UNIVERSITY OF CALIFORNIA PUBLICATIONS.

COLLEGE OF AGRICULTURE.

AGRICULTURAL EXPERIMENT STATION.

MOSQUITO CONTROL.

By H. J. QUAYLE.

BULLETIN No. 178.

(Berkeley, Cal., July, 1906.)

W. W. SHANNON,

SACRAMENTO:

: : : superintendent state printing.
1906.

BENJAMIN IDE WHEELER, Ph.D., LL.D., President of the University

EXPERIMENT STATION STAFF.

E. J- WICKSON, M.A., Acting Director and Horticulturist.

E. W. HILGARD, Ph.D., LL.D., Chemist.

W. A. SETCHELL, Ph.D., Botanist.

ELWOOD MEAD, M.S., C.E-, Irrigation Engineer.

C. W. WOODWORTH, M.S., Entomologist.

R. H. LOUGHRIDGE, Ph.D., Agricultural Geologist and Soil Physicist. (Soils and Alkali.) (Ab-

M. E- JAFFA, M.S., Chemist. (Foods, Nutrition?) [sent on leave.)

G. W. SHAW, M.A., Ph.D., Chemist. (Cereals, Oils, Beet-Sugar.)

GEORGE E. COLBY, M.S., Chemist. (Fruits, Waters, Insecticides)

A. R. WARD, B.S.A., D.V.M., Veterinarian and Bacteriologist.

E. W. MAJOR, B.Agr., Animal Industry.
RALPH E. SMITH, B.S., Plant Pathologist.

F. T. BIOLETTI, M.S., Viticultunst.

WARREN T. CLARKE, B.S., Assistant Entomologist and Supt. Farmers' Institutes.

H. M. HALL, M.S., Assistant Botanist.

JOHN S. BURD, B.S., Chemist, in charge of Fertilizer Control.

C. M. HARING, D.V.M., Assistant Veterinarian and Bacteriologist.
ALBERT M. WEST, B.S., Assistant Plant Pathologist.

E- H. SMITH, M.S., Assistant Plant Pathologist.

G. R. STEWART, Student Assistant in Station Laboratory.
, Assistant in Soil Laboratory.

RALPH BENTON, B.S., Assistant in Entomology.

LUDWIG ROSENSTEIN, Laboratory Assistant in Fertilizer Control.

i

D. L- BUNNELL, Clerk to the Director.

R. E. MANSELL, Foreman of Central Station Grounds.
JOHN TUOHY, Patron,

, Foreman,

Tulare Substation, Tulare.

J. W. MILLS, Pomona, in charge Cooperative Experiments in Southern California.

J. W. ROPER, Patron,

> University Forestry Station, Chico.
E. C. MILLER In charge

in, )

ROY JONES, Patron,

I University Forestry Station, Santa Monica.
N. D. INGHAM, Foremai

VINCENT J. HUNTLEY, Foreman of California Poultry Experiment Station, Petaluma.

The Station publications (Reports and Bulletins), so long as avail-
able, will be sent to any citizen of the State on application.

CONTENTS.

Page.

INTRODUCTORY 5

ACKNOWLEDGMENTS- 6

COMMON FACTS ABOUT MOSQUITOES 6

MOSQUITOES AND DISEASE 10

THE PRESENT CAMPAIGN 14

THE TERRITORY 14

WHAT WAS DONE ON THE SALT MARSH 15

THE FRESH-WATER PROBLEM 21

SUGGESTIONS FOR FUTURE WORK 25

FISH vs. MOSQUITOES ._ 26

OTHER NATURAL ENEMIES 29

BLUESTONE AS A MOSQU1TOCIDE . 30

EUCALYPTUS vs. MOSQUITOES 30

LEGISLATION 31

RESULTS ACCOMPLISHED 32

THE SPECIES CONCERNED—

Ochlerotatus lativittatus ._ 34

Lepidoplatys squamiger. - _ _ 41

Theobaldia incidens . 45

Culex tarsalis ... 48

OTHER SPECIES 50

SYNOPTIC TABLES 52

CALIFORNIA CULICID^-BIBLIOGRAPHY AND SYNONYMY 53

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MOSQUITO CONTROL WORK IN CALIFORNIA.

By H. J. QUAYLE.

Introductory.— The campaign against mosquitoes recorded in this
Bulletin was undertaken by the California Experiment Station at the
urgent request of the Burlingame Improvement Club. Late in May,
1904, a letter was received by the entomologist of the Station, asking
for aid in relief from mosquitoes in the vicinity of Burlingame, where
they had become exceedingly abundant and annoying. This request
was made too late to do any effective control for that season, but it was
recommended that a preliminary survey be made with a view to obtain-
ing data for future work. The writer was consequently detailed to
make this survey, and three weeks were spent in the neighborhood
making collections and locating breeding grounds. In this study it was
soon determined that the mosquito giving practically all of the trouble
(estimated at 95 per cent) was a species that bred in salt or brackish
water only, and that in any work looking toward control, the salt-marsh
area must receive first consideration. This being known, the pre-
liminary report made to the Burlingame Improvement Club gave but
little encouragement, because of the extent of the marsh land that must
be included in the problem. It was further stated, however, that if
they were considering the problem in earnest, and wished to go to
the expense necessary to control this large breeding ground, the Ex-
periment Station would be glad to outline a plan of campaign for
the following season.

Nothing more was heard about the matter until early in August,
when, owing to the excessive abundance of mosquitoes, due to the
emergence of a brood on the marsh, Mr. G. A. Pope, president of
the Burlingame Improvement Club, wrote again to the Station, ask-
ing if it would not be possible to at least mitigate the nuisance im-
mediately. In reply to this communication it was stated that the
mosquitoes now flying about would remain well up to the close of
the season, and that the prevention of other broods from appearing
would not lessen the numbers to any perceptible degree. It was pro-
posed, however, that a class of students from the University make
weekly trips to the territory, in order to secure more data as a
roundation for the practical control work. Such a course was, there-
fore, announced in the University curriculum, and some half dozen

6 UNIVERSITY OP CALIFORNIA— EXPERIMENT STATION.

advanced students in entomology thus availed themselves of the op-
portunity of getting acquainted with the practical side of the subject.

In the middle of February, 1905, the writer met with the members
of the Burlingame Improvement Club in San Francisco and outlined
a plan of campaign. In this plan it was recommended that, in so far
as possible, the work be of a permanent nature, such as ditching and
filling in, this to be supplemented by oiling, where it was necessary to
keep ahead of the developing mosquitoes, or where permanent work
would be done only at great expense. After estimating the amount
of ditching necessary on the marsh, the expense of repairing dikes and
the use of oil and other materials necessary, the minimum expendi-
ture was placed at $2,000. When this was submitted to the Club it
received a unanimous indorsement, and the consensus of opinion was
that the mosquito must go at any cost. Having this assurance of moral
and financial support we were ready to begin the active work of the
campaign at once, and a gang of men was immediately set to work.

The chief aim of the campaign was to get results in the control
work, and demonstrate to the people of the State in general, and of
this territory in particular, that the mosquito nuisance can be checked
if the people only take up the problem in sufficient earnestness. The
funds were contributed with this end in view, and, consequently, prac-
tically all of our energies were taken up with this phase of the prob-
lem, and there was little time left for a purely biological study, such
as we would liked to have carried on. However, many interesting
things were observed, and some additions made to our knowledge of
the species concerned.

Acknowledgments. — An expression of thanks is extended to the
members of the Burlingame Improvement Club, who made the cam-
paign possible, and particularly to their president, Mr. G. A. Pope,
whose encouragement and cooperation were greatly appreciated.
Thanks are also due the trustees and principal of the San Mateo High
School for allowing us the use of a room in the high school building
for laboratory purposes, and to Attorney George C. Ross, of Redwood
City, for the use of a room in his building at Millbrae for head-
quarters of the campaign in that section. Mention should be made also
of the Trustees of the city of San Mateo and the Board of Super-
visors of the county for their part in the cause in the way of legislation.

SOME COMMON FACTS ABOUT MOSQUITOES.

Since the present Bulletin is the first publication issued by the
Experiment Station on the subject of mosquitoes, and in order to
correct some erroneous ideas which prevail over the State regarding,
particularly, their breeding places and habits, an account of the better

MOSQUITO CONTROL WORK IN CALIFORNIA. 7

known facts, modified to apply to conditions in the bay region of the
State, is inserted here.

Life History.— The eggs of mosquitoes are laid, either singly or in raft-
like masses, in quiet water, which may be either fresh or salt, or in the
mud of drying pools. This latter situation, so far as observed, is selected
only by the salt-marsh species, and was first observed by Professor
Smith, of New Jersey, for the common salt-marsh species (Ochlerotatus
sollicitans) of the Atlantic Coast, and was also determined by us for
our common species (0. lativittatus) about San Francisco Bay. The
eggs hatch, in from one to four days, depending upon the species and
temperature conditions, and there emerges from the egg an active
creature popularly known as a "wriggler," which is the larval stage
of the insect.

This larval stage is passed in wTater, and not in alfalfa fields, freshly
sprinkled lawns, cypress hedges, and other equally impossible places,
as has been strongly maintained by many people whom we have met
with during the past year or two, among whom may be mentioned a
well-known Horticultural Commissioner, whose office is supposed to
require a certain knowledge of insects. Mosquitoes occurring in alfalfa
fields or recently sprinkled lawns may be accounted for from the fact
that they are attracted to moisture, but that they actually breed in
some 'water, possibly in the immediate neighborhood; in the case of
the alfalfa field it may be in the irrigation ditch. They gather about
cypress hedges in order to seek shelter from the strong winds. To
one who is familiar with the anatomy of the young mosquito it is diffi-
cult to conceive of them occurring anywhere but in water. The mouth
parts of the larval mosquito consist of a pair of hair-like brushes, which
are kept in motion most of the time, and their action is such that a
current of water, with all the small organisms that go with it, is
directed to the mouth and thus the larva gets its supply of food. Al-
though living in the water the larva is air-breathing, and obtains this
air by projecting a tube, situated on the posterior end of the body,
just above the surface film. Failure to obtain this supply of air very
soon results in the insect's drowning, and this largely explains the
effect of an insecticide, such as an oil, upon the surface of the water.
The oil forms an air-proof film over the surface which the larva can
not penetrate with its breathing tube. Thus the air supply is shut off;
besides, the oil itself undoubtedly acts directly upon the larva, as may
be inferred from the twisting of its body when it strikes the oil.

After molting or shedding its skin two or three times we have a
creature which looks like a larva coiled up at one end, and in this
stage it is the pupa. Now, instead of breathing through a single respir-
atory tube at the end of the body, it breathes by means of two respir-

8 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

atory siphons on the thorax. It may still be called a wriggler in
this stage, since it is capable of movement and will rapidly dart away
from its characteristic position at the surface of the water when dis-
turbed. Locomotion in this stage is accomplished by means of its flex-
ible abdomen, which bears at its tip a pair of swimming flaps. The
larval life of a mosquito lasts from one to three weeks, and the pupal
stage from two days to a week, depending upon the species and the
temperature and food conditions.

The adult winged mosquito emerges through a rent in the skin of
the pupa, and, after resting on this old discarded skin long enough
to dry its wings, it flys away, a fully developed insect, ready to begin
its active warfare upon man and other warm-blooded animals. It is
only the female, however, that seeks this source for its food supply,
the males not having developed a thirst for blood, and subsisting largely
upon the juices of plants. The length of life of the adult winged mos-
quito can at best only be approximated, but observations made during
the season just past show that they may live for three months, al-
though the great mass of them die in the course of three or four weeks.
The entire life cycle, therefore, may vary from two or three weeks to as
many months.

The number of broods appearing in a season depends upon the
species and the climate; the marsh mosquito, Ochlerotatus lativittatus,
in the San Francisco Bay region, was observed to produce a brood each
month from February to September inclusive, making eight in all,
while the common fresh-water form, Theobaldia incidens, breeds practi-
cally the year round in this region. Mosquitoes may pass the winter in
either of the three stages— egg, larva, or adult. The marsh species,
0. lativittatus, passes the winter in the egg state, while other species
of the sub-family Culicinae and one of Anopheles were found hiber-
nating.

Where Mosquitoes Breed. — In brief, mosquitoes will breed in any
quiet water; the water may be very foul or it may be very clean.
The}7 are not found in large bodies of water, except, possibly, near the
edges, but the small, insignificant pools are their favorite haunts. Not
a few people at Burlingame and Millbrae believed their mosquitoes
came from the Spring Valley lakes, and it was not until the present
campaign was carried well into the summer that they were convinced
of their error. On account of the continual rippling of the water in
these large bodies, and also because of the fact that fish are usually
present, no mosquitoes are found, barring the borders, in such situa-
tions. A very general breeding ground in the bay region of California
is furnished by the numerous creeks from the hills, drying up with the
cessation of rains and forming pockets and other stagnant pools along

MOSQUITO CONTROL WORK IN CALIFORNIA. 9

their course. Small containers of water, such as pails, barrels, or even
a tin can, may also furnish sufficient annoyance for a family during a
season.

Migrations.— People living in the vicinity of salt marshes must look
beyond their immediate neighborhood, and decide whether or not a
marsh at a considerable distance away is not furnishing them with
their supply of mosquitoes. This makes the problem of control work
much more difficult in such regions, and little can be done without
a general movement in which the whole community participates. The
salt-marsh mosquito in New Jersey has been known to migrate thirty
or forty miles, and we have observed our California species at least
ten miles from any breeding ground. The wind is an important factor
here, and usually such migrations occur only with a favorable wind.
For example, the Burlingame mosquitoes came from the marsh to the
north, from where the wind could easily carry them into the district.

Collecting and Studying Mosquitoes.— The collecting of larvae and
pupae is best accomplished by means of a small net, as shown in Fig.
1. This net is made by bending a heavy wire in the form as shown,
the ends being soldered into a ferrule to re-
ceive the handle, and over this frame is sol-
dered a wire screen of fine mesh. It is an
advantage to have the wire tight for the easy
transfer of the materials to the vials. A. net
measuring four or five inches across was
found to be the most convenient size, a larger

. . _ FIG. 1. Insect net.

net not being easy to manipulate among vege-
tation or in small pools or cracks. To transfer the specimens into
vials a small camel 's-hair brush will be found most convenient, or, in
the absence of this, the mouth of the vial may be placed so as to
inclose them and the insects washed in by the water of the vial. Eight-
dram homo vials are suitable for the larvae, and these should not con-
tain too much water, and should be brought to the laboratory with as
little jarring as possible, else the specimens will drown. A few may
be reared in these vials, but if there is a quantity, or the specimens are
newly hatched, they should be transferred to larger vessels where there
is a greater food supply.

For preserving larvae for future study they should be killed with
hot water and run through the grades of alcohol and finally preserved
in 95 per cent alcohol. A mixture which was found to preserve the
form and color well consisted of 5 per cent of glycerine, 2 per cent of
formalin, and water. Larval skins should be preserved for studying
the chitinous parts, or in the absence of these, specimens may be
treated in weak potash solution.

10

UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

The adults may be collected by means of vials, which are placed
over the specimens as they are resting upon the hands or clothing, or
by means of the ordinary insect net. The latter way should be used
especially for collecting males in the vicinity of the breeding ground.
Of course, the most preferable means of securing the adults is to rear
them from the larvae. They should be mounted immediately after
being taken, either on small paper triangles or with very fine pins.

FIG. 2. Anopheles.

MOSQUITOES AND DISEASE.

It is now a well-established fact that several species of mosquitoes
are the active disseminating agents of at least two or three kinds of
contagious disease. Space here will not permit of the many interesting
facts, or the conclusive proof by experimentation that has resulted from
investigations carried on along this line in recent years; but readers
who are interested in more than a mere statement of facts are referred
to special articles dealing with insects in their connection with disease.

MOSQUITO CONTROL WORK IN CALIFORNIA.

11

Malaria and Mosquitoes.— The old theory that malaria was caused by
miasma or swampy air has now given way to the more modern and
experimentally proved fact that mosquitoes belonging to the particular
genus Anopheles are responsible for the spread of this disease. The
Anopheles mosquito detains the malarial protozoan from the blood of a
malarial patient, which, after going through a course of development
within the body of the mosquito, is ready to be transferred to the
blood of the next person bitten by the mosquito.

This genus of mosquitoes should be known by every one, and Figs.

FIG. 3. Theobaldia.

2 and 3 should make this distinction clear. The Anopheles, it will be
•seen, has spotted wings, but this is not a character peculiar to the
genus, since the commonest species of Theobaldia, here figured from
the bay region of California, has spotted wings. The three appendages
projecting from the head of Anopheles are entirely characteristic, while
in the Culicinae there appears to be but one long process, the beak.
These, which occur on either side of the beak in Anopheles, are the
palpi, and are always as long as the beak, but in the Culicinae they are
short and inconspicuous in the females. The males are distinguished
by their bushy antennas, but since these do no biting, it is important to
know only the distinguishing characters of the females, as shown in the
figures. The figures also show the characteristic resting positions of
the two genera.

12

UNIVERSITY OP CALIFORNIA— EXPERIMENT STATION.

In Figs. 4 and 5 the normal position of the larva of a Culicinae and
Anopheles is shown — Theobaldia with its long breathing tube and hang-

FIG. 4. Anopheles larva.

FIG. 5. Theobaldia larva

ing at an angle, while the Anopheles has a short breathing tube and is
parallel with the surface of the water, and is a surface feeder, while
the Culicinae obtains its food from beneath the surface.

MOSQUITO CONTROL WORK IN CALIFORNIA.

13

There are three species of Anopheles in California, but only one,
Anopheles maculipennis , has been actually demonstrated to transmit
the malaria protozoan. The other species, however, are likely to do so,
and until they are proven incapable of acting as a host for the para-
site they should be regarded with some respect.

Mosquitoes and Filariasis.— The dreaded and incurable disease known
as filariasis, which is confined mostly to the tropics, is now known to
be transmitted from one patient to another by mosquitoes. This dis-
ease manifests itself in several forms ; one of the most common, known
as elephantiasis, attacks as many as a third of the natives in some of
the tropical countries, and invariably proves fatal.

Mosquitoes and Yellow Fever. — Yellow fever was, up to the last few
years, thought to be spread by fomites or contact with clothing or other

FIG. 6. Pupa of a mosquito (Theobaldia).

belongings of fever patients; but the investigations of our United
States army surgeons in Cuba in 1900 overthrew this conception re-
garding the spread of the disease, and proved by actual experiment
that the disease was transmitted by a certain species of mosquito
(Stegomyia fasciata). As a result of this knowledge the disease has
been practically stamped out of many places where it was formerly
prevalent, among which may be mentioned Havana, in Cuba, where it
is no longer dreaded in the degree that it was formerly.

Still more recent history has been made in New Orleans during the
past summer, and while there were a good many deaths, the disease
did not spread or cause the alarm that former epidemics have occa-
sioned, for the reason that the etiology of the disease was better un-
derstood. According to statistics compiled by Dr. J. H. White, of
the United States Public Health and Marine Hospital Service, the
total number of known deaths in the entire South up to October 15th

14 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

was 924. When it is understood that there was a total of 616 dead
and prostrated victims (according to the Interstate Medical Journal)
by the time the work of eradication was well under way, the results
are remarkable. In a letter just received from Dr. L. 0. Howard, of
the Department at Washington, he has assured us that all of the
preventive work carried on there by the State and city authorities
and of the United States Public Health and Marine Hospital Service
was directed solely against the yellow-fever mosquito. The work in-
cluded the screening of tanks, treating the gutters with oil, and other
measures looking toward the abolition of the breeding places ; the fumi-
gation of houses containing fever patients in order to destroy the adult
mosquito, and the protection of patients by netting in order that the
mosquito should have no opportunity to bite and later convey the disease.

THE PRESENT CAMPAIGN.

The Territory. — The territory involved in the present campaign is
included in the upper portion of the San Francisco peninsula, ex-
tending from South San Francisco on the north to San Mateo on the
south, a distance of about 10 miles. The average width of the peninsula
here is 10 or 15 miles. Extending midway between ocean and bay are
two parallel chains of hills, the one on the bay side averaging 500 or
600 feet above the sea, while the chain on the ocean side attains a
height of 2,000 feet at the south and gradually decreases toward the
north to 100 or 200 feet. The streams rising in these hills flow rapidly,
either into the bay or ocean, or into the chain of lakes which has been
made artificially between the hills, and is the source of San Francisco's
water supply. Beginning near South San Francisco, on the bay side,
and extending well across the peninsula, about parallel with the other
chains, is a ridge of 1,000 to 1,300 feet, which is known as the San
Bruno Mountains. This, together with the other two ridges (see map),
incloses a low area or depression not more than 200 feet in elevation,
and it is through this draw that many of the winds come from the
ocean, and are diverted by the San Bruno Mountains toward the south-
ward along the bay shore. In addition to this the winds entering the
Golden Gate are spread to the north and south along the bay, and it
is from these two sources that most of the winds of the territory find
their way from the ocean. Because of this prevailing direction of the
wind, the troublesome area on the marshes will lie largely to the north-
ward of a mosquito-infested district. It was on this basis of winds that
we came to the conclusion in the present campaign that the control work
should be done from San Mateo northward, and little attention paid to
the territory to the south; and the results have fully confirmed this
conclusion.

F

^s

8.

MOSQUITO CONTROL WORK IN CALIFORNIA. 15

The salt-marsh area included in this campaign consists of a narrow
strip along the San Francisco bay shore, varying from % to 2 miles in
width, and 10 miles long, or from San Mateo to South San Francisco.
No part of this area is continually covered with water, and it is all
above the lowest high tide. The higher tides, however, particularly
those accompanying full moon, almost completely submerge the area.
Extending from opposite Millbrae to the south, along the bay, is a
diked area of 500 or 600 acres. This dike was built about fifteen years
ago, and, excepting for a year or two after completion, has been
neglected, and consequently in very poor repair.

Extending over the entire marsh area is a complete network of
tidal creeks, which wind about in all directions, and thus furnish a rapid
drainage during low water. This fact also greatly simplifies the drain-
age problem, since no long ditches need be cut. The vegetation on the
marsh land consists of the common pickleweed (Salicornia ambigua) ,
which is the characteristic plant, and the finer salt-grass (Distichlis
spicata), which borders the pools and tidal creeks. There are no
tules or large rushes on this marsh, since there is no part of it that is
more or less continuously submerged with water.

What Was Done on the Marsh. — The actual work of control was
commenced February 27th, when a gang of men was started to work at
ditching on the salt marsh. This work was started near the Blackhawk
dairy, where the marshes begin north of Burlingame, it being the in-
tention to work northward toward San Bruno, and make the work
permanent as far as we would be able to go in a single season. How-
ever, the work went rapidly and the troublesome areas north of Mill-
brae were not so numerous as was figured, and consequently practically
the whole area was covered during the past season.

The ditching in the Blackhawk area consisted in connecting the pools
and areas of standing water with the tidal creeks in order that they
might drain more rapidly and before a brood of mosquitoes would have
time to develop. The largest of these ditches were 12 inches wide and
about 15 inches deep, and these served as main channels into which
smaller laterals were cut. These laterals, and, indeed, the greater part
of all of the ditches, were but one spade wide, and one or two spades
deep, according to the depth of the pool to be drained. Only where
the pools were very large and a great quantity of water to run off in
a short time was it necessary to make larger ditches. By "a spade"
here is meant the common California spade, which is about 6 inches
wide and 10 inches high. The Eastern drain spade has not yet found
its way to California; undoubtedly it would be preferable for the
deeper ditches in this kind of work. In addition to the well-defined
pools there was a considerable area in the Blackhawk region which

r.'

t^!#.C

* >«*^ •

w, \

FIG. 9. One of the main laterals, into which were cut smaller ditches.

FIG. 10. A large tidal creek in the diked area, almost dry.

MOSQUITO CONTROL WORK IN CALIFORNIA.

17

was covered with but a few inches of water for a considerable time
after each high tide, and before the rains ceased in the spring water
stood over this area almost continuously. Such areas had to be treated
by making a number of parallel ditches from 50 to 75 feet apart, in
order to permit of sufficiently rapid drainage. Rather extensive ditch-
ing was done here to make the area safe while the rains were still con-
tinuing, while later in the season, when the rains ceased, it would have

FIG 11. The lower gate on the dike, showing automatic gate in front of old one

manipulated by screws.

been safe with much less ditching. Small pools that were far from
tidal creeks were made safe by filling in rather than draining. The
size of the pool, and the length of ditch necessary to drain, will deter-
mine which of the methods is to be followed. In this way the marsh
area was gone over, doing away with all the places where larvae were
found or were likely to be found, for a distance of about a mile along
the bay northward, where the diked area was met with.

This part of the marsh presented a more difficult problem. The
2-Bul 178

18 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION.

dike, having been neglected for ten or twelve years, was in poor con-
dition, and there were several breaks in the upper end near Millbrae.
The gates were not in working order, and their floors were too high to
drain the area inclosed.

The breaks in the dike at the upper end permitted the water to back
up at the opposite side, and this, together with the fresh water from
the hills, kept the water level, at almost high tide, over a large part of
the area. To make matters worse, the dike, just after it was built, was
in effective operation just long enough to thoroughly dry the ground
and cause it to crack. These creeks, which are 4 or 5 inches wide and
2 or 3 feet deep, still exist, forming a complete network over most of
the area. Mosquitoes were found breeding in this area, and it was next
to impossible to get over the ground, even with waders. A consider-
able part of the area was submerged to the depth of a foot or more,
thus concealing from view the cracks and tidal creeks, which one was
likely to fall into at any step, and which made any attempt at rapid
progress somewhat discouraging.

It was at once evident, under these conditions, that if the area was
to be controlled, the dike must be either cut through in a number of
places in order to allow a freer circulation of water, or the breaks must
be repaired and the gates put in operation, and the water kept out.
The latter scheme was the one followed, because it would be possible to
make the area thoroughly dry, and thus the results would be more
certain. In attempting to operate the gates we were made to appreciate
the effect of a ten or twelve years' coating of rust on the large screws
by which the gates were manipulated. After the gates were put in
operation the breaks in the dike were repaired and the weak places
strengthened. The largest break repaired was immediately joining
the upper gate. This was 30 feet wide, and by the action of the water
had worn down so that at high tide there was a depth of 10 feet of water.
A double wall of sheet piling about 6 feet apart was sunk here and the
space between filled in with earth. The other breaks were repaired by
sinking a single wall of sheet piling in the center and filling in on both
sides with dirt.

After these repairs were completed the gates were operated, opened
at low tide and closed at high tide, for a week, but at the end of this
time there was still much water in the area, because the gate floors were
not low enough to lower the water level sufficiently. This made it
necessary to lower the gate floors and add an extension to the gates
to reach the lower level. This being done the gates were again operated
for several days, but it was found that, due to seepage of water through
the dike in many places, hand operating would have to be kept up
almost indefinitely. It was, therefore, necessary to replace these old-

*<FIG 12. Upper gate on dike. On right, double wall of sheet piling shows manner of

repairing large breaks.

FIG. 13. Upper gate on the dike. Beam in center shows former level of floor. Repair work on left.

20

UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

style gates, operated by hand, by automatic ones, and these were,
consequently, put in at both the upper and lower gates, and the floors
lowered 32 and 20 inches respectively. These gates were made to
swing on an axle at the top, the lower end being free and easily moved
by the pressure of the water, so that at low tide it was opened by the
pressure of water on the inside, and closed as the water from the high
tide rose on the outside.

The tidal creek which served as an outlet for the lower gate had
become filled in to a depth of 2 or 3 feet during the period the gate
was closed, and this was cleaned out for 300 or 400 yards toward the
bay in order to drain out the area inclosed by the dike.

FIG. 14. A typical hand-made ditch on the marsh.

With this work done upon the dike the area inclosed by it was treated
in much the same way as that outside, except that the network of cracks,
already mentioned, had to be filled in in many places, and several of
the tidal creeks deepened. The reward for all this work came later
in the season when the area was changed from a veritable breeding
ground to the safest portion of the marsh. Indeed, this area was the
key to the situation, and the excessive abundance of mosquitoes in this
particular territory was without doubt due to this extensive breeding
ground.

It is appropriate to mention here the connection of this work with
the reclamation of marsh lands. This tract of 500 or 600 acres, which
had been useful only for duck-hunting, is now thoroughly dry and
could be put to agricultural uses at very little additional expense. Such

MOSQUITO CONTROL WORK IN CALIFORNIA.

21

work has already been extensively taken up on the marshes below San
Mateo, and it has been found that a good crop of grain can be raised on
such land in the second year of its cultivation.. It is safe to predict
that all the marsh land involved in the present campaign will be under
cultivation before many years, and because of its proximity to the
metropolis of the coast should be very valuable.

Besides the marshes already mentioned, permanent control work was
done on the marsh about Millbrae and northward to San Bruno, and
also some drainage work at Coyote Point, opposite San Mateo. The
work at these places was much the same as that already described, and
further details are unnecessary.

FIG. 15. A large fresh-water pond. A favorite place for Anopheles.

In addition to this permanent work there was some oiling done on
the marsh where the ditching and filling work were not rapid enough
to keep ahead of a developing brood. The total amount of oil applied,
however, did not exceed 400 gallons, and most of this was applied
to the large tidal creeks in the reclaimed land opposite San Mateo.
The remainder was applied to pools where wrigglers appeared after a
high tide, and, the brood being checked, we had until the next high
tide in which to make the pools permanently safe.

The Fresh-Water Problem. — The fresh-water problem is a compara-
tively easy one in this section, because of the good drainage toward the
bay, and because of the cessation of rains in the early spring. Pools
and creeks that once become dry require no further attention during

22 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

the season, and this greatly simplifies control work against fresh-water
forms in arid climates like that of California. The most troublesome
breeding places for fresh-water mosquitoes in the Burlingame section
are in the numerous creeks coming down from the hills. Some of these
dry up very soon after the rains cease, but in others there may be
standing pools until late in the summer. These pools are due generally
to seepage which may make its appearance at different places along the
course of the creek.

During the present season most of these creeks were oiled and a few
were drained. Where the creeks soon become dry one application of
oil may be sufficient, and this is almost as satisfactory as draining,
since, owing to the heavy rains of winter, and the swift current, debris
is lodged in some places and holes made in others, so that the creeks
must be gone over every season. Moreover, many of the creek beds

FIG. 16. Same pond after drainage. Outlet in background.

along a part of their course are in solid rock, which makes draining
difficult. However, in spite of these objections, the experience this
year would warrant drainage, especially in the creeks where the water
remains in pools and pockets for several months after the winter rains.
In addition to the creeks already mentioned there are a few fresh-
water ponds in the territory, but the worst one of these has been drained.
This pond was on the Easton property, half a mile north of the
Burlingame depot, and was a favorite breeding place for the malarial
mosquito (Anopheles maculipennis) . The owner of the property
drained this pond at his own expense, which not only made useful a
tract that was formerly a waste, but also added to the value of the
land in the immediate vicinity, which has since been subdivided into
residence property, to say nothing about the riddance of the malarial
and other mosquitoes. The ditch draining this pond was made with

FIG. 17. Cutting the ditch for drainage of Easton pond.

FIG. 18. Cutting the ditch for drainage of Easton pond.

24

UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

horses and scrapers, and is 12 feet wide at the top, 4 feet at the bottom,
and from 3 to 5 feet deep.

A considerable amount of oiling was done on the fresh-water areas,
the permanent work having been pretty largely restricted to the marsh
lands. The oil used was a combination of heavy oil of 18 degrees
gravity and light oil of 34 degrees gravity, in the proportion of four
to one. This mixture made an oil that was just thin enough to spray
well from an ordinary spray nozzle, and yet was thick enough to
withstand very rapid evaporation. It was applied by means of a barrel

FIG. 19; The ditch after it was completed.

pump, where this could be used, but in the creeks and other situations
which could not be reached by horse and wagon, the ordinary knapsack
pump was used. The price of the heavy oil at Burlingame was 2 cents
a gallon, while the lighter oil was 2% cents a gallon. The former was
obtained from the Bakersfield district, while the latter was a product
of the Coalinga fields. The number of applications of oil depended
somewhat upon the nature of the pool and its exposure to winds, but
in no case could it be counted as thoroughly effective after a period of
four weeks.

MOSQUITO CONTROL WORK IN CALIFORNIA.

25

Suggestions for Future Work. — It is, of course, impossible to cover
all of the ground completely in a single season, and while no breeding
place on the marsh escaped us this year, new ones are likely to appear
in the future, so that the territory should be gone over for two or three
years, or until every possible breeding place is rendered safe. The
large tidal creeks opposite San Mateo harbored mosquito larvae during

FIG. 20. Draining in one of the typical fresh-water creeks of Burlingame.

the past season, and are likely to give trouble again next year. Mos-
quitoes from this breeding ground, however, may not get as far north
as Burlingame, but they will certainly reach San Mateo, which is just
opposite. There is also a small creek running alongside the road at the
Burlingame wharf that should be attended to during the coming season.
This was oiled during the past summer, but it is troublesome up to
July, and should be drained by putting a culvert through the road to
the bay. In this culvert should be built a self-operating gate, which

26 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION.

will allow the water of the ditch to pass out, but prevent the high tide
from entering again. The gates on the dike should be visited occasion-
ally to see that they are in working order, and are not kept from
closing by timbers which are likely at any time to drift in and lodge
in the gate. The dike should also be inspected for breaks or weak places,
particularly at the upper end opposite Millbrae.

On the fresh-water area all standing pools which are formed by the
late spring rains should receive attention by either oiling or draining.
It is recommended that the least amount of oil that must be used the
better, and that all the work should be permanent, where it is at all
possible, and this includes practically everything. The creeks should
be attended to immediately after the rains cease and drained by either
cleaning out the creek bed or filling in the holes, or both. Lastly,
every one should look to his own immediate premises and see that such
containers of water as horse-troughs, fountains, pails, or tin cans
are not furnishing mosquitoes for the neighborhood. In a city, or
thickly settled residence country such as Burlingame, community effort
is essential.

Fish vs. Mosquitoes. — A part of the plan of the present campaign
included the carrying out of some large-scale experiments on the use of
fish as a means of keeping the salt-marsh mosquito in check. However,
when the typical breeding place of this mosquito was well understood,
the idea was soon abandoned as impracticable. Where there were no
permanent pools, which were necessary for the maintenance of the fish,
there were no mosquitoes; whether this was due entirely to the fish we
are not yet ready to answer. So far as our present experience goes the
salt-marsh mosquito {Ochlerotatus lativittatus) prefers mud to water in
which to lay its eggs, and it is possible that the eggs would not be laid in
these permanent pools where fish are present. Whether the eggs are laid
here by preference of situation or through instinct in keeping away
from the fish is a question difficult to answer, but the fact remains that
it is the exception that mosquitoes are found in the salt-water pools
where fish are present.

But this is not all of the question. Practically all of the salt-marsh
mosquito larvae in the present campaign were in situations which were
unsuitable for fish, situations where fish would perish in a very short
time were they introduced. These situations are the pools that depend
entirely for their existence upon the monthly high tide, and which
dry up in from a week to three weeks thereafter. In order for fish to
be effective here they would have to be introduced after every high tide,
an operation which would be, obviously, impracticable. Fish are con-
sidered by zoologists as being a rather successful group in the struggle
for existence, and favorable situations for their development will usually

9. A

FIG. 21. The oiling outfit.

FIG. 22. Oiling in the creeks.

28

UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

be found stocked with them. And so in the present territory all per-
manent pools were pretty well stocked with fish. Of course this does
not preclude the feasibility of introducing carnivorous species in terri-
tories where they are not now predominant, or where the species are less
carnivorous, or wholly vegetable-feeders. But even in ponds that may
contain an abundance of fish in the freer water of the middle, the
vegetable tangle of the borders may be pretty well stocked with larvae,
where they breed undisturbed by most fish.

In a letter under date of October 9th from President Jordan, of
Stanford University, he states that the only fish likely to destroy mos-

FIG. 23. Making a ditch for diverting water, which formerly spread over a wide area, to a

definite channel.

quito larvae to any extent in the San Francisco Bay region, would be
the stickleback (Gasterosteus cataphractus) . We have found this species
in the permanent clear-water pools mentioned above, and it may be
effective in keeping the mosquitoes down here; but this fish, like all
the others, does not reach the pools where the mosquitoes really are;
that is, the temporary pools and areas formed by the higher tides.
In reservoirs, or fresh-water ponds artificially formed, or in fountains
and the like, or in the introduction of carnivorous forms in permanent
pools where they are not now present, fish must be considered as a
factor in mosquito control; but the mass of mosquito breeding-places
are beyond the limits of the typical environment for fish.

MOSQUITO CONTROL WORK IN CALIFORNIA. 29

Other Natural Enemies.— Besides fish there are several species of
insect relatives that prey upon the mosquito in both its aquatic and
adult life, and which are, to some degree, effective in keeping the num-
bers within reasonable limits.

The larvae of dragonflies are carnivorous in habits and feed upon the
mosquito larvae to some extent, but, like most of the other natural
enemies, they have been given all the credit, and probably more than
they deserve. We have found mosquito larvae common where there was
an abundance of dragonfly larvae in the pond, but in such situations
larvae were never seen to be fairly swarming, as they were in smaller
pools that were free from enemies of all kinds. Where dragonfly larvae
occur it is not unusual to also find fish, since dragonflies require the
greater part of the year, or more, to go through their development, and
hence require more or less permanent pools.

The larvae of the predaceous diving beetles (Dytiscidae) were also
found in places where water exists, at least for the greater part of the
year. These larvae are voracious eaters and are more active than the
sluggish dragonfly larva?, which prefer the mud or slime of the pond
bottom, and are no doubt more effective, individually, than the latter;
but in this territory they were never found to occur in large numbers.
Bodies of water that are favorable, therefore, for the development of
one kind of enemy usually harbor a variety of enemies, and all of these
taken together are effective in keeping the numbers of mosquito larvae
from becoming excessive.

There are several species of water bugs, including the water boatman
(Corisiclae) , water striders (Gerridae) , backswimmers (Notonectidae) ,
and water scorpions (Nepidae), that prey upon mosquito larvae, and
these may be found in less permanent pools than those already discussed.
A species of water boatman (Corisa) occurred in immense numbers in
some of the more permanent pools of the salt marsh, and in these pools
no mosquitoes were present. But there are too many conditions enter-
ing in to ascribe the absence of mosquitoes to this particular bug. In
several fresh-water pools where the water strider was abundant, mos-
quito larvae were seen in great numbers, and these water bugs seemed
to have no effect on the number of larvae. Of course, there was enough
difference in the numbers to make the supply of food far beyond the
demands of the enemy, but this too often occurs with the slower- develop-
ing predaceous enemies of the mosquito.

In general, in the present territory, the typical breeding places for
the mosquito are not the typical breeding places for most of its enemies.
The mosquito being more prolific and the number of broods so much
greater than most of its enemies, it persists in spite of them, and,
moreover, its distribution extends beyond the limits of most of its
enemies, which are restricted to more permanent breeding places.

30 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

Bluestone as a Mosquitocide.—A number of experiments were carried
on to test the value of copper sulfate for the destruction of mosquitc
larvae, but, since the results were essentially the same as those already-
given in detail in Prof. Smith's New Jersey report and also described
by Marlatt in Science for April 21, 1905, only the general conclusions
suggested by the experiments will be given here.

The value of bluestone as an insecticide depends largely upon its
power of destroying the small organisms, particularly algae, in the
water and thus depriving the larvae of food. . Obviously, this will be of
little use against pupae or nearly full-grown larvae, and in our experi-
ments these invariably developed into adults. Some large-scale experi-
ments were carried on in the field, but these proved more unsatisfactory
than those carried on in the laboratory. For example, a cattle-guard
on the railroad at Millbrae was fairly swarming with larvae and pupa^
of incidens, and copper sulfate was used at the rate of 1 to 1,000, much
beyond the practicable strength, yet adults continued to emerge in
great numbers. Indeed, there was no effect observed excepting that
a few of the younger larvae were killed. The water here was, to be sure,
very foul and the case was an extreme one, but in other clearer pools
the results were almost as unsatisfactory. Since in the present cam-
paign it was our business to keep down the mosquitoes, we could not
afford to prolong these negative field tests ; but if copper sulfate is to be
used at all it should be applied very soon after the eggs hatch, since
it is too slow acting to be of value against the later aquatic stages.
Its use is no doubt limited to reservoirs or small bodies of clean water
where it will not be precipitated so rapidly.

Eucalyptus vs. Mosquitoes.— It is recorded in some books, and we
have heard it stated on two or three different occasions during the past
year by physicians, in lecturing on mosquitoes and disease, that the
eucalyptus tree is effective as a repellant, and that where these trees
exist no mosquitoes will be found. In the Burlingame section all of
the numerous winding avenues are lined with eucalyptus; there are
eucalyptus along the highways, and there are groves of eucalyptus ; yet,
where these trees are most abundant it might be said that the mosquitoes
are most numerous. It was here that the first shipload of cuttings,
imported from Australia, were planted, and the eucalyptus tree is the
predominant cultivated tree of the territory.

During the summer of 1904 we captured in five minutes' sweeping,
immediately under eucalyptus trees, a pint cup full of mosquitoes !
Coyote Point, on the bay shore, has long been known by the residents
in the neighborhood as a famous place for mosquitoes; indeed, the
construction of a hotel at this point which has been under contemplation
for some time is said to have been abandoned because of the abundance

MOSQUITO CONTROL WORK IN CALIFORNIA. 31

of mosquitoes, yet this point is covered with eucalyptus trees. It should
not be understood from what has been stated that the eucalyptus tree
attracts mosquitoes. It does this only in so far as it affords shelter, and
other trees will do this as well, indeed much better, as for example the
Monterey cypress with its denser foliage, which is so common in this
section. So far as the experience in this locality is worth anything,
people need not entertain very high hopes of the mosquito pest disap-
pearing through the planting of the eucalyptus tree.

LEGISLATION.

The citizens of the city of San Mateo had been active for some
years in fighting the mosquito, but because of a lack of knowl-
edge of the situation, no very effective work was done. The fresh-
water areas were pretty well attended to, but mosquitoes were still
present, and these, as we observed during the season of 1904, were
of the salt-marsh variety. The fact that mosquitoes breeding on the
salt marsh migrate a considerable distance was not generally known
among the people of San Mateo, as is the case in most communities,
unless they have kept in close touch with the progress of mosquito-
control work. During the past year quite effective work was done,
through voluntary subscription, in keeping in check the fresh-water
species in the immediate vicinity. And this, together with the work
done by the Burlingame people, kept the city quite free from mosquitoes
during the past summer.

In order to make this work permanent, and, incidentally, to have
some check upon the obstreperous person who is still living in some past
age regarding his and his neighbor's welfare, the following law was
passed ; first by the trustees of the city of San Mateo, and later by the
board of supervisors of the county.

The following is a copy of that law :

ORDINANCE No. 106.

An Ordinance Forbidding the Maintenance of all Places Breeding Mos-
quitoes, Declaring Such Place a Nuisance and Providing a Penalty for
the Violation of the Ordinance.

The Board of Trustees of the City of San Mateo do ordain as follows:

Section 1. All pools of water, or other places in which mosquitoes are being
bred, are hereby declared to be a public nuisance. The Board of Health of San
Mateo is hereby given authority, and it is made its duty, upon the complaint, in
writing, of any resident of said city, to condemn as nuisances, any such pools of water
or other places in which mosquitoes are being bred, and order the summary abate-
ment thereof.

Sec. 2. Upon being notified by such Board of Health, of the existence of such
pools of water or other places in which mosquitoes are bred, and that the same has
been declared a public nuisance by said Board of Health, it shall be the duty of the
person or persons responsible for the maintenance thereof, to forthwith abate such
nuisance, and all persons refusing or neglecting to forthwith abate such nuisances

32 UNIVERSITY OP CALIFORNIA — EXPERIMENT STATION.

as directed by said Board of Health, shall be deemed guilty of misdemeanor, and
upon conviction thereof shall be fined not more than fifty (50) dollars, or to be
imprisoned in the county jail not more than twenty-five (25) days, or by both
sucli fine and imprisonment.

Sec. 3. This ordinance shall take effect and be in force from and after fifteen
days after its passage.

Introduced the 24th day of July, 1905.

Passed and adopted as an ordinance of the city of San Mateo, this 17th day
of July, 1905, by the following vote :

Ayes, and in favor of the passage of said ordinance — Trustees J. H. Hatch, Geo. A.
Kertell, M. J. Powers, J. P. Weller, W. H. Brown.
Noes, and against the passage of said ordinance — None.
Absent — None.

Wm. H. Brown,
President of the Board of Trustees of the City of San Mateo.
[seal.] Attest: R. H. Jury,

City Clerk and ex-officio Clerk of the Board of Trustees
of the City of San Mateo.

1 " ... '■". — r*"t ■> — . ■ ' . ■ , : — 7! "

i^Ks&S-r . 0 ■ •

pP

*> - * V*J

v, ~; ^ :**

FIG. 24. Scene in the Burlingame gardens in 1904. Workmen were obliged to wear
netting for protection against mosquitoes. Such apparatus was not seen in 1905.

RESULTS OF THE CAMPAIGN.

During the summer of 1904 the mosquitoes in the Burlingame district
were almost intolerable. Gardeners and other workmen were obliged
to wear mosquito netting for protection. In walking along the roads
in the vicinity of the hills mosquitoes would gather so abundantly on
one's clothes that sometimes the color of the suit was almost obscured
beneath the general effect of the light brown produced by the marsh
mosquito. It has been stated in another connection that on one occa-
sion a pint measure of mosquitoes was captured in five minutes' sweep-
ing ! These were, without exception, Ochlerotatus lativittatus from the
salt marsh.

Owing to the delay due to the extensive repairs on the dike, a brood of
mosquitoes emerged from the diked area before our control work became

MOSQUITO CONTROL WORK IN CALIFORNIA. 33

effective. They consisted, partly, of the brown marsh species, Ochlero-
tatus lativittatus, but mostly of the gray marsh species, L. squamiger.
These made their way to the hills opposite their breeding ground, and
squamiger got as far south as Burlingame and San Mateo, while lativit-
tatus was limited to the territory about Millbrae. Squamiger was rather
abundant at Burlingame during March and April, but gradually dis-
appeared until late in June, when no more were seen during the season.
An occasional incidens was sometimes met with, due to the fact that
a few fresh-water pools escaped treatment; but their numbers were so
few as to be hardly noticeable.

Regarding the brown marsh species (Ochlerotatus lativittatus) which
were so abundant and vicious in preceding years, and against which the
main work of the campaign was directed, the rather remarkable result
was obtained that throughout the entire season in the Burlingame section
not a single specimen was seen. This mosquito, then, was practically
annihilated for a distance of 10 miles along the bay shore, and, had we
been able to get on the diked area earlier, squamiger would undoubtedly
have met a similar fate. As it was, it gave practically no trouble after
May, and completely disappeared by July. It may be argued that the
season or some other condition had something to do with the results.
But the fact that they were abundant enough in other situations about
the bay, and that this early brood gave promise of a good season for the
mosquito, would indicate that the control work was the chief factor in
the problem, in view of the fact that millions of larvae were killed on the
marsh.

The ultimate results of such a warfare against mosquitoes can
hardly be realized. Before the campaign was well started, it had a
direct influence upon the real estate of the district, and many people
were induced to locate in the territory largely on the basis that the
mosquito nuisance was solved. This region is essentially a country of
homes, and many of the people of wealth, having their business interests
in San Francisco, come here to live during the summer. They come
here in order that they may live out of doors, and with hordes of
hungry mosquitoes waiting to devour them, as was the case in previous
years, the desirability of inaugurating a warfare against the pests can
at once be appreciated.

THE SPECIES CONCERNED.

The four commonest species, and the only ones that counted very
largely in the control work, were : Ochlerotatus lativittatus, Theobaldia
incidens, Culex tarsalis, and Lepidoplatys squamiger. These are treated
in detail in the following pages, while there is added synoptic tables
for determining the adults, and a bibliography of all the species known
to occur in California.
3— Bul 178

34

UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION.

Ochlerotatus lativittatus.

Habits of the Early Stages.— The eggs of this species are laid, so far
as our observations go during the past year, in the mud of pools which

4

cf

7

<5~

70

//

•4>7n%

FIG. 25. Claws of Mosquitoes.

1, 2,

3 — First, second and third of Culex tarsalis.
6— First, second and third of Theobaldia incidens.
9— First, second and third of Lepidoplatys squamiger.
10, 11, 12— First, second and third of Ochlerotatus lativittatus.

4, 5,

7,

are formed by the monthly high tide, and which dry up before the suc-
ceeding high tide reaches them. This was demonstrated several times
during the season by taking mud from such pools and submerging it

MOSQUITO CONTROL WORK IN CALIFORNIA.

35

with ordinary sea water, when the wrigglers would appear in from
three to four days. Another method of determining this egg-laying
habit consisted in sinking ordinary soap boxes, the bottoms first being
removed, to a depth of two or three inches in the mud of pools where
larvae were likely to appear. These boxes were thoroughly screened on
the top to prevent any possible entrance of adults, and were kept from
floating away with the high tides by means of stakes driven into the
ground. When the high tide reaches the pool the mud inclosed by the

FIG. 26. A typical breeding pool on the salt marsh.

higher tides.

Reached only by the

box would be covered with water through seepage from below, the box
being high enough to allow no water to enter at the top, thus allowing
no possible chance for the eggs to be deposited in the water. In a few
days larvae would appear in the box in as great numbers proportionally
as in the pool outside the box. This egg-laying habit was further verified
by the fact that throughout the season there were no instances recorded
where larvae appeared in permanent pools, or, at least, where there was
not a perceptible lowering of the water, where eggs could be laid at the
borders.

36 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

About the middle of May of the present year, in a letter addressed
to Professor Smith, of New Jersey, we stated that larvae had then just
begun to appear in the large tidal creeks on the reclaimed land opposite
San Mateo, and questioned the fact that in this case the eggs were laid
in the mud. Our observations since that time, however, tend to show
that, even here, the eggs were laid in the mud of the creek borders. We
were led to doubt the habit of depositing eggs in the mud here because
up to this time no larvae had appeared, and there was no perceptible
lowering of the creek, while in the smaller pools larvae had been appear-
ing for a couple of months.

We now believe that this lateness of the larvae was due to the tem-
perature of these large bodies of water not being sufficiently high to
favor the development of the eggs. These creeks were also seen to lower
considerably later in the season, which would afford abundant oppor-
tunity for egg laying at the borders in the previous season. Moreover,
larvae in the smaller pools appeared more abundantly each month until
June, despite the fact that no adults were seen in the vicinity during
the present season. This can be accounted for only through the fact
that the eggs which were laid during the previous season did not all
hatch with the high tides of early spring, the great majority not appear-
ing until the higher temperature of May and June.

The larvae of this species are not confined to brackish water only,
or to normal sea water, but may develop abundantly in water of a
higher saline content than even sea water. The water in a number of
instances where lativittatus larvae were found tested 4.5 per cent of
salt, or 1 per cent higher than normal sea water.

An experiment to test the effect of a change of these larvae to fresh
water was made, and a number were placed in pure rain water, but
they seemed to enjoy the change and went through their development
in due course of time.

The typical places where lativittatus larvae were found were the pools
and depressions bordering the edge of the marsh, where only the water
of the monthly high tide found its way. After the rains had ceased in
the spring the broods appeared as regularly as the tides themselves, as
may be seen from the table on the opposite page. These larvae were
first seen on February 20th in 1905, and the last brood in 1904 disap-
peared on September 25th. They were generally found in pools or
situations which contained rather clean water, but in the diked area
they were found in water highly impregnated with a reddish mineral
deposit, probably ferric iron. This gave the water a distinctly reddish-
brown color, and the larvae and pupae taken from such pools were
covered over with a coating of the same deposit.

MOSQUITO CONTROL WORK IN CALIFORNIA.

37

Table showing Relation of Tides to Appearance of Broods of Ochlerolatus lativittatus.

The heights, in feet and tenths, are from the soundings of the Coast and Geodetic
Survey for this region. The appearance of broods was checked up from our notes. The
observations were made on practically the same pools extending for five miles along th"
marsh, and which were reached only by the monthly high tide, and which dried up in
from ten days to three weeks.

b

SB

MAY.

JUNE.

JULY.

W

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s

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W

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*&

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gg

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J»CTQ

o §

p'ap

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Moon.

2P

P 66

Moon.

ST &

0 p

Moon.

-i

£ so

'

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1

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tf 3

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Feet.

Feet.

1

?eet.

1

5.2

5.5

5.8

2

5.2

New

5.6

New

5.8

3

5.2

5.6

5.8

4

New .

5.2

5.6

5

5.2

5.7

6

5.5

5.4

7

5.3

5.3

5.2

8

5.3

5.0

5.4

9

5.2

5.1

1st quarter. _

5.4

10

5.0

1st quarter..

5.3

5.6

11

1st quarter. .

4.8

5.5

5.8

12

4.5

5.7

5.9

13

5.3

6.0

6 1

14

5.5

6.1

6.2

Larvae

15

5.7

6.2

Larvae

6.1

Larvae

16

5.9

Full i

Larvae

Full

6.0

Larvae

17

6.1

6.1

Larvae

5.7

Larvae

18

Full

6.1

Larvae

5.8

Larvae

Larvae

19

6.1

Larvae

Larvae

5.4

Larvae

20

Larvae

5.5

Pupae

4.9

Pupae

21

5.9

Larvae

5.1

Pupae

4.9

Pupae

22

5.4

Larvae

5.0

Pupae

5.0

Pupae

23

5.2

Larvae

5.1

Adults

5.0

Adults

24

4.9

Larvae

3d quarter ._

5.2

3d quarter __

25

3d quarter. .

5.0

Pupae

5.2

5.2

26

5.1

Pupae

5.3

5.3

27

5.2

Pupae

5.4

5.5

28

5.3

Pupae

5.5

5.6

29

5.3

Adults

5.6

5.8

30

5.4

5.8

5.9

31

5.5

New .

5.9

In the newly reclaimed land north of San Mateo there are some areas
which contain numerous cracks in which the water stands at a couple
of feet below the surface. A search in these failed to find any larvae,
and we were informed by people living on this land that they were
seldom troubled with mosquitoes. That they were not found in such
situations may be due to the high mineral content of the water, or
that they are not favorable places for egg laying. The chemist of the
salt works in the vicinity stated that there was seldom any life found
in these deeper cracks, because of the mineral matter contained in the
water. The appearance of larvae in the cracks in the diked area was
confined to the early part of the season, none being seen after April,
and these may have come in as the water became lowered from the sur-
face level where it stood before the dike was put in repair.

38

UNIVERSITY OP CALIFORNIA — EXPERIMENT STATION.

Habits of the Adult. — This mosquito, hatching from its breeding
place on the salt marsh, makes its way inland, usually in the direction
of favorable winds. During June, 1904, they were found abundantly
in the hills beyond the Spring Valley lakes, a distance of 10 miles from
the salt marsh. They are active all day, but particularly late in the

FIG. 27. Genitalia.

1. Ochlerotatus lativittatus. 3. Culex tarsalis.

2. Theobaldia incidens. 4. Lepidoplatys squamiger.

afternoon and early evening, when there is but little wind. They have
been seen to congregate in innumerable numbers in the wooded canons
of the hill slopes in the Burlingame section, and make life interesting
for man as well as stock. This species is particularly bold and vicious,
and does not hesitate to thrust its beak through a couple of thicknesses

MOSQUITO CONTROL WORK IN CALIFORNIA.

39

of clothing. It is not as troublesome in houses and is seldom found
there, but prefers the sheltered places out of doors. It can, however,
readily make its way through ordinary mosquito netting, as was observed
in our breeding cages, which were first covered with this article. And

<*17)9(

FIG. 28. Ochlerotatus lativittatus.
1, larva; 2, antennse; 3, mentum; 4, spines on breathing siphon, showing
variation; 5, scale of eighth abdominal segment; 6, eighth and ninth abdom-
inal segments and siphon ; all enlarged.

here it might be stated that there should be a demand created for netting
of a finer mesh than that now in common use, to compel the manufac-
turers to supply this demand. The netting or screens now in the
market allow some species to go through very readily, and as we are

40 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION.

writing this, in spite of the fact that the windows of the room are sup-
posed to be well screened, we have captured four species of mosquitoes,
two of which are Anopheles.

The males of this species were found nowhere except on the marsh
or in very close proximity to their breeding ground. The females that
were found on the hills during the present year were not found to
contain eggs; but since there was but a single brood, and these not
very abundant, further observations are necessary before it is safe to
form a conclusion as to whether or not the migratory forms are barren.

Description of Larva.— Length of full-grown larva to tip of breathing
tubes, 7-8 mm. Head broadest opposite the eyes. There is a tuft of
three or four hairs near the base of the antennae and one or two smaller
ones more posteriorly. A rectangle is formed by four single hairs
about the middle of the vertex. The antenna is of moderate length, of
about the same thickness throughout, slightly curved inward, and bear-
ing short scattered spines upon its surface. At its middle point is a
small tuft of four or five hairs, and at the apex is one long and three

FIG. 29. Wing of Ochlerotatus lativittatus, $.

shorter spines, and a blunt, peg-like process. The mouth brushes are
rather large, with the hairs on the inner side curved at the tip and
pectinated. The mentum is normally triangular, with 9 to 10 uniform
teeth on each side of the apex. On the eighth abdominal segment are
22 to 25 scales, with spines at the tip and along the sides pointing in the
same direction. The respiratory siphon is about two and one half
times as long as wide at base ; the lateral rows of spines, extending about
half-way to apex, consist of 18 to 20 spines, rather long and toothed at
the sides. The ninth segment is longer than broad, with two or three
dorsal and a row of 12 to 15 ventral tufts at apex. The tracheal gills
are shorter than the segment.

Description of Adult.— A very light brown mosquito, almost straw
color, with brown stripes on thorax. It is of medium size, and the
hind tarsal joints are banded at both base and apex, the last one being
wholly white.

Head black; scales light yellow, with darker erect forked ones pos-
teriorly; palpi and beak dark brown.

MOSQUITO CONTROL WORK IN CALIFORNIA. 41

Thorax with golden-brown scales, a strip of brown ones on each
side of median line ; femora and tibia yellowish brown, darker at
apices. Tarsi light brown, the front one having base and apex of first
two joints and base of third white ; the middle one with base and apex
of first three and base of fourth white; the last one with the first four
joints at base and apex and the fifth wholly white. The claws are all
one-toothed.

Wings with mixed yellowish white and brown scales, which are broad-
ened at tip. Petiole of first submarginal cell not quite as long as that
cell ; cross vein at apex of second basal cell its own length from the cross
vein above.

Scales on abdomen yellowish white ; two large rectangular spots of
dark brown scales on each side of median line of segments two to five
the appearance of two broad interrupted bands.

Genitalia. — Basal clasp segment stout; the apical segment slender,
with a slight constriction near base, widest at middle, and ending in
the usual spine. Claspette at basal third of clasp segment; a row of
strong spines on margin. Basal portion of harpes setaceous, with three
or four long spines on inner side near apex. Terminal segment smooth,
and as long as basal part. Harpago stout, bent, ending in an acute-
recurved hook. Setaceous lobes prominent, bearing from three to six
stout spines. (See Fig. 27.)

Size, 6 mm. Wing expanse, 10-12 mm.

Lepidoplatys squamiger.

Habits of Younger Stages. — So far as our acquaintance goes with this
mosquito during the past season, it is wholly a salt-marsh form. We
were on the lookout for this species in fresh-water pools during the
season, because Professor Smith found what had been determined as
squamiger in New Jersey to be limited entirely to fresh water. After
Professor Smith's attention was called to this difference in habits he
wrote us that upon closer examination it proved to differ from the
typical California squamiger, and that it was a new species. It is said
that this squamiger was taken at San Rafael in 1904 in one or two cases
in fresh-water pools. It is not improbable, of course, that this species
may be found in fresh water, but if one season's experience will justify
the conclusion it is the exception to find it in such situations in this
particular region.

The larvse of this species were almost invariably found in the identical
situations with lativittatus, which has already been fully discussed.
The striking difference in habits of the two, however, is in the fact that
lativittatus is many-brooded, while squamiger is limited to probably
two. Squamiger larvae were about as common as Ochlerotatus lativ-

42

UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

ittatus in the early season, but they were not seen after April. They
first appeared with 0. lativittatus February 20th, but disappeared by
the last week in April.

Having left the State about September 1st we were unable to follow
it later than that date, but the control work of the present season would,
in all probability, have prevented any further broods from appearing
anyway. However, in a trip made to the territory on September 20,
1904, adult sqaamiger were flying about rather abundantly, and males

FIG. 30. A cattle-guard on the Southern Pacific railroad. A case where man helps

the mosquitoes.

were found on the marsh, which would indicate that a brood had recently
emerged.

Negative evidence points to the fact that, like 0. lativittatus, the eggs
remain over winter and hatch in the following February or March.
Owing to the early disappearance of the species we were given no
opportunity for studying the egg-laying habits; but since the larvae
were found in the same situations with 0. lativittatus, it is likely that
the egg-laying habit is similar in the two species.

Habits of Adult. — This species is also migratory, and while it was
not found across the hills toward the ocean, as was 0. lativittatus, it was

MOSQUITO CONTROL WORK IN CALIFORNIA.

43

found abundantly enough at Burlingame and San Mateo, and in the
hills at least three or four miles from its breeding ground.

This was the only species that appeared in numbers during the past
season in Burlingame, and this was due to an early brood which

e^9f

FIG. 31. Lepidoplatys sqxtamiger.

1, larva; 2, antennae; 3, mentum; 4, siphonal spines, showing variation;
5, scale of eighth abdominal segment; 6, eighth and ninth abdominal seg-
ments and siphon; all enlarged.

emerged from the diked area. No adults emerged, to our knowledge,
after March 25th, but a few still persisted in the residence section
until July 1st, which would seem to indicate that the maximum adult
life may be three months. In our notes it is recorded that on May 16th

44 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION.

adults of squamiger were common on the marsh, and all were females
with eggs well developed. The egg-laying, therefore, may be pro-
longed for nearly two months after emergence; altogether, our notes
on this species indicate that it is longer lived than the others of this
section. Its biting propensities are about as well developed as the
brown marsh species, and the only thing that prevents it occupying a
place of annoyance equal to 0. lativittatus is that it is fewer-brooded,
and consequently less in numbers.

In 1905 the first adults of this species were seen on February 27th
and the last on July 2d. In 1904 a brood was observed in the middle
of September. Three or four specimens taken in the hills, in April,
about three miles from the marsh, had eggs partly developed, but these
were the only ones seen with eggs, excepting on the marsh. The great
majority of those that made their way to the hills never returned to
the marsh. No adults were seen on the marsh after the middle of May,
although they were seen in the hills up to July 1st.

Description of Larva.— Length of full-grown larva to tip of breath-
ing tubes, 10 mm. A robust larva usually of a dark gray color. Head
broader than long, widest just posterior to the eyes. Near the base
of the antennas is a tuft of four or five hairs. The antennae are short,
slightly curved inward, with a small tuft of hairs at the middle not
reaching to apex, and with scattered spines over its surface. The apex
is terminated in one long spine, often crooked, one about one half as
long, and two shorter ones, and with a small, peg-like process. The
mouth brushes are composed of a thick mat of hairs curving inward,
those on the inner side being sharply curved at tip and finely pectinated.
The mentum is broadly triangular, with 9 to 10 uniform teeth on each
side of apex. The lateral patches of scales on the eighth segment are
composed of from 26 to 30 scales, each scale being armed at the tip with
spines, those at the tip being the longest. Respiratory siphon not more
than three times as long as broad at base, two rows of toothed spines
extending from base to about middle; near the end of row is a small
tuft of four or five hairs. Ninth segment longer than broad, bearing
two dorsal tufts and a ventral row of twelve or fifteen tufts. Tracheal
gills short, not exceeding width of segment.

Description of Adult.— A rather large mosquito, with very sealy
wings. Scales mixed with white and black, giving a general color of
gray. Base of tarsal joints and segments of abdomen white.

Head black, with whitish scales on posterior part; palpi with beak
lighter brown in middle, with apical fourth darker; antennae dark
brown.

Scales of thorax pale yellow, mixed with black along the sides and
with a dark-brown median band dorsally; there are also golden-brown

MOSQUITO CONTROL WORK IN CALIFORNIA. 45

scales sparsely scattered over thorax. The femora are pale brown,
lighter beneath, and covered with white and black scales, more numer-
ous above. The tibia are darker in color, with mixed white and black
scales, and on either side below are rather long black hairs, also present
on femora and tarsi. The tarsi are black, with occasional white scales ;
the bases are banded with white or pale yellow scales, more prominent
on hind tarsi ; claws single-toothed.

The wings are densely clothed with white and dark-brown scales,
giving a general color of gray. The scales on the dorsal two thirds
mostly broad and truncate, while on the apical third long, narrow ones,
tapering slightly at each end, are more numerous. Petiole of sub-
marginal cell about two thirds as long as is cell; cross vein at apex of
second basal at least equal to its length from the one above it.

The abdomen is black, with scattered whitish scales; the base of the
segments with rather broad band of similarly colored scales.

Genitalia. — Basal segment strongly curved on inner side, broadening
just before tip. Apical segment rather strongly curved at tip, ending
in an articulate spine. Claspette setaceous, and situated at base of
basal segment. Harpes long, jointed, ending in blunt process, which
surrounds base of apical joint; inner side strongly setaceous. Apical
joint abruptly bent at basal one third and curved at tip. Harpago not
quite reaching to apex of basal joint of harpe. Tip heavily chitinizell
and recurved. Setaceous lobes acutely pointed, bearing two or three
long spines at tip. (See Fig. 27.)

Size, 7 mm. Wing expanse, 12-15 mm.

Theobaldia incidens.

Habits of Early Stages.— This is the commonest fresh-water mos-
quito in the bay region, and may be found in every conceivable place
where there is standing water. The small pools and containers of water
about residences are sure to be stocked with this mosquito. It may
breed in very foul water, and has been found at the outlet of sewers.
It is also the commonest species breeding in the creeks in this section.
The eggs occur in raft-like masses of a hundred or more. They
are very conspicuous floating upon the surface of the water. Larva?
of this species have been found from January to November.

Habits of Adult. — This is the typical house mosquito of the section,
and will find its way into houses if there is any opportunity for entering.
Next to the salt-marsh species it is the most troublesome, and is a ready
biter. Specimens may be found at any season of the year, though
they are not active for two or three months during the winter. At this

46

UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION.

season they have been found in cellars, under stone bridges and other
protected places, and seemed to be partly hibernating. The species
may be met with at any time of day, but are more in evidence toward
evening. So far as is known it goes but a few hundred yards from its

<?}?0f

FIG. 32. Theobaldia incidens.

1, larva; 2, antennae; 3, mentum ; 4, siphonal spines, showing variation;
5, scale of eighth abdominal segment; 6, eighth and ninth abdominal seg-
ments and siphon; all enlarged.

breeding place, and if it is troublesome in the house its breeding ground
will more than likely be found on the premises.

Description of Larva. — Length of adult larva to tip of breathing
tube, 10-11 mm. A robust larva of dark gray or greenish color. Head

MOSQUITO CONTROL WORK IN CALIFORNIA. 47

broadest posteriorly ; on vertex, forming a slight arch with the antennae,
are six tufts of hairs, three on each side of median line, the two central
ones being farthest apart. The antennae are short, curved inward,
slightly tapering toward tip, with a tuft of hairs on upper side slightly
proximal to middle, and bearing at its tip four spines, two at the ex-
treme tip and two just back of tip, and an articulated truncate peg.
The mouth brushes with hairs on inner side slightly curved at tip and
finely pectinated. The mentum triangular, with 12 to 14 teeth, slightly
larger toward base, on each side of apical tooth, which is largest.
Scales on eighth abdominal segment arranged in triangular form and
numbering 50 to 55. Each scale bears rather long spines, which are
not spreading. Respiratory siphon three times as long as width at
base ; on each side, extending about two thirds of the way to apex, are
two rows of spines, those at the proximal one third toothed, while the
rest are long, slender, and hair-like. The ninth segment is slightly longer
than broad, with three or four tufts on dorsal side, and a row of 12 to
15 on ventral side. The tracheal gills are about one and one fourth
times the length of segment.

Description of Adult. — A large mosquito, with prominent black spots
on the wings. The only other California species, excepting Anopheles,
with spotted wings is annulatus, which may be distinguished by the
bands on middle of tarsal joints. Head black, with golden-brown scales
on occiput, erect forked ones on posterior margin; in front are long,
curved, black bristles, projecting forward. The eyes are immediately
surrounded with a narrow stripe of straw color; palpi annulate with
dark brown, becoming darker at tip. Antennae dark brown.

Thorax with black and golden-brown scales, and numerous black
bristles, those over base of wing brown. Two narrow prominent stripes
of black scales extending one each side of median line from anterior
edge to base of wings.

Wings clothed throughout with narrow linear scales. A cluster
of such scales occurs on radius 2 just anterior to cross vein connecting
with radius 4, one at point of branching of radius 1 and 2, and a
third at the junction of medial 1 and 2. Petiole of first submarginal
cell about one half the length of that cell ; cross vein at apex of second
basal cell meeting, or very nearly, with the one above it.

Femora dark brown to black above with scattered white scales, below
and at extreme tip white ; tibia black above, whitish below, and narrowly
banded at tip with white; tarsi of almost uniformly dark brown, with
very faint markings of yellow at apices. Claws simple.

Genitalia. — Basal segment of clasp short and stout, suddenly nar-
rowed on inner side near apex. Terminal clasp segment tapering grad-
ually to tip. Claspette a prominent pyramidal lobe, bearing two stout

48 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION.

spines at apex. *Harpagones rather broad, straight, central processes,
ending in a curved hook. Setaceous lobes obtusely rounded, with 7
to 9 slender spines. Between these is a median lobe, bearing eight very
stout and bluntly pointed spines. (See Fig. 27.)
Size, 7 mm. Wing expanse, 15 mm.

Culex tarsalis.

Habits of Younger Stages.— The larvas of this species were found in
the same situations as incidens. It is not so widespread, however, and
incidens may be found without tarsalis, but the converse of this was
seldom observed. It was never found in foul water, and seems to prefer
the clearer pools. No pool was seen swarming with these larvas, and
they appear not to be as rapid breeders as incidens.

Habits of the Adult. — Little opportunity was afforded for studying
the habits of the adult of this species, since they were but rarely met
with. Those that were seen occurred with incidens, and it is probable
that the habits of the two are somewhat similar.

Description of Larva. — Length of adult larva to tip of breathing
tube, 8-9 mm. Head broadest at eyes, abruptly narrowed before the
antennas ; on vertex just above the antennas is a tuft of 6 to 7 hairs, two
similar tufts on each side of median line on the middle of vertex, and
a small tuft of three or four hairs above and below the eyes. The
antennas are long, slightly curved inward, of about the same thickness
to the tuft, where it suddenly narrows, the whole surface being covered
with scattering hairs; the tuft is on the apical one third and consists
of 20 to 30 hairs. At the tip are three long spines and one short one,
and a short, stout peg; the antennas are narrowed slightly at the base,
and arise from a shoulder of the head.

The mouth brushes are long and wide apart, with long scattered
straight hairs on the inner side. The mentum is rather sharp pointed
and with 9 to 10 teeth on a side, the apical one, and the ^cond and
third, being the largest. The scales on the eighth segment number 32
to 35, with walled spines at the tip and sides. The respiratory siphon
is at least four times as long as broad at base. The rows of spines,
consisting of 12 to 15, extend about one third way to apex; the spines
are broad, short and many-toothed ; there are three or four tufts at
middle and one near the apex. The ninth segment about as long as
broad, with the usual apical tufts of hairs. The tracheal gills are about
one and one fourth times the length of segment.

* Dr. Felt, N. Y. State Museum Bulletin 97, p. 480, records these as wanting,
while Dr. Dyer, N. Y. Jour. Ent. Soc, Vol. XIII, p. 55, describes them as
"cylindrical and truncate." If we have homologized the parts correctly they are
distinctly visible, particularly in potash preparation.

MOSQUITO CONTROL WORK IN CALIFORNIA.

49

Description of Adult.— A medium-sized mosquito with brown thorax,
and black abdomen with white bands. Beak banded, and tarsal joints
white at both base and apex.

s M

Cmvf

FIG. 33. Culex tarsalis.

1, larva; 2, antennae; 3, mentum; ■!, siphonal spines, showing variation;
5, scale of eighth abdominal segment; 6, eighth and ninth abdominal seg-
ments and siphon; all enlarged.

Head with yellowish-brown tomentum on occiput and furcate at tip ;
palpi uniformly black ; beak black, with broad band of white at middle.

Thorax brown to black, with golden-brown tomentum on dorsum ;
plurae whitish ; femora black above, and below and at tips white ; tibia
4-Bul 178

50

UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION.

black, with base and apex white ; tarsi black, and banded with white
at both ends. Claws all simple, bearing no teeth.

Wings with dark-brown slender scales throughout. Petiole of first
submarginal cell about one half the length of that cell; cross vein at
end of second basal less than its length from the one above it.

Abdomen black, with well-defined bands at base of segments; venter
white.

Genitalia. — Basal segment of clasp curved, suddenly narrowed on
inner side near tip. Apical segment stout, tapering to tip ; terminal
spine present. Claspette, situated on apical one third of basal segment,
is composed of a conspicuous spatulate organ, two curved spines, and

FIG. 34. Wings of Culex tarsalis; 9 above; $ below.

three closely set stout spines, which are generally recurved at the tip.
Harpes stout, bearing at apex a tuft of stout spines. Harpago bearing
at its tip conspicuous stout teeth arising in different planes. Setaceous
lobes broadly rounded and bearing slender spines. (See Fig. 27.)

Other Species.

Besides the four troublesome species already described in detail
there were found early in the season in a cattle-guard on the Southern
Pacific Railroad at Millbrae the larva? of variapalpus, and a few adults
were also taken in the vicinity. Nothing was seen of this species after
the middle of April, though, of course, the control work may have had
something to do with this.

MOSQUITO CONTROL WORK IN CALIFORNIA.

51

Anopheles maculipennis was taken from the pond along the earline
one half mile north of the Burlingame depot, and also from another
pond on the west side of the county road opposite the Blackhawk dairy.
The larvae were fairly common here, and males were collected from the

\\ 2.

m^^^mi&mmBWMflM\

WtoBrnmnrm

^^^'^^

"XT 4

FIG. 35.

1. Theobaldia inczdens 9 3. Lepidoplatys squamiger 9

2. Culex tarsalis 9 4. Ochlerotatus lativittatus 9

grass by sweeping. A trip was made to San Rafael on June 8th, and
the marshes to the east of the town were visited. Here, in the wide tidal
creeks in land that was partly reclaimed, we expected to find 0. lativ-
ittatus larvae, but were surprised to find Anopheles maculipennis the
commonest form, although the water was distinctly brackish.

52 UNIVERSITY OF CALIFORNI A — EXPERIMENT STATION.

SYNOPTIC TABLES.

The following synoptic tables include all the species known to occur
in California at the present writing :

Table for determining the Genera and Species of California Culicidse.

a. Legs densely clothed with coarse erect scales Psopophora ciliata.

a. Legs not densely clothed with coarse erect scales.

b. Palpi, in females, as long as beak Anopheles.

c. Palpi of uniform color.

(1. Wings with conspicuous rectangular yellowish-white

spots on apical fourth of front margin A. punctipennis.

dd. Wings without such spots A. maculipennis.

cc. Palpi banded ; light area at base of three distal seg-
ments A. franciscanus.

bb. Palpi in female not as long as beak.
c. Tarsal claws toothed.

d. Lateral wing scales narrow, but slightly tapering to

bases Ochlerotatus.

e. Apices of palpi and ring at middle white 0. varipalpus.

ee. Palpi not so marked.

/. Last joint of hind tarsi wholly white . O. lativittatus.

ff. Last joint of hind tarsi not wholly white ..0. sylvestris.
dd. Lateral wing scales generally broad, tapering to

bases Lepidoplatys squamiger.

cc. Tarsal claws not toothed.

d. Cross vein at end of second basal cell more than its

length from the one above it Culex.

e. Beak banded C. tarsalis.

ee. Beak not banded.

/. Segments of abdomen banded at apex C. territans.

ff. Segments of abdomen banded at base C. pipiens.

dd. Cross vein at end of second basal cell less than its
length from the one above it.

e. Wings spotted Theobaldia.

f. Tarsal joints banded at middle T. annulatus.

ff. Tarsal joints not banded at middle T. incidens.

ee. Wings not spotted Culiseta consobrina.

MOSQUITO CONTROL WORK IN CALIFORNIA. 53

CULICIDAE IN CALIFORNIA.*

1. Anopheles maculipennis Meig. (quadrimaculatus Say, annulimanus Wulp).

Aldrich, J. M. Cat. Diptera, p. 121.

Berkeley, W. N. Laboratory Work with Mosquitoes. 1902.

Dyar, H. G. Ent. Soc. Wash. Proc, 5 :45-51. 1902.

Ent. Soc. Wash. Proc, 0:37-41. 1904.

N. Y. Ent. Soc. Jour., 11 :23-27. 1903.

N. Y. Ent. Soc. Jour., 13 :23. 1905.

Felt, E. P. N. Y. St. Mus. Bull. 79. (See Index.)

N. Y. St. Mus. Bull. 97. (See Index.)

Giles, G. M. Gnats or Mosquitoes, p. 326. 1900.

Howard, L. O. U. S. Dept. Agr., Bur. Ent, Bull. 25, n. s., 1900.

Mosquitoes. 3900.

Johannsen, O. S. N. Y. St. Mus. Bull. 68. 1903.
Ludlow, C. S. Medical Record, January 20, 1906.
Smith, J. B. N. J. Agr. Ex. Sta. Bull. 171.

■ N. J. Report on Mosquitoes, p. 168. 1904.

Theobald, F. V. Monograph.

2. Anopheles punctipennis Say (hiemalis Fitch).

Aldrich, J. M. Cat. Diptera, p. 122.

Dyar, H. G. N. Y. Ent. Soc. Jour., 10:194-201. 1902.

N. Y. Ent. Soc. Jour., 13 :23. 1905.

Ent. Soc. Wash. Proc, 5 :140-48. 1903.

Felt, E. P. N. Y. St. Mus. Bull. 79. (See Index.)

N. Y. St. Mus. Bull. 97. (See Index.)

Fitch, Asa. Am. Jour. Agr. Sci., 5 :281-282. 1847.
Giles, G. M. Gnats or Mosquitoes, p. 322. 1900.
Howard, L. O. U. S. Dept Agr., Bur. Ent., Bull. 25, n. s., 1900.

Mosquitoes, 1901.

Johannsen, O. S. N. Y. St Mus. Bull. 68. 1903.
Lawrence. Long Island Board of Health Rept 1903.
Ludlow, C. S. Medical Record, January 20, 1906.
Robinson, F. W. Rept. Eliz. N. J., pp. 1-15.
Smith, J. B. Rept. N. J. Agr. Ex. Sta. Bull. 171.

Report on Mosquitoes, p. 163. 1905.

Theobald, F. V. Monograph of Culicidjp.

* This list of California Culicidae has been checked up through the courtesy of
Dr. L. O. Howard, by Mr. D. W. Coquillett, of the Bureau of Entomology.
Washington. Mr. C. S. Ludlow, in the Medical Record for January 20, 1906,
also records dorsalis, signifer, and spencerii as occurring in the State.

The classification of Culicidae has recently undergone considerable change, par-
ticularly within the old genus Culex, which is in the above list represented by five
genera. Most workers in the group are agreed on the genus Culex as now restricted,
and also on the genera Theobaldia and Culiseta. There is, however, not a general
concurrence on the other two genera, and to aid in the reference to the literature
which has appeared during the last year or two, the following synonymy, so far
as it concerns the California species, is here given :

Lepidoplatys Coq. = Taeniorhynchus Nev. Lem. (Coquillett),

Grabhamia Theob. (Dyar),
Culicada Felt (Felt).
Ochlerotatus Arrib. = Cylicada Felt (Felt),

Ecculex Felt (Felt and Dyar),
Taeniorhynchus Nev. Lem. (Coquillett),
Grabhamia Theob. (Dyar).
The species curriei has been redescribed by Mr. Coquillett as lativittatus.
Professor Smith has since stated that his species is distinct from squamiger and
that it is a new species,

54 UNIVERSITY OP CALIFORNIA — EXPERIMENT STATION.

3. Anopheles franciscanus McC.

McCracken, Isabel. Ent. News, Jan. 1904.
Dyar, H. G. N. Y. Jour. Ent. Sec., 13 :23. 1905.
Felt, E. P. N. Y. St. Mus. Bull. 97. 1905.
Ludlow, C. S. Medical Record, January 20, 1906.

4. Culex tarsal is Coq. (willistoni Giles, kelloggi Theob., af finis Adams).

Aldrich, J. M. Cat. Diptera, p. 132.
Coquillett, D. W. Can. Ent., 28:43-44. 1896.
Dyar, H. G. Ent. Soc. Wash. Proc, 6:37-41. 1904.

Jour. N. Y. Ent. Soc, 13 :23. 1905.

Felt, E. P. N. Y. St. Mus. Bull. 97. 1905.

Howard, L. O. U. S. Dept. Agr., Bur. Ent, Bull. 25, n. s., 1900.

Mosquitoes. 1901.

Ludlow, C. S. Medical Record, January 20, 1906.

5. Culex territans Walk, (apicalis Adams).

Aldrich, J. M. Cat. Diptera, p. 132.

Dyar, H. G. Ent. Soc. Wash. Proc, 5:140-48. 1903.

■ Ent. Soc. Wash. Proc, 6:37-41. 1904.

■ Jour. N. Y. Ent. Soc, 13 :26. 1905.

Felt, E. P. N. Y. St. Mus. Bull. 79. 1904.

N. Y. St. Mus. Bull. 97. 1905.

Ludlow, C. S. Medical Record, January 20, 1906.
Smith, J. B. Rept. N. J. Agr. Ex. Sta., p. 325. 1905.

6. Culex pipiens L. (aestuans Wied., pungens Wied., fatigans Wied., boscii Desv.,

cubensis, Bigot).

Aldrich, J. M. Cat. Diptera, p. 130.

Dyar, H. G. N. Y. Ent. Soc. Jour., 5:45-51. 1902.

N. Y. Ent. Soc. Jour., 10 :194-201. 1902.

N. Y. Ent. Soc. Jour., 13:26. 1905.

Ent. Soc. Wash. Proc, 5 : 140-48. 1903.

Ent. Soc. Wash. Proc, 6:40. 1904.

Felt, E. P. N. Y. St. Mus. Bull. 79. (See Index.)

N. Y. St. Mus. Bull. 97. (See Index.)

Howard, L. O. U. S. Dept. Agr., Bur. Ent., Bull. 25, n. s., 1900.

Mosquitoes, 1901.

Johannsen, O. S. N. Y. St. Mus. Bull. 68. 1903.
Lawrence. Long Island Board of Health Rept.
Ludlow, C. S. Medical Record, January 20, 1906.
Robinson, W. F. Eliz. N. J. Rept.
Smith, J. B. Ent. News. 15:49-51.

Rept. N. J. Agr. Ex. Sta., p. 305. 1905.

Van Dine, D. L. Agr. Ex. Sta. Haw., Bull. 6.

7. Ochlerotatus varipalpus Coq. (sierrensis Ludlow).

Aldrich, J. M. Cat. Diptera, p. 132.
Coquillett, D. W. Can. Ent., 34:292-93. 1902.
Dyar, H. G. Ent. Soc. Wash. Proc, 6:37-41. 1904.

Jour. N. Y. Ent. Soc, 13 :25, 28, 54.

Felt, E. P. N. Y. St. Mus. Bull. 97. 1905.

8. Ochlerotatus lativittatus Coq. (curriei Coq.).

Aldrich, J. M. Cat. Diptera, p. 132.
Coquillett, D. W. Can. Ent. 33 :258-260. 1901.
Dyar, H. G. Jour. N. Y. Ent. Soc, 13:25, 54, 187.

Ent. Soc. Wash. Proc, 6:40. 1905.

Felt, E. P. N. Y. St. Mus. Bull. 97.

Ludlow, C. S. Medical Record, January 20, 1906.
Quayle, H. J. Ent. News, Jan., 1906.
Theobald, F. V. Monograph.

MOSQUITO CONTROL WORK IN CALIFORNIA. 5f)

9. Ochlerotatus sylvestris Theob.

Aldrich, J. M. Cat. Diptera, p. 131.

Dyae, H. G. Jour. N. Y. Ent.. Soc, 10:194-201. 1902.

Jour. N. Y. Ent. Soc, 13 :24. 1905.

Ent. Soc. Wash. Proc, 5:140-148. 1903.

Ent. Soc. Wash. Proc, 6:37-41. 1904.

Felt, E. P. N. Y. St. Mus. Bull. 97.

Ludlow, C. S. Medical Record, January 20, 1906.

10. Theobaldia incidens Thorn, (panticcps Adams).

Aldrich, J. M. Cat. Diptera, p. 126.

Dyar, H. G. Ent. Soc. Wash. Proc, 6:37-41. 1904.

N. Y. Jour. Ent. Soc, 13 :24, 55. 1905.

Felt, E. P. N. Y. St. Mus. Bull. 97. 1905.
Ludlow, C. S. Medical Record, January 20, 1906.
Theobald, F. V. Monograph of Culicidae.

11. Theobaldia annulatus Schran.

Aldrich, J. M. Cat. Diptera, p. 126.

Felt, E. P. N. Y. St. Mus. Bull. 97.

Osten Sacken, C. R. U. S. G. & G. S. Survey Bull. 3.

Ludlow, C. S. Jour. N. Y. Ent. Soc, 10:131. 1902.

■ Medical Record, January 20, 1906.

12. Culiseta consobrina Desv. (impatiens Walk., inornatus Will., pinguis Walk.).

Aldrich, J. M. Cat. Diptera, p. 128.

Can. Ent, 35 :208-210. 1903.

Coquillett, D. W. Can. Ent., 35:218. 1903.
Dyar, H. G. Jour. N. Y. Ent. Soc, 11:23-27. 1903.

Ent. Soc. Wash. Proc, 5 : 140-148. 1903.

Ent. Soc Wash. Proc, 6 :37-41. 1904.

Felt, E. P. N. Y. St. Mus. Bull. 79.

N. Y. St. Mus. Bull. 97.

Theobald, F. V. Monograph.

13. Lepidoplatys squamiger Coq. (denicdmannii Ludlow).

Aldrich, J. M. Cat. Diptera, p. 131.
Coquillett, D. W. U. S. N. M. Proc, 25 :84-85.
Dyar, H. G. Jour. N. Y. Ent. Soc, 13:22, 187. 1905.
Felt, E. P. N. Y. St. Mus. Bull. 79.
Quayle, H. J. Can. Ent., Jan. 1906.
Smith, J. B. N. J. Ex. Sta. Kept, p. 221.

14. Psorophora ciliata Fabr. (molesta Wied., rubida Desv.).

Aldrich, J. M. Cat. Diptera, p. 124. 1905.
Dyar, H. G. Jour. N. Y. Ent. Soc, 13:23. 1905.
Harris, H. T. Ent. News, 14 :232-233. 1903.
Felt, E. P. N. Y. St. Mus. Bull. 79.

• N. Y. St. Mus. Bull. 97.

Garman, H. Kentucky Ex. Sta. Bull. 96.
Giles, G. M. Gnats or Mosquitoes, p. 345. 1900.
Howard, L. O. Can. Ent., 32:353.
Johannsen, O. S. N. Y. St. Mus. Bull. 68.
Robinson, W. F. Rept. Eliz. N. J. 1903.
Theobald, F. V. Monograph.

STATION PUBLICATIONS AVAILABLE FOR DISTRIBUTION.

REPORTS.

1896. Report of the Viticultural Work during the seasons 1887-93, with data

regarding the Vintages of 1894-95.

1897. Resistant Vines, their Selection, Adaptation, and Grafting. Appendix to

Viticultural Report for 1896.

1898. Partial Report of Work of Agricultural Experiment Station for the years

1895-96 and 1896-97.
1900. Report of the Agricultural Experiment Station for the year 1897-98.

1902. Report of the Agricultural Experiment Station for 1898-1901.

1903. Report of the Agricultural Experiment Station for 1901-1903.

1904. Twenty-second Report of the Agricultral Experiment Station for 1903-1904.

BULLETINS.

Reprint. Endurance of Drought in Soils of the Arid Region.

No. 128. Nature, Value and Utilization of Alkali Lands, and Tolerance of Alkali.
(Revised and Reprint, 1905.)

131. The Phylloxera of the Vine.

133. Tolerance of Alkali by Various Cultures.

135. The Potato-Worm in California.

137. Pickling Ripe and Green Olives.

138. Citrus Fruit Culture.

139. Orange and Lemon Rot.

140. Lands of the Colorado Delta in Salton Basin, and Supplement.

141. Deciduous Fruits at Paso Robles.

142. Grasshoppers in California.

143. California Peach-Tree Borer.

144. The Peach-Worm.

145. The Red Spider of Citrus Trees.

146. New Methods of Grafting and Budding Vines.

147. Culture Work of the Substations.

148. Resistant Vines and their Hybrids.

149. California Sugar Industry.

150. The Value of Oak Leaves for Forage.

151. Arsenical Insecticides.

152. Fumigation Dosage.

153. Spraying with Distillates.

154. Sulfur Sprays for Red Spider.

155. Directions for Spraying for the Codling-Moth.

156. Fowl Cholera.

157. Commercial Fertilizers.

158. California Olive Oil; its Manufacture.

159. Contribution to the Study of Fermentation.

160. The Hop Aphis.

161. Tuberculosis in Fowls. (Reprint.)

162. Commercial Fertilizers. (Dec. 1, 1904.)

163. Pear Scab. .

164. Poultry Feeding and Proprietary Foods. (Reprint.)

165. Asparagus and Asparagus Rust in California.

166. Spraying for Scale Insects.

167. Manufacture of Dry WTines in Hot Countries.

168. Observations on Some Vine Diseases in Sonoma County.

169. Tolerance of the Sugar Beet for Alkali.

170. Studies in Grasshopper Control.

171. Commercial Fertilizers. (June 30, 1905.)

172. Further Experience in Asparagus Rust Control.

173. Commercial Fertilizers. (December, 1905.)

174. A New Wine-Cooling Machine.

175. Tomato Diseases in California.

176. Sugar Beets in the San Joaquin Valley.

177. A New Method of Making Dry Red Wine.

CIRCULARS.
No 1. Texas Fever. No. 13. The Culture of the Sugar Beet.

2 Blackleg. 15. Recent Problems in Agriculture.

3! Hog Cholera. What a University Farm is

4. Anthrax. For.

5* Contagious Abortion in Cows. 16. Notes on Seed- Wheat.

7 Remedies for Insects. 17. Why Agriculture Should be

9 Asparagus Rust. Taught in the Public Schools.

10. Reading Course in Economic 18. Caterpillars on Oaks.

Entomology. (Revision.) 19. Disinfection of Stables.

11. Fumigation Practice. 20. Reading Course in Irrigation.

12. Silk Culture.

Copies may be had by application to the Director of the Experiment
Station, Berkeley, California.