559 142.5 633.45

1916 8210 58,121 128.5 552.30

Average Average Cost per

baits per acreage acre

acre per man

per day

1915 8.7 66.9 .065

1916 - -- 7.1 63.9 .067

Effect of Poison. It is very difficult to approximate the
proportion of squirrels killed by the poison. Under certain
conditions, as in the vicinity of fields of young grain the
squirrels do not take the poison well. In other places, and
for the most part throughout the area treated, the poison
was well taken and individual colonies were noted in which
nearly all of the squirrels had been killed by the poison. Our

REPORT OF STATE BOARD OF ENTOMOLOGY

19

own observations and an inquiry among the residents familiar
with the area treated led to the conclusion that at least half
of the squirrels had been killed by the 1915 poisoning and a
further reduction of about 50 per cent was roughly estimated
to be the result of the treatment in 1916.

Results of Control Work.

In estimating the effect of the control measures in the
reduction of ticks, several methods are employed. Unfor-
tunately all of these are open to more or less criticism. The
most promising method is one in which an index of the sea-
sonal rate of infestation of ground squirrels is obtained and
used for comparison. A series of these rodents from the tick
infested area are killed (by shooting) and immediately placed
in white muslin bags. The ends of the bags are tied to pre-
vent escape of the ticks and the examination is made several
hours later. By this time the larval and nymphal ticks
have detached and are found crawling on the bag or in the
hair of the dead animal.

In the following table is shown the infestation rate
for three seasons:

Nymphal Infestation.

Reduction from

q; O ^

^ 'Z'Jl

Normal 181

1915 333

1916 - 376

Larval

1 ^
d >. d^
ZZ Zp.

863 4.76
232 0.69
159 0.42

■3
S

o
Z

85.6%
91.3%

Infestation.

39.3%

> ^^

S dS d^

Normal 59 735 12.4

1915 - 269 312 1.16 90.7%

1916 268 25 0.093 99.7% 92%

The "normal" is based on a series of squirrels examined
in 1910. The most interesting comparison is found in the
average nymphal infestation in 1915 and '16. as exactly the
same area was covered in each season. The 1910 records
were made in a portion of this area. The larvae commence

20 REPORT OF STATE BOARD OF ENTOMOLOGY

to appear on the squirrels the latter part of June and the
average infestation is taken from the squirrels examined
after the first larvae are found. The examination of squir-
rels is of further value in showing the exact points in which
development of ticks is occurring.

The average infestation of domestic animals with adult
ticks and the proportion of engorged ticks present is also
employed as a method of estimating results, but is not of
great value. Such data as are at hand are shown below.
The numbers of engorged females per animals (per day) as
given in the last column, are used for comparison.

Infestation of Cattle and Horses.

(u o S o o" S o a5 2" § S

Normal 235 289 8 1.23 .034

1914 1720 622 11 .36 .0063

1915 1793(a) 728 18 .4 .01

1916 1024 1648 9 1.6 .0087

The normal records were made in 1914 in a nearby local-
ity in which conditions were similar to those in the control
district. The data for the different years are not strictly
comparable, since it is not possible to examine animals under
the same conditions and with the same frequency each sea-
son. In 1916 it appears that the average number of ticks
per animal for the whole district is greatly increased. As
a matter of fact, this is due to the fact that a few animals
in a small but heavily infested portion of the district were
frequently hand-picked instead of dipped, as in previous years.

A third method of estimating results is the collection of
unfed adults from the infested fields by dragging a piece of
white flannel cloth about over the grass and brush where the
ticks are awaiting hosts. Several factors such as wind, tem-
perature, and time of season operate against the effectiveness
of this method and the results are hardly comparative.

In 1915 and '16 records were kept of the numbers of
ticks picked up by the squirrel poisoners. These figures are
more or less comparable, as the number of men, area covered
and time of year were practically the same.

(a) — The number of ticks not counted on 60 other animals examined.

REPORT OF STATE BOARD OF ENTOMOLOGY 21

Ticks Collected by Squirrel Poisoners

>.

p.

1- >>

i

<u Hi

o

ay

in

"c

c

•^tS

d

■c^

1915 April 6 132 758 5.74 53°F.

to
April 17.

1916 April 8 126 372 2.95 45°F.

to
April 17.

It was indicated by this comparison that in 1916 the
density of ticks had been reduced 48 per cent from the pre-
vious year. This was as great, in fact a slightly greater re-
duction than was to be expected from the 1915 record of the
status of nymphal infestation of ground squirrels.

In interpreting the results, the complicated life history
of the tick must be taken into consideration. Our studies
have shown that under western Montana conditions this
species has a two- and three-year life cycle. A reduction
of the number of ticks engorged in any spring would result
in an equal reduction of the larval ticks fed in the summer
and of the nymphal ticks feeding the second spring, but
would effect only a half of the active adults present during
the third and fourth season, since the active adults are made
up of two separate broods probably in nearly equal numbers.
For example, a reduction of 85 per cent of engorged females
in both 1914 and '15 should give a reduction of 42 per cent
of active adults in 1916 and an 85 per cent reduction in 1917.
The destruction of rodents is considered to effect the abund-
ance of ticks in direct ratio to the percentage of rodents
killed. The nymphal infestation of ground squirrels in 1915,
combined with the estimated reduction of these animals, in-
dicated an approximate reduction of 92 per cent of that brood
of adults and a proportionate (46%) reduction of the total
adult supply for 1916. Interpreting the nymphal index for
both 1915 and '16 in the same way, a 94 per cent reduction
of active adults is indicated for 1917.

Field Experiments.

In the way of experimental results, the most definite in-
formation has been obtained from observations made in a
field of 320 acres which is being freed of ticks by the starva-

22 REPORT OF STATE BOARD OF ENTOMOLOGY

tion method. The field was known to be well infested with
ticks in 1910 and '11. In 1914 it was fenced and has been
kept entirely free of domestic animals for three seasons.
About half of the field was cleared of timber and brush and
40 acres were put under cultivation. In addition to the elim-
ination of domestic animals, squirrel poison was distributed in
the field in 1915 and '16 with an estimated reduction of 60
to 75 per cent of these animals.

The following data have been recorded on the compar-
ative infestation of this field, the results being attributed
to the elimination of domestic animals and the destruction
of squirrels.

Examination of Ground Squirrels in Experimental Field.

o Nymphs Larvae

s

e

cS 03 >

X W) 0

d . ^ ^ S >

0) o o > o •

1910 __ _ 10 59 5.9

6 43 7.1

1915 -.... 14 2 0.14

1916 _. 10

The average rate of nymphal infestation for this vicinity
in 1910 was 4.8 and for larvae. 12.4. It is therefore evident,
although the number of squirrels examined is small, that the
development of ticks is greatly reduced. The owner of the
field, who is very familiar with the conditions there, stated
that the reduction in adult ticks in 1916 was very marked.
By another season it is expected that the full effect of the
starvation rnethod will be in evidence in the abundance of
adults.

Sheep Experiments. Two experiments with sheep are
under way to determine their status as hosts of the spotted
fever tick. These were undertaken on the theory advanced
by Fricks^ that sheep might prove to be unsuitable hosts of
the ticks because of the wool and lanolin oil secreted in the
wool. One experiment is with a band of one thousand sheep
on an area of about twelve hundred acres. No results have
as yet been obtained from this experiment. In the second
one a ten-acre field in an area of high tick infestation has
been fenced and a few sheep were kept here in 1915 and '16.

1— Fricks, L. D. , U. S. Pub. Health Rep., 1913, pp. 1647-1653.

REPORT OF STATE BOARD OF ENTOMOLOGY 23

Frequent examinations were made and notes taken on the
number of ticks present, state of engorgement and number
killed by the lanolin in the wool or other factors. These
records are given below:

Big Creek Sheep Experiment.

Sheep in Field Examinations

m C to

fi -p CO to 0)

« ft 1^ .- - ^9>c

1>^ ci, :z; S ^z: J 0 ^H-^

1915 April 7 6 314 20 228 130 11

to
June 16. 3

1916 May 3 6 300 24 371 141 8

to
June 22. 6

1915 1916

Average number live ticks per sheep 11.4 15.4

Number engorged ticks per sheep per day.— .55 .33

Number sheep per acre .44 .6

Period — days 70. 50.

Number engorged ticks per acre for season 16.9 9.9

(on basis of above averages.)

I have no available records to show the comparative de-
velopment of ticks on horses and cattle under similar condi-
tions. A series of 75 of these animals examined late in the
season in 1914 showed an average development of one engorg-
ed tick per acre for the season. The locality was one of aver-
age infestation but much lower than in the experimental
sheep field. From this fact and from general observations ex-
tending over several years, it is concluded that under such
conditions the number of ticks which developed on the sheep
were more than sufficint to maintain a normal supply.

Cooperation.

The experimental control operations are under the gen-
eral supervision of Dr. W. D. Hunter and in close cooper-
ation with the Montana State Board of Entomology. Pro-
fessor R. A. Cooley, secretary of the Board, has been actively
interested in the furtherance of the work and the Board
has given financial assistance in the purchase of material for
the squirrel poison. I desire to acknowledge further the
helpful cooperation of the Montana State Board of Health,
the U. S. Public Health Service, and the Bitter Root National
Forest Service.

24 REPORT OF STATE BOARD OF ENTOMOLOGY

REVIEW OF ROCKY MOUNTAIN SPOTTED FEVER ERA-

DICATIVE WORK CONDUCTED BY THE UNITED

STATES PUBLIC HEALTH SERVICE IN THE

BITTER ROOT VALLEY, MONTANA,

1915- 1916.

By SURGEON L. D. FRICKS.

The work of eliminating Rocky Mountain spotted fever
from the Bitter Root Valley, Montana, as conducted by the
United States Public Health Service has been continued dur-
ing the past two years along the same lines as those indicated
to the State authorities in my last report made at the close
of the season of 1914. As a matter of fact there has been
no alteration of nor retraction from the principles of spotted
fever elimination as outlined by representatives of the Public
Health Service soon after the work was begun by them in
1911. Some of these principles have been amplified however,
as different investigations have thrown more light upon the
subject of tick destruction.

These principles are as follows:

(1) The majority of the ticks which transmit spotted
fever in the Bitter Root region breed on the domestic animals,
horses and cattle, as they graze over the foot hills during the
spring months.

(2) These uncultivated foot hills on the west side of
the valley are now suitable only for grazing purposes and
if possible should be so used.

(3) Because of practical difficulties which are unsur-
mountable, the dipping of domestic animals alone will not
eradicate Rocky Mountain spotted fever from the Bitter Root
Valley, and therefore the number of these animals, horses
and cattle, should be reduced in every practicable way.

(4) The destruction of small rodents in the infected
districts is highly desirable and the necessary expenditures
justifiable.

All of the eradicative work which has been conducted by
the Public Health Service in the valley has been based on
these principles and may be briefly reviewed for the year
1915 and 1916 as follows :

REPORT OF STATE BOARD OF ENTOMOLOGY 25

Dipping of Domestic Animals.

The dipping of horses and cattle in the infected districts
from Big Creek to Charlos Heights, a distance of thirty miles,
was carried on during the tick seasons of the two years
according to the regulations prescribed by the State Board
of Entomology in so far as existing conditions would permit.

One of the greatest difficulties encountered in dipping
in the Bitter Root Valley is the weather, which frequently
makes it impossible to carry out the dipping of domestic
animals at the necessary intervals during the tick season.

The season of 1916 was even worse than usual in this
respect. Spring began early and the ticks were beginning
to feed by the middle of March, but the cold weather
dragged on from the first of April until mid summer. The
latest record of its being too cold to dip during the year
was on May 25th.

The annual outlay for the operation of the three dipping
vats including chemicals and salaries of two vat tenders,
but exclusive of the salary of a competent supervisor is in
excess of $1,000.

Results secured in tick eradication by the dipping of
domestic animals which would warrant such an expenditure
from year to year for the few hundred head of live stock
involved have not been, and under the conditions which
prevail in the Bitter Root Valley, cannot be obtained.

For this reason continuous effort has been made by the
representative of the Public Health Service toward decreas-
ing in every way by legislation, regulation and substitu-
tion, the number of horses and cattle allowed to graze on the
west side of the valley.

Following several similar verbal requests made to the
State Board of Entomology, letters were addressed to the
Supervisor of the Bitter Root National Forest and the State
Board of Entomology at the beginning of the 1915 season
requesting that steps be taken by them toward the immediate
reduction of all horse and cattle grazing and finally the
complete abolishment of the grazing of horses and cattle for
speculative purposes on the west side of the Bitter Root
Valley.

In a reply received from the Supervisor of the Bitter
Root National Forest he stated that in compliance with the
request all permits for horses and cattle grazing on the

26 REPORT OF STATE BOARD OF ENTOMOLOGY

Forest reserve would be cancelled as soon as possible and no
more would be issued.

Upon request and as an aid to the handling and dipping
of domestic animals, a regulation was promulgated early in
1916 by the State Board of Entomology prohibiting the
bringing into the infected districts for grazing purposes of
domestic animals from February 1st to July 15th unless ac-
companied by a permit. This was a very necessary regu-
lation for keeping account of the movement of domestic
animals to and from the infected districts during the tick
season; but it was not expected that such a regulation would
reduce the number of domestic animals owned and grazed
within the infected territory.

For this reason the request to the State Board of Ento-
mology for additional legislation was repeated during the
season of 1916 and it is to be hoped that an attempt will
be made by the board to secure proper legislation this winter
for restricting, so far as practicable the grazing of horses
and cattle in the spotted fever districts of Southwestern
Montana.

Sheep Substitution.

Because of the inadequacy of the dipping process as
applied to horses and cattle in the Bitter Root Valley for
the destruction of spotted fever ticks and for the several
economic reasons enumerated in previous reports, experi-
ments have been conducted during the past four years for the
purpose of determining whether sheep could be satisfactorily
subistituted for the greater part of the horses and cattle
now being grazed on the west side of the valley.

It has never been claimed that spotted fever ticks could
not possibly breed on sheep under any and all conditions,
nor has the turning loose of large numbers of sheep to roam
at large among the west side foot hills been advocated by
the Government Health officials ; but it has been determined
that sheep can be profitably grazed over this district in such
ways as to decrease the tick infection.

During the past season six small bands were kept under
observation and the results obtained in tick destruction were
altogether good.

It has been necessary to inform the ranchers of the
Bitter Root Valley of the progress of these sheep experiments

REPORT OF STATE BOARD OF ENTOMOLOGY 2.7

from time to time through the lay press, and they have
been informed that the experiments are open to investigation
or criticism from any interested party.

Small Animal Destruction.

During the past two seasons the principal methods of
small animal destruction employed in the valley have been:

(1) Poisoning.

(2) Shooting.

(3) Trapping.

All of these methods of destruction are justifiable under
the existing Rocky Mountain spotted fever situation in the
valley.

Poisoning. One thousand pounds of groats poisoned with
strychnine furnished by the State of Montana were distri-
buted over an area of 100 square miles, fifty by two, during
1915, and 1500 pounds during 1916.

It was found that the ground-squirrels (Citellus colum-
bianus) would take this poison readily as soon as they are out
in the spring and again during July. The outlay for poison-
ing, including cost of poisoned grain and salaries of ten men
employed for from ten to fifteen days was approximately
five hundred dollars each season.

It is not expected that the expenditure for labor will be
continued indefinitely, but that after a few years the poi-
soned grain will be furnished to the ranchers and be distri-
buted entirely by them. Figured on this basis the outlay
should not amount to more than one hundred dollars per
season.

Shooting. One hundred thousand rounds of small caliber
rifle cartridges were used in shooting small rodents during
the two years. Slightly more than half of this number was
distributed to the west side farmers and used by them.
The cost of the cartridges was small (twenty-three dollars
per ten thousand) and the results worth the expenditure.

Trapping. In the Victor district where intensive rodent
destruction was carried on a small force of trappers was
employed both years. The method is expensive and only war-
ranted here .for experiment purposes. But the securing of a
small number of traps, and their constant use by the west
side ranchers has been strongly recommended.

28 REPORT OF STATE BOARD OF ENTOMOLOGY

ROCKY MOUNTAIN SPOTTED FEVER.
A Report of Laboratory Investigations of the Virus.'

By L. D. Fricks, Surgeon, United States Public Health Service

During 14 years of investigation by different workers
the following facts bearing upon the nature of the virus of
Rocky Mountain Spotted Fever have been determined:

Man, rhesus monkeys, and at least six varieties of small
wild rodents found in the Rocky Mountain region are sus-
ceptible to infection, while the larger domestic animals are
generally immune. Of the laboratory animals, guinea pigs
and white rats (Mus norvegicus albinus) are highly sus-
ceptible, while white mice (Mus musculus albinus) are ap-
parently immune.

The virus is transmitted to suceptible animals, including
man, by the bite of infective wood ticks (Dermacentor), re-
covery being followed by complete immunity. No other
biting arachnid or other insect has been found capable of
transmitting the virus. The transmission is not mechanical,
since a tick once infected remains so, the virus multiplies in
the tick and the female tick transmits the virus to her pro-
geny. The virus may be propagated indefinitely in guinea
pigs without loss of virulence by weekly blood inoculations,
but dies within a few days outside the animal body. It
will not pass through an ordinary Berkefeld filter under mod-
erate pressure, and many attempts to cultivate it aerobically
ih the usual laboratory media have failed.

Wilson and Chowning, in 1902, described a piroplasm in
the red blood cells of Rocky Mountain spotted fever cases
seen in fresh blood smears both stained and unstained, but
subsequent workers have failed to confirm their findings.

Ricketts reported diplococcoid bodies occasionally seen
in fresh blood smears stained with Giemsa stain and many
small bacilli found in infected tick eggs. He appears to have
considered these as different forms of a specific microorgan-
ism, but afterwards found similar bacilli in noninfected tick
eggs. Ricketts reported the agglutination of this bacilli
found in tick eggs by immune guinea pig serum, in dilutions
of 1 to 320. but was unable to cultivate the organism.

1 Reprint from the Public Reports, Vol. 31, No. 9, March 3, 1916, pp. 516-52]

REPORT OF STATE BOARD OF ENTOMOLOGY 29

Recent Investigations of the Virus.

In connection with the field campaign conducted by the
Pubhc Health Service for the purpose of ascertaining the
measures best adapted to the eradication of Rocky Mountain
spotted fever from a community, and for determining the
present areas of infection in the Rocky Mountain region, la-
boratory investigations of the virus have been carried on
both in the field laboratory at Victor, Mont., and at the
Hygienic Laboratory, Washington. It is believed that the
findings are of sufficient interest to warrant a preliminary
report thereon at the present time.

All attempts made to cultivate the virus on many differ-
ent media aerobically have failed, despite the fact that the
virus circulates freely in the blood stream, 0.1 c.c. of blood
frequently being sufficient to infect a guinea pig.

Attempts were made two years ago to grow the virus
anaerobically by mixing infected guinea pig blood with fresh-
ly melted and properly cooled glucose agar and glucose ascitic
agar, in different dilutions, with and without the addition of
normal guinea pig kidney. No uniform results were obtained ;
occasionally, however, anaerobic diphtheroid bacilli were en-
countered, but inasmuch as they were all found nonpatho-
genic for guinea pigs they were abandoned.

Following the announcement of the discovery of the
"Bacillus typhi exanthematici" by Plotz, and because of the
close clinical resemblance between Rocky Mountain spotted
fever and typhus fever, the different anaerobic bacilli, re-
ferred to above, which have been encountered since in cul-
tures, have been studied more carefully.

Ten strains of these anaerobic bacilli have been isolated;
some from dilute guinea pig serum plus normal guinea pig
kidney planted with infected blood, some from glucose ascitic
agar plus normal guinea pig kidney planted with infected
blood, and one from freshly boiled 1 per cent glucose broth
in fermentation tube in which 5 c.c. of infected guinea pig
blood had been planted.

These bacilli have not been found with anything ap-
proaching the frequency with which Plotz was able to recov-
er "Bacillus typhi exanthematici" from typhus cases, but in
the writer's routine work only from 5 to 10 drops of infected
blood were used for planting, after the chest wall has been
opened, that amount being well above the minimum infective

30 REPORT OF STATE BOARD OF ENTOMOLOGY

dose for guinea pigs. Plotz, on the contrary, regularly
used 2.c,c. or more of typhus blood, making the puncture
through the skin.

All of the 10 strains referred to are strict anaerobes,
growing equally well in deep stabs on freshly melted glucose
agar and ordinary agar, and in fresh glucose broth in fer-
mentation tubes.

These organisms are nonpathogenic to guinea pigs, are
not agglutinated with immune guinea pig serum and do not
show complement fixation with immune serum when used as
antigen. The macroscopic method of agglutination was easily
employed with cultures grown on fresh glucose broth in fer-
mentation tubes. (Microscopically an apparent clumping of
the bacilli is nearly always seen.)

These organisms, recovered from spotted fever guinea
pigs, resemble very closely morphologically and culturally
the two strains recovered from typhus guinea pigs by Hassel-
tine and Neill at the Hygienic Laboratory and the strain of
Bacilli typhi exanthematici kindly furnished by Dr. Plotz.

Anaerobic Fluid Media Cultures.

In an endeavor to cultivate the Rocky Mountain spotted
fever virus in fluid media under lessened oxygen pressures,
the following technique was evolved at the field laboratory,
Victor, Mont. :

Articles required:

Ten c.c. homeopathic vials, rubber stoppers to fit.

One-fourth inch glass tubing in 6-inch lengths.

One hand vacuum pump.

A constriction was drawn in the glass tubing, and a
small hole, into which the tubing would fit snugly, was burnt
in the rubber stopper. The stoppers with tube inserted and
the vials were sterilized separately. After the vials had been
filled with 8 c.c. of media and inoculated, the stoppers were
driven in tightly and sealed with paraffine, and the glass
tube attached to the hand pump. After five to 30 minutes'
exhaustion the glass tube was sealed at the constriction pre-
viously made and the culture then placed in the incubator.

While there was no exact measure of the vacuum obtain-
ed, or of its duration, it was possible to inhibit completely the
growth of aerobic organisms by this method when so desired.

REPORT OF STATE BOARD OF ENTOMOLOGY

31

The media used were human serum and guinea pig serum
with normal salt solution in different dilutions (1 to 2 and 1
to 3) and ascitic fluid undiluted; a piece of fresh guinea pig
kidney was added at the time of inoculation in practically all
instances. The material employed in inoculating the media
consisted of infected guinea pig blood and tissues, blood from
human cases of spotted fever, and infected tick eggs.

The following is a brief summary of the results obtained :
Forty-five series of vials were planted. In the beginning so
much time was consumed in searching smears made from,
the cultures for microorganisms that it was decided to de-
pend entirely upon animal inoculations, followed by immunity
tests, in order to determine if possible the presence of the
living virus in the cultures.

Ninety-seven guinea pigs were inoculated from these
cultures and later tested for immunity by the injection of 0.5
e.c. of known spotted fever virus.

The cultures tested were from two days to one month
old, the majority being less than two weeks old. All the
guinea pigs injected with cultures less than two weeks old,
when later given the immunity test, developed spotted fever.

Three guinea pigs out of ten inoculated with cultures
21 to 25 days old. either showed definite lesions of spotted
fever or were immune to the spotted fever virus, as shown
below :

Series No.

Culture
Medium

Material
Planted

Method

Animal
Inoculations

Immunity
Tests

Remarks

CI — J u u e

8 c.c. dilute

5 drops

Air exhau-

July 7, 5 drops

G. p. immune

G. p. showed

15. 1915.

human

seven til

sted, vial

injected into

to spotted

temperature

serum +

day g. p.

sealed &

g. p.

fever virus

above 40° C.

normal g.

blood.

kept at

injected

June 17 to 22,

p. kidney

37°.

June 30 and
again on
Aug. 6, 1915.

1915.

D2— June

do

7 drops hu-

do

June 29. 5 drops

G. p. D2a in-

G. p. D2b show-

17, 1915,

man spot-

injected into

jected Aug.

ed character-

ted fever

g. p. D 2 a.

28 developed

istic lesions

blood.

July 9,5 drops
injected into
g. p. D2b.

spotted fev-
er. G. p D2b
injected
Aug. 13 and
f 0 u n d im-
mune.

of spotted fe-
ver following
injection
of July 9, 1915.

H3— J u 1 y

do

Infected

do

Aug. 10, 5 drops

G. p. immune

15, 1915.

tick eggs
crushed.

injected into
g. p.

to spotted
fever virus
i n j e 0 t e d
Aug. 28, 1915.

Inasmuch as the Rocky Mountain spotted fever virus
ordinarily dies within 24 to 48 hours when kept at a tem-

32 REPORT OF STATE BOARD OF ENTOMOLOGY

perature of 37°. as the dosage of the cultures injected was
much less than the minimum infective dose of fresh virus,
and as in the inoculation of several hundred guinea pigs no
naturally immune guinea pig has been encountered, it seems
reasonable to conclude that a multiplication of the virus oc-
curred in the cultures CI, D2, and H3.

Centrifugation af the Virus.

Ricketts was unable to throw down the virus from
guinea pig and monkey serum when diluted with equal parts
of salt solution, even after prolonged centrifugation (six
hours.) Centrifugation with greater dilutions of normal salt
solution has been employed by the writer several times suc-
cessfully for the purpose of freeing the virus from a coccus
contamination. In this way, by injecting different layers of
the centrifugal material, a layer was found which would pro-
duce spotted fever in the inoculated guinea pig. without car-
rying over the contaminating coccus.

By increasing the dilution to 1 part of serum to 8 or 10
of salt solution it was found that the spotted fever virus
could be thrown down completely by four to six hours' centri-
fugation, as is shown in the following experiment:

After defibrinating 10 c.c. of spotted fever blood and
centrifugating for 15 minutes, 1 c.c of the serum was pipetted
off and diluted with 10 parts of normal salt solution. This
was then centrifuged for four and one-half hours at about
2,000 revolutions per minute. Ten c.c. of the supernatant
fluid was carefully drawn off and injected into guinea pist
S2. This pig showed no reaction whatever, and later devel-
oped spotted fever when inoculated with the virus; while
guinea pig SI. inoculated with three drops of the sediment,
developed spotted fever on the eigth day following inoculation
and showed all the characteristic lesions of the disease as
seen in the guinea pig. This experiment has been repeated
many times with similar results.

Microscopical Examination of Spotted Fever Blood.

Stimulated by the fact that the virus of Rocky Mountain
spotted fever does not pass through a Berkefeld filter (N)
under a pressure of 1 atmosphere, various investigators of
the disease have spent much time in searching fresh blood
smears for the causative orgaism, but without agreement
as to findings.

REPORT OF STATE BOARD OF ENTOMOLOGY 33

During the last three years the writer has examined
many blood smears prepared and stained by all the well-
known methods, from human cases, and from the known sus-
ceptible animals, particularly guinea pigs and white rats.
Frequently there have been found in spotted fever blood,
stained by the Giemsa method, extra corpuscular granules,
singly and in pairs, staining bright red and highly ref ractile ;
also, similar bodies within or in close proximity to the ery-
throcytes. The intracellular bodies are usually surrounded
by a pale halo. The presence of these granules was con-
sidered significant, but it has been impossible to differentiate
them with certainty from the granules sometimes found in
normal blood.

By dilution and centrifugation a method for concentrating
and distinguishing these bodies appears to have been found,
the best results having been obtained in the following man-
ner: Ten c.c. of infected blood is withdrawn by heart punc-
ture, defibrinated, and immediately centrifugated for 15 min-
utes. One c.c. of the surface serum is then pipetted off and
diluted with 10 c.c. of normal salt solution in an ordinary
centrifuge tube. One c.c. of the remaining serum, con-
taining some of the upper layer of red cells, is treated in
the same way. These fluids are then centrifuged for 6
hours, the supernatant fluid is carefully poured off, and
smears are made from the drop of sediment remaining and
stained over night with dilute Giemsa stain.

The serum smears show many bright red granular bod-
ies, singly and in pairs, highly ref ractile, accompanied by
larger light-blue bodies, and all surrounded by a pale-blue
matrix, the whole mass being rather indistinct but not en-
countered in the controls. The red blood cells appear to take
the stain normally, but in many of them are found round
or slightly elongated red chromatin bodies partially sur-
rounded by or in close approximation to a somewhat larger
deep-blue staining body Some of the chromatin bodies ap-
proach 1 mu in diameter, but the majority are smaller and in
these the protoplasm is elongated, extending well beyond the
chromatin body at both ends.

Some of the bodies are found clearly without the cells
and in the largest of these the red chromatin body is cen-
.trally located and surrounded entirely by the deep-blue stain-
ing protoplasm, the whole being crescentic in shape.

34 REPORT OF STATE BOARD OF ENTOMOLOGY

This method of preparing and staining blood smears has
been repeated many times with proper controls of normal
guinea-pig blood and with blood from pigs sick with diseases
other than spotted fever, with the result that the bodies
above described have never been found except in spotted
fever blood.

There appears to be some resemblance between these
bodies found in spotted fever guinea pig blood and those des-
cribed by Seidelin as having been found by him in yellow
fever blood; and in view of the criticism of Seidelin's work
made by Wenyon and Low, who claim to have found similar
bodies in normal guinea pig blood, one naturally hesitates to
draw any definite conclusions from the finding here reported.

From the fact that these bodies, on account of their
morphological and tinctorial characteristics, may be regarded
as probably of prozoan nature, and because they have thus
far been found only in blood from animals infected with
spotted fever, it is felt that the publication of their descrip-
tion at this time is justified, in order that other workers
may be on the lookout for them, and that their relationship
to Rocky Mountain spotted fever may be fully established.

The writer is indebted to Surg. A. M. Stimson and Asst.
Surg. R. R. Spencer for assistance in carrying on the above-
described investigations.

REPORT OF STATE BOARD OF ENTOMOLOGY 35

THE ETIOLOGY OF
ROCKY MOUNTAIN SPOTTED FEVER.

By S. B. Wolbach, M .D.

Associate Professor of Pathology and Bacteriology,

Harvard University Medical School,

Boston, Massachusetts.

This study was begun in response to an invitation on
the part of the State Board of Health and Board of Ento-
mology of Montana to investigate Rocky Mountain spotted
fever in Montana during the spring of 1916, In anticipation
of that visit laboratory work was begun in January, 1916,
in the bacteriological laboratory of the Harvard Medical
school with the virus of the disease obtained from Surgeon
L. D. Fricks. It was not possible to visit Montana because
of illness, but with the exception of three months the inves-
tigation has continued to the time of writing, using labor-
atory animals, guinea-pigs and monkeys. The writer wishes
to express his thanks to Surgeon L. D. Fricks for sending
infected ticks and blood from infected guinea-pigs, to Doctor
W. F. Cogswell, Secretary of the State Board of Health of
Montana, and to Professor R. A. Cooley, State Entomologist
of Montana for many courtesies and for the receipt of wild
ticks — Dermacentor andersoni. The present report is es-
sentially a summary of findings to date.

Pathology and Occurrence of the Parasite in Guinea-Pigs

and Monkeys.

Rocky Mountain spotted fever as reproduced in monkeys
and guinea-pigs has its characteristic lesions acute processes
in the superficial blood vessels and blood vessels of the geni-
italia. The lesion is an acute endophlebitis and acute endar-
teritis, leading to proliferation of endothelium and thrombo-
sis, often resulting in complete obliteration of blood vessels of
the skin and testes. The lesions of the blood vessels are re-
sponsible for the rash, the oedema, hemorrhages, and the
necroses. They correspond with the finding briefly rescribed
by LeCount of Chicago, who worked with material obtained
Jrom Doctor Ricketts. It is unfortunate, however, that in the
human no study was made of the peripheral blood vessels.
The character of the lesion resulting in complete or partial

36 REPORT OF STATE BOARD OF ENTOMOLOGY

occlusion of small arteries and veins explains the character
of the rash in the human, its long persistence and the occa-
sional sloughing of the skin which has been observed partic-
ularly upon the genitalia.

In the vascular lesions in monkeys and guinea-pigs there
has been found constantly in a large series of animals a
minute parasite. This organism commonly occurs in the form
of paired gramules or exceedingly short rods in pairs. It
occurs in large numbers in many lesions. The organism is
easiest demonstrable in sections of tissues which have been
fixed in Zenker's fixative and stained with Giemsa's stain.
They may also be demonstrated in sections fixed in Zenker's
fixative and stained in Loeffler's alkaline methylene blue at
55°C. for 24 hours and differentiated in a one to one thou-
sand solution of acetic acid in water. The organisms may
also be demonstrated in smear preparations made by scrap-
ing affected tissues with a very sharp knife held vertically.
Considerable patience is required to disintegrate the blood
vessels by repeated scraping, because it is necessary to obtain
isolated endothelial cells and smooth muscle fibres in order
to obtain satisfactory preparations.

The greatest numbers of the organisms occur in the
lesions of arteries and veins in the testicle and its append-
ages, in the cremasteric muscles and in the skin and subcut-
aneous tissues. One of the best regions for demonstrating
the organisms in smears is the tissues of the paws (feet)
after these become swollen, towards the end of the febrile
period in guinea-pigs.

There is considerable variation in the size of the organ-
ism as found in the guinea-pigs. — a larger form which occurs
as a lanceolate paired organism and a much smaller oval
form which is found closely packed in smooth muscle fibres
of the vessel walls and occasionally within cells in proliferated
endothelial (epithelioid) cells lying in the adventitia of bloo.:
vessels. In thick film preparations of the blood from infect-
ed guinea-pigs and monkeys only one type of the organism
may be found. This is the larger lanceolate rod in pairs.
Ricketts undoubtedly saw these organisms and described
them as having the form of "two somewhat lanceolate chro-
matin staining bodies separated by a slight amount of eosin
staining substance." In the present study these organisms
have not been seen in blood except in thick film preparations.

REPORT OF STATE BOARD OF ENTOMOLOGY 37

and therefore subjected to the action of distilled water.
The technic of making thick film preparations is as follows:
One or two large drops of blood are distributed on a micro-
scope slide over an area 1 cm in diameter. After the film
has dried it is de-hemoglobinized in distilled water; two or
three changes are necessary and the preparation must be
handled gently in order not to detach the film. When the
preparation has become colorless it is dried in the air, fixed
for fifteen minutes in absolute alcohol, dried and stained
with Giemsa's stain. Subjected to the above treatment the
organism occurs in pairs and consists of two deeply stained
oval or lanceolate bodies colored deep red or purple and sur-
rounded by a small amount of bluish stained material. It
would appear as if this type of the organism were rich in
chromatin material, if the coloration by Giemsa's method may
be accepted as a criterion. The organisms in the blood are
never very abundant, but they usually can be found in thick
film preparations after a search of from five to fifteen min-
utes. They are most abundant in the first days of fever. In
smear preparations from infected tissues, forms similar to
those found in thick film preparations of blood are encounter-
ed, as well as much smaller oval and rod-shaped organisms
which stain much less deeply and which take a bluish color-
ation with Giemsa's stain. Normal guinea-pigs and guinea-
pigs infected with a strain of Typhus (Brill's disease) ob-
tained from Doctor Peter Olitsky of the Mt. Sinai Hospital of
New York were used as controls in studying the occurrence
of the parasite in the blood stream; always with negative
results. All attempts at cultivating this organism from
guinea-pigs have failed, and many methods were employed,
using media suitable for the cultivation of spirachaetes, bac-
teria and protozoa. The organism has, however, been studied
in infected ticks, and its presence is characteristic of and ex-
clusively a feature of infective ticks.

Occurrence of the Parasite in Ticks.
Infected ticks were secured by allowing them to feed
one or more times upon infected guinea-pigs. Their infec-
tivity was subsequently proved by allowing them to feed
upon normal guinea-pigs. Ticks which were proved to be
non-infective by feeding once or twice upon normal guinea-
pigs were used for controls. It was found that a single
feeding often did not render a tick infective. Occasionally

38 REPORT OF STATE BOARD OF ENTOMOLOGY

two or even three feedings upon an infected guinea-pig were
necessary to make a tick infective.

In testing for infectivity of the ticks, each one was con-
fined in a close meshed wire gauze capsule fastened with
adhesive plaster to the shaved abdomen of a guinae-pig.
From two to five days were allowed for each feeding. The
capsules served also to retain the feces passed by the ticks,
the amount of which in each experiment offered an additional
index of the amount of blood ingested. It was observed that
the feces collect in the form of small balls which soon be-
come hard and dry and do not soil the skin of the guinea-pig.

The procedure usually employed in examining the ticks,
infested and control, was as follows: The dorsal surface was
removed as carefully as possible under the dissecting micro-
scope. From one-half of the tick, salivary gland, Malpighian
tube, leg muscle, and a portion of the intestinal diverticulum
were removed and smear preparations were made which were
stained with Giemsa's stain, as well as preparations for the
microscope with dark field illumination. The remainder of
the organs were then removed in one mass from the ventral
plate. The capitulum is left attached to the organs for the
purpose of handling during fixation and imbedding processes.
The tissues were fixed in Zenker's fixative, imbedded in par-
affin and serial sections made, which were stained by
Giemsa's method.

In ticks which were proved to be infective, parasite iden-
tical with those found in the tissues of guinea-pigs and
monkeys were found. Both types of parasites occurred, the
minute form predominating. In no instance were the para-
sites found in ticks which were proved to be non-infective.

The distribution of the parasite in the infected tick is
wide and subject to some variation. They are found most
abundantly in striped muscle, although occasionally they may
occur in enormous numbers in the Malpighian tubes, both
in the epithelial cells and in the lumina of the tubes. They
are very numerous in the ganglion, or brain, in the main
nerve trunks, in the salivary glands and walls of the sali-
vary gland ducts. They are numerous in the smooth muscle
fibres of the uterus and vagina. They are occasionally very
numerous in the esophagus and are always to be found
sparsely distributed throughout the intestinal tract. They
have been seen in spermatozoa and ova.

REPORT OF STATE BOARD OF ENTOMOLOGY 39

It is worthy of note that there is no cellular reaction
on the part of the tick to the presence of these parasites,
even when they are present in enormous numbers. A similar
absence of reaction to the presence of a parasite, Spirocheta
duttoni, was observed by me in the tissues of the African
tick, Ornithodorus moubata (Jour. Med. Research, Vol. XXX,
0. 1.) The morphology of the parasite is indentical with
that found in guinea-pig and monkey tissues. It is possible
now definitely to state that there are two principal morpho-
logical types — one, a lanceolate diplococcoid organism, which
is considerably larger than the other type, a small, rather
slender rod-shaped form. The lanceolate type is also found
in the circulating blood and stains fairly deeply with the
chromatin coloration, that is, reddish purple; at each end
there is a small amount of pale blue staining material. The
smaller, rod-like form stains bluish, or bluish purple, accord-
ing to variations in the staining technic. and may contain
granules, bi-polar or more numerous, as were described in
preparations from guinea-pigs. It is obviously poor in chro-
matin staining material. To these types may be added a
third, which, however, probably should be included with the
rod form. It is a minute oval coccoid form which ranges in
size down to forms just visible with the best optical equip-
ment. They stain bluish with Giemsa's stain and have been
found most abundantly in smear preparations of infected
ticks. They are also to be seen in the sections in masses
within cells, too compact to be resolved except at the peri-
phery of the clumps. They occur also inside the nuclei of
certain cells, namely the epithelial cells of the Malpighian
tubules. Greatly distended nuclei are occasionally found filled
with minute paired granules. Ruptured nuclear membranes
filled with these masses have been found.

No new light has been obtained in regard to the exact
nature of this organism. The arrangement in pairs, end to
end, and in tissues, in chains of considerable length, supports
the evidence that division occurs by transverse fission, as
in bacteria. The lanceolate chromatin-rich form is the only
type found with any constancy in the circulating blood of
infected animals, and it is reasonable to suppose that this
represents a more resistant stage of the orgaism, although
no proof has been obtained on this point. The orgaism as
observed in suspensions of crushed tissues of the tick by

40 REPORT OF STATE BOARD OF ENTOMOLOGY

dark field illumination is non-motile. It does not retain the
stain by Gram's method.

Summary and Conclusions.

An organism having definite peculiar characteristics may
be found in large numbers in the lesions characteristic of
spotted fever in experimental animals, guinea-pigs and monk-
eys. These lesions are essentially proliferative in character.
The cells which respond in largest numbers to the action of
the organisms are endothelial cells. These accumulate in great
numbers in the vessel walls and around the vessels. They
may be seen in mitoses in various locations, in lymphatics
and in blood vessels. While this organism has not been cul-
tivated in artificial media it has been proved to multiply
in ticks — Dermacentor andersoni — fed upon infected guinea-
pigs. The organism in ticks is morphologically indentical
with the organisms as found in the lesions of guinea-pigs and
monkeys, although the minute chromatin-poor forms are
much more abundant.

This paras'te does not occur in the tissues of ticks
proved to be non-infective.

The distribution of the parasite in the infected ticks in-
dicates that the transmission occurs by way of the salivary
gland secretion. Transmission by fecal contamination of the
wound caused by the tick in feeding does not seem possible
because of the character of the tick's feces.

At the present time it is impossible to classify this or-
gajiism. Individually the organisms as they occur resemble
bacteria. The very definite occurrence of two morphologica'
types, one exceedingly minute, usually occurring in great
masses and poor in chromatin, the other occurring in smaller
numbers, rich in chromatin, larger in size, and having the
peculiarity of being the only form that is found in the blood
stream of infected animals, would indicate the existence
of a more complicated life cycle than is common to bacteria.
The peculiarities in the distribution of the organism in the
tissues and the staining reaction are reminiscent of these
characteristics in spirochaetes. It is quite possible that we
are dealing with a wholly new type of micro-orgarism.

The facts presented in the above report have been ade-
quately controlled in regard to the distinctive character of
the lesions in experimental animals and in regard to the

REPORT OF STATE BOARD OF ENTOMOLOGY

41

specificity of the parasite described in experimental animals
and in ticks. While it is highly desirable to confirm the pre-
sence of the parasite in human lesions, this evidence is not
essential for the conclusion that the parasite described is
the causative agent of Rocky Mountain spotted fever.

Description of Plates.

Plate 1. Fig. 1, Arteriole of skin of guinea-pig showing
parasites in the smooth muscle cells.
Photomicrograph, 2000 diameters.

Fig. 2. Small vein of testicle of guinea-pig show-
ing parasites in the endothelium and
smooth muscle fibres.
Photomicrograph, 2000 diameters.

Smear preparation from salivary gland of
infected tick ; shows many parasites in the
neighborhood of the nucleus, which has
been partly disintegrated in the making
of the preparation.
Photomicrograph, 2000 diameters.

Fig. 4. Paired lanceolate type of organism found
in circulating blood. Thick film prepar-
ation. Monkey.
Photomicrograph, 2000 diameters.

Plate 2. Fig. 3.

Fig. 5.

Fig. 6.

Plate 3. Fig. 7.

Fig. 8.

Paired lanceolate type of organism found
in circulating blood. Thick film prepar-
ation. Guinea-pig,
Photomicrograph, 2000 diameters.

Smear preparation from teased tissue of
guinea-pig. Shows many organisms in
endothelial cells.
Photomicrograph, 2000 diameters.

Salivary gland of infected tick showing
the parasites in a gland acinus of the
second type.

Camera lucida drawing from a section,
1500 diameters.

Portion of wall of intestinal diverticulum
of an infected tick, cut tangentially.
Shows scattered lanceolate forms through-
out the muscle coat, and one smooth mus-
cle fibre packed with the smaller type of
the organism.

Camera lucida drawing from a section,
1500 diameters.

FIGURE 1

FIGURE 2

FIGURE 6

44

REPORT OF STATE BOARD OF ENTOMOLOGY
PLATE 3

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FIGURE 7

FIGURE 8

REPORT OF STATE BOARD OF ENTOMOLOGY 45

SOME FACTS OF IMPORTANCE CONCERNING THE

ROCKY MOUNTAIN SPOTTED FEVER TICK, (DER-

MACENTOR VENUSTUS BANKS,) IN

EASTERN MONTANA.

By R. R. Parker, Ph. D., and R. W. Wells.

As the result of a week's preliminary survey of tick con-
ditions in eastern Montana in 1915 it was found that the
investigations previously carried on by the State Entomolog-
ist and the United States Bureau of Entomology in the Bitter
Root Valley threw but little light on conditions in the
former portion of the State and that control measures adapt-
ed to western Montana conditions were inapplicable. There-
fore, during the season of 1916 a field station was established
at Powderville on the Powder River in territory known to
be infected, and studies were made of the bionomics of the
tick and of economic conditions that would need to be con-
sidered in a control program. Actual investigations were
carried on from March 27 till September 1. It should be
borne in mind that the region studied was relatively very
small in comparison with the extent of tick infested terri-
tory and that some of the results will be of general interest,
some only of local import.

The results of the investigation may conveniently be
discussed under the following headings: (1) topography, (2)
character of vegetation, (3) species of ticks found, (4) tick
abundance, (5) economic conditions bearing on control, (6)
wild mammals as hosts of the spotted fever tick, (7) domestic
animals as hosts of the spotted fever tick. (8) ticks on human
beings, (9) life history notes, (10) longevity experiments,
(11) means by which ticks are spread.

Topography.

The country in general may be said to consist of river
and creek valleys and of hills, the hill country being by far
the most extensive. In the section studied the valleys are
comparatively narrow and consist of bottom land, that which
the river has most recently left, and of bench land, which
extends from the bottom land to the hills. The bench land
is usually of greater extent. Creeks cutting across the val-
leys to the river wear deep gullies, many of which are dry
during the summer except after heavy rainfalls.

46 REPORT OF STATE BOARD OF ENTOMOLOGY

Character of Vegetation.

Sage brush is the most common plant Hfe. It grows
most luxuriantly on bottom land and wherever on other types
the soil is damp. It is abundant on bench land, much less
common on the hills. Considerable stretches of bench land,
however, may be barren except for sparse grassy growth.

Trees are scarce and likely to decrease further with the
increase of settlers. Open stands of cottonwoods are found
along the rivers and in some places occupy considerable por-
tions of the bottom land, especially in bends of the river.
In such places heavy undergrowth of brush is not infrequent.
Cottonwoods are also sometimes found fringing creek beds.
Shrubby growth occurs along some of the creeks but is not
dense. Occasional hills and ridges occur that bear very open
stands of scrubby pine.

Species of Ticks Found.

Several species of ticks were found on a variety of host
animals, wild and domestic. The most abundant species was
the wood tick, Dermacentor venustus Banks, the only agent
known to transmit Rocky Mountain spotted fever in nature.
Other species of ticks encountered were the rabbit tick,
Haemaphysalis leporis-palustris Packard, the spinose ear
tick, Ornithodorus megnini Duges, and species of Ixodes, the
most abundant of which was Ixodes king! Bishopp. It was
suspected that at least one other species of wood tick, the
eastern dog tick, Dermacentor variabilis Say, might be found.
Though not met with in the vicinity of Powderville. several
specimens taken from men's clothing at Kirby, in Big Horn
County, were received by Professor Cooley. Specimens were
also received by us from North Dakota, where it is reported
as abundant and frequently found on man.
Tick Abundance.

Wood ticks have been known to the residents in south-
ern Custer County for at least 25 years and probably have
been there even longer. As far as can be judged on hearsay
evidence, they have increased somewhat in abundance. One
of the most interesting developments is the fact that there
are occasional years of unusual tick abundance. The season
of 1915 was of this character with the difference that the
ticks were more numerous than at any previous time re-
called by the ranchers. The last previous season of great

REPORT OF STATE BOARD OF ENTOMOLOGY 47

abundance was said to be during 1908. Between these sea-
sons of great abundance were intervening years d iring which
ticks were relatively scarce, though possibly gradually in-
creasing in numbers. The factors which have determined
this great variation in numbers are important to determine,
but are obscure at present ; climatic conditions, availability of
hosts for the immature stages of the tick and for the en-
gorgement of females must all be considered and correlated.
The above statement of occasional tick abundance should be
qualified to this extent, that though it seems to hold true
for the largest portion of the section studied, there are,
nevertheless, small local areas characterized by greater abund-
ance of certain host species and different habitat conditions
where ticks are reported to be abundant every season. Prac-
tically all our studies were carried on in territory answering
the former conditions. The past season was one of only
moderate tick infestation.

The season of 1915 was apparently a good year for al]
species of ticks found in the territory considered.

Economic Conditions Relating to Tick Abundance and Control.

A study of industrial conditions has indicated several
points of apparent importance; (1) the principal pursuits are
the raising of horses, cattle and sheep, (2) only a small por-
tion of the land is under cultivation, (3) individual holdings
of land are relatively large, (4) habitations are mainly found
in the valleys near the rivers and creeks. These conditions
are likely to be modified to no inconsiderable extent, how-
ever, if settlers continue to come into the country as rapidly
as they have the past two seasons. Modifications are likely
to be apparent along the following lines; (1) an increase in
the number of small holdings, (2) an increase in the number
of work horses and milk cows, (3) an increase in the number
of persons living in regions away from the valleys, (4) an
increase in the acreage under cultivation, and (5) a decrease
in the amount of range land and the consequent hastening
of the time when a great proportion of what is now range
stock will be kept within fenced areas.

At present the proportion of horses used for domestic
purposes and pastured in proximity to habitations is rela-
tively small. Most horses are those raised for speculation and
are pastured on the open range. A few milk cows are gen-

48 REPORT OF STATE BOARD OF ENTOMOLOGY

erally kept at the ranches and homesteads, the remainder
are range stock. Most cattle men find it necessary to winter
their range stock in fenced areas in or close to the valleys.
Such cattle are usually in the valley during the first part of
the tick season in the spring. Ti ey may later be brought
in from the range for branding. Horses also may be brought
in several times during the tick season. Sheep are frequentl5
driven for considerable distances in the spring from the
winter to the summer ranges, often crossing the valleys near
habitations. Lambing usually occurs in May, shearing in
June. The shearing pens are generally some distance from
the ranches.

Crops are grown almost entirely for local consumption.
They are mainly corn, alfalfa, and various small grains.
Small garden plots are the rule. Hay is cut in considerable
quantities, but almost entirely from uncultivated land.

Wild Mammals as Hosts of the Spotted Fever Tick.

A survey of the wild mammalian fauna and its relation
to the life history and abundance of the tick was an import-
ant feature of the investigations. The results of the season's
work, though incomplete, contain considerable information of
value. Twenty-six species of wild mammals were found to
be present. One thousand and thirty-seven specimens belong-
ing to 22 species were examined for ticks. One thousand and
five specimens belong to 11 species that were found to be tick
hosts. The names of these animals, the number of each
species examined, the number and per cent of each species
infested and the stages of the ticks which were found to feed
on each are indicated in the accompanying table. The writers
are indebted to Mr. E. A. Preble of the United States Biolog-
ical Survey and to Professor Spaulding of the State College
for the indentification of most of the mammals.

A comparison of the wild mammals found to be tick
hosts in the. Bitter Root Valley shows but three species
common to both localities, the cottontail rabbit, the coyote
and the badger. A still more significant difference, however,
is the fact that in eastern Montana we find among the small
mammals, an apparently important host of adult ticks. This
is the jack rabbit. Of 84 jack rabbits examined 56 or 66.66
per cent were infested with adults and of 68 examined before
July 1, 49 or 72.08 per cent. A fully engorged female was

REPORT OF STATE BOARD OF ENTOMOLOGY

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50 REPORT OF STATE BOARD OF ENTOMOLOGY

taken from a jack rabbit as late as August 12, It is per-
haps a question what proportion of females become fully
engorged on this host, but specimens scarcely more than one-
fourth engorged deposited fertile eggs. It is an interesting
fact that of 157 adults taken from jack rabbits, 102 were
males and only 55 females. Ticks from horses, on the other
hand, average about equal numbers male and female. The
average number of adult ticks per jack rabbit examined was
1.87, the average per horse 1.44. In one instance 14 adults
were taken from a single rabbit. These rabbits are also im-
portant as nymphal and perhaps as larval hosts; 36 nymphs
have been taken from one rabbit. In another instance, 20
nymphs from one host all molted to adults. Considering the
abundance of these animals it is evident that they are an im-
portant factor in tick abundance. Porcupines are also hosts
of adult ticks, though their importance remains to be deter-
mined. In localities where numerous they may be of some
interest. A fully engorged female was taken from one of
these animals on July 27. The eggs commenced hatching
on August 31. Two adults were taken from prairie dogs but
their occurrence on this host is considered accidental. Though
coyotes examined were found uninfested, it is likely that they
are hosts of the adult tick.

Jack rabbits, cottontail rabbits, prairie dogs, chipmunks,
deer mice, prairie mice, grasshopper mice, pack rats, and
kangaroo rats are hosts of both larvae and nymphs. Sper-
mophiles and porcupines are nymphal hosts. In marked
contradistinction to the conditions which exist in the Bitter
Root Valley no one species of small mammal, unless it may
possibly be the jack rabbit, stands out as of preeminent im-
portance as a nymphal host. Pack rats are efficient hosts
but are not present in sufficient numbers to be of great
moment. On June 29, 45 larvae and nymphs were taken
from one rat. Chipmunks may be important in certain lo-
calities where conditions favor their existence in relatively
large numbers. Kangaroo rats and deer mice are interesting
possibilities, the latter because of their great numbers.
Under suitable conditions large numbers of them are found
in comparatively small areas. Grasshopper mice are scarce
and relatively unimportant. Prairie dogs are abundant
locally, mainly on the bench land, and are much less common
in the hills. This season's work would indicate that they are
not of great importance.

REPORT OF STATE BOARD OF ENTOMOLOGY 51

In the paragraph preceeding, several animals have been
mentioned as larval hosts. Under laboratory conditions the
prairie dog is an extremely efficient larval host. Only one
was found infested with larvae in nature during 1916, but
larvae were secured from them in 1915, when ticks were more
numerous. Cottontails may be important. One hundred and
eleven seed ticks were taken from a cottontail on July 31,
1915. Unfortunately only 22 were determined, but all these
were Dermacentor venustus. During 1916 the great majority
of seed ticks were taken from animals of nocturnal habits.

It is of interest to note in connection with the import-
ance of rabbits as adult hosts, that they were very abundant
for several years previous to 1915. In 1914 they began to
die off and decreased greatly in numbers in 1915. Local re-
sidents reported grubs in the backs of thin and sickly-looking
rabbits. This probably indicated bot flies, though whether
they were responsible for the great mortality is another
question. The only rodent bot fly captured in the locality
was Cuterebra tenebrosa Coquillett. Similar epidemics of a
periodic nature have been reported from many parts of the
west and northwest.

Another point worthy of mention is the fact that those
animals which were found both in rocky situations in the
hills and under valley conditions showed the highest per-
centage of infestation with the immature stages of the
tick in the former places. This was particularly noticeable
among the deer mice, which showed much lighter infestation
under valley conditions. Rock strewn hillsides and rock
crowned hills are common among the hills bordering the
Powder River Valley.

Certain of the observations made seem to indicate that
ticks may sometimes be abundant in the absence of domestic
animals. This condition requires further investigation.

Domestic Animals as Tick Hosts.

Under this heading are included horses, cattle, sheep,
dogs, cats and pigs. Only adult ticks are know^n to occur on
these animals. One hundred and sixty-one horses were
examined and 252 ticks secured, 115 males and 117 females,
an average of 1.44 ticks per horse. From fifteen range
horses examined in June an average of 6 adults per animal
were collected and from 146 work and saddle horses ex-

52 REPORT OF STATE BOARD OF ENTOMOLOGY

amined from March 27 to August 27, an average slightly
less than one tick per animal. This seems difficult to under-
stand if it indicates the true proportion of ticks that feed
on these two types of horses and necessitates a study of
condition on the open range to determine what small mam-
mals, under range conditions, engorge the immature stages
of the tick. Rabbits may be responsible. One resident re-
ported removing 37 ticks from a single range horse early in
July. From a work horse examined 7 times between April
15 and May 18, 33 ticks were secured; other horses in the
same pasture had very few ticks on them. In 1915 ticks
must have been very abundant on horses. One person des-
cribed them as so numerous on the bellies of his work horses
that they were scraped off repeatedly with a stick. Hand-
picking was practiced by many ranchers.

As all cattle except a few milk cows were range stock,
opportunities to examine them for ticks were not common.
Calves tied or held for branding or vaccination were examin-
ed on several occasion. From 150 calves examined April 11,
7 ticks were removed, from 4 on April 17, 1 tick, from 136
on June 7, 5 ticks. In each instance all the ticks taken were
females. They were found attached to the brisket behind the
forelegs. Those taken on June 7 were kept to see if they
would deposit eggs. Though all were more than half en-
gorged but one lot of eggs was deposited and these few
in number and not fertile. All the females became abnormal
in appearance and soon died. Residents perfectly familiar
with the tick and its occurrence on horses, reported never
having seen it on cattle. Milk cows were examined several
times with negative results. It is difficult to interpret this
fact in view of the importance attached to cattle as tick
hosts in western Montana and definite conclusions cannot
be based on such meagre and unexpected results.

Between April 8 and June 15, 7 sheep were examined.
From these 7 adults were secured, 4 males and 3 females.
One female was fully engorged, 2 males and 1 female at-
tached, 2 males unattached and 1 male dead in the wool.
Several herds sheared during the middle of June were
examined by the shearers and in part by us. Ticks were
found on but 2 sheep and were unfortunately lost before
they were turned over to us for determination. Some of
the residents claim ticks to be most abundant in territory

REPORT OF STATE BOARD OF ENTOMOLOGY 53

ranged over by sheep, others the opposite. Horses in sheep
territory were apparently as badly infested as elsewhere.
Sheep owners reported ticks yery common on sheep in 1915.
It is impossible to make any suggestions concerning the
importance of sheep as adult hosts.

A single tick was removed from dogs, though many
were examined. The infested dog was herding sheep. Ticks
were said to be common on dogs in 1915. Cats and pigs
were examined with negative results.

Ticks on Human Beings.

Ticks were common on persons during the season of
1915, considerable numbers sometimes being picked up dur-
ing one day. Though ticks were relatively far less abundant
during 1916, the great majority, of persons had found them
on their body or clothing at one time or another during the
season. Their occurrence on persons may be from early
March to at least well toward the middle of August. One
of the cases of spotted fever in 1915 occurred in late July,
the tick, well engorged, having been removed on July 31.
Dermacentor variabilis has previously been mentioned as
occurring on a man at Kirby, Big Horn County.

Sores caused by ticks were frequently heard of, the
bite in several cases having been received in 1915, local irri-
tation being still present. In the cases examined the scars
greatly resembled those of small pox vaccination. One case
was reported of a boy bitten several years ago, who has quite
severe, recurring, local symptoms each spring.

The residents have fully recognized the importance of
the tick as the transmitting agent of Rocky Mountain spot-
ted fever and were found to exercise considerable care
against ticks becoming attached to their persons.
Life History Notes.

Information concerning the life history of the tick
under eastern Montana conditions was gleaned from several
sources; engorged females, nymphs and larvae taken from
wild and domestic animals, records of engorgements secured
from rearing experiments and the subsequent moltings and
records of the seasonal occurrence of larvae, nymphs and
adults on various host animals. The first larvae were taken
on May 18. the last on August 21; the first nymphs on
April 10, the last on August 30; the first adults on March
27, the last on August 31. Adults were reported from about

54 REPORT OF STATE BOARD OF ENTOMOLOGY

the first of March. The preoviposition period was found to
vary from 6 to 14 days (25 records between April 8 and
August 21), the oviposition period from 15 to 40 days (23
records between April 17 and August 23), the incubation
period from 24 to 51 days (17 records between April 17 and
August 31), the period of larval engorgement from 1% days
to 51/^ days (4830 records between June 22 and August 21),
the larval premolting period from 8 to 26 days (2806 records
between May 26 and August 29), the period of nymphal en-
gorgement from 4 to 10 days (194 records between July 3 and
August 4), the nymphal premolting period rrom 15 to 53
davs (195 records between May 8 and September 3.) Under
experimental conditions it was found impossible to success-
fully engorge larvae after the middle of August. Nymphs
also showed less inclination to attach. Adults were present
in greatest numbers from the middle of April to the middle
of Juno. In 1915 they were said to have been abundant till
the middle of July.

The tick evidently passes the winter as unfed nymphs
and unfed adults, possibly also as engorged nymphs and
unfed larvae. This is similar to conditions found in the
Bitter Root Valley. Other conditions differ somewhat; the
adults appear earlier and stay later, there being no abrupt
decline in adult abundance, indicating that a greater per-
centage of adults engorge after July 1. Wherein the life
cycle in the two sections of the State will be found to differ
may be expected to hinge to some extent on what happens
to the eggs deposited by females engorged during this pro-
longation of the adult feeding period, and to larvae that may
hatch from them. Larval ticks were found about 6 weeks be-
fore their normal appearance in the Bitter Root Valley, but
whether such earlier occurring larvae had overwintered or
hatched from eggs deposited during the spring of 1916 is
mere supposition. On the basis of laboratory data the latter
possibility is admissible, but it may not be possible under
more natural conditions. The period of nymphal premolting
(under laboratory conditions) was much shorter than in
western Montana and may affect the length of the life
cycle in some particulars. Larvae and nymphs show a
marked disinclination to feed after the middle of August,
adults somewhat earlier.

REPORT OF STATE BOARD OF ENTOMOLOGY 55

Longevity Experiments.

In order to increase our knowledge of the life history of
the tick and to secure information likely to be of value for
control purposes, a series of longevity experiments was
started. In nature ticks had been found on animals living
under four conditions of flora and soil covering which might
have an influence on the longevity of unfed ticks of the
several stages. These conditions were as follows; (1) rocky
areas. (2) sage brush areas, (3) grassy areas, and (4) areas
of small extent occupied by open stands of trees with dense
underbrush. Adults and nymphs were released in cages
under conditions typifying the first three conditions named
and larvae under condition one. Rocks may be considered as
affording complete shade, sage brush partial shade and
grassy areas no shade. Both cages and longevity tubes were
used.

As it was impossible to secure sufficient ticks for these
experiments in nature, it was necessary to rear them under
laboratory conditions. Thirty-seven cages of animals were
infested with seeds and nymphs; 4830 larvae were engorged
on prairie dogs, and 1144 nymphs on prairie dogs, jack rab-
bits, cottontail rabbits, Belgian hares and pack rats. In the
actual experimental work 163 adults, 690 engorged nymphs.
1219 unfed nymphs and several hundred larvae were re-
leased.

Means by Which Ticks Are Spread.

In eastern Montana there are no apparent natural bar-
riers against the spread of ticks. The limit of spread from
any given locality is that of the ranging powers or habits
of the host animals. Cattle, horses and sheep are the most
important agents of dispersal, due to their unrestricted move-
ments and wide radius of travel. Cattle should perhaps be
considered as potential agents until their importance as
tick hosts in eastern Montana is more certainly determined.
Among small wild animals, jack rabbits are important and
are extensive travelers, though their ultimate range is
scarcely likely to be as great as that of horses and cattle.
Coyotes may also be important.

Due to the untrammeled movements of so many hosts
of the adult ticks we would naturally expect that infestation
in any given area would be less severe than in fenced or

56 REPORT OF STATE BOARD OF ENTOMOLOGY

naturally limited areas of the same size, in which host
animals were confined. Similarly the number of infected
ticks in any given locality would be likely to be smaller and
the chances of human infection correspondingly less. This
is the apparent condition which has existed in eastern
Montana as compared with the Bitter Root Valley.

REPORT OF STATE BOARD OF ENTOMOLOGY 57

HOUSE FLY CONTROL IN MONTANA.

An investigation of house fly conditions in Montana was
begun in 1914 and a summary of the results was pre-
sented in the First Biennial Report. During the season of
1915 the work was continued in a different form in Miles
City and results of much practical value in house fly control
were secured.

The house fly is now well known to be a very import-
ant factor in the spread of various diseases. Moreover,
flies have been exceedingly abundant in Montana and a study
of the particular conditions found in Montana wa? very ne-
cessary. So far as could be done without interfering with
the work on the spotted fever tick this work has been taken
up by Dr. Parker.

We already have sufficient information to enable us to
cooperate with cities and individuals in control work. Num-
erous newspaper articles have been written and lectures
have been given.

A condensed summary of the house fly follows:

The House Fly and the Control of Flies.

R. R. Parker, Ph. D.

In the first biennial report of this board (pages 35 to
50) the results of preliminary investigations conducted at
Laurel, and other cities in the Yellowstone Valley, concern-
ing the habits and control of the house fly were briefly
summarized. Sufficient data were then collected to per-
mit action in an advisory capacity to cities, towns and insti-
tutions and individuals interested in control work.

As far as cities in this State are concerned, the following
is a general statement of the facts to be considered in-
outlining fly control:

1. That the house fly mainly breeds in horse manure.

2. That the house fly also breeds in other animal
manures (especially pig manure), refuse of various sorts, and
human excrement.

3. That unclean conditions serve to attract flies to
any given locality.

4. That adequate measures for the control of the house
fly will control many other species that are annoying and

58 REPORT OF STATE BOARD OF ENTOMOLOGY

troublesome and only less dangerous because of fewer num-
bers.

5. That fly control should aim,

(a) to prevent egg-laying in so far as possible.

(b) to prevent flies that may be breeding in
manure, garbage or other refuse, from matur-
ing within city or town limits, by proper care
pending removal and by removal at sufficiently
frequent intervals.

(c) to ultimately so dispose of waste that flies
breeding therein will not mature.

(d) to so care for materials which attract flies
that they will attract them to the least possible
extent.

6. The proper disposal of manure is a most difficult
problem to meet. Its use agriculturally is not extensive
enough nor does it come at the proper time of the year to
assist from the standpoint of control. Therefore, so long as
measures for its care within city or town limits, and for its
removal, do not injure the manure as a fertilizer nor pre-
vent its use as such, any means recommended for its suitable
disposal are amply justified.

7. That one condition very difficult to satisfactorily
control is the presence of large corrals in or near cities.

8. Control measures should cause the least possible
outlay of money and expenditure of time and place the least
possible responsibility on the individual that is commensur-
ate with successful results.

9. That no one system of control can be recommended
in detail to cover all conditions ; only fundamental principles
are of general application.

10. Detailed regulations are not necessarily strict but
•tend to simplify procedure.

11. Health inspectors are an important accessory to
intensive control but only feasible in larger cities.

12. Fly control is purely and simply a question of
common decency and cleanliness and its intensive and suc-
cessful application serves to materially better sanitary con-
ditions.

When the above statement of facts is reduced to a
working basis, the following subjects are those of most
essential importance for regulatory measures.

REPORT OF STATE BOARD OF ENTOMOLOGY 59

(a) The temporary care of horse manure at the point

of production, pending removal.

(b) The removal of horse manure.

(c) The ultimate disposal of horse manure.

(d) The temporary care of garbage and refuse at the

point of production, pending removal.

(e) The removal of garbage.

(f) The ultimate disposal of garbage.

(g) The elimination of the insanitary privy.

It is important for any community desirous of initiating
fly control to recognize the fact that there are two view-
points from which control may be regarded, (1) as a measure
to reduce insects which are an annoyance and pest, (2) as
a means of bettering sanitary conditions. If control is at-
tacked from the second viewpoint it is more intensively ap-
plied than if approached from the first, but the results
likely to be attained from the first will be greatly enhanced.

During the seasons of 1915 and 1916 the fly work, de-
signed to add to our knowledge of the habits and economic
importance of flies and to disseminate the practical and
scientific application of the same among the people of the
State and interested parties, has been pursued along the
following lines:

(1) experiments to determine the radius of dispersion
of the house fly, (2) lectures (popular and scientific), (3)
recommendations for control measures, (4) publications, (5)
exhibits, (6) miscellaneous.

Experiments to Determine the Radius of Dispersion of
the House Fly. Several investigations have been conducted
during recent years for the purpose of securing information
concerning the flight of the house fly and its possible limits.
The results, however, have been very indefinite as to the
actual limits of flight and the number of flies represented
in all these experiments total less than 50,000, the largest
number used in any one experiment being 2,500. But when
we consider that house fly dispersion means the possible
spread of flies breeding out at any given breeding area,
large or small, it is at once evident that we are concerned
with a period of time equivalent to the average life of the
fly and with the number of flies which breed out during
this interval. Taking the average length of life as from
three to four weeks, it is apparent that the numbers of

60 REPORT OF STATE BOARD OF ENTOMOLOGY

flies mentioned above would represent but a small portion
of those which might emerge from even a small manure
pile and that while the results obtained would be relatively
correct yet they can by no means be considered as final.
Perhaps the general concensus of opinion resulting from
such observation as pertain to dispersion under city condi-
tions can best be summed up by the statement. "That the
distance flies may travel to reach dwellings is controlled by
circumstances. Almost any reasonable distance may be
covered by a fly under compulsion to reach food or shelter.
When these are close at hand the insect is not compelled to
go far and, consequently does not do so." To show the
inadvisability of holding to this opinion it is only necessary
in view of the summer's results to indicate why the small
numbers of flies used in previous experiments constitute
a weak point. From our viewpoint flies are considered as
spreading outward from a given center, the breeding place.
Naturally flies are more abundant at points in relatively
close proximity, because, even though they might migrate
from this zone their numbers are maintained by the con-
tinual emergence of adults. But as they spread outward they
must, of necessity, become constantly more and more scat-
tered and their capture increasingly difficult until a point is
finally reached the chances of their capture becomes reduced
to infinity. But this point is extended further and further
with each increase of the number of flies emerging during a
given period, the length of which is limited to the average
length of life. Consequently we are justified in assuming that
experiments dealing with comparatively small numbers are
not indicative of finality. With these points in mind and
realizing that, for the most part, the conditions in all Mont-
ana towns and cities are essentially similar though perhaps
differing considerably from those concerned in the experi-
ments mentioned above, the headquarters for the season's
observations were located at Miles City which afforded the
combination of conditions best suited to the work, namely,
abundance of flies, lack of intensively applied control mea-
sures and representative size.

It is only possible to give a comparatively brief sum-
mary of the work in this paper. A total of 387,877 marked
flies were released from four release stations during a period
of 35 days. Two of these release stations were situated on

REPORT OF STATE BOARD OF ENTOMOLOGY 6T

the west side of the city (the sales yards and the city dump),
one in the center of the city and one on the east side. Of the
marked flies, 1.056 were recaptured at 78 recapture stations,
so located that every part of the city was under observation.
Marked flies from the sales yards were recaptured at 62
stations out of a possible 69. This figure was higher than
that for other release stations due to the fact that a much
larger number, 248,140 flies, were released from the sales
yards. However, the figures and localities for all release
points were such as to show that flies from each one were
distributed to very part of the city. Also, flies were not only
captured within Miles City, but it is significant that marked
flies from all release points were recaptured at the State
Industrial School, which is seven hundred yards beyond the
eastern limits of the city and the farthest point at which
recaptures were attempted. Flies from the city dump and
sales yards not only crossed the city but also the 700 yards
of open country intervening, in order to reach this point, a
total of 3,500 yards (nearly two miles) and 3,070 yards re-
spectively. The longest radius at which flies were recap-
tured within the city was 2,333 yards (about one and one-
third miles) which was the most distant station within the
city from any release point.

The investigations, however, were not confined to num-
bers and locality alone, but also concerned the factors which
influence dispersion, that is, those factors which control
the direction of flight and the relative abundance in differ-
ent localities. Wind, temperature, state of weather, etc., are
among the factors which have been previously suggested and
while under certain conditions and circumstances they un-
questionably play their part, they assume less importance
when dispersion is considered for long periods of time, unless
some special locality offers unusual climatological conditions.
A much more practical viewpoint is obtained when we con-
sider the movements of flies to be determined by their
reactions to their surroundings ; that is, by external stimuli.
A discussion of this point is necessarily highly involved and
concerns stimuli which cause movements, those which cause
inactivity and the conditions under which either kind is
dominant. It is sufficient for this report to indicate that
movements and consequent dispersion are, in the main, de-
pendent on the stimuli (odors) received from feeding areas

62 REPORT OF STATE BOARD OF ENTOMOLOGY

and breeding areas, a statement which is substantiated by the
summer's results.

The result's above stated indicate the following points
of practical significance under city conditions in Montana:
(1) That flies from a given breeding area may spread over
a territory within a city of at least five square miles, (this
is based on the longest radius found within city limits and
within which it was found that flies were distributed to all
parts), (2) that the actual limit of dispersion within cities
may be considerably greater than this, (the number of flies
recaptured at the State Industrial School indicates that flies
may be abundant even at distances of nearly two miles from
their breeding place; that is, that they may spread over a
territory of twelve square miles), (3) that flies by no means
remain close to their breeding grounds even when food and
''shelter" are abundant, but that they lead an extremely
migratory existence and will not only cross a city or consid-
erable portions thereof, but will leave it and fly across open
country to points some distance beyond; (4) that conditions
within a city which are favorable to fly breeding are of im-
portance not only to the residents, but to farmers and others
in its vicinity; (5) that even in a city of considerable size,
every person who permits conditions favorable to fly breed-
ing to exist on his premises is maintaining a nuisance which
is of actual or potential concern to every other person within
city limits (this is not only because of the possible migration
of flies to any given locality, but also because flies are
naturally attracted to stores, dairies and other sources of
food supply where they may contaminate food) ; (6) that
the importance of general cooperation in order to secure
successful results in control work is strongly emphasized
(the cleaning up of a few places here and there has little
value) ; (7) that fly control measures, intensively applied,
are far reaching in their effectiveness as a means to help
secure general sanitary conditions, both from educational
and practical viewpoints; (8) that it is highly necessary to
control these conditions which make any locality (feeding
or breeding areas) attractive to flies (as indicated in the
"First Biennial Report" of the Board the three biggest prob-
lems of fly control in Montana are the proper care and dis-
posal of garbage, the proper care and disposal of manure
and the elimination of the open privy.)

REPORT OF STATE BOARD OF ENTOMOLOGY 63

Lectures. Lectures, (some illustrated), planned to stim-
ulate an interest in fly control, the reasons why it should be
undertaken and the benefits to be derived therefrom, have
been delivered in the following cities and to the following
organizations: Bozeman — Chamber of Commerce, Women's
Civic Club, students of the State College, public school tea-
chers, Young Men's Christian Association, and Rebecca's;
Havre — Directors of Chamber of Commerce, Chamber of
Commerce, Women's "Baby Week" meeting, and public school
teachers; Miles City — Chamber of Commerce and Tri-County
Teachers' Institute of 1915. Lecture work in both Bozeman
and Havre was supplemented by the use of slides in the
moving picture houses.

Lectures of a strictly scientific character were delivered
before the Science Club of the State College at Bozeman
and the Bozeman Medical Association.

In July, 1916, a paper concerning garbage disposal in
small towns was read before the State Health Officers Asso-
ciation at Miles City.

Recommendations for Control Measures. Recommend-
ations for fly control have been made to interested organiza-
tions in the cities of Bozeman and Havre. These recommend-
ations have been made with the idea that intensive and,
therefore, thoroughly efficient control is the most desirable
aim, because it must be recognized that measures adopted
for fly control are fundamentally measures for good sanita-
tion and for improving conditions detrimental to public
health. Hence the nearer it is possible to approach the ideal
the most effective will the efforts have been. The carrying
out of such measures, as adapted to cities of the size repre-
sented, involves an initial financial outlay and the adoption
of regulatory measures which of necessity call for adequate
time to make the preliminary moves. In both cities noted
above there is an earnest disposition to inaugurate active
work at the earliest possible moment. Indeed the lectures
given in these cities and the active interest of certain local
organizations has already done much to improve general
sanitary conditions, the value of which will be greatly en-
hanced under proper direction and supervision.

Suggestions for interesting the townspeople in fly con-
trol have been made to interested parties in the town of
Hysham.

64 REPORT OF STATE BOARD OF ENTOMOLOGY

Control measures recommended to the Montana Power
Company are to be adopted at their construction camp at
Holter.

The installation of incinerating plants has been recom-
mended when possible. Incineration is unquestionably the
most sanitary method for the disposition of garbage.

Requests for advice concerning fly control have also been
received from two State institutions, the State Industrial
School at Miles City and the State Insane Asylum at Warm
Springs. Measures recommended to the former institution
were adopted during the summer of 1915 and afforded im-
mediate beneficial results. A visit to Warm Springs was
made in June of 1916 and a detailed plan of control submitted.

Publications. Publications concerning flies and fly con-
trol n)ay be divided into three groups, (1) newspaper articles,
(2) contributions to the Bulletin of the State Board of
Health, and (3) scientific papers. A considerable number of
newspaper articles have been written, especially as supple-
mentary to lecture work. Under the general heading of
"The House Fly in Relation to Public Health in Montana,"
three articles have been published in the Bulletin of the
State Board of Health. The first of these concerned the
habits of the house fly and its relation to man, the second
discussed its importance as an agent in the distribution of
disease organisms and the third dealt with the means of
control. A fourth article presented in a popular way the
results obtained in the experimental work on dispersion car-
ried on at Miles City.

One article dealing with the dispersion work just men-
tioned was published in the Journal of Economic Entomology
for June, 1916. This paper was purely scientific.

Exhibits. Exhibits illustrating the habits of the house
fly and its near relatives were prepared for the State Fair
at Helena in 1915 and 1916. These exhibits attracted con-
siderable attention and intelligent interest, attesting the
general realization of the importance of such matters in re-
lation to public health.

Miscellaneous. Plans for a maggot trap and for a man-
ure box have been prepared, which may be obtained by appli-
cation to Professor R. A. Cooley, Secretary of the State
Board of Entomology. The maggot trap is an arrangement
particularly adapted to country conditions and perhaps af-

REPORT OF STATE BOARD OF ENTOMOLOGY 65

fords the best means yet devised for controlling the house
fly with a minimum expenditure of time and care on the
part of the individual and is at the same time one which
permits the most economic preservation of manure which is
to be used for fertilizing purposes. The manure box was
designed for use under city conditions, and is adapted for
use in narrow alleys. The idea incorporated in its construc-
tion is adaptable to diverse conditions; the box is built on to
the stable, the manure being put into it from within and
removed from an outer door. The manure is never exposed
out of doors. Its successful use is dependent upon the
prompt placing of manure in the box before flies have
deposited their eggs on it in the stable and systematic and
periodical removal at sufficiently frequent intervals. Such
an arrangement will appeal to those who take pride in
keeping their premises neat and clean.

Several opportunities have presented themselves for
continuing the observations made at Laurel in 1914 and
reported in the First Biennial Report concerning flies breed-
ing in human excrement. Additional species of coprophagous
flies have been reared.

Notes concerning the seasonal occurrence of certain ex-
creta frequenting flies have also been made, mainly under
ranch conditions.

During October an investigation was made at the con-
struction camp of the Montana Power Company at Holter,
upon the request of the Secretary of the State Board of
Health, to determine the possible responsibility of flies in
connection with an outbreak of typhoid fever. This involved
certain bacteriological tests which have not yet been com-
pleted.

Need of Further Investigation.

Although the subject of fly control is one that is being
attacked energetically in all parts of the country there is
considerable to be learned concerning its habits and life
history that will be of importance from the standpoint of
control. In spite of the fact that investigations on this
insect are being actively pursued by the United States Bur-
eau of Entomology and in several states, there is no reason
+0 believe that these will solve our problems in Montana.
Indeed in those localities where investigations are being most

66 REPORT OF STATE BOARD OF ENTOMOLOGY

actively prosecuted the conditions affecting control are
utterly different from those in most sections of this state,
The question of how the house fly hibernates in Montana is
an important one to solve because of its bearing on efficient
control measures. Another problem concerns the manner of
properly caring for manure during its temporary storage in
cities and towns, especially those of small size. Other prob-
lems concern the ultimate disposal of manure and garbage
and are largely of an economic nature.