-' /

THE LIBRARY

OF

THE UNIVERSITY

OF CALIFORNIA
LOS ANGELES

u

MOSQUITOES

X.

MOSQUITOES

HOW THEY LIVE; HOW THEY CARRY
DISEASE; HOW THEY ARE CLAS-
SIFIED; HOW THEY MAY
BE DESTROYED

BY

L. O. HOWARD, PH.D.

DEPARTMENT OF AGRICULTURE, WASHINGTON, D. C.

NEAV YORK

MCCLURE, PHILLIPS & CO

190 1

> 3 > >

Copyright, June, 1901, bt
McCLURE, PHILLIPS & CO.

CcC««*«*«

f^ i

S INTRODUCTION

SOME years ag-o I was visiting* a family in the moun-
tains. It was during" a dry season, and Avater was
^, scarce. There were no swamps, no lakes or pools,

£vj and the drinking-- water was taken from spring's ; yet mos-
^ quitoes were so plentiful that it was necessary to screen
the porches, that sitting- out of an evening mig-ht be made
possible. I asked where the water came from in which
^ they washed their clothes, and they replied, as expected,
^ " From a rain-water tank," which, as it happened, was sit-
uated under the porch. I investigated the tank and found
it literally alive with mosquito larvae. A pint of kero-
sene stopped the breeding, and as the water was drawn
from a faucet near the bottom of the tank the kerosene
did not injure it.

The indifference of this family as to the source of their
local mosquito pest, or rather their combined ignorance
^ of and indifference to the subject of the breeding-places,
^ was at that time — and it was not so very long ago — char-
acteristic of people in general. It was my good fortune,
through the wide-spread newspaper accounts of my kero-
sene experiments in the Catskill Mountains in 1892, to
become more or less identified with many practical experi-
ments in the destruction of mosquitoes from that time
on. Interest in the subject became very great, especially

QUrfe'^QQ

vi INTRODUCTION

among" summer residents of the country, and especially
near the sea-shore, even before the ag-ency of mosquitoes
in the sjiread of disease became established, and before
it became a g-enerally accepted fact. With the very per-
fect proof that the mosquitoes of the genus Anopheles are
instrumental in the carriage of malaria, the interest be-
came intensified, and the late discovery of our Army
Yellow-fever Commission in Cuba, that a mosquito is the
conveyor of yellow fever, has added to the general interest
in the subject. In fact, the whole mosquito question is a
live topic of the da3^ Knowledge of mosquito habits is
more general than at any previous time, and almost everj^-
one is interested in the subject of mosquito extermina-
tion. With the knowledge which we now possess, it
seems almost incredible that people should all these
years have suffered, more or less i3atiently, the torment-
ing bites of Culex and the insidious but more dangerous
punctures of Anopheles without making the slightest ef-
fort to abate the nuisance and the danger, bej^ond slap-
ping, in a revengeful way, at individual biters. In many
places infested with mosquitoes nothing could be easier
than to put a stop to the whole tormenting plague. In
many other cases the problem is a more difficult one, but
in even the worst cases, by a judicious effort, which
should be a community effort, and by the expenditure of
a greater or smaller amount of monej% much relief can be
gained. In fact, Mr. W. J. Matheson, of New York, was
quite right when, in the summer of 1900, just before com-
mencing a successful crusade against the mosquitoes on
the north shore of Long Island, he wrote me that there

INTROD UCTION vii

seemed to him to be no more reason for enduring the
mosquito scourge than in allowing- small-x^ox to ravage
communities, as it used to do before the days of Jenner.
Work against mosquitoes is being undertaken everywhere,
by individuals and by communities. The interest in the
subject, from both medical and lay points of view, has be-
come so great that fjersons are not satisfied with half
knowledge, but must know the whole mosquito story, and
it has been with the purpose of supplying in some part
this demand for information, that this book has been pre-
pared. It tells what is known about mosquitoes from the
biological point of view, from the medical point of view,
and from the practical side. An especial effort has been
made to show, in a straightforward way, to physicians how
the different kinds of mosquitoes can be distinguished,
and to indicate the characteristic habits and breeding-
places of those forms which spread malaria and yellow
fever. Directions are given for collecting mosquitoes and
for rearing their early stages, and an especial effort has
been made to display fully and practically the remedial
measures which should be adopted in mosquito -ridden
neighborhoods.

TABLE OF CONTENTS

PAGE

Introduction, v

CHAPTER I.

Mosquitoes in General, 1

The Life Round of Mosquitoes, 1

Parthenogenesis Among Mosquitoes, ... 4

How Long can the Larvae Live Under Water? . . 5
How Long may the Larvae Live ? .... 6

How Long can the Larvae Live Out of Water ? . .7
Length of Life of Adult Mosquitoes, .... 9

Transformations of Mosquitoes Artificially Hastened, 12
Mosquito Songs, . . . . . . . .13

How Far do Mosquitoes Fly ? Are They Carried by

Winds? 16

Carriage of Mosquitoes by Railway Trains and other Con-
veyances, 25

Queer Places in which Mosquitoes Breed, . . .28

Food of Adult Mosquitoes, 84

Abundance of Mosquitoes, . . . .' . .31)

The Northern Mosquitoes, 42

The Poison of Mosquito Bites, 44

CHAPTER IL

Malaria and Mosquitoes, 48

ix

TABLE OF CONTENTS

CHAPTER III.

PAOE

The Common Mosquitoes of the Genus Culex, . . 66
Dr. J. B. Smith's Observations on Culex jmngeiis, . . 83

CHAPTER IV.

The Malarial Mosquitoes of the Genus Anopheles,
The Life History of Anoplieles JiiacuUpenjiis,
European Observations on the Same Species,
Natural Breeding Places of Anopheles,
The North American Species of Anopheles,
Food of Anopheles Larvae,
Length of Life of Adult Anopheles, .
How Anopheles Bites, ....

CHAPTER V.

91
93
107
109
113
117
118
119

Mosquitoes and Yellow Fever ; Mosquitoes and Fili-

ARIASIS, 121

The Yellow-fever Mosquito, . . . . . .131

Mosquitoes and Filariasis, .140

CHAPTER VI.

Other Genera of North American Mosquitoes, . .144

Genus Psorophora Desvoidy, 144

Genus Me^^arhinus Desvoidy, 152

Genus Aedes Meigen, 153

Stegomyia, Toxorhynchites, Uranotaeniaand Conchylias-
tes, 155

CHAPTER VIL
Natural Enemies of Mosquitoes, . , , . .156

TABLE OF CONTENTS xi

CHAPTER VIII.

PAGE

Remedies Against Mosquitoes, 167

Remedial Work Against the Early Stages, . . .170
The Use of Kerosene on Breeding Pools, . . .171

Other Substances Against the Early Stages of Mos-
quitoes, . . . . . . . . .193

The Abolition of Breeding Places by Drainage or by

Filling, .198

Introduction of Fish into Fishing Ponds, . . .211

Remedies Against Adult Mosquitoes 211

Eucalyptus, 215

The Castor-oil Plant, 217

Remedies for the Bites, 218

CHAPTER IX.
How TO Collect and Preserve Mosquitoes, . . . 220

CHAPTER X.

The Classification of the United States Mosquitoes, 229

3

45

46

53

LIST OF ILLUSTRxVnONS

Where Mosquitoes Breed by Millions, . . • Frontispiece

PAGE
FIG.

1. Culex tccniorhf/ncJms, Common Atlantic Coast "ring-

legged ' ' Moscjuito,

2. Section of Mosquito's Head showing poison gland, .

3. Salivary Glands of Culex and Anopheles (after Christo-

phers), ....••••'•

4. Experimental House Occupied by Drs. Sambon and Low

on the Campagna in the Summer of 1900 (from the
Journal of Tropical Medicine),

5. Malaria House on the Campagna, seen from a distance

(from the Journal of Tropical Medicine),

6. Egg Mass of Culex pungens,

7. Yonn^ hurx'^ oi Cule.r pmigens, . . . •

8. Mouth -parts of Larva of C?^/e,^'i/?/w,yeM.s', .

9. Full-grown Larva of Culex pungens,
10. Pupa of CiUex pungens, with Anal Segment below

greatly enlarged,

\\. Ki\v\\ilsii\\e oi Culex pungens, . • • • •
VI. A.i\\x\iYQnvA\eoi Culex pungens, . • • •

13. Resting Position of Anopheles maculipennis, .

14. Anopheles and Culex (after Watei-bouse),

15. Anopheles niaculipetmis, Adult, . . • •

16. Egg Mass of Anopheles maculipennis,

00

67
69
70

71

72

74
75
95
95
9(')
97

xiu

xiv LIST OF ILLUSTRATIONS

FIG. PAGE

17. Individual E^gs of Anopheles maculipennis, . . .98

18. Young Lcarva of Anopheles maGtili2)ennis, . . .100

19. 19a. Half-grown Larva of Anopheles maculipennis in

comparison with Culex Larva, 101

20. Half-grown Larva of Anopheles maculipermis, . . 102

21. Full-grown Larva of Anopheles maculip)ennis, showing

head upside down, with top of head above, at left ;
greatly enlarged, 103

22. Enlarged Head of Larva of Anopheles maculipennis, un-

der side (after Nuttall), 104

23. Enlarged Head of Larva of Anopheles maculipennis, from

side (after Nuttall) 105

24. Pupa of Anopheles in comparison with Pupa of Culex, . 106

25. 'Resid oiYxxW-QvovfnluSiYxaioi Anopheles jjunctipennis, . 108

26. Anoj)heles punctipennis, a:d\x\tie\iisAe, . . . .110

27. AnopJieles punctipennis, adult male, from side, . . Ill

28. Anopheles crucians, adult female, 114

29. Anopheles argyritarsis, adult female, . . . .116

30. Stegomyia fasciata, Sidvilt ie\\i3i\e, 123

31. Stegomyiafasciata,Sid\x\tm2i\Q, 127

32. Stegomyia fasciata, adult male, from side, . . . 132

33. Stegomyia fasciata, body scales, 133

34. Larva and Pupa of Stegomyia fasciata, with enlarged

parts, 135

35. '^io\\.ih.-\)3bYis oilj'AYYa. oi Stegomyia fasciata, . . .137

36. Cross Section of Head and Beak of Mosquito, showing

Filiarias entering Beak, 141

37. Psorophora ciliata, adult female, 145

38. Females of Psorophora ciliata at rest on side wall and

ceiling, 146

39. Male of Psorophora ciliata, from side, .... 147

40. Young Larva of Psorophora ciliata, 148

LIST OF ILLUSTRATIONS xv

FIG. PAGE

41. Full-grown Larva and Pupa of Psorophora rdliata, with

enlarged parts, . . . . . . . .149

42. Aedes fuscus, adult female, 158

48. Toxorhynchites rutilus, adult female, . . . .154

44. Oasterosteus aculeatus — Stickleback, . . . .158

45. Oamhusia affinis^ male and female — Top-minnows, . 159

46. Fmidulus notatus— Tloi> -minnow, 160

47. Lepomis pallidns — Sunfish, 163

48. Claws of Front Feet of Culex stimulans, male and fe-

male, 230

49. Claws of Front Feet of Culex pertiirbans, male and fe-

male, 231

50. Wing of Culex consohrinus and Culex pipiens, showing

petiole of first submarginal cell, ..... 233

MOSQUITOES

I

Mosquitoes in General

The Life Eouiid of Mosquitoes.

ALL mosquitoes, so far as known, are aquatic in
their early stages. It has never been shown that
any of them lay their eg-g-s anywhere except in
water. Their larvae live under the surface of the water,
although they are true air-breathers ; that is to say, they
must come to the surface of the water to breathe. This
breathing is performed through branched tracheal tubes
within the body, which terminate in an orifice at the end
of a prolongation of one of the last segments of the ab-
domen, and which from this fact is known as the respira-
tory tube. This tul^e is pushed at intervals up through
the surface film of the Avater and air is drawn down into
the tracheae. The larvae feed either at the surface or
below the surface, and their food is composed of all sorts
of floating particles, and in the case of some of the larger
forms they may even bite aquatic vegetation. They are
rajud breeders and pass the pupal condition also in the
water, but floating normally at the surface. In the pupae
they breathe not from a breathing tube at the anal end of
the abdomen, but from two trumpet-shaped tubes issuing

1

2 MOSQUITOES

from the top of the thorax. The thorax of all is much
swollen, aud with all pupa) the bodies seem lighter than
air, so that they float at the surface without exertion. The
pupc^, however, are active — sometimes very active. The
abdomen, with anal oar-like flaps, may be quickly and
violently agitated so as to draw them down below the
surface, when it becomes necessary to escape from a fish
or from some predatory aquatic insect. This great activity
is necessary for the preservation of species, since stagnant
j)ools abound with carnivorous forms of life, and such a
little, fat morsel as a mosquito pupa, if it always stayed
quietly at the surface, would stand no chance. When
one tries to catch a pupa with his thumb and forefinger,
at even the approach of the hand it disappears like a
flash, rising slowly to the surface again when the active
movements of the abdomen cease ; that is to say, when
it gets tired or when danger ceases to threaten.

All mosquitoes, so far as known, are rather rapid
breeders. They pass through several generations in the
course of a year, and hibernate in both adult and larval
stages. Over-wintering mosquitoes ma}^ frequently be
found in the cellars of houses, in cold garrets, in barns,
under the lids of water-tanks, under bridges and stone
culverts. In the extreme Southern States many mosqui-
toes are active all through the winter, and in most tropi-
cal regions they may breed all the year round. In dry,
tropical regions, however, they breed only through the
rainy season, and in the dry spell the species is iierpetu-
ated by the persistence of the adults, which either remain
active, or more usually rather inactive or dormant, just

^^

/

\

\

>'■

v

/■

>

Fig. 1.— Common Atlantic Coast " wing-Ic<?ged " Mosquito {^Culex
sollicitans) ; greatly enlarged. (Author's illustration.)

4 MOSQUITOES

as thoug-h they were hibernating-. In such dry spells
the males generally die and the gravid females live over.
This is also the case in winter hibernation in the north ;
females are, as a rule, impregnated when hibernation time
comes, and they live until the ice melts and the weather
becomes of the proper temperature for the laying of eggs.
As shown by recent observations by Mr. J. Turner Brake-
ley and Dr. John B. Smith, larvae, on the approach of
wdnter, may be frozen up in the ice and when thawed out
resume their growth, so that many undoubtedly hibernate
in this way.

Parthenogenesis Among Mosquitoes.

We have just stated that the males impregnate the
females and then die during- the early winter or during
the early part of the dry spell in tropical countries, but
there is evidence that parthenogenesis, or virgin birth,
sometimes occurs with mosquitoes, as it does with so
many of the lower forms of life.

Professor V. L. Kellogg, of Stanford University, reared
in a covered jar, from the pupa a female mosquito Avhich
almost immediately laid eggs. There was no other mos-
quito in the jar and certainly no mating. From these
eggs there hatched larvae, which grew very slowly and
nearly reached full growth before they died. None of
them succeeded in reaching the pupa stage. It is possi-
ble that they died on account of their abnormal birth, but
there is also the possibility that they died from lack of
proper food, and that under other conditions adults

MOSQUITOES m GENERAL 5

might have been rearecT. Professor Kellogg's observa-
tion indicates plainly that interesting studies can be
made with mosquitoes in this direction, and it will be
especially interesting- to observe the sex of the adults
reared from wigglers of virgin birth.

How Long can the Larvae Live Under Water?

In observations which I have made upon mosquito
larva? of the genus Culex, I have been unable to time
them below the surface for more than two minutes. As a
rule they return to the surface to breathe after the expi-
ration of not more than a minute. With the larv?e of
Anopheles, as will be shown later, the case is different.
Although the larvge remain at the surface of the water
during the early part of their lives, when they become
full grown they will descend to the bottom and mouth
over the slimy grains of sand or water-plants which are to
be found there. In this operation they have been timed
by one of my assistants, Miss Sullivan, and remained
ten minutes before ascending for air. It seems also,
from observations made by Dr. John B. Smith, that even
Culex larvse may stay below for a longer period than I
have observed. In the Entomological News for March,
1901, he states that he has timed them under water for as
long a period as ten minutes, and in a later publication
states that these same larvae which were CuJex pungens
which had been taken in ice, remained under water for
fifteen minutes and more.

MOSQUITOES

How Long may the Larv?e Live?

Professor Kellogg- reported an interesting series of ob-
servations in tlie Entomological Neics for April, 1899, in
which he shows that eggs were laid by a mosquito in his
laboratory August 9th. (The eggs, by the way, were laid at
4.30 in the afternoon, a novel fact in itself, since it has
been supposed that they were only laid after dark, and
presumably usually in the dark hours of early morning.)
These eggs hatched October 10th, and were kept alive in a
jar of water at a temperature of from 50'^ to 75° F. under
normal conditions as regards light. They grew in size
very slowly and one after another died. But the sole
survivor lived until February 16th, when it died at the
ripe old age of four months and a week. None of them
reached the pupal condition. As mentioned above, Pro-
fessor Kellogg thinks that their death may have been
due to the fact that their mother was a virgin and the
slowness of their growth may have been due to lack of
proper food and water.

We have stated above that mosquitoes hibernate in the
adult condition. That has been a matter of common obser-
vation and has been a generally accepted fact. I have
always supposed it to be the only mode of hibernation,
but an observation by Mr. J. Turner Brakeley, of Hor-
nerstown, N. J., made during the past winter, indicates
that they maj^ occasionally pass the winter in the larval
condition. Dr. John B. Smith wrote me, under date of
January 30, 1901, that Mr. Brakeley went out into the

MOSQUITOES IN GENERAL 7

marshes and collected a considerable number of the
leaves of the pitcher plant {Sarracenia) filled with a solid
mass of ice. He brong-ht them into the house and
thaAved out the contents, and as a result sent Dr. Smith
two bottles of very lively mosquito larvae. It seems that
the temperature of the marshes had been 2i° F. below zero
and everything had been frozen solid for some time.
Mr. Brakeley wrote that the larvae were embedded in dif-
ferent parts of the ice, and that in looking through the ice
you could see the insects. He sent over one hundred of
these thawed-out larvae to Dr. Smith, who stated that
they reached him in good condition and that they lived,
moulted, and grew thereafter in his laboratory. Adults
issued in March and proved to be Culex 2nmge?is. The
great numbers in which these larvae were found, suggests
to Dr. Smith that larval hibernation must be extremely
common, not only in New Jersey and in pitcher plants,
but elsewhere and in other accumulations of water. The
observations are of extreme interest and importance.

How Long can the Larvae Live Out of Water?

The fact that these insects remained dormant when
frozen up in ice for an indefinite period, from the obser-
vations of Mr. Brakeley, might at first seem to indicate
that the theory Avhicli has been advanced, that when their
mud-bottomed breeding-places dry up they remain alive
in the earth, is in a measure substantiated. But, in
reality, it has little bearing upon summer temperature
conditions. Experiments which I have tried on a small

8 MOSQUITOES

scale in glass vessels have shown that the larvne of Culex
will exist for some little time in wet mud and that some
of them Avill successfully transform after water has been
added, but in no case were we able to revive larv?e in
mud from which the water had been drawn off for more
than forty-eight hours, and after twenty-four hours only
a small proportion of the larvae revived. These results
accord very accurately with those reached by English
observers in Africa, and, in fact, accurate observations
have not carried the larvae out of water alive for more
than forty-eiglit hours. The impression to the contrary
has probably been gained from observations on pools
which in realit}^ did not entirely dry up. Mr. C. A.
Sperry, of Chicago, has made observations upon a pond
which dried up and in Avhich he could find no dead larvae,
but he writes that after a week it rained and as soon as
the rain stopped he found the mosquito larvae all through
the water as lively as ever, and they began to issue as
adults in about a week from that time. Mr. Benjamin S.
Pascal, of Newfield, N. J., has sent to me an account of
observations of his own which indicate to him that mos-
quitoes may breed in grass or moist earth.

In the summer of 1900, I watched a slowlj^ evaporating
pool with great interest. It contained a surface area of
about twentj^-four square feet, and was fed entirely by
rain-water and surface drainage. It was well stocked
with mosquito larvae, and after a long drought the water
was observed to have evaporated almost entirely, onh^ a
small puddle remaining in the centre, which contained at
the outside only three or four cubic inches of water. It

MOSQUITOES IN GENERAL 9

was dark in color, owing to the drainage from a manure-
pile near by, and when glanced at casually showed no
signs of life ; but on dipping in a coffee -strainer it was
found to be literally massed with nearly full grown mos-
quito larvae, many hundreds of which had been brought
together into this restricted place. Drying continued
until there was almost no water left, but before the larvae
died, that is to say, about twent3'-four hours after the
water contents were estimated at from three to four cubic
inches, there came a heavy rainstorm which filled the
pond with water, after which it was seen to contain ap-
parently its usual stock of mosquito larvae. From this
observation we are able to estimate the usual happenings
in a mosquito pool. As the water dries the larvae grad-
ually retire to the deepest point, and after the pool is
apparently dried up there is still enough moisture at
this deepest point to keep the larvae alive a number of
hours. That they may die, and that, as I believe, they
invariably do die in the absence of all moisture and in a
space of time which must be reckoned by hours and not
by days, is evidenced by the laboratory observations
mentioned alcove.

Length of Life of Adult Mosquitoes.

It is very difficult, in fact practically im])ossible, to
estimate the normal length of life of the adult of any
species of insect that flies. We may keep them in con-
finement and count the few days of their life, but the
conditions are abnormal and cannot be made perfectly

10 MOSQUITOES

normal. An insect in a broeding-cage may die in twent}^-
four lionrs, but that does not mean that it may not live
for weeks outside. Certain insects die quickly from
fright under such conditions, or from violent efforts to
escape. I once covered a very large Yucca plant with
gauze netting and placed under the netting about a hun-
dred honey bees, in order to see whether the flowers of
Yucca could be fertilized by bees. In twenty-four hours
every one of the insects was dead, and yet we know that
the honey bee is a long-lived insect. Such evidence as
we have, however, shows that mosquitoes are also long-
lived. It seems that they cannot live many days with-
out plenty of air. Dr. Yeazie, of New Orleans, writes
me that he has kept them alive Avith various substances
for a month. AVithout water or food, the limit seemed
to him, from his observations, to be live days for all va-
rieties he tried. If there is no water in the house he
states that the mosquitoes will leave the house and seek
water. He has seen them repeatedly go down into a
pitcher or a glass, remain for a few minutes, and then fl}^
awa3^ He thinks that they do that principally to get a
drink, although he has found eggs in a glass of water
and in pitchers. Mr. Mitchell, of Yietoria, Tex., how-
ever, writes that he kept a number of mosquitoes in a
box once, to see how long they could live on air, and that
on the twentj^-first day none had died. Medical ob-
servers in their experimental work with the mosquitoes
of the genus Anopheles have been able to keep adults
alive under glass, by feeding them upon slices of banana
or some other fruit, for weeks, the banana being renewed

MOSQUITOES IN GENERAL 11

every three or four days. Dr. Woldert, of Philadelphia,
has kept adults for two weeks or more in a bottle with a
slice of banana, sprinkling- the g-auze-covering- occasion-
ally wdth water. He has even kept them for from fifty
to sixty days, but this was in the fall of the year, and, as
we have elsewhere shown, mosquitoes hibernate in the
adult condition and the significant life-period of the
adult is the summer period. We know that they will
live through the winter, but we do not know whether,
under normal conditions, those hatching in the spring
will live through even half the summer. There used to
be a current idea that when a female mosquito sucks a
full meal of blood she is never able to bite again, since
it was thought that she is unable to thoroughly digest
such a meal. This idea, however, has been completely
exploded in the experimental medical work, and a more
approximate estimate of the length of the adult life has
been reached in this experimental medical work, than
has been elsewhere gained. The army surgeons who
have been working on the subject of mosquitoes and
yellow fever have shown, as, in fact, had Dr. Finlay be-
fore them, that the same mosquito will l:)ite and suck
blood again and again, and Drs. Eeed, Carroll, and Agra-
monte have demonstrated that the yellow-fever mosquito
will not convey the disease until at least twelve days
have elapsed since the time when it bit a yellow-fever
patient. In the case of Anopheles and malaria there
must be an interval of seven or eight days for the j^roper
development of the malarial organism in the ])ody of the
mosquito, before the disease can be conveyed through a

12 MOSQUITOES

puncture to a healthy individual. The best we can do,
then, is to say that the adult mosquitoes live indefinitely
— certainly, under favorable circumstances, even in sum-
mer, for several weeks — and that they may bite an indef-
inite number of times.

Observations by Fermi and Lumbao on Onlex pipiois in
Italy led them to believe that this mosquito, after emerg--
ing, devotes itself to blood-sucking and similar pleasant
occupations, but that egg-laying- only takes place after
from fifteen to twenty days, and that after egg-laying the
females die. This observation may be perfectly correct,
but it is contrary to the customary rule with insects, since
it is almost a law that after the issuing of the adults the
first and main business of life is the perpetuation of the
species.

Transformations of Mosquitoes Artificiallj^ Hastened.

In the summer of 1900, while engaged in making experi-
ments as to the insecticidal effect of creosote-oil poured
upon the surface of water in breeding-jars containing
mosquito larvae, I made what seems to me to be a most
interesting observation. In one battery jar containing
three quarts of water, eight j^ nearly full grown larvae of
Culex stimulans and C. 2^erturham were placed, and one-
fourth of an ounce of creosote-oil of a specific gravity 1.035
at 60° F. was i)oured. This was jar No. 1. In another
jar were two quarts of water in which were placed 150
larvae of the same species, all full grown or nearly so.
Upon this water, three-sixteenths of an ounce of a some-

MOSQUITOES IN GENERAL 13

what heavier creosote oil was poured. This was jar No. 2.
When at 4.15 p.m. the creosote was poured in jars 1 and 2,
no i3UiD8e were observed, but all larvae were full grown or
nearly so. After fifteen minutes ten pup^e were observed
in jar 2 and five in jar 1. Ten minutes later fifteen were
counted in jar 2 and thirteen in jar 1. Twenty minutes
later there were nineteen in jar 2 and twenty-two in jar
1. Fifteen minutes later still there were nineteen in jar 2
and twenty-two in jar 1. Thirty minutes later there were
seventeen in jar 2 (two having- died in the interval) and
twenty-eight in jar 1. As above stated, over night a num-
ber of adults issued, ten in jar 1 and eight in jar 2, and
twenty-four hours later ten more adults issued in jar 1.
It must be remarked that the full grown larv?e struggled
violently on perceiving the uncomfortable presence of the
creosote, and as they were just ready to transform, this
violent struggling evidently assisted in the breaking of
the larval skin, leaving the pupa bare. This transforma-
tion from larva to pupa is hardly as interesting as the
rapid development of adults, eighteen of which issued
within fifteen hours after transformation to pupa, whereas
l^reviously the shortest duration of the i)upal state which
we had observed was forty-eight hours. It looks like an
effort of nature to perpetuate the species in the presence
of a unique emergency.

Mosquito Songs.

Probably owing to an association of ideas, the curious
sound made by mosquitoes as they approach one's ear is

14 m<>s(^)vit()i:h

to iriost i)(3()[)l(i oxtr(;iii(!ly irriiniiii.^. Tliis fjiiiit sound
will \Viik(Mi many from ilic- somi(l(!si sl('<'|). it is not loud,
juid ill (|ii;ility in;iy i)<'rli;ii)S Ix^st Ix; ('oni[);ir(!d to tli(; dis-
tant ii()i<'- ol' a l)a;j;|)i|)('-. TIk; soujid is ai)[)arcntly pio-
diicod, as with ili(;s and otli(!i- di|)t()rous insects, not by
the ra[)id vi])i-atioji of tlio win<4S, but ])y tlio vibrations of
a cliiiinoiis proci^ss in tin; lar^^o tj"a,clH!;(' jiist Ix^hind tlii!
tliora('ic S[)ira(*l(;s. Those vil)ratioiis aio pioduccxl l)y the
air (buin;^' r<!S|)i ration. ])ia,<j;<)n-llies and bees, as well as
flies, sin^'' in tliis way. With bc^es, liow(;v(!r, the ]'a[)id
vibration of the win^s causers am^thei- hnni, and the two
notes are most r<;a,dily (bstin^uished, the win^- tone of the
honey ])ee bein^- A', whil(5 tlio breathin*^- voice is at least
an ()ciav(i hi^ln^r, and somcitinies niiu! or ten full tones
hii;h(!r, ^oin^ to IV and ('". 'J'Ik; exact musical note of
th(! diflere-nt S|)(!ci(;s of mos(|iiito(!S seems not to have been
investi.^attid, but as loiii^- jil^o as 1871, A. ]\b M;iyer, in the
course of his res(;arches in a(H)Ustics, made souk; most in-
tei'(!stin^- (!X[)eriments with the supposed auditory appa-
laius of sonn; spcu-ies of (^nlcx, which, unfortunately, was
not naincMl. JNlMycr (established the fact that some of the
ani(enn;i,l hairs of lln; male moscpiito are auditory. With
tuning-fork expciiments he showcul that som(; of the haiis
ar(i espcH'ially timed so as to rciSpond to vibrations num-
bering;' 512 ])(!r S(;cond. Other hairs vibratcid to other
notes. 1 [e- also (^xperinnrntcd with tin; son.^- of the hiuiale,
and sh()W(Ml tliat tine aiidiioiy hairs of tlu^ mah; anteniKe
vibrat(vwh(Mi the son^' of th(5 female comes at ri^ht angles
to tlunn. Jf the son*^'" is diri^ctly in front of the head it
will be most fully perceived by the hairs. If the son^^ of

MOSQUITOES IN GENERAL 15

the female affects one aiiteuiia more than the other, the
male turns his head until both antennae are affected, and
is thus able to determine the exact direction of the female,
to which he then Hies. Mayer found that the male can
thus i^uide himself to within five degrees of the exact
direction of the female. His conclusion is that " these
insects must have the faculty of the perception of the
direction of sound more highly developed than in any
other class of animals." Mayer carried his experiments
farther, and made large wooden models of the hairs, with
which he conducted interesting experiments. His paper
is published in full in the Araerican Journal of Science
and Arts, vol. viii. (1874), pages 89-103, and should Ije
read by those interested in this subject.

Kecently, Mr. A. DeP. Weaver, an electrical engineer
of Jackson, Miss., wrote me that while engaged in some
experiments in harmonic telegraphy, in wdiich a musical
note of a certain pitch was produced by electrical means,
he was amazed to find that when the note was raised to a
certain number of vibrations per second, all mosquitoes,
not only in the room where the a})paratus was, but also
fr(Hn other i:)arts and from outside, would congregate
near the apparatus and would be precipitated from the
air with astonishing force, striking their bodies against
the apparatus. He states that he therefore covered a
large surface with sticky fly-paper and after sounding the
note for a few seconds captured all the mosquitoes in the
vicinity. He then devised an apparatus t(^ electrocute
th(3m. A section of wire window screen witli the paint
reuKjved was mounted (jn a board and small [>ins were

16 MOSQUITOES

driven between the meshes, the heads coming flush with
the surface of the screen. All the pins were connected
together electrically, the whole forming one electrode of
the secondary coil of an induction coil, while the wire
screen formed the other electrode. An alternating cur-
rent of high potential was then passed and when the
note was sounded the insects precipitated themselves
against the screen and Avere immediately electrocuted.
Mr. AVeaver, unfortunately, does not state whether males
only were captured in this wa}^ His letter was an
extremely interesting one, and surely his sticky fly-paper
experiment suggests that further exi^erimentation in this
direction would be worth while.

Apropos to the difference in the musical note of differ-
ent kinds of mosquitoes it should here be stated that, as
will be pointed out in our consideration of the malaria-
bearing mosquitoes of the genus Anopheles, the sound
made by the female Anopheles is distinctly lower in
pitch than that made by the less harmfid mosquitoes of
the genus Culex. An interesting parallel to this is the
fact that the villain in the play has usually a bass voice !

How Far do Mosquitoes Fly? Are They Carried by

Winds?

A very important point to be considered by persons
who are engaged in extermination work against mosqui-
toes is the one suggested by the heading of this section.
To the owner of a large estate it is most discouraging to
anticipate that at the close of careful remedial work, in

MOSQUITOES IN GENERAL 17

which the di'ainage of breeding-places and keroseniug of
breeding-pools has been carried on, hungry swarms of
mosquitoes may fly in from a distance or may be carried
in by winds, to camp upon his grounds and in his house
and renew the annoyance of the irritating punctures, and
perhaps even to seek out some neglected breeding-place
and start new generations. Therefore the question of the
length of flight is a most important one. In the summer
of 1900, Mr. W. J. Matheson, living at Lloyd's Neck, Long
Island, a spot formerly infested by mosquitoes to an ex-
traordinary degree, by intelligent exterminative measures
succeeded in practically stopping the breeding of mos-
quitoes upon this rather narrow neck of land. It resulted
that his house was mosquito-free until toward the end of
August. Then, after a gentle and continuous wind of
two or three days' duration, specimens of another kind of
mosquito put in their appearance in large numbers.
The explanation was obvious. These mosquitoes had
flown across a strip of water forming one of the entrances
from Long Island Sound to Oyster Bay, for a distance of
a mile or a little more, aided by the gentle and continu-
ous wind.

This incident points out an important condition of
aftairs. Ordinarily, it may safely be said that mosqui-
toes do not fly far. Where there is water favorable for
egg-laying in the immediate vicinity of the place of their
birth, and especially where there are warm-blooded ani-
mals upon which they may feed, they have no migratory
incentive. Then again, they are not strong fliers, as in-
sects go. It seems perfectly certain, from the evidence

18 MOSQUITOES

which has been collected, and especially by that adduced
by Mrs. C. B. Aaron in her essay in the little book en-
titled " Dragon-flies versus Mosquitoes " (The Lamborn
Essays, Appleton k Co., 1890), that mosquitoes are very
careful not to take wing during a strong breeze. Mrs.
Aaron's words are worth quoting :

The migration of mosquitoes has been tlie source of much mis-
apprehension on tlie part of tlie public. The idea prevalent at
our seaside resorts that a land breeze brings the swarms of mos-
quitoes from far inland, is based on the supposition that this in-
sect is capable of long-sustained flight and a certain amount of
battling against the wind. This is an error. Mosquitoes are
frail of wing ; a light puff of breath will illustrate this by hurl-
ing the lielpless creature away, and it will not venture on the
wing again for some time after finding a safe harbor. The preva-
lence of mosquitoes during a land breeze is easily explained. It is
usually only during the lulls in the wind at such times, that
Culex can fly. Generally on our coast a sea-breeze means a stiff
breeze, and during these even the Odonata, and often the robust
and venturesome Tabanid*, will be found hovering on the lee-
ward side of the houses, sand-dunes, and thick foliage. In the
meadows south of xVtlantic City, N. J., large swarms of Culex are
sheltered in the dense grass or wind-battered tree-tops on the off
side of the sand-dunes. Here, in common with all localities so
exposed to searching wind, the trees and large bushes are much
stunted in growth and battered down to a flat top and common
level by the wind. In these matted branches, dense with the
close-clustered foliage, the mosquitoes may be discovered in such
numbers as to bring despair to the heart of the student who is
plotting their final extermination. While the strong breezes last,
Culex will stick close to these friendlv shelters, though a cluster

MOSQUITOES IN GENERAL 19

of houses may be but a few rods olT, tilled with uususpecting mor-
tals who iuiagine their toruieutors are far inland over the salt
meadows. But if the wind dies down, as it usually does when
veering, out come swarms upon swarms of the females, intent
upon satisfying their depraved taste for blood. This explains
why they appear on the field of action almost immediately after
the cessation in tlie strong breeze ; on the supposition that they
were blown far inland, this sudden reappearance would be un-
accountable.

Many observations made by the writer and by his cor-
respondents support these views which Mrs. Aaron has
expressed. Mr. W. C. Kerr, of Staten Island, an excellent
observer, is strongly of the opinion that mosquitoes are
not blown over from New Jersey to Staten Island. Pro-
fessor Herbert Osborn, formerly of Ames, la., has noticed
that in dry seasons small pools wdtliin a quarter to a half a
mile from the college buildings at Ames, dry up, and the
mosquitoes disappear, in spite of the fact that within
about a mile there are large pools which never become
dry. One of my former assistants, Mr. E. M. Keese,
found in Baltimore that by treating breeding-places a hun-
dred feet or a little more from his house with kerosene,
the supply of mosquitoes in his house was greatly re-
duced, although there w^ere many other breeding-phices
only twice as far away. Dr. John B. Smith, a well known
entomologist, has recorded his observation that mosqui-
toes will not rise or take flight when a Imsk breeze is
blowing, and that even a comparatively slight breeze will
keep them from the upper stories of houses.

Dr. H. T. Fcrnald, however, after several summers'

20 MOSQUITOES

work at the Cold 8i)riiig- Harbor Laborator}^ on Long-
Island, has stated that with a south breeze, especially
after a prolonged and gentle wind of five or more hours'
duration, mosquitoes become very troublesome and it is
the local supposition that they are carried from the south
shore of Long Island, fifteen miles away. This is, the
writer finds, the general opinion at several points on the
north shore of Long Island, but observations Avhich he
has made on the mosquito topography of that x^ortion of
the island have shown that there are usually many breed-
ing-xilaces much nearer than the south shore, and usually
quite near the infested places, which will much more
easily account for the mosquito supply. In fact, careful
observations made by Mr. H. C. Weeks, of Bayside, Long
Island, have shown that in the immediate vicinity of the
Cold Spring Harbor laboratories there are many breed-
ing-j)laces of such extent and such capacity as to indicate
that the south shore theory must be abandoned.

So many instances, in fact, have come to my attention,
where extensive breeding-places profusely stocked with
mosquito larvae have been overlooked by the people of
given neighborhoods, that I have, as a general rule, be-
come more or less incredulous on the subject of extended
mosquito flights. Fermi and Lumbao, in their report on
operations in Sassari, state that the mosquitoes of the city
do not go far from their original breeding-grounds, since
they find sufficient food near the habitations of i^eople
and animals. The reason which the Italian authors give
for this absence of migration may be correct or incorrect,
but their experience has shown that where a house loca-

3I0SQU1T0ES /A' GENERAL

21

ted near the centre of a city or village is found to be in-
fested by mosquitoes, search for the larv* should be
made in the house or near it, particvilarly in cellars or
cisterns, in wells, in water-troughs, in sinks and tubs in
the yard and so on. The truth is that people do not take
the trouble to make the careful search, and prefer to jump
to the conclusion that the mosquitoes have flown in upon
them from a distance. Mr. C. A. Sperry, of Chicago,
writes that he is perfectly satisfied that mosquitoes are
never distributed by the wind. When the wind l,lows they
are always on the ground, clinging to a support. They
are seldom, if ever, seen as high as the third flat in the
city He further makes tlie suggestion that the idea that
they are conveyed by the wind deters many people from
makino- an effort to rid themselves of the nuisance, which
can so''easily be accomplished. In one case, at a summer-
resort on Long Island, a man told him that the mosqui-
toes came there from New Jersey, while not two hundred
yards from his house was a pool that m Mr. bperry s
opinion produced all the mosquitoes that were such a
troublesome pest and drove hundreds away from Ins place.
Mr. Sperry is a close observer of mosquitoes and has
studied them for years. . . ,• i

Dr 0 W Stiles, of AVashington, however, is mclmeil
to take a somewhat opposite view from Mrs. Aaron. He
informs me that it has been his experience, at his summer
cottage on the New Jersey coast, that mosquitoes bother
his family only after land breez.^s have cnt.nued for sev-
eral days The cottage is situated about one-third ot a
mile awav from the woods, toward the sea and witbn, one

22 MOSQUITOES

hundred yards of tlie surf. As it is absolutely isolated
from trees, and as the mosquitoes do not appear during
a lull in the breeze, but only after several days of land
breeze, it appears to him that the popular view of the
influence of land breezes upon spreading- mosquitoes sea-
ward is not wholly without foundation.

All the evidence so far adduced refers to more or less
normal conditions and, in fact, such conditions are the
only ones which need practicall}^ be considered. Under
very exceptional conditions, however, it seems perfectly
plain that mosquitoes may migTate for considerable dis-
tances ; two such instances are described in the following-
lines quoted from a recent letter received from the Hon-
orable J. D. Mitchell, of Victoria, Tex., a reliable ob-
server and a naturalist.

. . . I have witnessed, in my life, two migrations of mos-
quitoes, that will always be fresh and vivid in my memory.

Where the Colorado River empties into Matagorda Bay, a
marsh is formed over the lowlands, by a raft in the river ; this
marsh contains about eighteen square miles, and is a magnifi-
cent breeding-place for mosquitoes.

I used to ranch it on the peninsula-like body of land, formed
by Carancalma Bay on the east, Matagorda Bay on the south,
Keller's Bay and Creek on the west, and the Calhoun County
north line on the north (refer to coast maps of Texas), The dis-
tance between my ranch property and the marsh above described
is, by bay route, about forty miles ; the way the crow flies, about
thirty-five miles. My ranch was situated on Carancalma Bay,
near the north end of land.

The first migration occurred in October, 1870. There had been
an overflow from the upper country, which tilled the aforesaid

3I0SQUIT0ES IN GENERAL 23

marsh, but the balance of that section was very dry and needing
rain, and there Avere no mosquitoes. A fairly strong easterly wind
had been blowing for three days ; on the evening of the third day
the mosquitoes arrived, Hying high, about fifty feet, and looking
like a cloud or mist coming over Carancahua Bay. At the ranch
they set everything on fire that had blood in it, and all work was
suspended by unanimous consent. Cattle and horses rounded-up
milled continuously ; all work stock was turned loose as quick as
possible and they went to the round-ups at full speed, and little
or nothing was done for nearly five days ; by this time the main
body had passed, though plenty remained to make everything
uncomfortable for about two weeks. This migration was from
east to west and the line was about three miles wide — above and
below this there were no mosquitoes.

Migration No. 2 occurred in October, 188G. They came from
the same marsh before described — this migration confined itself
to the Matagorda Bay shore line, reaching inland about half a
mile ; there were as many mosquitoes in this limit as there were in
the three miles of migration No. 1. They clouded the sky, bent
down the grass with their weight, and made all driftwood and
ground the same color. All stock left the shore and went north
outside of the line of marsh. The wind was light and from the
south, and did not affect the mosquitoes in their flight, which was
westward ; the main flight was low, ten or twelve feet high and
always in the same direction. With three other men I rode into
the swarm to a large pile of drift and trash and set it on fire, and
stood in the smoke for some time watching them. They passed
sometime during the third day, leaving very few stragglers be-
hind. By inquiry, I traced botli of these swarms from the marsli
before described to fifteen or twenty miles west of my ranch, a
total distance, air line, of fifty or sixty miles.

No. 1 crossed Trupalacios Bay, where it was five miles wide, and
Carancahua Bay, where it was one mile wide. No. 2 holding to

^4 MOSQUITOES

the shore Hue, crossed Trupahieios Bay, three miles, Carancahua
Bay, at Pass, 300 yards, Keller's Bay, at Pass, half mile, Cox's
Bay, one and a half miles, and Port Lavaca Bay, four miles.

It may incidentally be stated tliat malarial mosquitoes
of the genus Anopheles seem much less capable of ex-
tended flight than the commoner mosquitoes of the genus
Culex. Dr. F. A. Young, of the British Army Medical
Service, on his way home from Shanghai, where he had
been conducting experimental work against malarial mos-
quitoes, called on me in February, 1901, and stated that
it was his firm conclusion that, as a rule, Anopheles will
not fly over two hundred yards, and that a breeding-place
more than two hundred yards from the house will not
supply malarial mosquitoes to that house, provided there
are other houses nearer. He mentioned a number of cir-
cumstantial instances supporting this view. Christo-
phers and Stephens, however, in their reports on the
malarial expedition to Sierra Leone, state that it is cer-
tain that under some circumstances Anopheles may fly
much greater distances than has been supposed. In one
small inland house which had been occupied by one old
man, five or six Anopheles were to be caught each morn-
ing. These were freshly hatched and could only be de-
rived from a breeding-place three to four hundred yards
away. In another place the same writers show a fliglit
of six hundred yards. But, after all, what are even six
hundred yards ? In an effort to free a locality from ma-
laria such distances become insignificant.

On the whole, it seems to the writer that in almost no

MOSQUITOES IK GENERAL 25

cases need an individual or a community be deterred
even for a moment from attempting remedial work
against mosqnitoes by the idea that the mosquito supply
is likely frequently to be renewed by flights from long
distances or even from distances of much more than a
single mile. A far more serious source of re-establish-
ment of the mosquito supply will be considered in the
following section.

Carriage of Mc^squitoes by Eailway Trains and other
Conveyances.

That mosquitoes are carried by railway trains must be
a matter of common observation to everyone who traAxls.
That this method of distribution is and has been a very
important one, has, however, been rather generally over-
looked. It is said that mosquitoes were unknown in
Hawaii until brought over in sailing vessels from the
United States. On these sailing vessels they had proba-
bly bred more or less continuously in the water-liarrels,
and when once introduced into the islands they bred with
great facility in the swamps and freshwater ponds, and
to-day these insects are said to be very abundant there.

Beyond the statement which occurs in Nuttall's mono-
graph (1899), where the probable influence of winds, rail-
ways, and ships in the dissemination of mos(piitoes is
briefly mentioned, the subject had received ]U'aeti('ally no
consideration until it was l)rought out in the bulletin en-
titled, " Notes on Mosquitoes," prepared by the author
and published by the United States Department of Agri-

26 MOSQUITOES

culture, in August, 1900. It was tliore stated that by
means of railway trains unlimited quantities of mosqui-
toes are carried unlimited distances, and on emerging-
from the cars they start to breed, even where mosquitoes
are ordinarily rare, or would be rare under ordinary con-
ditions. In this way, even mountain-resorts were said to
get their supply of lowland mosquitoes, and the con-
stantly increasing danger of this method of distribution,
through the perfection of the railway service and the in-
crease in the number of through cars, was pointed out.
It was shown that although the State of New Jersey, as
an example, has a bad mosquito reputation, that does not
necessarily mean that there are any more breeding-places
in the interior of the State, or that New Jersey mosqui-
toes are any more prolific than elsewhere. The constant
abundance of mosquitoes in New Jersey seemed to the
writer to be dependent upon the fact that the coast is
lined by many swamps, and that all through the summer
evenings many trains are started inland from nearly a
dozen points on the coast, from Weehawken to Cape
May. These trains may contain mosquitoes by the hun-
dreds, and at every stop they may fly from the cars and
seek breeding-places near the railway.

A discouraging feature of this method of spread is that
although exterminative work of the most thorough char-
acter may be carried on in any locality near a railroad,
new supplies of mosquitoes are constantly being brought
in and will begin to breed wherever water can be found.
I called attention to the fact that in the Catskill Moun-
tains one place which had come under my observation

MOSQUITOES IN GENERAL 27

was free from mosquitoes, until tlirough cars on the
railroads brought tliem up from the vicinity of New York
City.

After the publication of this bulletin some doubt was
expressed by the newspaper reviewers of the importance
of this method of dissemination ; but confirmatorv evi-
dence of a striking character has since been gained, al-
though, as a matter of fact, the proposition was so self-
evident that it did not need confirmation. The interest-
ing commimity work undertaken against mosquitoes by
the city of Winchester, Ya., and which will be referred to
in detail in the chapter on remedies, has brought out the
fact that Winchester Avas at one time a favorite summer-
resort, and that mosquitoes were practically unknown, but
that with the establishment of a night train on the Balti-
more & Ohio Railroad, running from Camden Station,
Baltimore, in the summer-time, mosquitoes began to be a
positive annoyance in Winchester. Unfortunately, with
the establishment of this night train, or about the same
time, Winchester extended its system of water-works and
did not build sewers. As a result, with the arrival of the
mosquitoes from Baltimore there was a plentiful su])ply
of standing water all through the city, and conditions
were thus perfect for the dcA^elopment of mosquitoes in
enormous numbers.

Mr. C. A. Sperry, of Chicago, who formerly lived in
Mexico, has informed me that in the City of Mexico, be-
fore the railroads were built to Tanqjico and Vera Cruz,
there were no mosquitoes. They were brought up from
the coast, however, in the cars, and established them-

28 MOSQUITOES

selves there. Taminco and Yera Cruz, both low-lying-
cities, had always had mosquitoes in numbers. The City
of Mexico, lying- on a table-land 7,000 feet above the sea-
level, and Avitli a cool and pleasant climate, having- no
mosquitoes, thus with the addition of railroad facilities
became infested.

Mr. C. P. Lounsburv, government entomologist of the
Cape of Good Hope (in litt.), is responsible for the state-
ment that the railroads in Cape Colony have been re-
sponsible for taking" mosquitoes to many inland towns
whicli before the advent of the iron horse were quite free
from the pest. Another correspondent gives the details
of a precisely similar introduction of mosquitoes into a
high -lying Missouri town.

In a simihir way, stage-coaches are responsible for the
spread of mosquitoes. Grassi, the Italian investigator,
states that he counted two hundred specimens of Anoph-
eles on the inside of a coach, during a drive lasting two
hours through the plains of Capaccio, and the same
observer has recorded the capture of malarial mosquitoes
in a railwa\^ carriage travelling from Florence to Berlin.

Queer Places in which Mosquitoes Breed.

In the report of the Liverpool School of Tropical Medi-
cine's Malaria Expedition to Sierra Leone, it is stated
that mosquitoes were found breeding in the broken bot-
tles which Avere placed upon the top of a stone wall to
act as a clieval de /rise, and that they were found also
breeding in the flower vases on the tables in the houses

MOSQUITOES IN GENERAL 29

of European residents, the servants liavinf^ conscien-
tiously changed the flowers every mornino-, but with a cor-
responding lack of conscientiousness omitted to change
the water. I have found them breeding in an old tin tcj-
mato-can on the dumps in Washington. Mr. W. P. Seal,
of Delair, N. J., writes that he finds the larva? of mos-
quitoes in rain-filled hollows in apple, maple, and other
trees, often at a considerable distance from the ground.
Mr. Pratt has found them breeding in a liolloAv stump
near Bladensburg. Mr. Pergande has shoAvn that they
breed in the closed sewers in Washington, entering
through the perforated sewer-traps and emerging tli rough
the same holes. Mr. Matheson showed me an old disused
well which was covered with a board cover, but on lifting
the cover mosquitoes were found roosting on the under
side in large numbers. There was a crack in the cover
sufticiently large to admit them, and they smelled the
water below, worked their way through the crack and
bred in the old well. They will breed in all water-tanks,
and the cover must be absolutely tight, since gravid fe-
males are so strongly attracted by water that they will
work through a crack wdiicli seems almost too small to
admit their bodies. Dr. John B. Smith says that they
are found in New Jersey in great num])ers in the pitchers
of the pitcher plants of the genus S(irraccni((.

These statements refer for the most part, if not entirely,
to the common mosquitoes of the genus Culex, which we
assume to be comparatively harmless from the disease-
carrying standpoint, but they indicate plaiid3^ that where
one's object is to rid a house or a neighborhood of mos-

30 310SQUIT0ES

quitoes, in order to avoid their irritating- punctures and
to produce the condition of general comfort which the ab-
sence of mosquitoes brings, no possible si:>ot where water
can accumulate should be overlooked. The smallest pos-
sible collections of slag-nant rain-water become breeding-
places and may swarm with larvae. Mr. E. E. Austin, of the
Liverpool Tropical School Exi^edition, has seen in AVest
Africa that discarded bottles, Swiss milk and sardine tins,
and cocoanut husks, frequently swarm with larvae, while
the water which accumulates in disused calabashes and
other vessels lying about outside of houses is used for
breeding. Mr. R. H. Pettit (Bui. 18G, Mich. Agric. Col-
lege Exp. Sta.), in a report on " The Insects of the Upper
Peninsula of Michigan," writes as follows : " Land that is
being cleared furnishes an ideal place for them to breed.
Holes made in removing stumps and into which water
has settled are often fairly alive with wrigglers." He
collected a large number of larv?e and pupa3 from a hole
which would hold only a small quantity of water, and
bred adults from them.

"We have mentioned above that Dr. Smith has found
them breeding in the pitchers of the pitcher plant, and
Dr. Henry Strahan, in the Journal of Tropical Jledicine
for August, 1900, shows that mosquitoes breed in Lagos,
West Africa, in similar plants. In the summer of 1900,
Mr. W. J. Matheson, of Lloyd's Neck, Long Island, after
a most successful work, which included the drainage or
treatment with kerosene of every i^ossible ascertained
breeding-place within a half mile or more of his house,
in October, on going into his greenhouse, noticed three or

3I0SQU1T0ES IN GENERAL 31

four mosquitoes, and on looking- around for their breeding-
place lie discovered it in a tank at tlie corner of the
greenhouse, in which the gardener was in the habit of
keeping- from thirty to forty gallons of cistern water, in
order that it might be of the temperature of the g-reen-
house. The tank Avas apparently full of mosquito larvae.
On measuring out in a quart jar, and counting them, Mr.
Matheson estimated that there were probably in the neigh-
borhood of three thousand larvae. This is a very inter-
esting instance as illustrating the point upon which we
have just insisted, since, after the exterminating work
which had been done, these three thousand mosquitoes
would have caused considerable annoyance to the house-
hold, and might have given rise to the opinion that they
had flown in from an unknown distance.

Mr. H. C. Weeks, in the Scientific American Siq^pleinent
for January, 1900, very forcibly jiuts one aspect of mos-
quito breeding in the following words : "... a care-
ful supervision by those whose study of the subject
quickly enables them to detect the dangers from old
sources, as well as from new ones arising from constantly
changing conditions, especially about the towns — the
building of a railroad, the making of a drive, the block-
ing of an outlet to water by the washings of a storm or
the falling in of some excavated materials, the building
of a new house whose waste water is' not properly cared
for, these and a hundred others are exigencies which re-
quire an interest in the subject and a careful and minute
watchfulness."

Mr. Pergande's interesting discovery that they breed

32 MOSQUITOES

in the closed sewers in Washing-ton, deserves more de-
tailed mention than we have given it. His house in
northeast AYashington being infested with mosquitoes
and no exposed standing water occurring in the vicinity,
he thought of covering* the small perforated sewer-trap
in his back yard with a wire screen. To prevent the pos-
sibility of mosquitoes entering- the screen from the out-
side, a layer of cotton Avas placed around the edge of the
trap on wdiicli the screen rested. On August 24th tAvo
females of Culex 2)^oige?is were found under the screen.
September 3d another was found in the same place, but
it went back to the sewer as soon as the rays of the sun
struck the screen. September 6th, 10th, and 11th, five
more were caught. Female mosquitoes in search of
breeding-places had evidently flown through the sewer-
trap perforations, had found standing- water in the sewer
and laid their eggs, from which a generation of adults
was develox3ed.

There are other localities in Washington, far removed
from the Potomac Eiver front, where mosquitoes are more
or less abundant, and where there seems to be no standing
water in which they can breed. It therefore seems rea-
sonably sure that this sewer-breeding may be rather com-
mon in certain cities where the general slope is so slight
that the water may almost stand still for a few days, in
the absence of very heavy rains which flush the sewers. Of
course such breeding will easily be stopped by a little
neighborhood work, either by occasionally pouring a little
kerosene down the sewer-traps or by covering them with
a wire screen, as did Mr. Pergande in his experiments.

MOSQUITOES IN GENERAL 33

Another instance of the necessity of searching out of
the way p>laces for mosquitoes and larvae has recently
been told me by Dr. James Carroll, U. S. A., a member of
the Yellow-fever Commission. Visiting an army officer in
charge of a post in Cuba, he found the yellow-fever mos-
quito in numbers in the quarters. The officer in charge
could not imagine where they came from, as, under orders,
he had had every possible breeding-place exterminated,
either by surface drainage or by petrolizing. Dr. Carroll
noticed that the table in the dining-room had been insu-
lated by placing its legs in small jars of water, the surface
of the water being carefully covered with kerosene. In
going into an adjoining room, however, he found that a
table there had also been insulated in the same way, but
that the water about only one of the legs of the table had
been covered with kerosene, while the jars under the
other three legs were swarming with mosquito larvae.
This was the fault of the orderly, an Irishman, who liter-
ally obeyed orders in kerosening such vessels as had been
pointed out to him, but no more. Enough mosquitoes
bred in these three jars to stock a large community.

It is common opinion that mosquitoes do not need
standing water in which to breed. It is generally suj^-
posed by non-observant people that they are able to breed
in wet grass, and it is a common observation, as recently
expressed by a correspondent of the Pacific liuml Press
of San Francisco, that mosquitoes are more abundant
about well watered lawns than in vacant lots, with the
dry, sandy surface which they naturally have in a dry
summer season. But there is not the slightest evidence

34 MOSQUITOES

that any such condition of affairs can exist. In such
cases as that described by the Calif ornian, the mosquitoes
are naturally attracted by the moist air. They search for
breeding-places, and are attracted by moisture, however
slight ; and then, too, it is well known that they drink
water, and while the drops on the grass-blades will not
induce them to lay eggs, they can readily fill their stom-
achs in the absence of the more highly nutritive liquid
known as human blood. Some men drink water instead
of beer, but it is a sad fact that no mosquito is ever known
to drink water when she can get blood. In the California
case, the humidity of the air around the sprinkled lawn
pleased the mosquitoes better than the dry air of the
vacant lots, and in the face of the multifarious and unob-
served opportunities for the collection of small quantities
of water, many of which w^e have just indicated, there will
always be found some explanation for mosquito abun-
dance, other than that they will breed in wet grass. There
is this to be said, however, as has been pointed out more
fully in another paragraph, that in dry seasons mosqui-
toes will live until the rains come, and this is especially
true of pregnant females. Nature cares for the perpetua-
tion of the species, and in some way provides for the ex-
istence of individuals until the perpetuation of the spe-
cies is assured.

Food of Adult Mosquitoes.

With little doubt it is only the females of mosquitoes
which draw blood, and with as little doubt female mosqui-
toes are normally plant-feeders. When we consider the

MOSQUITOES IX GENERAL 35

enormous numbers in which mosquitoes occur, it is safe
to say that only an infinitesimal proportion of them ever
taste the blood of a warm-blooded animal. They have
been seen with their beaks inserted into juicy j^lants;
they have been observed sucking ripe fruit, watermelons,
and even boiled potatoes. There are in this country
great tracts of marshy lands into which warm-blooded
animals never find their way, and in which mosquitoes
are breeding in countless numbers.

But they are not confined to plants and warm-blooded
animals. They attack other insects, although observa-
tions on this point are not common. Dr. H. A. Yeazie,
of New Orleans, informs me, however, that he has seen
mosquitoes stinging the Cicada, or " locust," as it is in-
correctly called, and also the soft skinned pupa of the
same insect. Dr. H. A. Hagen has recorded an observa-
tion where he saw a mosquito in the Northwest engaged
in feeding on the chrysalis of a butterfly. Cold-blooded
vertebrates are also attacked. Mr. J. Turner Brakeley, of
Hornerstown, N. J., writes that he has seen a black ter-
rapin surrounded by a swarm of mosquitoes, but that she
paid no attention to them, possibly because she was en-
gaged in egg-laying. Moreover, there are several in-
stances on record in which mosquitoes have been seen
puncturing the heads of young fish. That mosquitoes
suck the blood of birds is also well proven. In the course
of Koss's original observations in India with a malarial
disease of sparrows, he had no difliculty in inducing
mosquitoes to bite these ])irds, and a recent correspond-
ent of the Bdlfintore Sun nearly lost some pet canaries

36 MOSQUITOES

through the bites of mosquitoes, which seemed especially
attracted to these birds.

To revert once more to the plant-feeding habit, j)ersons
engaged in the study of malarial relations of mosquitoes
have found that they feed readily upon fruit, and bananas
are a favored article of diet. Dr. John B. Smith, of llut-
gers College, informs me that he has seen males and
females of what is probably Cukx sollicitans attracted
by the blossoms of wild cherry, and appear to dig into
the centre of the blossom, at Anglesea, N. J. So abun-
dant were they that he captured hundreds by sweeping his
net over the blossoms.

The male mosquito seems to be exclusively vegetarian
in its diet. The beak in this sex is weaker, and does not
seem fitted for the penetration of the skin of even a
tender-skinned animal. Its food it probably chiefly
gained by sipping exposed liquids. They are often
seen sucking at drops of water or molasses, or beer, or
wine. Dr. St. George Gray, of St. Lucia, British West
Indies, finds that down there he can almost daily catch
one or two males on the neck of a decanter, or in a wine-
glass that has just been used. He has made some inter-
esting observations on the intoxicating effect of Avine
upon the males. It appears from these observations and
the beer-drinking habit of the males, as observed by
Schwarz, that in any discussion of sex habits into which
the mosquito may be lugged as an example that blood-
thirstiness may exist in the female sex, this statement
may be offset by the fact that even with this creature the
male sex is the one that is prone to alcoholism.

MOSQUITOES IN GENERAL 37

In spite of what wo have just said about the non-pene-
trating- mouth parts of male mosquitoes, Dr. C. W. Stiles
informs me that he and Hurst (the author of an im-
portant pai)er on the pupal stag-e of Culex, Manchester,
1890) made an observation in the summer of 1889, at Leip-
sic, which convinced him that either the males do oc-
casionally bite or that occasionally females possess
feathered antennae. Stiles and Hurst were out in a row-
boat one evening- and were bitten a number of times by
Onlex nemorcdis. One individual which bit Stiles on the
left hand was crushed, and in the crushing act a consider-
able quantity of blood exuded — enough to make a fair-
sized blood-stain on his skin. Upon examining the dead
body he was surprised to note that it possessed male an-
tenna^. Hurst also examined it, and remarked that it was
the first instance he had known where a male Culex had
actually been caught sucking- blood. Dr. Stiles tells me
that Hurst intended to place the observation on record,
but that he does not think it was ever published. Dr.
Stiles is so well known as an accurate observer, that some
other explanation than faulty observation must be offered
in this instance.

This observation, although apparently without pre-
cedent, leads to a decision coinciding- with that of JcW'-
dens (1801), who thought that the male mosquito could
bite, and wrote, according to Dimmock, " But since the
male is also provided Avith a sucking seta it is not com-
prehensible why it should not use it for the same pur-
pose." Dr. Dimmock, in his admirable dissertation upon
" The anatomy of the mouth-parts and of the sucking ap-

G90393

38 310 SQ UITOES

paratus of some Diptera" (1881), made a most careful
study of the mouth-parts of both male and female mosqui-
toes. His conclusions are decidedly against the possibil-
ity that male mosquitoes can bite warm-blooded animals.
He says, " I have tried to have the male mosquitoes bite
me when in the held where they were al)undMnt, but they
did not seem attracted, as the female mosquitoes were, to
my person ; the}^ flew away indiflerentl}^ without lig'hting
upon me. I have often taken male mosquitoes, Avith all
possible care to prevent disturbing- them, beneath a glass
cover on my hand, letting them remain long enough to
be as tranquil as they were when upon the leaves and
grass of the field, but they Avould neither bite nor show
any desire to do so, nor have I been able to feed male
mosquitoes with water, saliva, or fresh blood, all of which
liquids the females often drink with avidity.

" Upon anatomical grounds, I 1)elieve that male mos-
quitoes take liquid food, although I have never dissected
their stomachs to see what this food was. They have
mouth-parts and jDharynx developed sufficiently to suck
liquids ; but the absence of barbed maxilla, of a free hy-
popharj^nx, and of cesophageal bulb, leads one to suppose
that they take a smaller quantity of food than the females
do, and that they do not obtain it by piercing the skins
of animals."

There is a European species of mosquito, Ctdex salinus
Ficalbi, which is said to be diurnal in its habits, and to
live in salt water, of which the male is said to bite, and
to possess mouth-parts quite like those of the female.

MOSQUITOES IN GENERAL 39

Abundance of Mosquitoes.

In modern times everyone who likes out-door life, espe-
ciall}^ men interested in hunting- and fishing-, is able to tell
mosquito stories Avhich rival the somewhat rare instances
which come down to us from ancient times. I have heard
sportsmen, in fact, vie with each other in describing the
abundance of mosquitoes in certain localities, but, familiar
with the tendency of hunters and fishermen to indulg-e in
the rhetorical fig-ure known as hyperbole, as evidenced in
the general acceptance of a specific meaning as applied in
the expression " a fish story," or the adjective " fishy," one
is warranted in a certain measure of disljelief. It is un-
doubtedly true, however, that certain localities in this
country are almost uninhabitable because of the great
numbers of mosquitoes found there, many otherwise
desirable neighborhoods do not improve for this reason,
and some regions are absolutely unsettled on this ac-
count. Professor E. AV. Hilgard, of the University of Cali-
fornia, has written me that up in northern Washing-ton,
in the pine forests north of Spokane, the gray mos-
quito, or Culex, seems to be the sole possessor of the land,
and is a fearful nuisance, as in arctic regions. The first
thing- on going- into camp is to establish a close line of
smudges above the wind, so as to enable the pack animals
and the men to eat in comparative peace, but about mid-
night the entire swarm is back again. He states that
there are scattered hikes in that region where they breed,
but they must migrate considerable distances. He further

40 MOSQUITOES

writes tliat in Montana he has seen all the workhorses in
the field sheathed in sheets during- the day, and these Avere
dotted with small blood spots.

An observation made by my colleague, Mr, E. A.
Schwarz, at Corpus Christi, I have had occasion to quote
several times. He says that at this place, when the wind
blows from any other direction than south, " hundreds of
thousands of millions " of mosquitoes blow in upon the
town. Great herds of horses run before the mosquitoes in
order to get to the water, but that with a change of wind
the mosquitoes disappear. The instance mentioned by
the Hon. J. D. Mitchell, of Victoria, Texas, and which is
quoted in the section on " How Far Do Mosquitoes Fly ? "
is another indication of the enormous numbers in which
these insects maj' occasionally occur, even in localities
where they are ordinarily not very abundant.

In olden times, mosquitoes appear to have been quite
as numerous as they are to-day, and the literature of pop-
ular entomology contains many instances of the enormous
numbers in which mosquitoes have occurred in times past.

In ancient Greece, according to Pausanias, inhabitants
were forced to abandon their homes on account of mos-
quitoes' making it impossible for them to remain. Mionte,
a rich city of Ionia, was abandoned by its inhabitants on
account of mosquitoes which forced them to flee to Mileta.
The same thing happened with Pergamo, a beautiful city
in Asia. Someone has called attention to the fact that
Theodoretus says that Sapor, King of Persia, was com-
pelled to raise the siege of Nisibis by a plague of gnats,
which attacked his elei3hants and beasts of burden, and

MOSQUITOES IN GENERAL 41

so caused the rout of his army. Kirl^y and Spence say,
" 111 the neighborhood of Crimea tlie Russian sokliers
are obliged to sleep in sacks in order to defend themselves
from the mosquitoes, and even this is not a sufficient se-
curity, for several of them die in consequence of mortifi-
cation produced by the bites of these furious bloodsuck-
ers." The same writers state that Captain Stedman, in
America (probably in ante-Revolutionary days), mentions
that he and his soldiers were forced to sleep with their
heads thrust into holes in the earth, and their necks
wrapped around with hammocks, and Humboldt says that
somewhere in South America the inhabitants pass the
night buried in sand, which covers them to the depth of
three or four inches, leaving- out only the head, which is
covered with a cloth. There is even a mosquito story
which possibly affects the veracity of George Washington !
Isaac Weld, in his " Travels through North America,
1795-1797 " (London, 1799), in speaking of Skenesborough,
in northern New York, dilates upon the number and fe-
rocity of mosquitoes and says, " General Washington told
me that he never was so much anno3^ed by mosquitoes in
any part of America as in KSkenesborough, for that they
used to bite through the thickest boot." Now, knowing
that the boots of those days were very thick, and that the
mosquitoes of that time must have been structurally iden-
tical with those of to-day, there arises instantly the ques.
tion of veracity between Mr. Weld and General Washing-
ton, and as we know from Dr. Weems's veracious history
that General Washington was so constituted tliat he C(^uhl
not tell a lie, it looks very much as though Mr. Weld, like

42 MOSQUITOES

certain other travellers who have written books on their
return home after extended travel, was somewhat inclined
to overstate the truth.

Far Northern Mosquitoes.

As is well known, the mosquito-pest is hy no means
confined to the tropics or even to temperate regions.
The stories which the returning- gold-hunters from
Dawson City and other Alaskan localities tell of the
abundance and ferocity of Alaskan mosquitoes, are
hardly to be matched by any mosquito story which I
have heard, historical or otherwise. Many of my
friends in the United States Coast and Geodetic Survey,
and the United States Geological Surve}'^, who have
formed members of summer parties for survey work in
Alaska, have come back to this country with a much
stronger idea of the importance of the practical study of
insects than they had when they started, their acquaint-
ance with mosquitoes having become so intimate and
their knowledge of their ferocit}" having reached such a
pitch that the first question which the}^ ask on returning
is : " If I have to go up there next summer, what under
the sun can I do to keep from being bled to death by
mosquitoes ? " They state that they never experienced
or even imagined anything in the mosquito line quite
equal to those found in Alaska. Mr. W. C. Henderson,
of Philadelphia, says, concerning Alaskan mosquitoes,
" The}^ existed in countless millions, driving us to the
verge of suicide or insanity."

MOSQUITOES IN GENERAL 43

That mosquitoes should develox) in such extraordinary
numbers in the arctic regions is remarkable when we con-
sider the extreme brevity of the summer season. Surelj;
only a very few generations have an o^^portunity to develop.
They must therefore hibernate in great numbers even in
that extreme cold, and their occurrence in this way in such
localities, when we consider the coraj^arative scarcity of
mammalian life, indicates in a forcible way how small a
part the blood of warm-blooded animals plays in the nor-
mal economy of mosquito life.

It did not need these recent experiences, however, to
assure us of the abundance of mosquitoes in arctic regions.
Kirby and Spence tell extraordinary stories of their
occurrence in Lapland, where their numbers are said to
be so i^rodigious as to be compared to a fall of snow
when the flakes are thickest, or to the dust of the earth.
There is a mention of this abundance in the narrative of
C. F. Hall's second arctic expedition, and on the Polaris
Expedition, Dr. Emile Bessels was obliged to interrupt
his work in the Davis Straits (latitude 72° north) on ac-
count of the multitude of mosquitoes.

In explanation of these extraordinary numbers — and all
these stories are unquestionabl}^ measurabW true — we
must only think of the universal occurrence of standing
water and of the fact that the food required by mosquito
larvae is very small and very insignificant, consisting
mainly of the micro-organisms which exist in stagnant
water, and of the further fact that enormous nundjers can
breed successfully in a very small water supply. As an
indication of this latter fact, Lugger, in 189G, undertook

44 3I0SQUIT0ES

to count the larva? in an ordinary rain-water barrel. On
July 6tli, the water in one barrel was filtered and was
found to contain 17,251) eggs, larva? and pup?e. On July
22d, 19,110 additional ones were counted. If anyone is
mathematically inclined, let him assume that half of these
developed into female mosquitoes, each one of Avhich laid
400 eggs, and that twelve generations breed in a summer
in the northern United States. It will then be perfectly
obvious tliat a large neighborhood may be well supplied
with mosquitoes from a single neglected rain-water barrel.

The Poison of Mosquito Bites.

That fine old observer, Reaumur, rather thought that a
poisonous fluid was secreted by the mosquito and that
its x)uiTOse was to cause the blood to flow more readily
when it bites. Later observers have accepted this state-
ment, or have denied the existence of such fluid, stating
that the swelling following the bite was caused by the
irritation of the puncture, without the aid of poison.
Dimmock (1881) convinced himself that a poisonous saliva
was introduced. He noticed that if the mosquito punc-
tures the skin without entering a blood-vessel, although
it may insert its x3roboscis for nearl}^ its full length, no
poisonous effect is produced upon the skin ; but when the
proboscis strikes blood and the insect draws its fill, the
subsequent swelling and iwisonous effect are obvious.
He argued that these eff'ects indicate a constant outpour-
ing of some sort of i^oisonous fluid during the blood-
sucking process.

3I0SQUIT0ES IN GENERAL

45

The question was finally set at rest by Macloskie (1887),
wlio succeeded in demonstrating a poison gland in mos-
quitoes and in showing that this poison gland is connected
by a duct with the mouth-parts. This venemo-salivary
duct is very fine, running backward in the lower i^art of
the head in the throat and terminating in the prothorax
in glands of characteristic structure. The glands are in
two sets, each set consisting of three glands, two of which

Fig. 2. — Section of head of Mosquito showing poison
enlarged. (Redrawn from Macloskie.)

fhind at

are ordinary salivary glands and the third (between the
other two) having a difterent appearance and structure
and secreting the poison.

Miall, of England, as late as 1895 stated that it could
not positively be said whether poison is injected into the
wound or not. Overlooking, or not accepting, Macloskie 's
demonstration, he says : " No poison has hitherto been
demonstrated, and there is some reason to believe that the

46 MOSQUITOES

irritation of the wound is slight in cold weather and only
becomes intense during- great summer heat."

The purpose of the mosquito i)oison has been a sub-
ject of some conjecture. The old Reaumur hypothesis,
that it causes the blood to become more liquid and more
readily sucked ujj by the mosquito, has had its adherents.

Fig. 3. — Salivaiy glands of Culex at right, Anopheles at left : greatly
enlarged. (After Christophers.)

Osten Sacken and Miall, however, believe that it is prob-
able that the piercing mouth-parts of the mosquito were
originally acquired for the jDurpose of sucking the juices
of plants, and Macloskie advances the idea that the chief
food of mosquitoes is not animal blood but the proteids of
plants, and that probably the poison ejected may prevent

3I0SQUIT0ES IN GENERAL 47

the coagulation of all proteids and so j^romote the pro-
cess of suction.

The amount of irritation caused by the x^oison of mos-
quitoes varies greatly with different individuals. Some
people suffer severely from their bites, Avhile others are not
at all affected. This is a matter of common observation.
I have seen a man hunting snipe in a marsh with his face
protected, but with his neck left exposed. His neck had
been rejieatedly bitten and w^as so x^oisoned as to utterly
destroy its symmetry. At the end of the day he no longer
X^ossessed a neck, but from his shoulders to his head was
simply a gradual slox^e !

There can be little doubt that x^eoxde become inoculated
against this x^oison. Persons living in mosquito-ridden
localities as a rule suffer less than those who come there
from more favored regions, and it seems likely that after
a severe case of mosquito-X3oisoning the inoculating effect
may last for a long while. An instance of this has been
sent me by the Kev. Edward Everett Hale, who wrote,
under date of August 29, 1900:

" I think I am an instance of inoculation by mosquitoes'
virus. More than fifty years ago I went into the Maine
woods going to Katahdin. The first afternoon we were
out hardly an hour, Ijut at night, when we went into
camx^, I counted sixty well defined mosquito bites on my
right hand alone. Now from that time to tliis I have
hardly been troubled by mosquitoes. I dislike their song
at night, and if I saw one on my hand I should kill it, but
after the moment of the sting I never rcincniber that I
have been bitten."

II

Malaria and Mosquitoes

THE principal cause of the present widespread inter-
est in the subject of mosquitoes and mosquito-
extermination is the perfectly satisfactory proof
which has been gained during the i3ast few years that
they are resi3onsible for the transmission of the malarial
g-erm from malarial patients to healthy people. The
causative micro-organism of malaria was discovered by
the French army surgeon, Laveran, in Algeria in 1880.
From that time to the present, a small army of workers
of several different nations have been working upon the
life history of the malarial parasites, not only of human
beings but of birds, and our present knowledge is quite
complete. The idea that mosquitoes might possibly
spread malaria had been suggested a number of times.
The most forcible argument, however, was presented by
Dr. A. F. A. King at Washington, Avitli whom the idea was
entirely original, in a paper read before the Philosophical
Society in 1882. The actual demonstration, however, was
not brought about until much later, and in this actual
demonstration workers of several nations had a share.
The researches of MacCallum, of Johns Hopkins Univer-
sity, while investigating the malarial disease of the com-

48

JIALABIA AMj MOSi^UITOES 49

iiioii crow, contributed i2;reatly to tlie elucidation of a
kjiotty point in the life liistoiy of the parasite ; the stud-
ies of Koss upon the malarial disease of sparrows in India
proved effectively the transmission of this disease by
mosquitoes ; while the exi^erimental demonstration of
the transfer of the parasite of human malaria by mosqui-
toes was first performed by Italian investigators, al-
thoug-h it has since been done many times in many parts
of the world by workers of many different nationalities.

The life history of the malarial parasite of human kind
maybe briefly summarized as follows: All of the mahi-
rial parasites are protozoans, that is to say animals — and
not bacteria, that is to say plants. In the human blood
these protozoa inhabit the red blood cori)uscles and in
the blood they g-o through a sporulating- existence, which
may continue indefinitely unless checked by quinine or
in some other way. In the red corj)uscle the j)arasite
appears as an amosbula which g-radually grows until it
nearly fills the interior of the corpuscle, digesting- appar-
ently the red coloring matter of the blood and forming, as
the result of this digestion, pigment spots in its interior.
On reaching full growth the nucleus of the anujebula
suljdivides, each division gathering about itself a certain
amount of protoplasm, until instead of the single amoe-
bula the corpuscle contains a large number of spores.
The walls of the corpuscle then break, and the spores are
liberated into the blood serum. From a single infection
this sporulation or liberation of the spores takes place
[)ractically simultaneously and marks the beginning of
the malarial si)asm.

50 210SQUIT0ES

The three different kinds of malaria, namely, that in
which the fever recurs everj^ two days, known as tertian
malaria, that in which the fever recurs every three days,
known as quartan malaria, and the severe autumn fever,
known as jestivo-autumnal fever or tropical malaria — by
far the most dangerous of the three — are by some writers
supposed to be caused by distinct species of parasites.
This view is not held by other writers. But at all events,
the period of development of the sporulating stage of the
organism differs in length of time. As is ver}^ well
known, it frequently happens that the malarial fever or
chill will recur every day. That means, in tertian mala-
ria, that there has been a reinfection on one of the alter-
nate days, the development of the amoebulas being con-
stant in point of time, one set sporulating twenty -four
hours after the other set. It is just as this sporulation
occurs — just as the spores are liberated into the blood
serum — just as the malarial spasm is about to begin, that
the administration of quinine is most effective. It seems
to kill the spores when they are liberated, but appears
to have very slight effect upon the org-anism when it is
enclosed in the red blood cor^^uscle.

This sporulating- development, each of the liberated
spores attacking and entering- new red corpuscles, may
continue as above stated indefinitel3\ But not all of the
amoebulas undergo this develoj^ment. Some of them, so
long as they remain in the human body, apparentl}^ die
and are digested b}^ the leucocytes.

When, however, these forms are taken from the human
body, even when a blood sample is simply placed under

JIALAIilA AXD MOSQUITOES 51

the microscope for examination, they undergo a develop-
ment entirely different from the sporulating" form. Some
of them g-row large, others put out slender filamentary
arms, or llagella, as they are called, which separate from
the body of the organism and fuse with those which do
not flagellate. This is the true sexual generation of the
parasite, the flagellating forms representing the male sex
and the recei^tive forms the female sex. The develop-
ment \\\) to this point will take place anywhere outside of
the human body — in the stomach of mosquitoes of the
genus Culex, or, presumably, of other biting insects, but
it is only in the stomachs of the genus Anopheles, so far
as observed, that a further develoiiment takes place.
After the fusing of the flagella with the female germs in
the stomach of the Anopheles mosquitoes, the fertilized
organisms attach themselves to the walls of the stomach,
penetrate the inner walls, and locate themselves just
under the outer muscular wall. They then rapidly
increase in size until they eventually become five times
as large as at first. They are now known as Z3'gotes.
Clear spaces begin to appear on the surface. These
clear spaces are known as centromeres, and they are
rapidly surrounded by minute short dark lines, which,
when seen under a very high power of the microscope,
are shown to be spindle-shaped cells, known as blasts.
These blasts rapidly increase in number until eventually
they fill the entire zygote, obscuring the centromeres, and
when this condition of affjiirs is reached the z^'gote bursts
and the blasts are liberated through the muscular wall of
the stomach into the body cavity of the moscjuito. They

52 3I0SQUIT0ES

are active and penetrate rapidly into the tissue of the
salivary duct and so into the proboscis of the mosquito,
and, with the saliva or poison, they enter the blood of the
next warm-blooded animal which the moscpiito l)ites. It
is then supposed that the blasts enter the red blood cor-
puscles and the development re-begins at the stage where
we took it up.

It is thus shown that the full development of the mala-
rial parasite cannot take place within the human body ;
that the Anopheles mosquitoes are necessary secondary
hosts ; that the sexual generation of the parasite takes
place only in mosquitoes of the genus Anopheles ; and
further, that the old ideas of malaria from bad air (and of
course the word mcdaria means bad air), swamp " miasma,"
and so on, are to the minds of those familiar with the
subject of the biology of these low forms of life com-
pletely overturned.

Reasoning from the life history of the parasite alone, as
observed, would not, however, satisfy the minds of jieople
at large, and, in fact, it did not satisfy many medical men
who were not especially familiar with this field of bio-
logical research. Very many practical demonstrations
have therefore been made. One of the most interesting
was that carried on by Professor Grassi, the Italian,
during the summer of 1900, in the Plain of Cappacio, near
Salerno. The objects of this experiment were : (1) To
afford an absolute proof of the fact that malaria is trans-
mitted exclusively by the bite of Anopheles mosquitoes ;
(2) To found, on the results of recent research, a code
of rules to be adopted for freeing Italy from malaria

31 ALAR FA AND MOSQUITOES

53

in a few years. The experiment consisted in protecting"
from malaria railway emplo3^es and their families, living
in ten cottages, at the stations of St. Nicolo, Yarco,
and Albanella, situated along the Battipaglia-Keggio

Fio, 4. — Exporiiiicntnl House Occupied by Drs. Snniboii and Low on tlie
C:inip;vu:n:i in the Suninier of 1900. (From the Journal of Tropical
Medicine. )

Railway. They numbered 104 persons, including thirty-
three children under t(ni years of age. Of these 104 in-
dividuals, at least ('l<'vcii. including fonr children, had
never suti'ered from the disease, not having [)reviously

54 MOSQUITOES

lived in a malo.rious district ; a certain number, it ap-
peared, had not suffered from it in two or three years,
and all the others, that is to say, the har^e majority, had
suffered from it during the hist mahirial season, some of
them even in the winter. During the maharial season,
the health of the protected individuals was good, with the
exception of a few cases of bronchitis and a case of acute
gastroenteritis. None of these cases were treated with
quinine. The 104 persons, Avith three exceptions, had re-
mained free from malaria up to September 16th, the date
of the report.

Another very striking experiment which during the
autumn of 1900 was mentioned in newspapers all over the
world, was that performed by Doctors Sambon and Low,
of the London School of Troi^ical Medicine, in the Ro-
man Campagna, during the late summer and early autumn
of 1900. They had constructed a comfortable little five-
roomed wooden house about three hours' drive from Ostia,
in one of the most malarious portions of the Campagna.
The house was tightly built and was thoroughly screened.
The experimenters lived in this house through the period
when malaria is most i^revalent. They took no quinine
and no health precautions beyond the fact that at sun-
down each day they entered the house and remained there
until daylight the next morning. Dr. Rees, of the London
School, visited them and occupied the house with them
for a portion of the time, and all three conducted labora-
tory work in one of the rooms, which was fully equipped
for such a purpose, and led a busy and contented life.
They visited the neighboring villages and investigated

MALARIA AND MOSQUITOES 55

outbreaks of tlie fever in men and cattle. They received
and entertained many visitors who were interested in the
experiment. They turned indoors before six o'clock and
then stood at the windows and timed the first appearance

•k'^'^

Fig. 5. — Tlio JMahiria Mouse on llic ('aiupjii^iiM, seen from a distance.
(From the Journal of Tropicul Medicine.)

of Anopheles, which would come at a certain hour each
evening- and try to enter the screened windows and doors.
As Dr. Rees expressed it, " It must have been very tanta-
lizing for them to be unable to o-et at us." AVhen the
rains set in, everyone said that that was the critical time

56 3WS QUI TOES

of the experiment. The peo})le in the surronnding coun-
try generally became feverish and ill, which meant simply
that tliey Avere all full of malaria, and the chilling- caused
by the rain brought about an explosion of the fever. The
experimenters, however, went out into the rain and got
soaked to the skin, but their health remained perfect.
Not the slightest trace of malaria developed in either of
them ; as above stated, the spot where the house was built
was probably the most malarious one in the whole Cam-
pagna, and it was situated on the banks of one of the
canals, which was literally swarming with Anopheles
larv?e. The prevalent idea that the night air of the Cam-
pagna is in itself so dangerous was included in the ex-
periments and the windows were alwaj's left oi3en at
niglit, so that if the marsh air had anything to do with
malaria tlie}^ would have contracted it.

A check experiment was carried on at the same time.
Anopheles mosquitoes which had been fed on the blood
of a sufferer from malaria in Eome, under the direction
of the Italian authority Bastianelli, were sent to London
early in July. A son of Dr. Patrick Manson, the famous
investigator who first i)roved the transfer of filaria by
mosquitoes, offered himself as a subject for experiment,
and allowed himself to be bitten by the mosquitoes. He
had never been in a malarious country since he was a
cliikl, but in due time was taken with a well-marked ma-
larial infection of the double tertian t3"i:)e, and micro-
scopical examination showed the x^resence of numerous
parasites in his blood.

No more perfectly practical demonstration is probably

MALABIA A AW MOSQUITOES 57

demanded than is offered by these two experiments, but
it will be interesting- to American readers to give the re-
sults of some American work.

Dr. W. N. Berkeley, in tlie Bledlad Record of January
26, 1901, gives a most interesting- acconnt of a malarial
outbreak in a small town near New York City during^ the
summer of 1900. Around a large pond in the vicinity of
the town four or five fresh cases had recently developed
in August. The first case was that of a coachman who
had caught malaria elsewhere and had relapsed. From
his quarters in a long row of stables on (me side of the
pond the infection had passed along to other stal)lemen
and servants on the same side, to the distance of a quarter
of a mile from the original site, and a quarter of a mile in
another direction across the pond one other case appeared
in a small child. Dr. Berkeley went to the town and dis-
covered that Aiiopheles macul'qyennis \vas fairl}^ abun-
dant in every bedroom in that area in which proper search
was made. The breeding-places seemed to be segregated
pools at the end of the pond (the ]H)nd itself contained
fish) and i^ost-holes and excavations. These last were
numerous, as many buildings were going up. The fol-
lowing practical measures were adopted: (1) Extermina-
tion of all the AnoiDlieles found in houses by a party of
men sent out for the puri^ose, and this was followed b}^ a
systematic introduction of screens in windows and doors ;
(2) Filling in of the smaller breeding-places and the
drainage of the ])<)nd ; (3) The seclusion of every mala-
rious patient by netting and otherwise from the bite of

58 31 OS QUI TOES

mosquitoes, so lonf^: as lie liad g-ermsinliis capillary blood.
The results were as prompt as tliey were gratifying. Not
a single new case of malaria developed ; Anopheles dis-
appeared entirely from houses where it had been previ-
ously a night terror, and Culex was greatly diminished
in numbers.

The results reached by Dr. Berkeley were admirable,
and lie advises the following official steps for greater
New York :

1. Eecpiire malarial cases to be reported as scarlet fever
and diphtheria are now. Malaria is at least as dangerous
as scarlet fever ; economically it is far more of a scourge,
for it affects adult breadwinners as well as children.

2. Send an inspector to every infected house, who shall
instruct the people to kill all the Anopheles in the house,
to provide the windows and doors with screens, to isolate
the patient with particular care from mosquitoes, and to
cause all the standing water in the vicinity to be drained
or heavily petrolized.

Eigid treatment with quinine should be insisted upon
and the drug furnished gratis to those unable to pay, as
diphtheria anti-toxine is now supplied. Dr. Berkeley
believes that in a summer or two it would be possible,
by these measures, to reduce the number of local cases
by more than ninet}^ per cent.

Another interesting case has been reported to me by
the Rev. Wm. Brayshaw, of Chaptico, Md. Chaptico is
situated at the head of a wide-spreading bay or elbow of
the Wicomico River, about eight miles from the point
where this river enters into the Potomac at Rock Point.

MALARIA AND MOSQUITOES 59

The tide is ordinarily aboiit two feet at tlie full. The vil-
lage rests between two hills of 80 or 90 feet elevation. The
vriley is almost flat, and consists of marshy pools, in
which the mud or ooze can easily be pierced with a strong
pole to a depth of several feet. Three of these pools or
ponds are directly in the rear of the house known as the
rectory in which he resided with his wife on June 24, 1899.
Neither of them had ever had malaria or fever before, bTit
the mosquitoes were so numerous that it was impossible to
take rest at night for a while. On July 11th his wife was
taken with malaria, and on September 4th had to be re-
moved to the mountains. Mr. Brayshaw himself was sick
most of the time, and every house in the village had from
one to five persons suiJering from malaria. He proposed
ditching and drainage, but there was no money, and every-
body laughed at the idea, as many of the citizens had
lived there from childhood to an advanced age. There
did not seem to be sufficient fall to carry off the " effete
matter " On May 19, 1900, he gained the consent of the
property owners to ditch through their land a distance of
560 feet to Chaptico Creek. He paid for this himself.
The expense was about $40. The result he sums up as
follows : " During the summer of 1899, from May to Octo-
ber the mosquitoes were so numerous that life was a
burden during the night, and they were so small that nets
seemed to have no effect upon them. Froni May to Octo-
ber 1900, quite a nu.nber visited us, until June l-2th, when
they disappeared, and we were free from them until the
last six days in September, when I found a local cause for
their breeding. In the sunnner of 1899 every house in the

60 MOSQUITOES

villag-e had from one to five persons sick with chills and
fever, and other malarial tronbles ; doctors in constant at-
tendance. In the summer of 1900 there were only two spo-
radic cases of chills, both caused by neglig-ence or in-
attention to ordinary caution. Everyone in the village
seems quite free from malaria since July 10th."

In Cuba, as a result of the mosquito- extermination work,
which will be mentioned in the chapter on " Yellow Fever
and Mosquitoes," Colonel J. R. Keane, U. 8. A., Surg-eon-
in-Charg-e at Havana, wrote me, January 12, 1901, that in
his opinion there had been a very marked reduction of
malaria at the military posts in w^estern Cuba.

The principal arguments in favor of the idea that mal-
aria may also enter the human system in some other way,
are that there is malaria where there are no mosquitoes,
and that there are many mosquitoes in localities where
there is no malaria. These points are adduced by per-
sons wdio, while admitting- that it has been proved that
Anopheles transmits malaria, and that possibly this is the
only method Avhich has been proved, still insist that there
may be, and even that there must be, other methods. As
a matter of fact, it is practically impossible to prove that
there is local malaria Avhere there are no Anopheles. The
bite and method of attack of Anopheles is so insidious that
these mosquitoes attract very little a'iention where they
are not especially numerous. One may be bitten by them
while asleep at night almost without realizing it. Anoph-
eles may be present wdiere there is no malaria, since it
wdll always remain uninfected unless some vertebrate ani-
mal suffering- with the disease comes to its neighborhood.

3IALABIA AND MOSQUITOES 61

There was no autoclitlionous case of malarial fever for
years at tlie League Island Navy Yard, although there
was a distinct breeding--o-round for xVnopheles near by.
Woldert has caug-ht larvjio of Anopheles in a clear pool of
water in the Pocono Mountains of Pennsylvania, a notable
health resort, at an elevation of three thousand feet above
sea-level. The statements that malaria has prevailed when
there were few or no mosquitoes are always too vague to
be of value, because it is not definitely stated whether the
cases w^ere relapses or fresh infections. In cases where
mosquitoes are numerous, moreover, and there is no mal-
aria, to the point which we have already made that prob-
ably no malaria has been brought into the vicinit}" may
be added the fact that when mosquitoes are numerous,
almost without exception they are found to be the com-
mon species of Culex, which, as shown, have nothing- to
do with malaria. It is often stated, for example, that
malarial fever is caused by excavating the ground ; newly
turned earth is said to be responsible for it, but, as a
matter of fact, as pointed out by Ross, there are millions
of people constantly engaged in digging without suffering
from the disease more than do others, and then also ex-
cavations always result in surface pools of water, m which
for a time Anopheles will frequently he found breeding.
One curi(ms case has been mentioned by Mr. D. E. Hutcli-
ings, in the English journal, Nature, in which he stated
that he knew of a medically authenticated case of malaria
having been caused by fresh earth carried past a Avindow
in buckets by coolies. This statement is criticized by
Ross in the following words : " Which fact was medically

62 MOSQUITOES

authenticated— the fact that the patient suffered from ma-
laria, or that his mahiria was caused by the earth carried
past in buckets ? I can understand the first being certi-
fied to by a doctor, but scarcely the second. How did the
doctor prove that the fever was produced by the earth in
the buckets ? It seems to me that the only way in which
he could have done so in a trustworthy and scientific
manner would have been to infect a second person by
having- the buckets carried past a second time. I doubt
whether such instances— and we see hundreds of them in
the press — will bear close examination."

It has been claimed by Italian observers and others,
that there is a very exact coincidence between the geo-
grai^hic distribution of malaria and Anopheles mosqui-
toes. Bearing on this point, the conclusions reached by
Nuttall, Cobbett, and 8trangeways-Pigg, in their studies
in relation to malaria (Journal of Hygiene, vol. i., No. 1,
January, 1901), are very imi^ortant. They are as fol-
lows :

1. The disappearance of ague from Great Britain does
not depend upon the extinction of mosquitoes capable of
harboring the j^arasites of malaria.

2. Three species of Anopheles {A. macui'q>ennis, A.
hifu7xatus, A. 7iignpes) are to be found in Great Britain in
all districts which were formerly malarious, but also in
places concerning which there is no record of the former
prevalence of ague.

3. The Anopheles to-day are most numerous in low-
lying land containing many ditches, ponds, and slowly
flowing water, suitable for their habitat, and correspond-

MALARIA AND MOSQUITOES 63

ing- to the districts where ag-ue was formerly preva-
lent.

4. Since the disappearance of ague does not depend
upon the extinction of Anopheles, it is probahly due to
several causes operating together :

(«.) A reduction in the number of these insects conse-
quent upon drainage of the land, this being in accord
with all the older authors, Avho attributed the disappear-
ance of ague largely to this cause.

{h.) Keduction of the population in infected districts as
the result of emigration, about the time when ague disap-
peared from Eng-land. This would naturally reduce the
number of infected individuals, and thus lessen the
chance of the Anopheles becoming- infected.

(c.) It is possible that the use of quinine has reduced
the chances of infecting the Anopheles, through checking
the development of the parasites in the blood of subjects
affected with ague.

Of these, the first-mentioned cause seems to have been
chiefly operative. The possibility is not yet excluded of
there being another intermediary host besides man, capa-
ble of harboring the parasite, and, assuming that this
were so, this host may have become extinct in the low-
lands where it is known that the fauna and flora have al-
tered.

5. The coincidence of the geographical distril)utiou of
ague and Anopheles as claimed by Grassi for Italy, and
as probably holding good for other parts of the world, is
hereby disproved for England, and consequently the gen-
eralizations are proved to l)e premature whereby he ex-

64 3I0SQUTT0ES

eludes other blood-sucking- insects from being possible
hosts of malarial parasites on the strength of his sup-
posed geographical agreement.

6. Since the geographical distribution of Anopheles in
England is wider than the former distribution of ague in
that country, we are forced to conclude that it is not a
matter of the geographical distribution of Anopheles as
much as of their numerical distribution.

7. Our observations having proved the existence of
Anoidieles in non-malarious districts, we believe that they
will explain the occasional occurrence of ague in out of
the way places, Avithout making it necessary to assume
that malaria-bearing moscpiitoes have been freshly im-
ported, for, given suitable conditions of temperature and
the requisite number of Anopheles, a malarious subject
coming from other parts might w^ell infect the local in-
sects, wdiich in turn would spread the infection to healthy
persons.

8 We would suggest to those engaged in the investi-
gation of malaria in other countries, that they search as
carefully for Anopheles in non-malarious as in malarious
regions. More data as to the number of these insects in
various localities are certainly required, though Ave are
fully aware that numerical estimates permit of a consider-
able degree of error. Nevertheless, they would always
possess a relative value.

Grassi has repeatedly asserted that the geographic dis-
tribution of Anopheles in Italy coincides with that of
malaria, and on the strength of their wdder geographic
distribution he excludes a number of blood-sucking creat-

MALARIA AND MOSQUITOES 65

ures, such as mites, ticks, stable-Hies, gad-Hies, black-
flies, puukie-flies, lice, bedbugs, and Culex, from being
possible carriers of malaria.

Probably nothing more need be said in regard to the
general subject of malaria and mosquitoes. The case is
abundantly proven, and it remains necessary from the
health standpoint to know all about the mosquitoes of the
genus Anopheles — how and where they live and breed,
and how to distinguish them from other mosquitoes in all
stages of their existence. All these facts will be con-
sidered in Chapter IV.

Ill

The Common Mosquitoes of the Genus Culex

CULEX is an old genus named by Linnaeus in 1735,
wliicli for a long time comprised all the mosqui-
toes. But other genera have been erected, and now
the mosquitoes are included in a family known as the Cu-
licidae, which comprises several genera and very many
species. Culex, however, is the typical genus, and in-
cludes the commoner, most abundant, and most wide-
spread kinds of mosquitoes. We have at least twelve
species in the United States, and probably more than
two hundred species exist in different parts of the world.
The genus has no geographic limitation, and its species
are found in the Arctic regions as well as in the tropics.
Not only has the genus itself apparently no territorial re-
strictions, but the individual species are many of them
widespread. There are a half dozen or more which may
be found practically everywhere in the United States.
There are others which extend from Cuba to Alaska. A
few others are more restricted. The life history of the
common European Culex, known as Culex j^h^ieiis, was
studied and described very accurately as long ago as 1691,
by Bonanni, in his " Micrographia Curiosa," published at
Rome that year, and I am not sure that mosquito biology

66

THE COMMON MOSQUITO 67

was not well known at an even earlier date. The French
observer, Reaumur, studied the same species more than
150 years ago, near Paris, and his account of the devel-
opment of Culex has remained standard from that time
almost to the present day. The full life history of no
American species of Culex, however, was published until
1896, when the life history of Culex puwjens Wiedemann
was worked out by the writer at Washington and pub-
lished in Bulletin 4, n. s., of the Division of Entomolog-y,
of the United States Department of Agriculture.

Fig. C. — Egg Mass of Culex imngens ; enlarged; with individual eggs,
still more enlarged, at left. (Author's illustration.)

Culex pungens is one of our common North American
species. It abounds everywhere, from the White Moun-
tains of New Hampshire down into Central America, and
is, perhaps, the most abundant of our mosquitoes. It
breeds exclusively in fresh water, and its larvae may
everyw^here be found in water buckets and barrels, in
transient pools of rain-w^ater, in fresh-water swamps, along
the borders of inland lakes and ponds, and, in fact, in all
of the out of the Avay places which have been mentioned
in Chapter I. Its life history may be taken as typical of
the genus Culex, all other species probably closely re-

68 MOSQUITOES

sembling- this form in all of their early stages aucl in
their i^eriods of development.

The female lays her eg-^^s upon the surface of the water,
balancing herself upon some floating object during the
operation, and extruding them in an irregular, raft-shaped
mass, which is usually shaped something like a pointed
ellipse somewhat convex below and concave above, all of
the eggs standing on end and closely api:)lied, side by
side, in from six to thirteen longitudinal rows, with from
three or four to forty eggs in a row. The number of eggs
in each batch varies from 200 to 400. As seen from above,
the egg mass is gray-brown, from beloAV, silvery-white,
the latter appearance being due to a film of air which
XDrotects them from the water. It seems impossible to
wet these egg masses. They may be pushed under the
water, but bob up apparently as dry as ever. As the
eggs are very small, being only 0.7 mm. long, and 0.16
mm. in diameter at the base, the entire egg mass is not a
large object, seldom, in fact, reaching a length of more
than a quarter of an inch. The mass separates rather
regularly and the eggs are not stuck together very firmly.
After they have hatched, the mass Avill disintegrate in a
few days, even in perfectly still water. The individual
eggs are slender, broader and blunt at the bottom, and
somewhat i)ointed at the tip. The tip is always dark
grayish-brown in color, while the rest of the egg is dirty
white. Sixteen or more hours after laying, the eggs
hatch, generally about noon on warm da^^s, but some-
times they will remain unhatched for two days or even
longer, especially in cold weather.

THE COMMON 3I0SQUIT0

69

The larvffi issue from the under side of the egg masses
and QiW extremely active at birth, wrig^^ling- rapidly in
the water about the eggs. They are very minute and
move so rapidly that it is difficult to form any impression
of their shape and structure except when they are at rest.

Fig. 7.— Young Larvae of Culex pungens ,

tration.)

enlarged. (Author's illus-

They come frequently to the surface to breathe, and dur-
ing the first few hours many of them remain under the
egg mass, where they get air from the air film by which
the egg mass is surrounded. One of the first peculiarities
which strikes one on observing these newly hatched
larv» or wrigglers under the lens is that the mouth is
furnished with tufts of filaments which are constantly in
vibration. The head is large, the antennae long, the thorax
somewhat swollen, and the abdomen slender. The sides
of the body are furnished with stiff bristles. From the
next to the last segment of the abdomen there protrudes

70

MOSQUITOES

a long tube nearly as thick as the body itself, and it is
this tube which is extruded from the surface of the. water
every time the larva rises to breathe. The object of this
extrusion is to get air, and this tube is the breathing tube
of the insect. Its extremity is furnished with a breathing

Fig. 8. — Mouth-parts of Larva of Cule.v pungens ; greatl}" enlarged.
(Author's illustration.)

hole, or spiracle, and into it run two main trachejie, or
breathing tubes, which extend through the body of the
insect, giving off branches here and there, and thus carry-
ing air to all of its tissues. The true end of the body is
furnished with four flat flaps, the exact purpose of which

THE COMMON MOSQUITO

71

is not known, but which may possibly function as gills
while the larvae are very young-, and are certainly of use as
swimming organs. When
the breathing tube is at the
surface of the water the
body of the wriggler ex-
tends down below the sur-
face at more or less of an
angle with the water sur-
face, and its mouth-parts,
as just stated, are constant-
ly in vibration, bringing
into its mouth any minute
particles which float in sus-
pension in the water. Oc-
casionally it descends to
the bottom, jerking its body
violently from one side to
the other. The flaps at the
end of the body undoubt-
edly assist in this motion.
The jerking motions are
not so evident when
larva or wriggler is
scending" as when it

the
de-
be-
comes necessary for it to
ascend once more ; in other
words, its specific gravity
seems to be greater than that of the water and sometimes
it can be seen to descend without effort, simply sinking

Fig. 9. — Full-grown Larva of Culex
punge?is ; enlarged. (Author's il-
lustration.)

72

MOSQUITOES

down. After one of tliem has wriggled up to the surface
of the water, its breathing tube extrudes, fresh air runs
into its trachea), and the tension of the so-called surface

film of the water assists it
in maintaining its position.
After an introductory wrig-
gle, which pulls the breath-
ing tube below, the insect
sinks. The larval Cidex ap-
pears to pass through three
different stages of growth,
reaches maturity, and trans-
forms to pupa, in a minimum
of about seven days in warm
summer weather.

The pupa differs markedly
from the larva in the great
swelling of the thoracic seg-
ments, as shown in the ac-
companying cut. The pupa
seems to be all head and
thorax, with a slender abdo-
men and with two large flaps
at the end of the abdomen,
which assist it in swimming
whenever it feels that it has
to swim. In this stage the
Fig. 10.— Pupa of Culex pun- insect is lighter than water.
gejis; enlarged, with Anal Seiif- -ri • j« i l j.i

mentbelow, still more enlarged. It remains motionless at the
(Author's illustration.) surface and when disturbed

THE COMMON 3I0SQUIT0 73

does not sink without effort, as does the larva, but is
only able to descend by violent muscular action. It
wriggles and swims as actively as does the larva and
soon reaches the bottom of the water. As soon as it
ceases to exert itself, however, it floats gradually up
to the surface once more. As x^ointed out in our con-
sideration of the habits of mosquitoes in general, this
activity on the part of the pupa is necessary to preserve
it from fishes and from its natural enemies. It is very
active and difficult to capture. The mortality of the
pupa3, however, is not great, except through the efforts
of fish and its other enemies, while that of the wrigglers
or larvae is apt to be great through drowning. When-
ever a larva becomes sick or weak, or for any reason un-
able to exert sufficient muscular force to wriggle to the
surface at frequent intervals, it drowns. It seems almost
like a contradiction in terms to speak of an aquatic insect
as drowning, but this is a frequent cause of mortality
among mosquitoes. This fact also explains the efficacy
of the remedial treatment which causes the surface of the
water to become covered with a film of oil of any kind.
Aside from the actual insecticidal effect of the oil, the
larvae drown from not being able to reach the air. Or
they may draw drops of oil into the tracheae, clogging
them and preventing the passage of the air. The struct-
ure of the larvae and pupae at the different stages is so
well shown in the accompanying figures as to render it
unnecessary to describe them fully. One peculiar struct-
ure of the pupa, however, has already been pointed out
in the general consideration of mosquitoes, and that is the

74

3I0SQUIT0ES

trumpet-shaped breatliiDg- org-ans, which now issue from
the thorax and no longer from the abdomen as with the
larva. In Culex pimgens, these ear-shaped, trumpet-like

Fig. 11. — Adult male of Ciilex pungens; with parts enlarged. (Author's
illustration.)

breathing" organs are rather slender and of the propor-
tions indicated in the figure.

The duration of the pupal stage in midsummer with
this species at Washington is about two days. A mini-
mum generation, therefore, of Culex pimgefis will occupy
ten days, as follows : sixteen to twenty-four hours for the
egg ; seven days for the larva, and two days for the pupa.

THE COMMON 310 S QUITO

75

In my observations on this species I was interested to
notice that on the first day the adults which emerged
from the pupae were invariably males ; on the second day

Fig. 13.— Adult female of Culex pungens; enlarged. (Original.)

the g-reat majority were males, but there were also a few
females ; the preponderance of males continued to hold for
three days ; later the females were in the majority.

The duration of a generation as indicated above, is, as
we have seen, a minimum duration. If a spell of cold
weather should come in the middle of the summer, the

76 MOSQUITOES

life of the wrig-glers may be almost indefinitely pro-
longed. I have watched them for twenty days, during
which time they did not reach full growth. The short-
ness of the minimum generation, however, is very signifi-
cant and accounts for the fact that swarms of mosquitoes
develop upon occasion in surface pools of rain-w^ater,
which may dry up entirely in the course of two weeks or
Jess, or in a chance bucket of water left undisturbed for
that length of time.

Dr. John B. Smith has reared the species, as elsewhere
stated, from larvj^e found in Januarj^ frozen in ice. In
studying the larvae after they had been thawed out he
found that they remained under the water for a long
time, certainly fifteen minutes, and i:>robably much
longer. These observations thus differ radically from
those which I made in summer, and show that these larvae
must be studied still more before we know all that ma}^
be found out about them.

This species, Culex pungens, is said by Dr. H. A. Vea-
zie, of New Orleans, to breed most extensively in the
gutters in that city. The}^ are found in gutters in which
the water runs slowly, but more plentifully in those where
there is no current. In gutters that receive the refuse of
the gas works, tar factories, soap works, and oil establish-
ments, there are no larvae. They live in gutters contain-
ing Mississippi Eiver water, but do not prosper. Dr.
Yeazie thinks the fine sediment in the Mississippi water
blocks their breathing tubes, since they flourish well in
this water after it has been filtered.

Reverting once more to the distribution of the different

THE COMMON 3I0SQUIT0 77

species of Culex, I have been able to determine, by exam-
ination of the locality labels in the collection of the United
States National Museum, that in almost every locality in
the United States there may be found five or six siDecies
of this genus. The commoner forms are Oidex conso-
brbius, C. stimidans, C. 2)erturla?is, C. ^j>?<;^^(?/^,s, and C im-
p'lger, and these forms are found almost all over the
country, from New England to Texas, and even to
southern California. C, coasohrinus is perhaps a more
northern form than the others, and is one of the species
which occurs in Alaska. It is also found in the White
Mountains in New Hampshire and in the Catskill Moun-
tains in New York, and occurs on the Saskatchewan River
in British America, and in Minnesota and North Dakota.
We have in this country no species of the genus Culex
which inhabits really salt water and, in fact, no species of
mosquito can definitely be said to occur in water as salt
as the ocean. Three or four Australian species are said
to live in salt water, but, so far as I have been able to
learn, there is not sufficient substantiality in this record.
Oulex salinus of Europe is also said to breed in salt
water. We have in the United States, however, a species
of Culex which occurs in brackish water, that is to say, it
is able to breed in, and i:)refers apparently to breed in,
the brackish swamps which are occasionally overflowed
at very high tides, though not affected by the daily
high tide. This is Culex sollicitcms (see Fig. 1), a small
gray mosquito which has its legs banded with black and
white. It is ordinarily known as the ring-legged mos-
quito and is the most common form on the Atlantic sea-

78 MOSQUITOES

coast. It occurs along- the New Jersey coast, the Long
Island coast, along Staten Island, at Virginia summer
resorts, and at Tybee Island, Ga., and St. Aug"ustine
and Charlotte Harbor, Fla. Curiously enough, Dr. A. D.
Hopkins states that what is probably this same species
apparently breeds in West Virginia in pools and small
streams fed from coal-mine drainage, the water of which
contains a large percentage of sulphate of iron.

There is no doubt that this Culex breeds in great num-
bers in the pools left by the highest tides, which subse-
quently become freshened to some extent by rains or by
the entrance of spring water. It has been caught, how-
ever, considerable distances inland, and the question
arises, has it been carried to such spots by trains only,
or will it breed after being* so carried for at least one or
two generations in fresh water? Mr. Benjamin S. Pas-
chall, of Newfield, N. J., caught this species in August,
1900, in his garden. They could be found anywhere in
the long grass, practically by the thousands. Newfield
has one of the highest altitudes in South Jersey, being-
about 130 feet above the tide and over thirty miles from
the sea. In Mr. Paschall's o^Dinion, the species must
breed there. There had been no wind for a long time
before their appearance and the microscope showed all
specimens to be freshly hatched. On September 4th, he
tried an experiment and placed a pail of water in a spot
where these insects were thickest. By the end of a week
he had procured many eggs, and September 14th he
succeeded in hatching out several hundred mosquitoes,
but not one single specimen of sollicitans; all were 2^un'

THE COMMON MOSQUITO 79

gens. He concludes tliat Culex sollicitans appears in
the perfect state tliroug-hout South Jersey, being found
from May to October, but is not always common. Mr.
La Eue Holmes, of Summit, N. J., has several times
sent me specimens of sollicitans taken at Summit, which
is about twelve or fifteen miles from the nearest salt
marsh. I am inclined to think that although this species
may be found widespread through the summer in various
parts of New Jersey, this abundance is due to its car-
nage in numbers from the sea-coast by railway trains,
and even if it does breed for a generation or two in
fresh water, the supply is constantly renewed from the
sea-shore.

Oulex impiger is another of the more northern mos-
quitoes, having been collected by Mr. Trevor Kincaid on
the Harriman Alaskan Expedition, and having been given
me by Dr. Walter Evans, of the United States Department
of Agriculture, who has investigated the agricultural re-
sources of Alaska. Mr. F. C. Pratt has found it breeding
in privy vaults in Alexandria, Va., and this species is
likely to be the one found usually in such places, where
the water is fouled with decomposing or excreted animal
matter.

The distribution of our commoner species of Culex, so
far as known to the writer, is as follows :

Culex coj^sobrinus Desv.

Habitat : White Mountains, N.H. ; Beverley, Mass., Septem-
ber 38 (Nat. Mus.) ; Catskill Mountains, Greene County,
N.Y., 2,500 feet (Howard); Hlinois, March 21, April 21),
May 6, October 16 (Nason); St. Anthony Park, Minn. , April,

80 MOSQUITOES

May, on snow (Lugger) ; Saskatchewan River, British
America; South Dakota (Nat. Mus.j ; Lineohi, ^eb.
May, September (Bruner) ; Colorado (Nat. Mus.) ; Hot
Springs, Ark. (Curry); Los Angeles, Cal., February (Co-
quillett) ; Argus Mountains, Cal., April (Nat. Mus.) ; Santa
Fe, N. Mex., July (Cockerell) ; New Orleans, La., Novem-
ber (Thayer) ; Ottawa, Canada, May (Howard) ; Summit,
N. J. (Holmes) ; Trenton, Ontario, May 24 (Fletcher) ; Flat
River, Mo., November (Pergande).

CULEX ANNULATUS Meig.

Habitat : New Bedford, Mass. (Johnson) ; Lincoln, Neb.,
May (Bruner) ; Santa Fe, N. Mex., July (Cockerellj ; Stan-
ford, Cal. (Kellogg) ; Laggan, British Columbia (Wick-
ham).

CULEX IMPIGER Walk.

Habitat : White Mountains, N.H. ; Beverley, Mass., May 24,
June 2 (Nat. Mus.) ; Ithaca, N.Y., July 9 and 17, August
28 ; Wilmuth, N.Y., June 10 (Comstock) ; Saskatchewan
River, British America (Nat. Mus.) ; Minnesota (Lugger) ;
Loudoun County, Va., August 26 (Pratt) ; Tyrone, Ky.,
July 14 (Carman) ; Georgia (Nat. Mus.) ; Mesilla, N. Mex.
(Cockerell) ; Isle of Pines, West Indies (Scudder) ; Port-
land, Jamaica (Johnson) ; District of Columbia, September
12 (Barber); Alexandria, Va. (Pratt) ; Ogdensburg, N.Y.,
June 3 (Howard) ; Buffalo, N.Y. (Wright) ; Middletown,
Conn., June (Davis) ; Ottawa, Canada, May 31 (Howard);
Chats Rapids, Quebec, May 24 (Fletcher) ; Buckeye, Wash.
(Nat. Mus.) ; Stikine River, British Columbia (Wickham) ;
City of Mexico (Herrera).

GULEX PERTURBANS Walk.

Habitat : Lakeland, Md., August 8 (Pratt) ; Virginia, August
17 (Pergande); Tick Island, Fla., May 12 (Johnson);

THE COMMON MOSQUITO 81

Texas (Nat. Mus.) ; Bayamon, Porto Rico, January (Busck) ;
District of Columbia, September 1-5 (Barber) ; St. Elmo,
Va., June, July, Virginia Beach, August (Prattj ; Mel-
bourne, Fla. (Peek); Cuba (Lazear, Read).

CULEX PUNGENS Wied.

Habitat : Ottawa, Canada (Fletcher) ; White Mountains,
N.H. ; Beverley, Mass., September 5 ; Cambridge, Mass.,
September IG to November 5 ; Boston, Mass. ; Baltimore,
Md., November 5 (Nat. Mus.), November 26 (Lugger);
Charlton Heights, December 1 (Pratt) ; District of Colum-
bia, January 30, March 5, May 6 and 15, June 28, July 11,
August, October 10, 15, 25 and 31, November 4, 8, 13, 16
and 23, December 23 (Pergande) ; Ithaca, N. Y., May 29,
July 17, August 28 (Comstock) ; Illinois (Nason) ; Minne-
sota (Lugger) ; Lincoln, Neb., September 20 (Brunerj ;
Lexington, Ky., November 10 (Garman) ; New Orleans,
La., December 17 (Howard); San Antonio, Tex., May 5
(Marlatt) ; Hot Springs, Ark. (Curry) ; Georgia, August
(Coquillett) ; Melbourne, Fla. (Peek) ; Portland, Jamaica
(Johnson) ; Mexico City (Barrett) ; District of Columbia,
August 22, 28, September 1 (Barber) ; Jackson, Va., October
(Thayer) ; Woodstock, Va., June (Pratt) ; Newport News,
Va., October (Thayer); Stillwater, Okla., June (Bogue) ;
Philadelphia, Pa. (Woldert) ; New Orleans, La., June
(Veazie) ; Eastern Texas (Woldert) ; Summit, N. J., May
(La Rue Holmes) ; Newfield, N. J. (Paschall) ; Middletown,
Conn., June (Davis) ; Cuba (Lazear, Reed) ; Agric. College,
Miss. (Herrick) ; Flat River, Mo., November (Pergande),
Bluefields, Nicaragua (Wailes) ; Guanajuata, Mex. (DiigOs).

CULEX STIMULANS Walk.

Habitat : White Mountains, N. H. ; Beverley, Mass., June 2,
July 9 ; Cambridge, Mass., May ; Jamaica Plain, Mass.,

82 MOSQUITOES

August 25 (Nat. Mu-s.); Siasconsett, Mass. (Wilder) ; Bal-
timore, Md. (Lugger) ; Illinois, August 1, September 15,
October 5 (Nasoii) ; Agricultural College, Mich. (Gillette) ;
Saskatchewan River, British America (Nat. Mus.) ; Lin-
coln, Neb. (Bruner) ; Colorado (Nat. Mus.); Ithaca, N.
Y., June 13, 18, 29, July 14, August 28 ; Wihuuth, N. Y.,
June 10 (Comstock) ; Rochester, N. Y. (Ewers) ; Buffalo,
N. Y. (Wright) ; Brooklyn, N. Y. (Van Matie) ; Georgia
(Nat. Mus.); Bladensburg, Md., May 27 (Barber); St.
Elmo, Va., June 5 (Pratt) ; District of Columbia, Septem-
ber (Barber) ; June 10 (Miss L. Sullivan) ; Ottawa, Canada,
June 1 (Howard) ; Ogdensburg, N. Y., June 3 (Howard) ;
Rochester, N. Y., June (Ewers) ; Summit, N. J., May (La
Rue Holmes); Middletown, Conn., June (Davis); Lake
Maxinkuckee, Ind. (Evermann) ; Mesilla, N. Mex., Octo-
ber 26 (Cockerell) ; Tacna, Ariz,, April 13 (Hubbard) ; Jua-
rez, Mexico, May 12 (Cockerell) ; Summit, N. J. (Holmes) ;
Flat River, Mo., November 1 (Pergande).

CULEX SOLLICITANS Walk.

Habitat : Maine, August ; Beverley, Mass., June, September
15 (Nat. Mus.) ; Siasconsett, Mass. (Wilder) ; Avalon, An-
glesea, and Atlantic City, N. J., July 10 to 29 (Johnson) ;
Summit, N. J., September (Holmes) ; Far Rockaway, Long
Island, N. Y., August 30 (Howard) ; District of Columbia
(Pergande) ; Georgia (Nat. Mus.) ; St. Augustine and Char-
lotte Harbor, Fla., July; Portland, Jamaica (Johnson) ;
Chesapeake Beach, Md. (Barber) ; Baltimore, Md. (Thayer);
Plymouth, N. C. (Thayer).

CULEX TARSALIS Coq.

Habitat : Argus Mountain, Cal. , April ; Folsom, Cal., July
3 (Nat. Mus. , Koebele) ; Stanford, Cal. (Kellogg) ; Corval-
lis, Oregon (McElfresh).

THE COMMON 3I0SQUIT0 83

CULEX TRISERIATUS Say.

Habitat : White Mountains, N. H. (Nat. Mus.) ; Delaware
County, Pa., June 12 (Johnson) ; Washington, D. C, May
5 and June 10 ; Loudon County, Va. (Pratt) ; Near Balti-
more, Md. (Thayer) ; Roanoke, Va., October (Thayer) ;
Middletown, Conn., June (Davis) ; New Jersey (Woldert).

Dr. J. B. Smith's Observations on Oulex pungens.

The observations made by the well-known State ento-
mologist of New Jersey on the larviB hibernation of Culex
paiigeiDs in pitcher plants are of such great interest that
they are given in full from advance sheets of an article
which Dr. Smith has been good enough to send me and
which was prepared for the Entomological News.

New Jersey's reputation for mosquitoes is well established, and
more people come into our State annually to be bitten by our
shore species than go to any other State in the Union for any
like purpose. In some of the swampy districts in the Pines they
make life a burden at times, so when my good friend, J. Turner
Brakeley, wrote me in the late summer that in looking at the
contents of some pitcher-plant leaves he had found mosquito
larvae in abundance in the water they contained, it made no
especial impression upon me. It was in a way what I Avould
have expected, though no one had noted this so far as I could
then remember. Dr. Riley at one time bred a number of species
from this plant ; but seems either to have found no mos(iuitoes
or to have ignored them. Mrs. Treat made many interesting
observations on the feeding habits of the plant itself, feeding the
leaves with raw meat in place of tlie insects that ordinarily fall
into them : but she also ignored the mosquitoes.

84 BIOS QUI TOES

Late in November (1900), I t^peiit three days witli Mr. Brakeley
at Lahaway and one of our walks was into a huckleberry and
wild cranberry swamp, where pitcher plants were abundant.
Though the weather was yet mild, mosquitoes were no longer
obtrusive. There were occasional specimens, to be sure, but they
seemed to be left-overs not yet in hibernating quarters. The
interesting point w^is that in every leaf examined there were
wrigglers, varying in size from an eightli to a quarter of an inch
in length. There was always a mass of insect fragments at the
bottom, say from one half to an inch in depth, and in composi-
tion this varied from a dense black ooze at the lowest point to
entirely or only partly decayed specimens at the top of the njass.
The question arose at once whether these larvae would yet
develop that season, and from published accounts I assumed
that they must, or perish. Dr. Howard, in his careful account
of the species of Culex, and especially C. puiigens, says nothing of
larval hibernation. He records finding adults and, indeed, this
was in accordance with my own experience.

The matter dropped here until late in January when, during a
bitter cold spell, Mr. Brakeley cut out a few pitcher leaves,
stripped them from the core of solid ice they contained, and
looking through it saw^ wrigglers imbedded in all parts of it, in
all sorts of shapes ; but mostly in a half coil. The temperature
of the bog liad been down to 2° below zero, as registered by a
standard minimum thermometer, and radiation probably lowered
this even more.

A number of leaves were gathered, the cores of ice with all they
contained were removed, and the lumps were placed together in
a jar in a moderately warm room. The ice melted slowly, and
as the larvae were gradually freed, they dropped to the bottom,
where for a time they rested, apparently lifeless. But as the
amount of ice decreased, feeble motions here and there indicated
a revival, and long before the lumps were completely melted.

THE COMMON MOSQUITO 85

those first released wero moving about actively. This, be it
noted, was in water not much above the freezing point. Soon
after the ice had melted and the debris had settled, the insects
were Ijusily engaged in apparent feeding.

The specimens were sent to me as a curiosity, January 22d, and
arrived in very good condition. A few had succumbed to the
dangers of the journey, but altogether there was a good lot
of lively wrigglers. The bottle was nearly full of water, it had
had a five mile wagon drive over a rough road, had been trans-
shipped no less than four times before it reached New Brunswick
and was thrown into the deliv^ery wagon. Under these circum-
stances any regular breathing of the kind usually described was
utterly out of the question, and diownings should have been
numerous ; but really only a very sm.ill number of specimens
died.

At short intervals other jars were received, all of melted ice
taken from pitcher plants, until I had several hundred active
wrigglers in eight different jars. Some of the leaf chunks, Mr.
Brakeley informs me, had only a very few larvae — ten or a dozen;
others ran as high as thirty or more.

The jars were all placed on a counter shelf near a steam radia-
tor and it was expected that in a few days there would be pup*
and adults. But the days passed into weeks and the weeks into
months, without change other than a gradual— a very gradual,
increase in size. The larvae were just as active and lively as they
could be expected to l)e, and w^ere feeding continuously; but
evidently something was lacking. Besides, they <lid not in all
respects behave as, according to Dr. Howard's account, they
sliould have done. I do not suggest that the account as printed
is not a perfectly accurate record of facts: merely that my speci-
mens were Jersey mosquitoes and therefore a law unto them-
selves.

As the fragments settled to the bottom, the water l)ecame

86 MOSQUITOES

almost entirely clear and larv* congreg:atecl over this sediment,
feeding head down and frequently rooting into it; varying the
process by working along the glass of the jar on the side away
from the light. It was very rare that an individual was
observed at the surface with the spiracle in breathing position.
I watched patiently several times, for fifteen minutes at a time,
without noting a single individual rising to the top. Mr. Dick-
erson, one of the students, watched more or less continuously
for two hours on one day and declares positively that during
that period only a small percentage of the entire number came
to the top. On two or three occasions where my work was such
as to allow it, I kept a jar within sight the entire day, and I
have no hesitation in saying that some individuals remained
below the surface for hours.

Occasionally a number of specimens would be at the surface,
feeding, head up, so that the mouth-brushes skimmed the sur-
face, and these w^ere watched on occasions for fully twenty
minutes without noting any attempt to assume the breathing
position. In fact, during the two months that these larvfe were
under daily observation, the rising to the surface to breathe was
the rare exception rather than the rule.

As to feeding positions, all of those figured by Dr. Howard
were noted. Usually they were head down, over the bottom
sediment, or head up, feeding along the sides of the glass or at
the top. The mouth-brushes serve as organs of locomotion as
well as for feeding, and the insects are perfectly able to make
their way from place to place Avithout moving any other part of
the body.

The jerky, wriggling motion is used w^hen they wish to get
away quickly, and as often to get down to the bottom as to get
up to the surface. They can, and often do, sink slowly to the
bottom without any motion Avhatever, and often, to sink more
rapidly, they curl themselves up into a ring. Occasionally a speci-

THE COMMON MOSQUITO 87

men will get hold of a bubble of gas forming at the bottom, and
will allow itself to be floated to the surface. It is immensely inter-
esting to watch these little creatures ; but as week after week
went by without change it became just a little tedious. To has-
ten matters a little, on March 1st I placed the two jars first re-
ceived on a water bath, which was kept at a temperature as nearly
constant as the varying gas pressure allowed. Ordinarily the
thermometer ranged between 100° and 110°, but it has gotten as
high as 120° and as low as 90°. These were exceptions, however,
and not exceeding the ordinary out-door range in June. The
temperature of the water in the jars ranged between 80*' and 90'
almost uniformly.

A difference in the rate of growth was observable after a few
days, and several specimens seemed approaching the adult con-
dition ; finally, on March 18th, I noticed the first pupa, seven-
teen days after placing the jar on the water bath. From this
the adult emerged March 21st and proved to be a female Culex
pungens. Three other pupae were formed within a week after the
first, and a second adult, also a female, Avas obtained March 24th.

As to the habits of the larvae in the two jars artificially forced
there was little to note as different from those in the normal
laboratory temperature, which varied from 40° to 78°, averaging
a little under 70° for the twenty-four hours. They fed in much
the same manner, kept away from the light as much as possible,
passed most of their time at the bottom, but were more lively
and more frequently at the surface. The jars were kept covered
except for a few minutes each day and in none of them did the
water foul, despite the vegetable and animal matter present in
each.

On March 24th I made an experiment that resulted fatally. It
occurred to me that possibly the slow growth was due to lack of
food, and Mr. Brakeley had written me that the wrigglers at-
tacked and devoured a small gnat which was breeding in his jars,

88 MOSQUITOES

suggesting that possibly a mutton chop might help matters
along.

On March 24th, I put a small lump of raw beef chopped fine,
into each of five experiment jars. The next day I could give only
a casual glance before going out of town, and this showed noth-
ing unusual ; l)ut the day after, March 26th, when I reached the
laboratory at 8 a.m. I saw at once that something was wi-ong, be-
cause all the living larva? were at the surface, head down, spira-
cles reaching the air. In every jar into which I had placed the
meat I noted the same appearance, and I hastily fished out every
particle. But it was too late : more than half were already dead,
others seemed to show fungoid growth proceeding from the seg-
ments, so, to prevent their dying, I killed them off with a dose of
formalin. One large jar received in February was left unharmed,
and this was placed on the water-bath March 26th. Nothing has
come from it at the date of present writing, and nothing may ever
come from it, but its history must be written later.

But this experiment, fatal as it proved, was of some value. It
shows that water too foul with animal decay is not suitable for
mosquito larvae.* Vegetable decay and the harder refuse from
insect bodies will help along the development ; Init beyond that
the Avater must be clean. It seems to indicate further that the
condition of the water may very largely determine the frequency
with which the supply of oxygen must be renewed from above the
surface. In June, with a supply of water at a relatively high
temperature in which microscopic life is swarming. I have no
doubt Dr. Howard's observations would be exactly duplicated.
With the same species in clear water, at relatively low tempera-
ture, the breathing habits are quite different and the insects ob-
tain, I have no doubt, a goodly portion of their oxygen from the

* This generalization is much too broad. The larva^ of Culex impiger,
for example, will swarm in water foul with decomposing animal matter,
and so, possibly, will larva? of certain other species of Culex.— L. O. H.

THE COMMON MOSQUITO 89

water itself. Just how they do this I am not prepared to say.
One thing may be considered as certainly established by this
series of observations : the insect can and does hibernate in the
larval stage, if this is not, indeed, the prevailing method. Mr.
Brakeley has scoured the swamps for miles about within the last
few weeks, and wherever he found pitcher plants almost or quite
every leaf had its supply of wrigglers. It is not, therefore, a local
phenomenon. Nor is it even suggested that pitcher plants alone
furnish breeding-places where the larva? hibernate ; but they are
remarkably safe resorts, protected to a very marked extent from
natural enemies. Is there any relation between plant and insect,
whereby the plant receives a benefit? Do the wrigglers in any
way prevent a foulness of the water from the insect fragments
until the plant has absorl^ed what it needs?

It is noticeable that during the whole winter only a single ex-
ample of Culex piingens was taken in the barns, storehouses, or
cranberry-sorting rooms, though they were diligently sought.
Anopheles punctipennis were found quite abundantly — between
twenty and thirty specimens having been taken on the windows
of the sorting rooms ; but no Anopheles larvae were found in any
of the collected leaves. As a Jerseyman, Mr. Brakeley ordinarily
pays little attention to mosquitoes, but he could not easily over,
look Anopheles, did it occur in any numbers in summer. He
says that it does not, and that he has never seen as many during
his years of residence in the Pines as he did this past winter.

My own experience is similar. I remember that about three
years ago I was annoyed by Anopheles very early in the year in
my store-room in the basement of the Station Building. Later
on I saw nothing of them, and I can say positively that the spe-
cies of this genus form no part of the often consideral)le swarms
in and near New Brunswick.

In the cellar of my residence I took Chdex pnngem, female,
March 22d, fiving. It could not well have developed there, and

90 BIOSQUITOES

of course there can be no doubt that the species hibernates as an
adult as well as in the larval stage.

These pitcher-x^lant leaves contain, besides mosquito larvae
of this species, considerable numbers of other larvse, which Mr.
Brakeley succeeded in breeding. Some examples submitted to
Mr. C. W. Johnson he pronounced to be Aedes fuscus O. S., a
species by no means commonly observed.

The present series of notes are not by any means a complete rec-
ord of the observations made on the wriggler colonies at New
Brunswick and in the Pines, and they are not even ended ; but
they will serve to call attention to one or two heretofore unob-
served facts. They also contain a suggestion. Is it not prob-
able that the mosquitoes that swarm in Alaska and in arctic
regions may pass the winter in the larval stage, frozen in the solid
ice, ready, when the melting time comes, to mature rapidly?

Hiding-places for adults are occasionally somewhat scant in
such regions, and the swarms are said to be even more numerous
and vicious than they are in New Jersey.

[Note.— Since this matter was put in type, Dr. Smith writes me that
from recent rearings he is led to believe that most of his statements,
especially with regard to the ability of larva3 to remain under water a
long time, lefer to Aedes and not to Culex. — L. O. H.]

IV

Tlie Malarial Mosquitoes of the Genus
Anopheles

TO pliysiciaus and others wlio are investig-ating tlie
malarial conditions of a given neigliborliood it
becomes very important to know everything con-
nected with this most noxious genus of insects. Not only
is it necessary to be able to recognize them in every stage
of their existence, but also to know the character of the
pools in which they will be found in their early stages,
since much time may be Avasted in searching for them in
places where they could not possibly occur, or in which
they are not likely to be found. This point must be borne
in mind, therefore, by those who, looking through this
chapter, think that the writer has gone into the subject
with apparently unnecessary detail.

The genus Anoi:)heles was founded by Meigen in 1818.
The first reference to its early stages which is to be found
in literature is in a paper entitled " Description of a New
Fish Avhicli I found in the water of the basin of 8. Mag-
loire of the Fauxbourg S. Jaques at Paris, which can be
called an Aquatic Caterpillar," published in Paris in 1754
by an observer who possessed the euphonious name of

91

92 MOSQUITOES

Joblot. He fignrc^s the larva, wliicli is recognizable as
that of Anopheles. The Dutch observer, Meinert, gave
the next accurate description and figure of the larva in
1886, and other descriptions and figures Avere published
by the Italian, Ficalbi, in 1899, and the Englishman, Giles,
in 1900. Th(^ various stag"es of one of these species were
described and tig-ured in 1900 h\ the Italian, Grassi, and
by the present writer. At the time I published these ob-
servations, I supposed that I was the first person in xVmer-
ica to have seen Anopheles larviie, but Dr. Charles Sedg--
wick Minot, of the Harvard Medical Colleg-e, wrote me,
after seeing" the first edition of Bulletin 25, that lie raised
Anopheles twenty-five years or more ago without suspect-
ing' its identity. At that time Dr. Minot was much in-
terested in entomology. He has since hunted up his old
notes, and has i)ublislied an account of his earl 3^ observa-
tions in the journal of the Boston Society of Medical
Sciences, vol. v., January, 1901,

The species which I studied in full in the summer of
1900, and which was treated in my Bulletin 25 as Anophe-
les qimdrimaculatus Say, has been definitely decided to
be identical with the Anoplieles maculipennh of Europe.*

* Osten SMcken, Entomologists Monthly Mdrinzine for December,
1900, paj^es 281-283, shows that Anopheles clavigcr Fab. has no exist-
enee. It never existed either as a type specimen, or as a scientilic con-
cept of a species. The correct name, therefore, of tlie common Anoph-
eles of northern and central Europe is Anopheles TivicuUpennis ]\I., of
which our American A. gimdrlmaculatvs Sa}^ is a synonym, as has been
shown by Theobald. Riithe wrote in Oken's Isis (1831, p. 1203), as
pointed out by Osten Sacked in the above article, as follows :

" Anopheles 7nacuUpennis M. h not uuconwnnn in the ]Mark Branden-
burg-, in localities where water is abundant ; for instance, it is quite

THE MALARIAL MOSQUITOES 93

Dr. W. S. Tliayer saw the Eiiropeau species in Grassi's
laboratory in Italy, and ou his return to this country told
me that he thought the two forms were identical ; and
the English student, F. V. Theol)ald, Avho is monograph-
ing the mosquitoes of the Old World for the British Mu-
seum, has studied a large series of specimens from this
country and has decided that the European and American
forms are identical. This at once suggests the interesting
question as to whether this abominable creature was in-
troduced from Europe to America or the reverse. It is
quite within the bounds of possibility that malaria was
originally an European disease and that not only was the
disease itself carried from there on sailing vessels, but
the mosquitoes which propagate it as well, at least to
America.

The Life History of Anopheles macuhpeimis.

The Adult.— The accompanying illustration (Fig. 15)
will show very well the general appearance of the
adult insect. It is a rather large mosquito and is very
bloodthirsty. It is attracted to the house in numbers.
The differences between the males and females are
well brought out in Fig. 15, and the striking feathery
antennae and palpi of the male render it very conspic-
uous. The wing markings and the color of the palpi
differentiate this species from our other species of

common about Fiifnwnlde in midsummer. Its stini:: is more painful
than that of any liiiat I know, and lias a mnch more pernicious effect.
During a botanical excursion of several days whicli I made with some
of my pupils, I noticed that the sting produced deep iMirulent wounds,
whicii it took several weeks of careful medical treatment to heal."

94 MOSQUITOES

Anopheles, and the long- palpi of the female at once
distinguish it from all sj^ecies of Ciilex.

Kesting- Position. — Owing- to the publication of a field
sketch made at Sierra Leone by a member of the Ross ex-
pedition, the writer has been much interested in watch-
ing the resting positions of the adult insects. He finds
that when resting upon a horizontal surface — such as the
ceiling of a room or the covering of breeding-jars — the
insect clings with its four anterior legs in a nearly i^er-
pendicular position, its beak thrust forward toward the
surface to which it clings. The hind legs are frequently
in motion, but as a rule hang downward with more or less
of a bend at the knee joint (femero-tibial articulation).
When resting upon a perpendicular surface, however —
such as the side wall of a room or the side of a breeding-
jar — the body is held only at a comi3aratively slight angle
from the surface. Sometimes it is nearly parallel with
the surface. At other times it assumes an angle of 10°
to 20° (occasionally even as great an angle as 30° to 40°),
the i^roboscis being held nearly in line with the body.
Here again the insect supports itself by the four anterior
legs, the hind leg dangling down with more or less of a
bend at the knee. This position is common to both males
and females, and is illustrated in Fig. 13. When the
body is held parallel, it will generally be found that one
of the middle or hind legs has been broken oft*. They
are very delicate and readily break.

The writer has taken the liberty of having Figure 14
engraved from a drawing sent him by Mr. C O. Water-
house of the British Museum. Mr. Waterhouse made the

:^

Fig. 13. — Resting Position of
Anopheles ; enlarged. (Author's
illustration.)

Fig. 14.— Resting Position of
Anopheles above, Culex l)e-
low ; enlarged. (From
skfteh by C. O. Water-
house.)

96

MOSQUITOES

drawing- liimself and wrote : " Whatever may be tlie
attitude of Anopheles, it is all in one line. Culex is angu-
lar, humpbacked."

Note of Female. — The peculiar hum of the mosquito is
well known. There is a distinct diiierence between the

Fig.

15. — Anopheles maculipemns, male at left, female at right; en-
larged. (Author's illustration.)

hum of A?iopheIes rnaculijyemiis and that of the com-
mon species of Culex, in that the former is noticeably
lower in tone. The note of Culex as it approaches the
ear is high in pitch ; that of Anopheles is certainly sev-

THE MALARIAL MOSQUITOES

97

eral tones lower and of not so clear a character. In
quality it is something- between the buzzing- of a house
tly and the note of Culex. Mr. Pratt states that he can at
once distinguish the two genera in this way as he is sit-
ting reading in the house, and the writer feels quite sure

Fig. 16. — Egg IVIass of Anopheles niacuUpennis ; enlarged. (Author's

illustnilioii.)

after listening to them in breeding-jars that the statement
is correct.

These observations have been made with an abundance
of material, nearly 100 adults having been under obser-
vation.

The Eggs. — The well-known and often-mentioned raft-
shaped masses of eggs of Culex are not even remotely

98

3I0S QUI TOES

resembled by the Anopheles ovipositions, and the indi-
vidual eg-gs are equally dissimilar. In the accompany-
ing- illustration (Fig. IC) the egg- mass of Anopheles is
illustrated for comparison with Fig. 7. In Culex from
200 to 400 eggs are laid in a mass ordinarily shaped like
a i^ointed ellipse, convex below and concave aboA-e, all
the eggs perpendicular, and stuck closely together at the
sides by some gummy secretion, and arranged in rows.
The mass with Anopheles, however, is laid loosely uiDon
the surface of the water, each egg lying upon its side
instead of being placed upon its end as in the egg mass of
Culex. They are not attached together except that the}^

naturally float close to each
other, and there are from 40
to 100 eggs in each lot. In
Culex 2^^^nf)ens the individual
egg is 0.7 mm. long and 0.16
mm. in diameter at the base.
It is slender, broader, and
blunt at the bottom, slenderer
and more pointed at the tip.
The tip is always dark grayish
brown in color, while the rest
is dirty white. The egg of
Anopheles when seen from
above is of rather regular el-
liptical outline, the two ends having practically the same
shape ; seen from this side, it is strongly convex below
and nearly plane above ; seen from below, it is dark in
color, and when examined with a high power is seen to

Fig. 17. —Individual Eggs of
AnopJieles mactiUpennis, from
below at left, from above at
right ; greatly enlarged. (Au-
thor's illustration.)

THE MALARIAL 3I0SQUIT0ES 99

be covered with a reticulate hexagonal sculpturing-. At
the sides, in the middle, there appears a clasping mem-
brane with many strong transverse wrinkles. Seen from
above, the eg^ is black except for a clasping membrane
which nearly meets on the middle line in the middle
third of the body, but retires to the extreme sides for the
anterior and posterior thirds. At each end the color is
lighter, with a group of from 5 to 7 minute dark circular
spots. It is 0.57 mm. long. Eggs laid April 26th hatched
April 30th. Others laid May 13th and 14th hatched May
16th and 17th.

The Larva. — The larva is quite as unlike that of Culex
pungens as is the egg. It differs in structure, in its food-
habits, and in its customary position, so markedly, that it
can at once be distinguished with the utmost ease. The
larva of Culex, it will be remembered, conies to the sur-
face of the water to breathe, thrusting its breathing tube
through the surface layer and holding its body at an an-
gle of about forty-five degrees with the surface of the
water. While in this position its mouth-parts are in mo-
tion and it is taking into its alimentary canal such minute
particles as may be in the water at that depth, but these
are naturally few in number and the larva descends at
frequent intervals toward the bottom to feed. The want
of oxygen, however, causes it to wriggle up again to the
surface at very frequent intervals. Its specific gravity
seems greater than that of water, so that it reaches the
surface only by an effort, and the writer has already
pointed out, in the case of Culex pungens, that when the
larva becomes enfeebled and is not strong enough to

100

MOSQUITOES

wriggle up to the surface, it drowus. Feeding as it does
at the bottom upon the heavier particles which sink, its
specific gravity is explained. The larva of Anopheles
77ucculipen?iis, however, habitually remains at the surface
of the water. Its breathing tube is very much shorter
than that of Culex, and its body is held not at an angle at
the surface, but practically parallel with the surface and
immediately below the surface film, so that portions of
its head, as well as its breathing tube, are practically out

Fig. 18. — Young liarva ot Anopheles macuUpennis ; enlarged.
(Author's illustration.)

of the water. Its head rotates upon its neck in a most ex-
traordinary Avay, so that the larva can turn it completely
around with the utmost ease, and feeds habitually with
the under side of the head toward the surface of the
water, whereas the upper side of the body is toward the
surface. In this customary resting position the mouth
parts are working violently, the long fringes of the
mouth-parts causing a constant current toward the mouth
of particles floating on the surface of the water in the
neighborhood, which thus gradually converge to this

THE MALARIAL MOSQUITOES

101

Fig. 19.— Half-grown Larva
of Anopheles maculipennis

miniature maelstrom and enter the alimentary canal. The
spores of algc^, bits of dust, minute sticks, bits of cast lar-
val skins, everything-
;^— in fact which floats,
follow this course, and,
<^/?'iP\K> watching- the larva un-

der the microscope,
they can plainly be seen to pass
through the head into the thorax
until they are obscured by the
dark color of the insect's back.
enlarged. (Author's illus- Occasionally, too large a frag--
tration.) ment to be swallowed with ease

clog-s the mouth. Sometimes it enters the mouth and
sticks. In such cases the head of the larva revolves
with lightning-like rapidity and the fragment is nearly
always disgorged, /

although some-
times it is swal-
lowed with an evi-
dent effort. Since
the Anopheles lar-
va feeds only upon
these light, floating
particles, its spe-
cific gravit}^ is near-
ly that of the water
itself, and it supports this horizontal position just beneath
the surface film with comparative ease, and, in fact, with-
out effort, the tension of the surface film itself being hardly

Fig. 19a. — Same stage of
Culex ; enlarged. (Au-
thor's illustration.)

102

310 SQUI TOES

needed to hold it. It requires an effort, in fact, for the
Anopheles larva to descend (which it apparently never
does up to the period of the final larval stage, except
when alarmed), while it requires an effort for the Cnlex
larva to ascend.

Structurally the differences between the half-grown
larvje of Culex and Anopheles are well shown in Figs. 19,
19a, and 20. The great size of the head of Culex, as con-
trasted with the small head of Anopheles, is a most strik-

-grown Larva of Anoplieles maailipennis ; enlarged.
(Author's illustration.)

ing difference. The very long respiratory siphon (as Miall
calls it) of Culex contrasts markedly with the short one
of Anopheles. The arrangement of the hairs is entirely
different ; the branching of the hairs of Anoplieles, as
contrasted with the simple hairs of Culex and the little
paired star-shaped (apparently branchial) tufts on the
dorsum of Anopheles, is entirely absent with Culex.
The flaps at the tail end of the body are similar in num-
ber, but are held in a somewhat different position.

THE MALARIAL MOSQUITOES

103

The larv.^ first studied — tliose which hatched from the
eggs on April 30th — grew very slowly for a number of
days. This was partly owing to cool weather in the early
part of May, and partly, I believe, to the absence of
proper food. They were reared in glass jars of water, with
sand at the bottom and a willow twig rooting in the sand.

Fro. 21. Full-grown Larva of Anopheles maculipennis slinwing head

upside down, with top of head above, at left ; greatly enlarged. (Au-
thor's illustration.)

As above noted, they swallowed every small particle float-
ing on the surface of the water, and the dark coloration
shown in Fig. 18 was largely due to the fact that most of
these food particles were dark colored. About the 10th of
May, the larv» having passed through two molts, a small
quantity of the green algfie growing on the lily ponds on
the Department grounds was placed in the jar. The

104

MOSQUITOES

larvpe commenced to thrive much better, grew rapidly,
and the g-eneral color of the body chang-ed to green. The
description of the habits given above held well until after
the last molt preceding the change to pupfe. In this final
larval stage, as shown in Fig. 21, the diameter of the
thorax became much greater in comparison with the rest

Fig. 22. — Head of Larva of Anopheles macnlipennis^ under side ; greatly
enlarged. (After Nuttall.)

of the bod}^ The larva was less marked, more incon-
spicuous, and altered its feeding habits to some extent.
After remaining at the surface of the water, feeding, as
before, uiDon floating particles, for some time, it would
wriggle violently and descend to the bottom, where it
would remain frequentl}^ as long as ten minutes before
reascending to the top. Its appetite was evidently so

THE MALARIAL MOSQUITOES

105

great that it was not satisfied with the floating parti-
cles, and when it descended to the bottom it mouthed the
particles of sand, apparently swallowing the slime on the
little stones and frequently even picking up quite a large
sand pebble and then dropping it again. In this stage
the individual which grew most rapidly remained only
four days, and transformed to pupa on the morning of the

Fig. 23. —Enlarged Head of Larva oi Anopheles macvHpennis, from side;
greatly enlarged. (After Nuttall.)

17th, after a larval existence of sixteen daj^s. The accom-
XDanying figures of the larvae have been drawn Avith such
care that detailed description will be unnecessar}^ They
were drawn from life under the compound microscope.
Some of the structures are puzzling, notably the organs
occurring on the dorsum of the abdominal segments,
shown most plainly in Fig. 20, and which look as though
they might be spiracles until they are examined under a

106

3I0SQUIT0ES

high power in the cast skin. The writer does not care to
risk an expression of opinion as to their function, although
possibly it is known, and they possibly occur in other dip-
terous larv8e. In the early stages of the larvae they re-
semble minute branchial tufts, but no tracheal connection
has been found.

The Pui^a. — The accompanying figure (Fig. 24) well rep-
resents the differences between the pupa' of Culex and

Fig. 24.— Pupa of Anopheles at right ; Cnlex at left ; enlarged.
(Author's illustration.)

that of Anopheles. In this stage the insects of the two
genera are not so markedly different as in the larval stage.
Structural differences need not be described, as they are
sufficiently shown in the illustration. The eye will at
once be caught by the difference in position, the pupa of
Culex resting in a more perpendicular attitude than that
of Anopheles ; and the marked difference in shape between
the respiratory siphons, which issue from the thorax in-

THE 3IALARIAL MOSQUITOES 107

stead of from the anal end of the abdomen, will at once
be noticed. The pupa of Anopheles is qnite as active,
when disturbed, as is that of Culex. If one touches the
surface of the water near it with the finger, the pupa at
once wrig-g'les violently away, returning shortly to the
surface for air.

The duration of the pupal stage in Anopheles varies
according to the weather. Five days was the minimum
observed during June, although several specimens re-
mained in this stage for ten days. The adults issue as
do those of Culex.

The entire life round, therefore, of Aiw^yJieles maculi-
^yennis in the generation studied by the writer is as follows :
egg stage, three days ; larval stage, sixteen days ; pupal
stage, five days ; making a total period in the early stages
of twenty-four days. It should be stated, however, that
during the early larval existence, toward the end of May
there occurred nearly a week of cool weather, so that it is
certain that in the hot season in July and August the
growth and transformations will be more rapid. It Avill be
remembered that the writer traced Culex pu7if/e?is through
an entire generation in the latter part of June, in ten days.

European Observations on the Same Sjiecies.

Nuttall and Shipley state that when the eggs are first de-
posited they are white, but that they soon blacken. They
are boat-shaped, and one end is slightly deeper and fuller
than the other. The thickening at the edge, which in pre-
vious paragraphs was called the clasping membrane, is

108

MOSQUITOES

composed of air chambers, and is used to keep the boat-
shaped egg with its flat surface uppermost. The English
writers have observed that when the eggs have been much
rubbed, the delicate membrane splits off and the egg ap-
pears with a glistening black surface like patent leather.
They have noted also that when the
egg, as frequently happens, is drawn
by capillary action a little waj^ up from
the water on a leaf, the head or blunt
end always points downward, so that
when the larva emerges it drops into
the water, and not up in the air.
Grassi says that the eggs of this
species lie in groups of from three to
twenty, side by side, like a bridge of
boats, but Nuttall and Shipley find
them in open pools in Great Britain
scattered about. According to these
observers the eggs hatch on the second or third day after
being laid, depending on the temperature, the young issu-
ing through a circular si^lit near the blunt end of the egg.
They also state that eggs which were dried less than five
days did not hatch. Full and detailed accounts of the
anatomj" of the larva and pupa are given by the English
writers in a paper entitled " The Structure and Biology
of Anoiiheles " {A. macnlipennis) in the Journal of Hygiene,
vol. i., No. 1, January, 1901 ; this article is beautifully
illustrated.

Fig. 2.1.— Head of Full-
grown Larva of
Anopheles puncti-
pennis ; enlarged.
(Author's illustra-
tion.)

THE MALARIAL MOSQUITOES 109

Natural Breeding- Places of Anopheles.

A number of the natural breeding-places of Anopheles
macuUiJennis and A. pmictiptmiis have been found by the
writer in the United States. They have always been found
in more or less permanent pools of water, either in the bed
of an old canal or in spring-fed woodland streams, or in
the side pools or shallows of field springs, or in artificial
excavations filled with surface water. In such places,
when supplied with a certain amount of green scum, the
little larvne will often be found resting at the surface of
the water, and occasionally darting from one spot to
another.

The larvae of A. piindipeimis diflfer from those of A. ma-
culipennis larg-ely in the marking- of the head, as indicated
in the accompanying figure. Tlie temperature of the
water which they inhabit varies from 18° C. to 25° C-
Nuttall and Shipley state that in England these larv^
are to be found in pools, ditches, backwaters of rivers
and canals, and in other slow-flowing- waters ; almost in-
variably in such waters as are clear and ver\^ rarely in im-
pure or brackish water. In their experience, they prefer
pools which are not shaded by trees, althougli I have
found them in this country on several occasions in a
dense shade. They are very rarely found in water con-
tained in barrels and troughs and fountain basins, and
they are very rarely found in the same water with the
larvae of Culex. Mr. E. E. Austin, in " The Keport of
the Proceedings of the Expedition for the Study of the

110

MOSQUITOES

Causes of Malaria at Sierra Leone," states that on
August 26, 1899, Dr. Prout and Dr. Berkeley found
Anopheles larvae mingled Avitli those of Culex in a tub of

Fig. 26. — Female of Anopheles punctipennis ; enlarged. (Author's illus-
tration.)

water in a yard at the Sanitary Office. With one excep-
tion this is the only instance in Avhich he found Anoph-
eles breeding elsewhere than in a roadside puddle or
ditch. Dr. C. W. Daniels, in the "Eoyal Society Reports

THE 3IALARIAL 3I0SQUIT0ES 111

to the Malarial Committee," December 31, 1900, says that
in Africa either larvse may be found alone, but in many
situations both are found together and even several spe-
cies of each. At least five species of Culex were found
with Anopheles larvae. " The less the movement of the
water the greater the probability of Culex larv* being
also found, and in a grass-grown river, the Anopheles

Fig. 27. — Male of Anopheles punctipennis, from side ; enlarged. (Orig-
inal.)

larvae will be more abundant near the stream and the
Culex larvae near the bank."

Nuttall, Cobbett, and St range way s-Pigg, in England,
captured Anopheles nine times with Culex in i^onds and
also took them with Culex in ditches in which the water
scarcely flowed, in water-logged boats, in stone troughs,
and in fact found them fourteen times together with

112 MOSQUITOES

Culex and ten times with lisli. Dr. F. A. Young-, a Brit-
ish army surgeon, has tokl me that in his experience if
the larvae of Culex and Anopheles are put into the same
vessel those of Anoj^heles will disappear.

Lieutenant-Colonel Yerbury says that " the natural
home of Anopheles seems to be damp swampy ground,
but not necessarily so wet as a marsh or a fen." Grassi
and Ficalbi state that A. iiiaculipenids is most frequently
found in flat land in Italy, the larvae requiring clear Avater
rich in vegetable food. E. E. Austen found in Freetown
that Anopheles larvae were in stagnant puddles, varying
from a foot to several feet, at the sides of the streets, but
many were met in the still water in little bays at the side
of slowly running shallow ditches. Whether the water
was clear or muddy seemed to make no difference, but
green algae were nearly always present and in some pud-
dles tadpoles were numerous. Dr. H. A. Yeazie, of New
Orleans, has found Anopheles larvae in the x^onds out in
the suburbs in the SAvamps back of the city. Dr. Wol-
dert, of Philadelphia, has found the larA^ae of both A. ma-
cullpcnnU 'A'n^ A. punctlpemds breeding in the same nar-
roAv and sloAvly floAving stream of fresh Avater, Avhicli
drained a marshy district formed by a railroad embank-
ment. He found larvae in this stream from June 19th to
November 11th and located five localities Avithin the city
limits of Philadelphia Avliere Anopheles breeds. Grassi,
at Metaponto, Italy, is said to have found Anopheles in
brackish water.

THE 3IALARIAL 3I0SQU1T0ES 113

The Nortli American Species of Anopheles.

So far as known at the present time we have but three
species of the mahirial genus in the United States, namely
A. mucurq^ennis Meigen (equals A. quadrwiaculatus Say),
A. j^ff'^ictq^ennls Say, and A. crucians Wied., although Mr.
Theobald, in his monograph, which will include the mos-
quitoes of the world, will describe forty-two species of this
genus, and possibly more.

A. riiaculi2)ennls is a rather insignificant species,
which is well illustrated in Figure 15, its wings being
nearly clear, but marked with four rather small dark
spots composed of groups of darker scales. Its palpi are
entirely black.

A. ^yunct 12)611 Ills is our handsomest species, and has a
yellowish white spot occupying about three-fourths of
the length of the front margin of the Aving. The scales
on the last vein are white and those at each end black.

A. crucians has the palpi marked with white at the
bases of the last four joints, and the scales of the last
wing vein white, marked with three black spots. The ac-
companying figures will enable a much readier differentia-
tion of this species than will any description.

As to distribution,^. ?/iaculi2)e/i?iis and A. 2nnicfi2)ennis
are found almost everywhere in this country. I have seen
specimens of A. macid'qtenn'is from New Hampshire, Con-
necticut, New York, District of Columbia, Maryland, Vir-
ginia, Florida, Texas, Louisiana, Indiana, Illinois, Min-
nesota, and Oregon. Dr. A. S. Packard has recorded its

114 31 OS QUI TOES

occurreuce at Brunswick, Me., in 1861-63. A. i^unctipen-
nis I have seen from Vermont, Massachusetts, Connec-
ticut, New York, NeAV Jersey, Pennsylvania, District of
Columbia, Maryland, Mississippi, Texas, New Mexico,

FiG.2S— Anopheles crucians, adult female; enlarged. (Author's il-
lustration.)

Kansas, Illinois, Indiana, Oregon, and Jamaica (B. W. I.).
Professor C. H. Fernald writes me that he has taken it at
Orono, Me., and that it is rather common at Amherst,
Mass. A. crucians I have seen only from the District of

TEE MALARIAL MOSQUITOES 115

Columbia, Yirg-iiiia, Georgia, Florida, and Louisiana.
The last species therefore seems to be a more southern
form, while the other two have a very wide distribution,
including- a considerable distribution to the North.

Dr. W. N. Berkeley, of New York, in the Afedical Record
for January 26, 1901, states that A. 2ywictipe7inis is abun-
dant in certain parts of Bronx Borough, particularly Je-
rome Park. A. maculipenniH appears to be universally dis-
tributed in the suburbs of New York. Since he learned
how and where to look for it, he found it nearly co-exten-
sive with all the cases of fresh malaria that he had the
leisure to go to and look into. It was present in such
widely separated places as Passaic, N. J., Tuxedo, New
York, Fordham, and Jerome Park, Mount Yernon, and
East Hampton. In East Hampton, on the authority of
Dr. F. P. Rolley, Dr. Berkeley says that until the summer
of 1900 no native malaria had been known at East Hamp-
ton, in spite of a large number of malarial mosquitoes. He
explains this in two ways : (1) That no malarious case had
recently been imported there to start an infection among
the mosquitoes, and (2) that the nights are cold, the
night temperature being considerably below the mini-
mum (77° F.) at which the malarial bodies are believed,
according to Koch, to develop in the stomach of the mos-
quito. The Anopheles was always found in buildings,
oftenest on walls and ceilings of recently used bedrooms,
and far most abundantly in the foul and ill-ventilated
bedrooms of the poor. The house females were usually
gorged with blood, and sluggish enough to be easily
caught. They were numerous in outdoor privies. He

116

3WSQUIT0ES

never found them out of doors. Males were caught in
houses also, but generally only one male to twenty

111

.x*

^y

■i^t''

Fig. 29. — Anopheles argyriUirsis, adult female ; enlaii^ed. (Original.)

females. He caught Anopheles in a house in the Bronx on
November 6th and on Christmas day. In a draughty, cold,
undero^round cellar in the same house he causrht a dozen

THE 31 ALA RIAL MOSQUITOES 111

or more, all females, mostly 7)?/?/c7f?):>e?z?H*.s and a few
maculipennis. They were in comx^lete hibernation, and
had to be knocked from the wall as if dead, but revived in
a glass tube under the warmth of the hand. 80 far as Dr.
Berkeley's observations go, the hyi^othesis of the Italian
workers that only fertilized females survive the winter, is
true.

Dr. Theobald Smith, of the Bussy Institute, has pub-
lished a paper entitled, " Notes on the Occurrence of
Anopheles punctipennis and A. quadrimaculatus in the Bos-
ton Suburbs," in the Journal of the Boston Society of Medi-
cal Sciences (vol. v., pp. 321-324, January, 1901) in which
he shows that he has found both species at Jamaica
Plain, although malaria does not exist there. The oc-
currence of the Anopheles, unless their breeding-places
are wiped out, shows that if malaria patients should come
to Jamaica Plain, the disease would rapidly spread.

The s]3ecies Anopheles argyritarsis, mentioned in Chap-
ter X. and illustrated in Fig. 29, is a very beautiful species
which occurs in Cuba, where it has been captured by Dr.
James Carroll of the Army Yellow-fever Commission.

Food of Anopholes Larvre.

As already indicated, the principal food of the larvfie of
Anopheles seem to be the spores of algap, but, as we have
pointed out, they will swallow anything which floats on
the surface of the water. I have seen one nearly choke to
death in the attempt to swallow a good sized bit. The
English observer, Dr. Daniels, in the course of his in-

118 MOSQUITOES

vestig-ations in Africa, found tliat tlie contents of the
intestines of the larvae are mainly vegetable matter — in
some cases entirely so. Occasionally limbs of minute in-
sects or crustaceans were found, as well as scales of mos-
quitoes or other insects. " On watching- them feeding it
is seen that all minute particles are drawn to the mouth,
but many of them are rejected. This rejection is some-
what arbitrary, as a particle at first rejected is often
subsequently swallowed. Among the bodies seen to be
swallowed I have seen living- minute crustaceans and
young- larvae, both of Anopheles and Culices, but as a
rule living- animals either escape or are rejected." Chris-
tophers and Stephens state that in their observations in
Sierra Leone the food of the majority of the Anopheles
larvae seemed to be a unicellular protococcus.

Length of Life of Adult Anopheles.

Physicians studying the adults in order to determine
the duration of the different stages of the malarial org-an-
ism have occasion to keep adult Anopheles alive in con-
finement. This has been accomplished up to eight weeks
by feeding them occasionally upon sliced bananas or
other fruits. The adults live for very considerable spaces
of time, as has, in fact, been pointed out in the first chap-
ter of this book. In colder climates the adults hibernate
often in houses, and in tropical climates the adults live
through the dry spell to lay their eggs when the rains
come and breeding-pools are re-established. The hiber-
nation of Anopheles in this country has been frequently

THE 3IALAmAL MOSQUITOES 119

observed. Dr. W. S. Thayer has informed me that he
found Anopheles crucians and AnopJieles macuVipennis
hibernating in enormous numbers in barns near New
Orleans, and in early February, 1901, Dr. H. A. Yeazie
wrote me that Anopheles punciipennis had been captured
in his house, in his office, and in the show-window of a
shop on Canal Street. Dr. A. Hassel, of Baltimore, found
Anopheles pimctipennis in his house in January, 1901, and
during this month his son and daughter developed ma-
laria, the diagnosis being perfectly confirmed by blood
examination. About a week before this were several
warm days. Probably the mosquitoes had been hibernat-
ing in his house and had become active on account of tho
warm spell.

How Anopheles Bites.

It is the experience of a number of observers, as re-
corded, that the bite of Anopheles is more insidious
than that of Culex. When not occurring in numbers,
they may bite a person while asleep and not be detected.
This point is especially used in answering the broad and
general statement that malaria may be developed where
there are no mosquitoes. Professor E. W. Hilgard, of
the University of California, wrote me in September,
1900, to the effect that in the coast marshes of the Missis-
sippi Sound, he has seen Anopheles in great numbers,
probably />?/7^c'ify>d/^/^/.^. Down there this insect is called
the black mosquito, and, as Professor Hilgard states, " is
noted for biting without a moment's refiection, plunging

120 MOSQUITOES

head foremost rig-lit into yon, while Culex always medi-
tates for a Avhile before biting-." Professor Hilgard
further stated that in those marshes there is little or no
malaria and that he had been exposed there for weeks
without injury, nor did the inhabitants complain of chills
or fever. But in the Arkansas bottoms it took him only
a few days to succumb, and the natives "luxuriated in
* aofue cake.' "

Mosquitoes and Yellow Fever ; Mosquitoes
and Flliariasis

IN 1881, Dr. Carlos Finlay, of Havana, noticed a cor-
respondence between the abundance of mosquitoes
and a period of increase of yellow fever in the
autumn, while during' the summer yellow fever had been
scarce and mosquitoes also scarce. This sugrg-ested to
him the idea that mosquitoes are responsible for the
transfer of the disease, and he conducted certain experi-
ments in which he claimed to have transmitted the
disease by the bites of the mosquitoes which had previ-
ously sucked the blood of persons suffering- with the
disease. Carrying on his idea further he proposed a
plan of inoculating non-immunes by the bites of infected
mosquitoes, on the theory that a mild type of the disease
would be produced which would afterward be protective
against reinfection of a more severe character.

Dr. Finlay 's theory w^as received with interest hy ph}^-
sicians and investigators, but with a very pronounced
general incredulity. His experimental work did not
seem to have been definite enoug'h to attract confidence
to his conclusions, nor was there enough of it. It is

121

122 3I0SQUIT0ES

rather strange that his published I3ai3ers did not excite
sufficient interest to induce other investigators to under-
take any experimental work in the same direction. This
fact in itself shows plainly the almost perfect incredu-
lity with which they were received. AYhen, however,
the beautiful results of the malarial investigators had
become generall}^ acce^^ted and it was shown beyond all
peradventure that not only do certain mosquitoes carry
filiaria, but also that some of them are necessary second-
ary hosts of the malarial micro-organisms, then it was
that a few people began to think of Dr. Finla}^ and his
theory. In the meantime, strong efforts had been made
to find the cause of yellow fever. Several micro-organ-
isms had been discovered and several investigators
announced the probable discovery of the causative germ.
Nearly all of these discoveries have been discredited b}^
subsequent observations. The organism which has
received the most support has been the Bacillus icteroides
of Sanarelli, but down to a ver}^ recent date the insistent
claim by the Italian investigator of the value of his dis-
covery has been disputed by competent observers.

The occupation of the island of Cuba by American
troops attracted the attention of Dr. Sternberg, Surgeon-
General of the Army, more strongly than ever before, to
the subject of ^^ellow fever, although he had long been an
ardent investigator of the cause of the disease, and, in
fact, was one of the Yellow-fever Commission who visited
Cuba in 1879, in an effort to investigate scientifically and
by modern bacteriological methods the causation of the
fever. In this early Cuban residence he became ac-

MOSQUITOES AND YELLOW FEVER 123

quainted with Dr. Finlay and with his mosquito theory,
and therefore, under these late conditions and with the
malaria case proven, he estal)lished a commission of army
surgeons, composed of Major Walter C Pieed, Suri^eon,
U. S. A., Dr. James Carroll, Acting Assistant Surgeon, U.

Fig. ZO.—SU(jomyia fasciata, adult female ; enlarf,^ed. (Autlior'

illustration,)

S. A., Dr. Jesse W. Lazear, Acting Assistant Surgeon,
U. S. A., and Dr. A. Agramonte, Acting Assistant Sur-
geon, U. S. A., and instructed them to investigate the
disease from the mosquito standpoint. The investiga-
tions carried on by this commission during the earl}^

124 MOSQUITOES

part of 1900 were extremely sugg-estive in their results.
In the course of the investig-ations, both Drs. Carroll and
Lazear were attacked by the disease. Dr. Carroll recov-
ered, but Dr. Lazear died — another of the long list of
martyrs who have suffered in the cause of scientific
research. In this preliminary work, which Dr. Keed
reported upon at the twenty-eig-htli annual meeting of
the American Public Health Association, Indianapolis,
Ind., October 23, 1900, it was shown that eleven non-
immune individuals had been inoculated by the bites of
the species then known as Cidexfasdatas,\i\n.Q\\ had previ-
ously fed upon blood of patients sick with yellow fever.
Dr. Reed was able to report two positive results in which
an attack of yellow fever followed the bite of a mosquito
within the usual period of incubation of the disease. In
one of the cases all other sources of infection could posi-
tively be excluded. The results of this preliminary work
were summed up in two conclusions : 1. Bac'dlas icte-
Toides Sanarelli stands in no causative relation to yellow
fever, but when present should be considered as a second-
ary invader in this disease. 2. The mosquito serves as
the intermediate host for the parasite of yelloAv fever.

The announcements made in this preliminary note ex-
cited much attention. The scientific standing of the in-
vestigators, as well as the positive result announced in
one of the cases, made the tlieor}^ at once one of serious
importance. Medical men, however, were inclined to wait
for further developments before expressing an opinion.
Their point of view was perhaps well summed up by the
British Medical Journal, which stated that although the

MOSQUITOES AND YELLOW FEVER 125

experiments "appear to show almost conclusively tliattlie
germ is conveyed by a special si^ecies of mosquito and that
the insect becomes infected only after ten to tliirteen
days from the time of the ingestion of the germ, the ex-
periments are really by no means conclusive. At the
most they are suggestive."

But the investigators themselves were by no means
satisfied Avitli the i^roof which they had gained. They
returned to Cuba in the autumn of 1900, and spent the re-
mainder of the autumn and the whole winter in further
experimental work. The results obtained were so posi-
tive and striking that, with the permission of the Sur-
geon-General, they presented an additional note before
the Pan-American Medical Congress, held in Havana,
February 4-7, 1901. This paper, presented by Major
Reed, records the details of the work done up to that
time and announces its results.

An ex]Derimental sanitary station was established in an
open, uncultivated field, about one mile from the town of
Quemados, Cuba, under the complete control of Major
Reed. The station was named Camp Lazear, in honor of
the brave physician who went to his death in the early
summer of 1900. A most careful series of experiments
was carried on to see whether yellow fever can be con-
veyed by fomites, that is, by personal contact with the
clothes or belongings of yellow-fever patients. As is
well-known, the consensus of opinion, both of the medi-
cal profession and of others, is in favor of the conveyance
of yellow fever in this way, and every efibrt is made to
disinfect clothing and bedding shii)ped from ports where

126 MOSQUITOES

yellow fever prevails. All articles of personal apparel are
subjected to disinfection and, as everyone knows, during
a time when the fever is epidemic in any of our Southern
States even the mails are disinfected before being allowed
to go North. There was further erected at Camp Lazear
a small frame house with a cubic capacity of 2,800 feet,
tightly ceiled and battened, provided with small windoAVS,
so as to prevent a thorough circulation of air through the
house, and with wooden shutters to prevent the disinfect-
ing qualities of sunlight. The windows w^ere closed by
permanent wire screens with a 5-millimetre mesh. The
vestibule was protected by a solid door and a wire screen-
door, and the inner entrance by a second wire screen-
door. In this way the passage of mosquitoes into the
room was effectually excluded. The average temperature
was kept at 76.2° F. for a period of sixty-three days, and
precaution was taken to maintain sufficient humidity of
the atmosphere. On November 30th, three large boxes
filled with sheets, pillowslips, blankets, and so on, con-
taminated by contact with cases of yellow fever and their
discharges, w^ere received and placed in the room. Most
of these articles had been taken from the beds of patients
sick with yellow fever in Havana. Many of them had
been purposely soiled with the excretions of patients.
These soiled sheets, pillowcases, and blankets were used
in preparing the beds in wdiich the members of the hos-
pital corps slept. During sixty -three days this building,
thus furnished, was occupied by seven non-immune per-
sons. Three of them occupied the room each night for
twenty days. Later a fourth box of clothing and bed-

MOSQUITOES AND YELLOW FEVER 127

ding- was added, some of it purposely soiled with tlie
bloody stools of a fatal case of yellow fever. Two of
tliem occupied beds from December 21st to January
lOtli, every niglit, wearing the very garments worn by
yellow-fever patients throughout their entire attacks,

YiG. "^l.—Sterjomyidfasciata, adult male ; enlarged. (Original.)

making- use exclusively of their much-soiled pillowslips,
sheets, and blankets. At the end of twenty-one nights
they went into quarantine (as had the former three) and
were released five days later. Two other non-immunes
occupied the same beds for twenty days more. The at-
tempt therefore which was made to infect this building

128 3I0SQUIT0ES

and its seven non -immune occupants during- a period of
sixty -three days was an absolute failure ; all seven were
released from quarantine in excellent health.

A precisely similar building was erected at Camp La-
zear, which was known as the infected mosquito building-.
The door and windows were placed on opposite sides of
the building- so as to give a thorough ventilation. It w^as
divided into two rooms by a wire screen partition extend-
ing from floor to ceiling. All articles admitted to the
building were carefully disinfected by steam before be-
ing placed therein. Into the large room of this build-
ing mosquitoes which had previously been contaminated
by biting yellow-fever patients were admitted. Non-
immunes were placed in both rooms. In the room in
which mosquitoes were not admitted the exj)erimentalists
remained in perfect health. In the other room six out of
seven persons bitten by infected mosquitoes came down
with yellow fever. In all, of persons bitten by infected
mosquitoes that had been kept twelve days or more after
biting yellow-fever patients before being allowed to bite
them, eighty per cent, were taken with the disease.

The conclusions reached after this careful experimen-
tation, have been summarized under eleven heads, as
follows :

1. The mosquito — C.fasciatus — serves as the intermedi-
ate host for the parasite of yellow fever.

2. Yellow fever is transmitted to the non-immune indi-
vidual by means of the bite of the mosquito that has
previously fed on the blood of those sick with this dis-
ease.

3I0SQUIT0ES AND YELLOW FEVER 129

3. An interval of about twelve days or more after con-
tamination appears to be necessary before the mosquito
is capable of conveying- the infection.

4. The bite of the mosquito at an earlier period after
contamination does not appear to confer any immunity
against a subsequent attack.

5. Yellow fever can also be experimentally produced
by the subcutaneous injection of blood taken from the
general circulation during the first and second days of
this disease.

6. An attack of yellow fever, produced by the bite of the
mosquito, confers immunity against the subsequent injec-
tion of the blood of an individual suffering- from the
non-experimental form of this disease.

7. The period of incubation in thirteen cases of experi-
mental yellow fever has varied from forty -one hours to
five days and seventeen hours.

8. Yellow fever is not conveyed by fomites, and hence
disinfection of articles of clothing, bedding, or merchan-
dise, supposedly contaminated by contact with those sick
with this disease, is unnecessary.

9. A house may be said to be infected with yellow fever
only when there are present within its walls contami-
nated mosquitoes capable of conveying the parasite of
this disease.

10. The spread of yellow fever can be most effectually
controlled by measures directed to the destruction of
mosquitoes and the in'otection of the sick against the
bites of these insects.

11. While the mode of propagation of yellow fever ha3

130 3I0S QUI TOES

now been definitely determined, the specific cause of this
disease remains to be discovered.

A Large supply of contaminated mosquitoes, carefully
preserved, has been brought to Washington by Drs.
Reed and Carroll and careful work is now being carried
on in an effort to find the causative organism of the dis-
ease. It seems quite probable that it will prove to be
some sporozoon, following in a measure a somewhat
similar life-round to that of the malarial organisms.

It is interesting to note that the very recenth^ pub-
lished " Interim Report " of Herbert E. Durham and the
late AYalter Myers, to the Liverpool School of Tropical
Medicine, based on observations on j^ellow fever in Bra-
zil, in the course of which Dr. Myers died, just as did Dr.
Lazear in Cuba, indicates the belief of these investigators
in the causative effect of a small bacillus which they
found in the organs of all fatal cases. They conclude
that the yellow fever is not due to a protozoon, and with
regard to the American results, they make the following
comment : " The endeavor to prove a man-to-man trans-
ference of yellow fever by means of a particular kind of
gnat, by the recent American Commission, is hardly
intelligible for bacillary diseases. Moreover, it does not
seem to be borne out by their experiments, nor does it
appear to satisfy endemiological conditions." It is
obvious that this report of the English investigators was
prepared before the final and more complete paper of
the American Commission was read by Dr. Reed in Hava-
na, and even with this granted, it was hardly fair in them
to style the investigations of the Americans " an endeavor

310SQUIT0FS AND YELLOW F EVE Li 131

to prove," etc. The Americans were after the truth, and
had no desire to learn anything but the truth, that is to
say, they did not endeavor to substantiate any particular
theory.

As a result of the investig-ations, the Governor-General
of Cuba, himself a medical man, General Leonard Wood,
became so impressed with the accuracy of the conclu-
sions that he authorized the promulgation of instructions
to commanding officers in Cuba, relative to x^rotection
against mosquitoes and remedial measures in connection
with their breeding-places. General orders were issued
requiring the enforcement of the use of mosquito bars in
all barracks, and especially in all hospitals, and the de-
struction of the larvae by the use of petroleum on the Avater
where they breed. (See Chapter VIII.) The medical offi-
cer who makes the sanitary inspection at each post is
charged with the supervision of the details of these jire-
cautions. As a result, the writer understands that the
jn-evalence of malaria has been greatly reduced in western
Cuba, and it is hoped that with regard to yellow fever
similar results will be shown during the coming year.

The Yellow-fever Mosquito.

The particular species of mosquito which was used by
Dr. Finlay in his original experiments, and Avhich is the
only form which has been shown by our Army Commis-
sion to transmit the disease, is the one which has been
referred to in this country as Culex fasciatus Fabricius.
It was so termed in the writer's bulletin, entitled "Notes on

132

MOSQUITOES

Mosquitoes," published as Bulletin 25, new series, of the
Division of Entomolog"y, of the United States Department
of Agriculture, August, 1900, and has been so named in the
published reports of the Commission. There now seems
very good ground for the belief that the wide-spread

Fig. 32.

■Adult Male of Steyomyia fasciata from side ; enlarged.
(Author's illustration. )

tropical mosquito usually referred to as Culex tceiiiatus of
Wiedemann, is really a synonym of this species. It will
be remembered that down to the present time we have
no evidence that any other mosquitoes than those of the
g-enus Anopheles transmit malaria, and that so far as
known all species of this genus have this pathological

MOSQUITOES AND YELLOW FEVER 133

characteristic. In the case of yellow fever, why should
one species of Culex be able to transmit the disease and
not another species, assuming, as it will be quite proper
to assume, that since this capacity appears to be of generic
importance with Anopheles, it would be of generic im-

FiG. 33. — Body Scales from Stegomyia fasciata ; the broad one from a
wliite stripe and the narrow one from a chirk surface ; greatly en-
larged. (From Photo-micrograph by Dr. Erwin F. Smith.)

portance in the case of yellow fever ? It happens that the
British Museum is investigating the mosquitoes of the
world. Specimens have been sent to the expert, Mr. F.
Y. Theobald, who has charge of the work, from all quar-
ters of the globe, and Mr. Theobald has made a special

134 MOSQUITOES

stucV of tlie morphological features of these insects.
Without knowing- the results of the American Commission,
Mr. Theobald had decided that Culex fasciatus or tamiatus
is not to be contained in the genus Culex, but that on
account of scale structure and other structural peculiarities
it must be placed in another genus for which he has pro-
posed the name of Stegomj^ia. A few other species for-
merly placed in the genus Culex he also puts in this new
genus of his, which arouses the iDresumption that they
also may be capable of transmitting yellow fever. At all
events, we have here a most interesting and suggestive
co-relation between obvious structural peculiarities and
pathological possibilities.

Stegomyia fasdata, as we must now, at least for the
present, call the only yellow-fever mosquito about which
we are at all certain, is an inhabitant of the warmer por-
tions of the globe. Mr. Theobald writes me that it occurs
in abundance in Cuba and all the West Indies, and that
he has had it from all the warmer countries, but not from
arctic and temperate climates. He has it even in the
w^armer portions of Europe, from Italy, Greece, Spain,
Portugal, Gibraltar, and Malta. He generalizes that it is
found north and south of the equator to 38° north and
south latitude. In the United States it is common in
most of our Southern States. I have seen specimens
from New Orleans, La. (Dr. H. A. Veazie and Dr. W. S.
Thayer), from Natchitoches, La. (Mr. C. W.Johnson), from
Napoleonville, La. (Dr. L. E. Flannagan), from eastern
Texas (Dr. A. E. Woldert), from Hot Springs, Ark. (Dr.
A. W. Wright), from Pelham, Ga. (Mr. D. W. Coquillett),

MOSQUITOES AND YELLOW FEVER 135

and from as far north as Virginia Beach, Ya. (Mr. F. C.
Pratt). From the West Indies, I have seen specimens

Fig. 34. — Larva uud Pupa of Stegomyin fdscuda, with enlarged parts
enlarged. (Original.)

136 MOSQUITOES

from the Isle of Pines (Mr. S. H. Scudder), from King-
ston, Jamaica (Mr. C. W. Johnson), from Cuba (Drs. Eeed,
Carroll, and Lazear), and from Bluefields, Nicaragua (Dr.
L. A. Wailes). Nearly all these places are well within
the yellow-fever belt. Virginia Beach, the northernmost
locality indicated, is only a short distance from Norfolk,
Va., which in former years has suffered from j^ellow-fever
epidemics. It must be said that the collections of mos-
quitoes which have been made are more or less accidental
and that no thorough means have been taken to ascertain
the exact geographic range of this or any other species
of mosquito. It is quite likely that thorough collecting
would show the existence of this species at a more north-
ern locality. In fact, if it should prove to be the only
species of mosquito which is capable of transferring this
fever, the epidemics of yellow fever in Philadelphia and
New York, and even in New Haven and Providence, about
the beginning of the last century, would indicate that at
that time, at least, this mosquito had a more northern
range, or at all events that it had been introduced at those
points by sailing vessels coming from the South, and that
it succeeded in breeding there at least for some x)art of a
year.

The insect itself is a very handsome one. The banded
legs and the conspicuous silver stripes upon its thorax and
abdomen render it rather readily recognizable. It is well
shown in the accompanying illustrations. It breeds almost
everywhere in standing water. So far as has been ascer-
tained, it does not breed in brackish water. Dr. Flanagan
sent me specimens in November, 1900, and wrote that the

frfkid'i(M?' ^I^Wi^,'/,

Fig. 35.-I\Iouni-pnrts of Larva of Ster/omyia fasnata ; greatly enlarged,
(Oriiiinal, C. L. Marlatt, del.)

138 3I0SQUIT0ES

bite of tliis species is worse in the autumn than in the
summer, and that it breeds in cisterns, which, in that sec-
tion, are in universal use for obtaining- drinking-water.
Mr. Pratt made some interesting observations on the
species at an Atlantic Coast summer resort, in a latitude
of about 36° 50' N., and succeeded in obtaining the larvae
and pupae, from which the accompanying drawings were
made. At that point he also found it breeding in the
rain-water tanks. Neither larva nor pupa differs greatly
from that of the species of the genus Culex, the charac-
teristics of which have been described in an earlier
chapter. It maj^ be of interest to note that before this in-
sect was connected with yellow fever, I learned that in
certain of the AVest Indies and in Louisiana it is known
as the " day mosquito." Dr. Yeazie, of New Orleans, and
Dr. St. George Gray, of St. Lucia, communicated this fact.
The latter writes that it is very vigorous and troublesome
in the early afternoon, from 12 M. to 3 P.M., after which it
takes a rest until 9 or 10 p.m.

It should be stated emphatically that it is probable that
this species has a wide range south of Mason and Dixon's
line, and that it probably occurs everywhere in what is
termed the lower austral life zone, extending to some ex-
tent into the upper austral zone. This fact, however, and
the existence of this mosquito in a given locality, does
not mean that there is any danger in such localities of
yellow fever, unless one or more cases of the disease are
brought into the locality and exposed in such a way that
mosquitoes have the opportunity to suck their blood and
fly away untrammelled to some healthy individual.

MOSQUITOES AND YELLOW FEVER 139

Hon. John E. Procter, in a paper entitled " Notes on
the Yellow-fever Outbreak at Hickman, Ky., 1878," pub-
lished in bulletin of the Kentucky Geological Survey, No.
1, 1879 (?), pp. 63-99, two maps, gave a most careful history
of all of the cases of yellow fever which occurred at Hick-
man in the summer of 1878, from which it appears that
the causation of many of the cases which remained ob-
scure is readily explainable on the theory of the transfer
of the disease by mosquitoes. Mr. Procter (now Presi-
dent of the United States Civil Service Commission)
on learning of the tliesis supported by the Army Yellow-
fever Commission, was struck by the fact that the mos-
quito theory explained away these doubtful cases, and
called the writer's attention to his publication. This is
the only yellow-fever report which the writer has exam-
ined carefully, but very likely many others have been
published which should be critically examined from this
point of view. Surely the detailed accounts of the older
epidemics in this country, so carefully described in La
Roche's admirable monograph on yellow fever, do not, on
cursory examination, offer any facts inconsistent with the
adoption of the mosquito explanation of the spread of the
dread disease.

The importance of this discovery to Cuba and other
tropical regions cannot be minimized. Word came to us,
April 1st, from Havana, that for the first time in the history
of that city the month of April began, in 1901, without a
single case of yellow fever within the city limits. Much of
this result is attributed to the admirable methods of san-
itation introduced by our army soon after the occupation

140 3I0SQUiT0ES

of the city. Some part of it must also be attributed to
the excellent quarantine service under the charge of the
United States Marine Hospital Service, but also, without
doubt, much of the result must further be attributed to the
hospital and barrack methods, and treatment of mosquito
breeding-places carried on under the direction of the
medical corps of the army.

Mosquitoes and Filariasis.

The first evidence scientifically obtained that mosqui-
toes play a part in the spread of a disease was in the case
of the parasitic worms of the genus Filaria, which are re-
sponsible in Oriental tropical regions for the terrible
disease known as elephantiasis. The adult worm lives in
the skin of different parts of the body, lodged in the
lymphatic vessels. The two sexes are found side by side,
and are capable of living there a long time. They ob-
struct at certain points the flow of the lymph. This ac-
cumulates and dilates the vessels and the lymphatic
spaces. This mechanical distention is accompanied by
an irritation of the vessels and of the surrounding con-
nective tissue. Thus, elephantiasis becomes established,
which, as is generally known, manifests itself in very dif-
ferent degrees and occupies different parts of the body,
such as the arm, the leg, or the scrotum.

The female Filaria enclosed in the lymphatic ^^essels
is viviparous. The embryos to which she gives birth
spread in the lymph and then with it into the blood, and
it is in the blood that they are comnionl3" observed.

MOSQUITOES AND FILARIASIS

141

They are found in abundance in the blood duiin<j; the
night or during sleep, but during the day, or, rather,
while the patient is awake, they cannot be found. There
seems to be no good exj)lanation of this periodicity, nor
is it absolutely exact, but it constitutes a very curious
adaptation of the parasite to the nocturnal habits of the

Fig. 36. —Cross Section of Head and Beak of ]\Ios(juifo, showing Filarias
entering Beak; enlarged. (Redrawn from Britis/i Medical Jounml.)

mosquito, which serves as an intermediary host. Having
more than twenty years ago proved this periodicity of
the embryos, Dr. Patrick Manson had the happy thought
that as mosquitoes bite men during sleep, perhaps they
may be agents in the transmission of the disease, and his
subsequent observations proved the correctness of this
idea. The Filaria embryos, according to his observa-

142 MOSQUITOES

tions, sucked into the stoiiKiL-lis of mosquitoes, lose tlieir
hyaline envelope, work through the wall of the stomach
and enter the muscles of the thorax, where they lodge
between the muscle bundles, remaining- there for two or
three weeks, growing and taking on the character of the
larva. This is as far as the evolution was for a long time
observed, but upon it was based a theory by which the
etiology of lilariasis was exiDlained. This was, that the
bodies of the mosquitoes falling in water, at death rap-
idly disintegrated, liberating- the parasites into the water,
which when drunk by human beings carried the parasites
once more into the human body.

9 Although plausible, it was difficult by this theory, as
Blanchard has pointed out, to explain the constant pres-
ence of the parasite in the lymphatics in the skin. How
can the animal introduced into the intestinal tube make
its way into the lymphatics of the arms and legs? It is
difficult to suppose that it does this by going through the
lymph vessels, which are provided with valves. Bancroft,
of Australia, suggested that possibly the Filaria might be
introduced into the blood of a healthy person by the bite
of the same mosquito, assuming that the embryos in their
penetration into the muscular part of the thorax might
work into the beak.

Through the researches of Bancroft, Manson, and Low,
following this idea, it was discovered that up to the sev-
enteenth day the larval Filarias in the mosquitoes are
found exclusively in the thoracic muscles, but after that
some of them begin to travel. They collect in the con-
nective tissue in the anterior i^art of the thorax in front

MOSQUITOES AND FIL ARIAS IS 143

of the muscles. They are then about eighteen to twenty
micromillimetres in diameter, and a little slenderer than
those Avhich remain in the muscles. By the twentieth
day those remaining- in the thorax have grown larger and
have begun to break down the muscular tissue. Those
which have migrated are found to have penetrated the
neck, accumulating in the head, and penetrating into the
beak. The question of transmission then becomes very
much like that of the transmission of the malarial germs,
and it seems reasonably sure that the Filaria is inocu-
lated directly into the skin by the beak of the mosquito,
and it is in the skin of man that the parasite accomplishes
its last metamorphosis and becomes adult. In the skin
they pair, and the embryos, issuing in the lymphatic
spaces or vessels, are carried by the lymph into the blood-
Thus the life round is comjDlete.

The mosquito which is concerned in this work is not an
Anopheles, as is the case with malaria, but a Culex. The
one studied by Bancroft in Australia is one of the com-
mon domestic Australian mosquitoes, Culex ciliaris
Linn., which is possibly a synonym of Culex pipiens Linn.
Other species may be involved, and, in fact, other biting
insects than mosquitoes, but these points are not yet
thoroughly determined.

VI

Otlter Genera of North Amermm Mosquitoes

HA^^ENG given a full consideration to the common
mosquitoes of the genus Culex, which includes by
far the majority of all of the mosquitoes which in-
habit North America, and having paid special attention
to the forms of the genus Anopheles, which comprises all
the species which have been i^roved to carry the malarial
germs, and having also told the story of the yellow-fever
mosquito, there remain for brief consideration the mos-
quitoes of the six additional genera known to occur in the
United States. The structural peculiarities of these six
genera are described in full in Chapter X., and since they
are few in number of species, and since until recently all
of them were unknown except in the adult condition, this
consideration must necessarily be brief.

Genus Psorophora Desvoidy

The insects of this genus are large mosquitoes, and
only one species, Psoropliora ciliata of Fabricius, inhabits
the United States. In this insect the palpi in the male
are longer than the proboscis, while in the female they
are less than one-half as long as the proboscis. The

144

OTHER GENERA OF MOSQUITOES 145

proboscis itself is straight. The most striking charac-
teristic, hovrever, is the presence of very peculiar erect
scales on the legs. The hind legs especially are fur-

FiG. 37.— Adult Female of rsorophora ciliata ; enlarged. (Author's

illustration.)

nished with large scales which are placed at right angles
to the leg itself, and similar scales are present in smaller
numbers upon the middle legs, and in very small num-
bers upon the end of the thighs of the front legs. P.

146

MOSQUITOES

ciliata is a very larg-e mosquito and is undoubtedly one
of the forms known in the South as gallinippers. It is
really yellowish in color, yet the general effect when one
glances at it or sees it flying is that it is very dark — al-

FiG. 38. — Females of PsoropJwra ciliata at rest on side wall and ceiling ;
enlarged. (Author's illustration.)

most black. The wings are not really spotted or dusky
but the very numerous dark scales on the main veins
make them appear dark. When seen in certain lights
they are prismatic in their color effect. I have said that
they are large. The length of the body of the female is
about ten millimetres, but the length from the tip of the
beak to the tip of the hind legs is nearly twice this.

OTHER GENERA OF MOSQUITOES 147

This large and liandsome mosquito * is a wide-spread
species and is known to occur in Massachusetts, New
Jersey, Pennsylvania, District of Columbia, Virginia,
Connecticut, Illinois, Indiana, Florida, Louisiana, Arkan-
sas, Nebraska, Texas, and California. It is, however,
rare in its northern range, and in Massachusetts and
New Jersey, for example, it is found only in low-lying

Fig. 39. — Male of Psorophora ciliata^ from side ; enlarged. (Original.)

regions. As a matter of fact, it seems to be really one
of those species which is a true inhabitant of what is
called the lower austral life zone, which comprises most
of our Southern States. It may have a tropical range,
but among the many mosquitoes which I have received
from Mexico, Nicaragua, and Cuba, this species does not
occur. Neither Psorophora nor the next genus, Mega-

* Many mosquitoes are really handsome, when seen under the lens,
but few people will admit that creatures which they so heartily detest
have any a3sthetic value whatever. This is plainly to be seen in the case
of snakes.

148

MOSQUITOES

rhinus, have been studied by investigators working- upon
the transfer of blood-inhaljiting parasitic germs by mos-
quitoes, and I have urged that physicians and bacteriob
ogists in our Southern States pay some attention to them

from this point of view.

Nothing was k n o w n
about the early stages of
Psorophora until the end
of August, 1900. In the
early part of the summer
(in June), a large series
of living specimens Avas
captured at St. Elmo, Va.,
by one of nw assistants,
Mr. F. C. Pratt, and we
expected that we should
be able to secure eggs
without difficulty and to
study the insect in its dif-
ferent stages. The females
were placed alive in hirge
battery jars, under condi-
tions which had repeatedly
been successful with mosquitoes of the genera Culex and
Anoi^heles, but no eggs were deposited. This brought
me to the conclusion that either the confined specimens
were not impregnated or that they had already deposited
all their eggs, or that their breeding habits differ from
those of other mosquitoes. On August 30tli some very
large mosquito larvie and pupae were received from Mr.

¥nr. 40. — Youdsj: Larva of Psoroph-
ora ciliaia ; enlari;cnl. (AuIIkji's
illustration.)

OTHER GENERA OF 3I0SQU1T0ES 149

William P. Seal, of the Aquarium Supply Company, j.t
Delair, N. J. On examining- tliem I felt sure tliat they

Fig. 41. — Full-grown Larva and Pu|):i of PsoropJwra cilinio . with en-
larged parts ; enlarged. ( Author's illustration.)

could be nothing- less than the larvfie and pupne of Fsoro-
plwra ciliata. The first specimens received were in alco-
hol, and Mr. Seal was informed of their probable identity,

150 MOSQUITOES

and urged to send on living- specimens in water, and to en-
deavor to rear the adult. It was then, however, unfor-
tunately^, too late. He Avrote that during- the summer a
small creek and some earth ponds on his place became
entirely dry, in consequence of which all fish in them
died. Some time in August there was a sufficient rainfall
to fill a few of the deepest places, which soon after be-
came almost alive with mosquito larvne. These were used
for fish-food, until it was noticed that they were develop-
ing to the pupa stage, when coal oil was immediately
poured on the water. It was while the coal oil was be-
ing applied that the big larv?e and pupie were first no-
ticed. Mr. Seal had been a collecting naturalist for
twentj-six years, supplying material for the aquarium
and for biological research, and had discovered some low
forms of life new to science, which were described by
Leidy and Eyder, but in all his experience he had never
seen such large mosquito larvae.

On being assured of the novelty and importance of his
observation, he promised to watch for the subsequent
appearance of similar larvae, and on September 20th
found other specimens which appeared after a rain which
occurred on September 15th or a little before. Mr.
Seal was able to distinguish between them and the
Culex larvae, and wrote that they were very scarce — per-
haps one of them to many thousands of the others. On
September 25th additional larvae and pupae were sent
in, and from these specimens the accompanjdng illustra-
tions were made.

The larva is structurally of great interest. On com-

OTHER GENERA OF MOSQUITOES 151

parison with larva of Cnlex, wliicli it resembles more
nearly than that of Anopheles, it will be seen that the
breathing- tube is longer ; that the anal flaps are longer
and more pointed, and the hair fringe on the under side
of the last segment of the body is much longer and
denser, while the mouth-parts are quite different. The
jaws are sharply toothed, and very long, and are used in
the mastication of food. Other mosquito larvae feed upon
spores of algse and other small particles which appear to
require no mastication, but this larva descends to the
bottom of the water and has been noticed to grasp a bit
of water-plant half an inch long and actually to chew it. r

The duration of the pupal stage was from four to five
days, and the adult insects issued on September 27tli and
28th. Young larvae were also found in this sending, and
one of them is shown in Figure 40.

The breeding-places in which these larvae were found
were small depressions in the bed of a small stream, and
similar hollows in certain small ponds, all of which were
dry the greater part of the summer. After they first
dried in the spring they were barren of fish and vegeta-
tion. Mr. Seal is satisfied that the insect is rare in tlie
vicinity of Philadelphia, and thinks that possibly he mny
have brought this si^ecies from the South, as he is in the
habit of shipping large quantities of aquatic j)lants from
the South, from January -Ith to about May 10th of each
year. He has a place some miles from Delair where he
grows Cabomba. The plant is very dense, and the creek
is full of fish, but in the water on top of the plant, which
grows to the surface, are large numbers of mosquito

152 MOSQUITOES

larvae. T\\e\ are out of sight and practically out of reach
of the fish.

The eggs of this interesting mosquito are yet to be
found, and it will be most interesting to see in what re-
spects they differ from the eggs of Culex and Anopheles.

Genus Megarhinus Desvoidy.

Another of the large mosquitoes which seem to be col-
lectively known in the South as gallinippers (probably
also some of the harmless crane-flies are so dubbed)
belong to this genus. In fact there are two of them
known in North America, namely Megarhinus lueineY'
rhoidalis F. (Mexico and Cuba), and M. portoricensis
Boeder (Mississippi). These mosquitoes also should be
investigated by Southern observers in regard to their
possible connection with malaria, or some other blood
disease. They are readily distinguished from other mos-
quitoes by the curved beak. The palpi in the male
are as long as the proboscis, but are short in the female.
The colors are bluish or greenish.

Nothing is known of the life history of the mosquitoes
of the genus Megarhinus, and some Southern observer has
an admirable chance to add to the sum total of human
knowledge by a series of careful observations on one of
these forms.

OTHER GENERA OF MOSQUITOES 153

Genus Aedes Meig-en.

The mosquitoes of this f^enus are minute forms, insignif-
icant in color, and apparently rare. One species, Aedes
fascus Osten Sacken, has been found at Cambridge, Mass.

Fr«. A2.—Atdesfuscus, feintile ; eiil:iri,^ed. (Aut;

illiisiration.)

Aedes ftismis, according to a recently- published note by
Dr. J. B. Smith, has been reared l)y Mr. J. Turner Brake-
ley at Horuerstown, N. J., from larvie found in the pitchers

154

MOSQUITOES

of the pitcher-plant (Sar?ricema). The determination was
made by Mr. C. ^\. Johnson, of Philadelphia, and is there-
fore undoubtedly correct.

Fig. AZ.—To,iorhynchitesrutihis, female ; enlarged. (Author's
illustration.)

As pointed out in the synoptic tables in Chapter X.
the palpi in both sexes are short, which distinguishes
these little mosquitoes from other North American
forms.

OTHER GENERA OF MOSQUITOES 155

Stegomyia, Toxorliyncliites, Uranoteiiia and
Ooncliyliastes.

As will be iDoiuted out and fully explained in Chapter
X., these four generic names are here used for certain
American mosquitoes for the first time. I am able to use
them in this book through the great courtesy of Mr. F. V.
Theobald, of Wye, England, who has sent me proof sheets
of his monograph of the mosquitoes of the world, now
being published by the British Museum. Stegomyia
includes, as has already been shown, the yellow-fever
mosquito, S. fasciata, and it also includes the species
mentioned in my previous writings as Culex signifer Co-
quillett, and which has been captured in the District of
Columbia and Virginia by Messrs. Coquillett, Barber, and
Pratt. Toxorhynchites includes the species previously
referred to as MegarJduus rutllus and which must now be
known as Toxorhynchites rutilus. Uranot?enia includes the
North American species previously known as Aedes sap-
pirhinus. Conchyliastes includes two species formerly
placed in the genus Culex and which must now be known
as Conchyliastes imisicns Say and Conchylicistes post i rat if s
Wied. The former species has l)een taken in Pennsylva-
nia, Virginia, District of Colund)ia, and Texas by Messrs.
Johnson, Pratt, Thayer, and Barl^er.

VII

Natural Enemies of Mosquitoes

WHEKE mosquitoes exist in rain-water buckets
and barrels they are apt to have none or very few
natural enemies. Their jDrincipal enemies when
in the aquatic larval and pupal stages are fishes and carniv-
orous insects. Most carnivorous insects are rather slow
breeders, and as a consequence they seldom deposit their
egg-s except in rather permanent pools, and naturally
fish are found only in such places. There are, however,
other enemies aside from these. Dr. C. W. Stiles informs
me that during the summer of 1889, when working with
C. H. Hurst, they collected at Leipsic a large number of
mosquito larv&e and i^upae, and that many of them died in
the laboratory. Upon opening one of the bodies, which
was quite distended, he found a species of Mermis, one of
the hair worms or hair snakes, coiled up in the body cav-
ity. Examination of other dead larvae or pupfe disclosed
the fact that nearly every one was parasitized by the same
species of Mermis. He showed the worms to Professor
Rudolph Leuckart, who informed him that he had re-
peatedly found the same Nematode in former years, and
that he had observed that in years when mosquitoes were
numerous the worm is very scarce. This led him to be-

156

NATURAL ENEMIES OF MOSQUITOES 157

lieve that the i^arasite was a not uuimpoi'tant factor in
destroying mosquitoes near Leipsic. Later, Dr. Stiles
found the same worm in mosquito hirv^e and pupa3 taken
from other breeding-phices, and it Avas quite noticeable
that the parasitized insects were weaker in their move-
ments than those that were not infected with the Avorm.
In the next summer (1890) he agaiu looked for the worm,
but found none, and it appeared to him that mosquitoes
were more abundant that year than in 1889.

Dr. Stiles also informs me that a Sporozoan of the
genus Glugea is referred to as parasitic in mosquitoes, but
that Labbe, in his recent monograph of the Sporozoa,
does not give Culex in his list of hosts. Dr. Stiles does
not recall who found this i:)arasite, nor does he knoAv
whether it is of any particular economic importance.

By far the most effective natural enemies of mosquito
larvie and pupae are fish. Almost all of the small carni-
vorous fish which inhabit swamp pools and still water
will feed upon mosquito larva). Nearly all of the minnows,
especially those forms known as top-minnows, of the gen-
era Fundulus and Gambusia, feed abundantly upon in-
sects found near the surface of canals, sIoav streams, mill-
ponds, and other similar places, and, although not at all
specific in their choice of the early stages of the moscpii-
toes, eat them perhaps with even more avidity than other
aquatic insects, especially such as are hard-shelled.
Then, too, the voracious little creatures known as stickle-
backs, and especially the forms known as Ga-'<tcrosicus aca-
leafu.s- and G. 7ji\'<pi/)osf/,s have this beneficial habit. Stickle-
backs, however, are by no means confined to insects for

158

3I0SQUIT0ES

food, but will feed upon other animals, including- good-
sized tadpoles. Anyone who has attempted to keep tad-
poles and sticklebacks in the same aquarium will realize
the truth of this statement. I once kept a large sized
tadpole in the same aquarium with a stickleback, which
it exceeded at least five times in size, and its personal
beauty w^as soon sadly damaged by the fact that the
stickleback subsisted upon meals taken from the edge of
the tadpole's tail. In his previously published bulletin

Fig. 44.— Stickleback {G asterosteus acnleatus) ; somewhat enlarged.
(After Jordau and Evermanu.)

on mosquitoes the writer recommended sticklebacks for
introduction into fishless ponds to destroy mosquito lar-
V8e, but Mr. W. P. Seal, of the Aquarium Supph^ Com-
pany of Delair, N. J., recommends the so-called top-min-
nows of the genus Gambusia, common in the brackish
waters of the Chesapeake system and southward. He
says these are the only fish he knows which will kill No-
tonecta (the water-boatman), but they do this only when
other food is scarce, and when the bugs are small. The fish
vary in size from an inch for the males, to about one and
three-quarter inches for the females. They live equally

NATURAL ENEMIES OF MOSQUITOES 159

well in i)nrely fresh water. He has raised them to the
fourth generation in tubs and i^onds, and they will breed
readily in tubs or aquaria. As destroyers of eggs and
larvae, and adults as well, of such insects as infest and

"J /ip"7"M^'",jiiiv"-iJ'i«'V'^>v--' y ' ' ,'

Fig. 45. — Top-minnow {Gambusia affiiiis) ; male above ; female below ;
somewhat enlarged. (After Jordan and Evermann.)

mutilate aquatic plants or lay their eggs in the water, Mr.
Seal finds these top-minnows vastly superior to any other
species of fish. Dr. H. F. Moore, of the United States
Commission of Fish and Fisheries, informs me that the
top-minnow, known scientifically as Gcunhusia affinis, is

160 MOSQUITOES

abundant in sluggish waters, fresh or brackish, almost
ever}^ where south of the Ohio Eiver. It feeds largely on
vegetable matter, but also on insects. Larval mosquitoes
have been found in its stomach. The species is vivipar-
ous, as indeed are most of the minnows of this genus, as
well as of the genus Fundulus, the young when born being
about three-eighths of an inch long. It is specially abun-
dant in the Gulf States. Dr. H. A. Yeazie, of New Or-
leans, writes me that this little fish is common about New
Orleans, and that Avliere it is present he has not been able
to find mosquito larvae of any kind. He has looked in

Fig. 46. — Top minnow {Fundulus notatus) ; sligiitly enlarged. (After
Jordan and Evermann.)

gutters and ponds where to all appearances there should
be plenty of larvae, and has found none, and very shortly
he saw the little minnows patrolling the pools. He says
they are great breeders, and ravenous eaters. They are
so small that they will go into the shallowest places, and
even wriggle on the side of the bod> to catch their prey.
They seem to live under the most adverse circumstances,
and do not die until all water is gone. He has seen them
so thick in a partly dried-up pond that they had no room

NATURAL ENEMIES OF MOSQUITOES 161

to swim, " yet they seemed liappy." As elsewhere stated,
they are viviparoiTS, and Dr. Yeazie says that a little
female will expel large numbers of the yonng at one time,
and that they can be raised in almost anything that holds
water. He has seen them swimming around under a layer
of ice, as unconcerned and active as they Avould have been
on a hot July or August day.

I have been thus explicit in referring to these fish, and
have illustrated the best forms, for the reason that a very
practical use can be made of them. It was stated a num-
ber of years ago in Insect Life, that mosquitoes were at
one time very abundant on the Eiviera in South Europe,
and that one of the English residents found that they
bred abundantly in the water tanks, and introduced carp
into the tanks for the purpose of destroying the larvse.
It is said that this was done with success, but the well-
known food-habits of the carp seem to indicate that there
is something wrong with the story. If top-minnows or
sticklebacks had been introduced, however, the story
would have been perfectly credible, and it points to the
practical use of fish under many conditions. Some years
ago Mr. C. H. Eussell, of Bridgeport, Conn., described a
case in which a very high tide broke away a dike and
flooded the salt meadows of Stratford, a small town on
the north side of Long Island Sound. The receding tide
left two small lakes nearly side by side, and of the same
size. In one lake the tide left a dozen or more small fish,
while the other was Ashless. An examination by Mr.
Kussell in the summer of 1891, showed that while the
Ashless lake contained tens of thousands of mosquito

162 3I0SQUIT0ES

larvee, that containing- the fish had no larvae. Mr. E. A.
Schwarz informs me that in Beeville, Tex., a little fish
which is known locally as a perch is put into rain-water
tanks for this express purpose.

There occur on many large estates in the northeast and
elsewhere, ponds which are used for watering- stock.
These are sometimes artificial ponds built with rock
bottoms to i3revent the exit of the water. They cannot
be drained, and on account of their purpose they cannot
be treated with kerosene. Into such ponds should be
introduced a plentiful supply of top-minnows or some
other voracious mosquito-eating fish.

In a later conversation with Mr. Seal, he told me that the
top -minnow was suggested because it is a top -feeder, and
being very small and slender, it penetrates to the remot-
est shallows of the waters which it may inhabit, especially
where plants abound and where larvae of mosquitoes are
sure to be found. On second thought, he was inclined to
think, however, that for general i^urposes the common
little flat sunfish, or " pumpkin-seed " as it is sometimes
called, would be a good fish to introduce into Ashless
ponds. It grows much larger, of course, but is very pro-
lific, and the young do not make a very great growth in a
year, so that the young of each year remain compara-
tively small, say from three -fourths of an inch to a half-
inch, until the young of the following year would be
ready for business, which would be by July 1st. The top-
minnow, he says, being a soft-raj^ed fish, becomes the
easy prey of larger fishes introduced into the same
waters, but the sunfish, being protected by spine-rayed

NATURAL ENEMIES OF MOSQUITOES 163

fins, enjoys greater freedom from molestation. The sun-
fish, he says, abounds in every pond and stream where
fish are plentiful, excepting cold mountain-streams.
Every aquarium dealer in any large city will be able to
supply the common sunfish. Mr. Seal further notes that
the common suntish is the most voracious of the smaller
fishes. It has a larger mouth than the top -minnow

Fig. 47. — Conmiun Sunti.sh or " Punipkin-sced " ; reduced. (After Jor-
dan and Evennann.)

and is wholly carnivorous, whereas the top-minnow is
omnivorous. On mature consideration, he gives prefer-
ence to the sunfish as most completely filling the bill.

There are other aquatic vertebrates, besides fish,
which destroy mosquito larvje. I am not sure that tad-
poles eat them — there seems to be some douljt on that
point— but my friend, Mr. Albert Koebele, informs me
that he imported into Hawaii from California a large

164 MOSQUITOES

number of the western salamander {Diemyd]flus torostts
Escli.) wliicli were liberated in the upper part of the
Makiki stream in the hope of reducing the large number
of mosquitoes breeding everywhere in small i30ols and
taro fields. He kept two of these salamanders for sev-
eral weeks in an open tank, and they devoured, and kept
the water free from, the mosquito larvae that bred there.
While hundreds of the newly hatched mosquito larvae
could always be observed, none of them ever reached full
growth. Mr. Koebele says, " It is to be greatly desired
that this valuable batrachian will increase to such num-
bers as to be able to help us keep in check the most
troublesome insect on these islands."

Then there are many predatory insects which feed upon
mosquitoes. The late Dr. R. H. Lamborn, of New York
and Philadelphia, was so impressed with the voracity
of dragon-flies that he offered a series of prizes for the
three best essays regarding the methods of destro}^-
ing mosquitoes and house-flies, especially designating
the dragon-fl}^ for careful investigation. The prizes were
awarded and the successful essays were published in an
entertaining volume entitled " Dragon-flies vs. Mosqui-
toes. The Lamborn Prize Essays." None of the essays
were able to solve the problem of the practical breeding
on a large scale of dragon-flies for mosquito extermina-
tion, and, in fact, the insect enemies of the mosquitoes
cannot be practically handled. Dragon-flies as larvae
feed upon mosquito larvae, just as they feed upon all
other aquatic insects and even upon small fish. As
winged adults they capture mosquitoes on the wing, just

NATURAL ENEMIES OF MOSQUITOES 165

as tliey capture other insects on the wing. The same
may be said of other predatory aquatic insects. Some of
the aquatic beetle larvae and some of the predatory water-
bugs undoubtedly destroy hundreds of mosquitoes. Any
stagnant pool, when carefully watched, will be found to
swarm with predatory animal life. From such a pool I
once took a half gallon of water which was teeming with
aquatic insects, including hundreds of mosquito larvae.
Among these insects there were three water-beetle larvoe
of the family Hydrophilidse, and in the course of a week
these three larvae practically devoured all of the other
animal life in the jar.

The adult mosquito also has its natural enemies. We
have already mentioned the dragon-flies, and many night-
flying birds, such as night-hawks and whippoorwills,
destroy them on the wing ; and bats, of course, feed upon
them. An observation is on record by the late Prof. F.
L. Harvey, in which he states that he found six hundred
mosquitoes in the crop of a single night-hawk. In No-
vember, 1900, Mr. E. P. Salmon, of Beloit, Wis., wrote
me, " There is a parasite, a little red louse, which attacks
the mosquitoes on Madeline Island a few weeks after
their appearance in June, and from the time this little
red louse shows itself on the mosquito under the mosqui-
to's wings, the mosquito begins to lose his strength.
After a few weeks, along toward the end of July, the
mosquito ceases to be very troublesome and seems to be
fighting with his parasite for his life." This parasite is
probably one of the little red mites which are found
upon flies, and particularly upon the common house-fly.

166 MOSQUITOES

The mosquito being' an aquatic insect, tlie mite ol^served
by Mr. Salmon may be one of the little water-mites of
the famil3^ HydrachnidjTe, but the mosquito issues from
its pupa so rapidly that this is hardly likely. It is more
likely to be one of the Trombidiidse, the young of which
maj^ crawl upon the mosquito when it is at rest upon the
plants.

Some observations upon the natural enemies of the
malarial mosquitoes of the g-enus Anopheles have been
made by Dr. C. AV. Daniels in East Africa ("Reports to
the Malaria Committee of the Royal Society," December
31, 1900). He saj^s that fish, and especially young" fry and
small fishes, will speedily destroy the mosquito larvse,
but in spite of this, Anopheles larv?ie are often found in
pools, rivers, etc., where fish are abundant, and pup?e and
mature larvae among- them. This is seen in open pools
as well as in the g'rass-grown rivers. He also says that
tadpoles do not attack the larvae even in captivity, and
g-oes on to say that larv?e of Coleoptera and drag-on-flies,
often found in numbers in water with abundant Anoph-
eles larv,^, even in captivitj^ do not seem to devour them.

In x^onds where there are larg-e-leafed water-plants,
mosquitoes frequently escape the attacks of fish, and
man3^ more of their natural enemies, bj^ holding- to the
water-surface, especially above partly submerged leaves.
This is esx^ecially the case with Anopheles larvae, which
remain quite at the surface during the best part of their
existence

VIII

Remedies Against Mosquitoes

AFTER a number of years' experience in fig-liting
mosquitoes, the present writer has come to the
conclusion that there is no reason why any com-
munity shoukl submit to the mosquito pLague. At first
he only went so far as to state that there are many places
where the source of the mosquito supply is circumscribed
and limited, and easily handled, and that in such places,
with a comparatively slight effort and small exi3ense,
mosquitoes could be controlled. As the work went on
and as experiments were tried on a gradually increasing
scale, it became more and more obvious that any neigh-
borhood, if it cares to take the trouble and go to the ex-
pense, may place its mosquito denizens hors du coialud.
But Avitli mosquito work, just as witli so many other pub-
lic measures, what is everybody's business is nobody's
business, and the result is that in many localities every-
one submits to the mosquito evil. In some instances, in-
dividual effort is all that is necessary ; in others, united
action on the part of tlie residents of a given neighbor-
liood or a given community is needed, and, as will be
later shown, there are still other measures which sliouhl

167

168 MOSQUITOES

be handled by still larger organizations— even by States.
Mr. Matbeson's clever phrase, referred to in the intro-
duction to this book, " There is no more reason why peo-
ple should suffer from mosquitoes than that i\\ej should
suffer from smallpox," is not an over-statement ; and that
the effort should be made when it promises success is
so self-evident that it only requires a few enthusiastic
and enlightened individuals in a community to convince
everyone of the desirability of an organized effort.

Setting aside the question of yellow fever, which only
at intervals concerns even the States along the Gulf of
Mexico, and is of vital and constant importance only in
tropical regions, a mere passing thought shows the eco-
nomic loss to a neighborhood in the prevalence of ma-
laria. While the actual death-rate may not be high, the
number of persons incapacitated for their full share of
work is always great. Families suffer in one way or an-
other, and the community, when the matter is considered
in a broad way, is a great loser. Aside, too, from ma-
laria, it is perfect!}^ obvious that a mosquito-ridden
neighborhood is not a desirable j^lace of residence. The
very fact of the abundance of mosquitoes keeps real
estate values at a depressed point. I know of one case
where a stretch of land near a large body of water af-
forded many excellent cottage and villa sites, but mos-
quitoes were so numerous that even domestic animals
could not be kept in a healthy condition, and the sole
population consisted of a few smoke-dried fisliermen and
their dogs. In this locality, by enterprising work on the
part of one man, who organized a company for the pur-

REMEDIES AGAINST MOSQUITOES 169

pose, the land was boug-lit, the mosquito-breeding- places
were practically abolished, summer residences were built,
and the company realized many thousands of dollars in
the course of two years. There are, within a hundred
miles of New York City, for example, hundreds of beau-
tifull3^ situated localities which are not utilized to their
full possibilities largely on account of the prevalence of
mosquitoes. There are many small towns which are un-
desirable for summer residence on account of the abun-
dance of mosquitoes, though in all other respects their
qualifications for this purpose are perfect.

Aside from the main questions of health and of the
value of land, come the other subsidiary questions of com-
fort, and of the unnecessary expense of screening' houses
with the thoroughness necessary in many localities, which,
Avhen considered in bulk, become important. It seems
then evident that it would be a positive economj" for a
community to spend, if necessary, even a large sum of
money in attempting mosquito-extermination. In ver\'
many cases, however, a small sum will suffice, i^rovided
it is administered with intelligence.

Dr. C. Fermi, after giving an account before the Medico-
physical Society of the University of Sassari, March 23,
1900, of his efforts to free the town from mosquitoes, esti-
mated the expense of freeing a town of 50,000 inhabitants
at from $200 to $300. This sum seems extremely small,
even with the low price of labor over there, but in the
case of Sassari the mosquito-supply was local, and the
insects bred almost entirely in household tanks and water
receptacles. It is with large marsh-areas or numerous

170 MOSQUITOES

ponds ill neigliboriiig woods, and especially with the high
brackish sea-coast marshes, that the expense would be-
come very great.

The consideration of the question of remedies may
most conveniently be divided into the following main
categories : (1) llemedial work against the early stages ;
(2) Eemedial work against the adults.

Eemedial Work Against the Early Stages.

In considering the question of remedies against the
earh^ stages, Ave again find it most convenient to sub-
divide the subject as follows : (1) The treatment of
breeding-places Avith insecticides ; (2) The abolition of
breeding-places by drainage, and (3) The introduction of
natural enemies into breeding-pools, which for any rea-
son it may be undesirable to drain, or to treat with oil.

Before undertaking work against the early stages of
mosquitoes in any given neighborhood, it becomes neces-
sary to make a thorough survey of the immediate sur-
roundings, and to learn with great accurac}^ all of the
places in which mosquitoes are breeding or may breed.
In the section entitled " Queer Places in which Mosqui-
toes Breed " (Chapter I.) an effort has been made to cover
the ground rather thoroughlv as an indication of what
must be looked for. All accidental receptacles for stand-
ing water must be emptied and must be kept emptied ;
waste ground in the vicinity must be thoroug'hly ex-
amined, in order to find whether there are hollows in
which rain-water accumulates or whether there are broken

REMEDIES AGAINST MOSQUITOES 171

bottles, empt}' cans, or discarded vessels of any kind.
About houses, tlie .greatest care must be taken to examine
every possible spot where still water may occur ; cisterns
must be covered tightly, Avitli, however, a sufficient aper-
ture covered with wire gauze to admit of a plentiful aera-
tion of the water ; rain-water barrels should be either
covered or treated with kerosene. In the surrounding
ground every permanent pool and every swamp-area
should be charted and the method of treatment determined
upon ; permanent i^ools not used for watering stock
should be treated with kerosene ; swamp-areas should
be drained ; and small depressions should l)e filled with
earth. All such work must be thorough and practically
perfect, else it is hardly worth while to undertake it.

TJte Use of Kerosene on Breedinr/ Pools.

As long ago as 1812, the writer of a work published in
London, entitled, "Omniana or Horne Otiosiores," sug-
gested that by pouring oil upon Avater the numl)er of
mosquitoes may be diminished. Delbceuf, in the Revue
Sclent 'if que, 1895, says that he used kerosene in this way
fifty years before. H. E. Weed, in 1895, stated that in the
French quarter of New^ Orleans it has been a common
practice for many j^ears to place kerosene in the w^ater
tanks to lessen the number of mosquitoes in a given
locality. Suggestions as to the use of kerosene w^ere
made by Mrs. Aaron, and by Beutenmiille-r, in the Lam-
born Prize Essa,vs, " Dragon-flies versus Mosquitoes " (I).
Appleton & Co., 1890). In 18G7 the x^i'esent writer used

172 MOSQUITOES

kerosene in a watering trough at Ithaca, N. Y. , and found
that mosquito larvae were killed by it, and in 1892 con-
ducted an experiment upon a larger scale in the Catskill
Mountains, indicating the quantity of kerosene necessary
for a given water-surface and showing that adult mosqui-
toes are captured b}^ a kerosene film ; that is to say, they
alight on the surface of the water in an attempt to de-
posit eggs and are destroyed b}^ the kerosene before the
eggs are laid. A full account of this last experiment was
published in Insect Life, vol. ii., 1892, and, since it at-
tracted considerable notice in newspapers, additional ex-
periments by others upon a larger or smaller scale were
speedily made. Mr. H. E. Weed rid the college campus
of the Mississippi Agricultural College of mosquitoes by
the treatment with kerosene of eleven large water-tanks.
Dr. John B. Smith recorded in Insect Life (vol. vi). suc-
cess with this remedy in two cases on Long Island. Pro-
fessor V. L. Kellogg conducted a similar series of experi-
ments upon the campus of Stanford University, California,
in which cases jDost-holes filled with surface water were
giving out large numbers of mosquitoes, but when a little
kerosene was poured into each hole the mosquito plague
was almost immediately alleviated. Kev. John D. Long,
at Oak Island Beach, Long Island Sound, and Mr. W. E.
Hopson, near Stratford, Conn., conducted large-scale ex-
periments with good results. Mr. E. M. Eeese, in Balti-
more, treated open sewers with kerosene with excellent
results. A little later (1898), Mr. W. C Kerr, on Staten
Island, did some large-scale kerosene work upon ponds
and swamps, which resulted most satisfactorily. In 1897

REMEDIES AGAINST 31 OS QUI TOES 173

Mr. M. J. Wiglitmaii oiled brackish nuirslies at an Atlantic
coast resort for a radius of about half a ijiile, reducing
the mosquitoes to innoxious numbers for an entire sea-
son. Dr. St. George Gray, of 8t. Lucia, British West
Indies, used kerosene in his well and in water- jars in his
yard with excellent result.

All of this work w^as done before the malaria discover-
ies directed the attention of European observers especi-
ally to the question of mosquito control. In the early
work of the Italian investigators the use of kerosene was
rather discredited, one of the reasons adduced being that
although kerosene is abundant and cheap in America, it
was not know^n to the Italians that it was extensively used
in this country — a pretty poor reason, but still, more or
less effective over there. Even Major Ross, the English
expert, seemed at first rather skeptical as to the value of
kerosene, but returned from his West African expedition
fully convinced of its value (Giles, 1900, pp. 76, 77), and
since that time the use of petroleum oils has gradually
become the standard treatment for mosquito-breeding
pools. For example, Fermi and Lumbao, the Italian in-
vestigators, think that one man, with one day's teaching,
could rid a good-sized city very largely of mosquitoes by
repeating ten to twelve times, through a summer of seven
months, the application of petroleum to the breeding-
places. Mr. W. J. Matheson, in the summer of 1900,
attained very successful results by treating an area of
several square miles on the north shore of Long Island
with kerosene, combined with certain drainage work.
The army regulations in Cuba provide for the treatment

174 3I0SQUIT0ES

of breeding-places with kerosene, and the results are re-
ported to have been admirable. The city of Winchester,
Va., during- the summer of 1900, was treated with kerosene,
under an ordinance of the city council, with such i^ood
results that in the spring- of 1901 the city council passed
a further regulation providing a penalty for the non-treat-
ment of breeding-places. This instance is one of such
wide-spread interest that the ordinances of 1900 and 1901
are printed herewith, together with a letter received in
October, 1900, from the mayor of the city.

[First Circular, 1900.]
PREVENT THE MOfSQUITO.

The City Council has passed the following Ordinance :

1. Be it ordained that on or before March 25, 1900, and at least
once each month thereafter until November 1, 1900, each owner
or occupier of a house or lot in the city, shall put into every pool
or sink which is open, or from which there is any opening or out-
let, kerosene oil at the rate of one ounce for fifteen square feet of
surface of said pool or sink, and that quantity for any surface less
than fifteen square feet.

2. And be it further ordained that one-half an ounce of kero-
sene oil shall during the same time be put in every open barrel or
hogshead kept for the puri)Ose of collecting rain-water ; and
water shall be taken from such barrel or hogshead by a spigot of
wood or metal placed as near as convenient to the bottom of said
barrel or hogshead.

3. It shall be the duty of the police, by proper inspection, to
see to the enforcement of this ordinance, and to supply to persons
unable to procure them the necessary oil and spigots.

REMEDIES AGAINST MOSQUITOES 175

I am assured on the highest authority that if this phm is care-
fully and persistently carried out, it will after awhile result in
entirely preventing the mosquito, whereas here its existence has
not long been established and is wholly due to local causes.
But the failure of a few to apply the oil on their premises will
defeat all efforts to get rid of this dreadful pest. An ounce of
oil will about fill an ordinary teacup ; smaller quantities will
suffice for spaces less than fifteen feet square ; a taljlespoonful is
enough for an ordinary rain-barrel ; every little pool, however,
must have its portion of oil, and the oil must always be renewed
when washed away by rain, and this is especially necessary for
rain-barrels. In any event the oil must be renewed at least once
a month.

I invite the cordial co-operation of all good citizens,

R. T. Baktox, Mayor.

[Second Circular, 1000.]

FIGHT THE MOSQUITO.

The efforts made by our citizens since March 25th, in obedi-
ence to the ordinance of the Common Council, to prevent the
development of the mosquito during this season, seem to have
resulted in most encouraging success. It is yet too early to de-
termine to what extent we have destroyed this pest, but there
can be no doubt of its having been done to a very large extent.
Every experiment carefully watched has demonstrated the effi-
cacy of coal-oil applications and all that seems to be needed is
to continue diligently the use of oil, but unless we do, all that
we have done in the past will amount to nothing. It is not
necessary to repeat suggestions heretofore published, lest, how-
ever, some may have forgotten its terms, I append hereto a copy
of the ordinance :

********

R. T. B.VRTOX, Mayor.

176 3I0SQUIT0ES

[Thud rirenlar, 1900.]

CONTINUE TO FIGHT THE MOSQUITO.

Although it is greatly diminished in nuiiil)ers, even to the ex-
tent of being no longer a serious trouble, yet by its unmistakable
presence here and there the mosquito has made it evident that
all of them are not dead. The success of the plan has far exceed-
ed our expectations for the first season. All that is needed now
to eliminate them as a feature of this community is to keep up
the light diligently until November, when we will take a rest
until the next season. The chances are that what we will do
next year will be mainly as a wise precaution against the possi-
ble recurrence of the pest. That you may not forget the history
of this insect and why it is possible to destroy them by the use
of oil. I repeat a publication made once before.

R. T. Barton, 3Iayor.
July 17, 1900.

How the Mosquito is Bred.

Its germinal period is often about twenty-five days from the
laying of the mosquito-egg to the full maturity of the insect, of
which time only about three days are spent in the eggs. The
average germinal period is about three weeks. I say "about"
for the time is not always exactly the same, depending, as it
does, very much upon the condition of the weather and water.

The female lays about 300 eggs at a time in some pond, cistern,
tank, cesspool, rain-barrel, or any quiet pool of water. The
eggs are glued together in the shape of a pretty little boat and
left to float and hatch. They retain this " wiggler" condition
for from five to fifteen days, remaining all the time in the water
but changing their skins several times.

REMEDIES AGAINST MOSQUITOES 111

After from five to fifteen days the larvae become pupae or "tum-
blers," so called from their bobbing up and down or turning
over in the water. After five to fifteen days of pupa-hood the
skin opens at the back and the mosquito comes out. It dries its
wings and is then ready for business on dry land. The female is
the business member of the house, and it is she who sings and
sucks the whole night through.

The natural food of the mosquito is vegetation, and with this
the male contents himself. It is the female alone that develops
a carnivorous appetite. The life of the mosquito is short, but
from the later hatchings of the fall a great number live over
winter in garrets, cellars, etc., for the cold does not kill them.

In early spring the female begins to lay her eggs, and as she
lays about 300 in each bunch, the rate of increase is prodigious.
Hence the importance of anointing with oil all pools of water.
When the female comes to lay her eggs she will desist, and lay-
ing them on some twig or leaf, they will perish. If she alights on
the oil-anointed water she perishes and her eggs perish with her.
If the eggs have been laid before the oil is put in the water and
the insects are in either larva or pupa state when the oil is put
in, it will destroy them.

The most important time then to fight this insect is just at
this season before they have multiplied, as they will do in a few
weeks if left alone. Since, however, the mosquito goes on lay-
ing and hatching until al)out November, it is necessary to fight
it all the season through^ perhaps several seasons through.

178 MOSQUITOES

[Letter from tfie J/^///or.]

WiNXiiESTEi;, \\\., October 5, I'JOO.
Dr. L. O. Howard,

Entomoloyical Bureau Agricultural JDex^t,
WasliuKjton, I). C.

Dear Sir : I have for some time had it in mind to write you
an account of our Avar againnt the mosquitoes in this town ;
thinking that inasmuch as we made the fight along the line of
your published suggestions you would be interested in learning
the extent of our success.

Until about ten years ago a mosquito in Winchester was as rare
as a horse in Venice. About ten years ago, the increase in their
numbers began to be apparent, but it was not until five or six
years ago that they became a positive annoyance. Their advent
here was attributed to a line of parlor cars established as a night
train on the B. & O. R. R. , running from Camden Station, Balti-
more, in the summer-time. This may have added to the num-
ber, for recent investigation has shown that the returning empty
cattle cars, which stand for a time at the stock-yards in Balti-
more, bring great numbers of mosquitoes all along this mountain
country wherever the trains run.

My own opinion, however, is that we owe the great increase to
the scanty original stock here, which was enabled vastly to
multiply its numbers because of a new and much extended sys-
tem of water-Avorks, which led to the greatly increased use of
bath-tubs and water-closets ; and having no system of sewerage,
the excessive use and waste of water stands in numerous cess-
pools, which are the prolific 1 breeding- pi aces of the mosquito.
Then, too, there is a stream of water, arched over where the streets
cross, which, after heavy rains and when the regular stream has
subsided to its ordinary dimensions, consists of a large number

REMEDIES AGAINST MOSQUITOES 179

of still pools, which are fine for the egg-hatching and larva and
pupa raising by the mosquito. The arches over this stream 1
found last spring to have been the favorite hibernating places <»f
the insect, and before they had fully time to wake up and go to
business, I had millions of them destroyed by sprinkling with
coal tar.

Last summer my attention was called to your suggestions about
the use of oil, by my brother-in-law. Dr. 11. W. Baker, of your
city. At my request he called on you and jorocured some of the
literature issued by you on the subject. 1 determined that 1
would urge the people here to try the experiment. In October,
1899, the mayor having died, I was unexpectedly chosen in his
place, and I then thought of trying to make the matter one for
municipal and methodical action. I therefore induced the Com-
mon Council to pass an ordinance, a copy of which I enclose to
you.

My proposition was greeted Ijy the papers and by the com-
munity generally with much merriment, and I was the subject of
some very sharp ridicule from the press at home and abroad.

The ordinance, as you will see, was without penalty, and the
course designed to be pursued by me was intended to be per-
suasive and not coercive. Early in the spring (March) I dis-
covered the mosquitoes buzzing out from a pile of plank when the
snow was six inches deep, and the first reports of the police Avho
undertook to anoint the run and all public pools, was that mill-
ions of them were found adhering to the arches, and the oil-cans
when brought out from use under the arches and in the pools
were covered with the dead insects.

I issued to the people small leaflets, giving an account of the
habits and gestation period of the mosquito, and ui-ging the peo-
ple to obey the ordinance and join me in a relentless fight against
the insect. I also asked many pen-sons to make experiments and
report their success to me. 1 was soon overwhelmed with re-

180 MOSQUITOES

ports and all of them of the most favorable eharaeter. One
entirely reliable gentleman reported to me that within five
minotes after he had anointed a rain-barrel, seventy-five mos-
quitoes (presumably females) came to the barrel and seventy-
three of them perished, while the other three made haste to
escape. In one case, a lady reported to me that she took nearly
a pint of the dead insects from a hogshead the morning after
putting the oil in it. These and reports like them greatly
encouraged my efforts, and soon the oil was in almost universal
use and the town smelled like a Standard Oil tank. I continued
from time to time to issue the leaflets, and followed them up with a
police inspection. The result has been a wonderful success. The
plague, while by no means entirely abated, has been decreased to
a marked degree. In many parts of the town, the nets used so
constantly heretofore have been thrown aw^ay, and there are no
mosquitoes at all. In other parts, while their numbers are
lessened, they still continu-e to be a nuisance. This difference is
doubtless due to the neglect of some persons in the particular
neighborhood to use the oil ; and also, no doubt, to peculiar
facilities afforded for mosquito breeding in some parts of the
to^vn more than in others. I observed a decided increase in the
number in the latter part of August and in the month of Sep-
tember.

Just now we are greatly increasing our efforts toward their
destruction, so as, if possible, to destroy the crop that would
hibernate, and thus reduce the number of l)reeders to live over to
spring.

There can be no doubt about the success of the scheme. All
that is needed is persistent, unremitting application of the oil to
all pools, sinks, water-closets, old cisterns, etc. , etc. , and another
season we expect to have an ordinance with a penalty attached
and to enforce the oil anointing even more systematically than
has been done this vear.

REMEDIES AGAINST MOSQUITOES 181

To your suggestions we are indebted for what promises to be
complete relief from this pest, and for an exemption during the
past summer to an extent that has added very much to the pleas-
ure and to the profit of living in this town. I thank you very
much in my own name, and in that of all of our people, for the
good that your wise and practical investigations have done.
Yours very truly,

R. T. Bartox

[First ClrcuJar, 1901. ]
MOSQUITO CAMPAIGN OF 1901.

The admirable results obtained during the last year from fight-
ing the mosquitoes seem to assure us that one more campaign
will end them for Winchester, and restore conditions existing a
few years ago when this insect was unknown here. The present
ordinance is more stringent than that of last year and provides a
penalty for its disobedience. Still, it is only the very few who
are driven by the fear of the law. Its successful enforcement de-
pends after all upon a cheerful compliance by the good and law-
abiding citizens. I publish the ordinance now, for y(mr informa-
tion, calling especial attention to the fact that the use of the oil
must begin on March 15th ; much earlier than hist year, as wo
learned from observation that we did not begin early enough
then. The oil niust be renewed at least every three weeks, and
I suggest, so that it may not be overlooked, that the first and fi:
teenth days of each month be " oil days " in your calendar.

I hope that it will not be necessary either to appoint an in-
spector or to impose a penalty for disobedience of the ordi-
nance.

R. T. Barton, Mayor.

182 MOSQUITOES

An Ordinance to provide a method for the destruction and pre-
vention of the mosquito in the city of Winchester.
Be it ordained by the Common Council :

1. That on or before March 15, 1901, and at least every three
weeks thereafter, until November 15, 1901, there shall be depos-
ited in every open pool or sink, or all from which there is any open-
ing or outlet, and upon the surface of every barrel or hogshead
kept for collecting rain-water ; and upon every receptacle of any
sort in which water is allowed to stand for as much as twenty-
four hours on every lot in the city of Winchester ; and on every
open pool of any sort in every street or square and along the
bed or course of the town run, in said city of Winchester ; kero-
sene oil, at the rate of one ounce for each fifteen square feet, and
a proportionate quantity for any less surface.

2. It shall be the duty of every owner or occupier of any house
or lot in the city to make the deposits of oil as provided in this
ordinance; and in the case of barrels, hogsheads, or other recep-
tacle kept on the premises for the collection of rain-water, water
shall be drawn from said receptacle by a spigot of wood or metal
placed as near as convenient to the bottom of said receptacle.

3. It shall be the duty of the police, under the instructions of
the mayor, to see to the enforcement of this ordinance, and to
supply persons unable to secure them with the necessary oil and
spigots.

4. The mayor shall have authority, if in his judgment the oc-
casion requires it, to appoint an inspector of j^ools, sinks, etc.,
removable at the pleasure of the mayor, and whose duty it shall
be to report any failure to comply with the provisions of this
ordinance ; and who, under the instructions of the mayor, shall
have authority to enter any premises, and himself make the re-
quired deposit of oil. The pay of said inspector shall not exceed
$5 a week, to be paid by the treasurer out of the pubUc funds.

5. Every owner or occupier of a lot who shall fail to t'omply

REMEDIES AGAINST MOSQUITOES 183

with, or shall offend against the provisions of this ordinance,
shall for each offence or failure be liable, upon conviction there-
of, to pay a fine of one dollar, Avhich shall be recoverable as in-o-
vided by section 9 of the General Ordinances of the City of Win-
chester.

6. The sum of $25 is hereby appropriated for the enforcement
of this ordinance, in addition to the compensation of the in-
spector, in case one shall be appointed.

I venture to predict that these papers will eventually
possess an historical value, since without doubt other
communities will soon follow the example set by this en-
terprising Virginian town, and that mosquito warfare on
these or somewhat similar lines will before long become
a part of the duty of very many communities and of all of
their citizens. ^

Taking, therefore, the value of kerosene as proven, a
word must be said as to the best grade of kerosene, and
the best method of applying it.

In choosing the grade of the oil two factors are to be
considered. First, it should spread rapidl3^ Second, it
should not evaporate too rapidly. The heavier grades of
oil will not spread readily over the surface of the water,
Ijut will cling together in spots, and the coating will be
unnecessarily thick. Mr. AY. C. Kerr, who conducted the
extensive experiments on Staten Island, to which we have
several times referred, tried several kinds of oil, and
found to be best adapted a low grade of oil known afi " fuel
oil," supplied by the Standard Oil Company. Of the oils
which he tried, some contained too much residuum of a
thick nature which appeared as a precipitate, and could

184 MOSQUITOES

scarcely be pumped ; some were too thick in cliill}^ weather
and conkl not be pum^Ded at all, while some w^ere limp,
easily handled, made a good uniform coating on the
ponds, and were very effective. So long as the oil flows
readily and is cheap enough, the end is gained, provided
it is not too light and does not evaporate too rapidly.
Mr. Matheson, in his North Shore experiments, arrived at
the same conclusion, and the petroleum which he found
satisfactory for use on the mosquito-breeding ground was
that known by the Standard Oil Company as '' light fuel
oil."

In the accounts of the early experiments of the English
observers in West Africa, it was found, according to their
reports, that the petroleum Avhich they placed upon runs
was not persistent, and that it was necessary to renew the
application at much more frequent intervals than has been
found to be the case in this country. The explanation of
this is undoubtedly that some light illuminating oil was
used, which was more volatile than was at all necessary,
and which at the same time was unnecessarily expensive.
The army workers in Cuba have been advised by the
writer to use this fuel oil of the Standard Oil Company.

I am informed by the Standard Oil people that at the
time Mr. Kerr's work was being carried on the price of this
oil was $2.25 per barrel, but that in March, 1901, the price
had advanced and was $3 per barrel, including the barrel,
f. o. b.. Point Breeze, Philadelphia, or Bayonne, N. J., an
allowance for the barrel to be made upon its return, the
allowance, however, depending entirely upon the condi-
tion of the barrel when received by the Standard Oil

REMEDIES AGAINST 3I0SQUIT0ES 185

Company. It thus appears tliat this is not a hig-h -priced
oil, and veiy likely in case of large-scale community work
it could be boug'ht by the tank-car at a very reasonable
rate.

Kerosene may be applied simply by pouring- it upon
the surface of the water, when it will spread of itself, or
be si3read rapidly by light Avinds, or it may be spread
through a spraying" nozzle. A spraying method was used
successfully on Staten Island by Mr. Kerr and his asso-
ciates. The laborers em^Dloyed were furnished with
bucket-pumx3S and were able to throw the spray into
ponds for a considerable distance from the shore. The
use of a spraying nozzle, how^ever, does not seem to me
to be desirable. I watched the oiling of ponds by this
method at a New Jersey town, where the work was being
carried on under the auspices of a ladies' town-improve-
ment association, in the early summer of 1900. The water
treated was all in small woodland ponds and there was a
great waste of kerosene. The spray was diffuse, and be-
came scattered over the vegetation on the borders of the
ponds, a large share of it being wasted in this wa3\ On
small ponds the oil can be sprinkled to advantage out of
an ordinary watering-pot with a rose nozzle, or, for that
matter, pouring it out of a dipper or a cup will satisfac-
toril}^ treat a small pond of, say a hundred square feet of
water surface. With larger ponds, a pump with a straight
discharge nozzle may be used. The straight stream will
sink and then rise and spread, until the whole surface of
the pond can be covered without waste. The English
observers advise mopping the petroleum npon the surface

186 MOSQUITOES

of the water b}^ means of cloths tied to tlie end of a long'
stick and saturated with kerosene. The use of such a
mop may be desirable, even where a straight discharge
pump has been used, in order to commingle two surface-
sheets of oil.

The question as to the frequency of application of
kerosene is an imi^ortant one. In my earl}^ experiments
I found that the kerosene was effective for some days
after the odor had disappeared and after the iridescent
effect upon the surface of the water had ceased to be per-
ceptible to the ejQ. A single application to a small pool
was certainly effective from twelve to fifteen days. The
persistence of the oil, however, will undoubtedly vary
with the temperature and with the character of the pool
— whether exposed to the direct rays of the sun or shaded
by trees. It is, at all events, safe to say that it will be j)er-
fectly effective under nearly all circumstances, for at least
a week, and probably longer. That means that for a Aveek
no mosquito can alight upon the surface and succeed in
depositing eggs, and that even if she could do so the
larv?e hatching from such eggs would be killed. There-
fore we must calculate from the end of such an effective
period to the end of the growth of larval and pupal life,
and just before this second period is reached the applica-
tion should be renewed. Under the most favorable cir-
cumstances it will take from seven to ten days for a mos-
quito larva to reach full growth, and the pupa to become
ready to give out the adult. Therefore, to the kerosene
week must be added at least a week of larval and pupal
growth, which would require a second application of kero-

REMEDIES AGAINST MOSQUITOES 187

sene after from fifteen to twenty days, in order to render
it impossible tliat any adult mosquito can be developed.
This period is too short, rather than too long, but it is ab-
solutely safe, and in any given locality observations will
indicate to what extent it may safely be lengthened. I
am quite inclined to believe that, even in tropical regions,
seventeen-day intervals will be perfectly safe, if the fuel
oil referred to above is used. My own experiments were
carried on with illuminating oil, and the fuel oil is more
jDersistent.

The first army orders issued in Cuba (Circular No. 8,
Headquarters Department of Western Cuba, October 15,
1900) required the treatment of breeding-pools once a
month. The second order (General Orders No. 6, Head-
quarters DeiDartment of Cuba, December 21, 1900) re-
quired the application of kerosene twice a month. The
Winchester ordinance, it will be remembered, designates
as the times of a^Dplication once ever\^ three weeks, but
the mayor suggests that the first and fifteenth days of
each month be " oil days."

As interesting records, the army circular and order are
given :

[^Circular No. S.^

Headquarters Department of Western Cuba,
QuEMADOS, October 15, 1900.

The following communication from tlie Chief Surgeon is \n\h-
lished for the information and guidance of couuiiandiug officers
in this department. The necessary action will be taken as tliere-
in recommended.

188 MOSQUITOES

Chief Surgeon's Office,
Headquarters Department of Western Cuba,
QuE.MADos, Cuba, October 13, 1900.

To the Adjutant- General of the De2)artment.

Sir : I have the honor to invite your attention to the follow-
ing facts and their bearing on the health of the connnand :

The role of the mosquito in the transmission of certain diseases
is now Avell established. The evidence is now perfect and con-
clusive that malaria, as well as filarial infections, are carried by
this insect, and there are reasons to suspect that it may be con-
nected with the transmission of yellow fever, also.

Every consideration of jDrudence, as well as comfort, demands,
therefore, the protection from them of the commands at all posts.
It is believed that this can be done with a very slight expendi-
ture of time and trouble, by the enforcement by post commanders
of two precautions, namely :

1. The enforcement of the use of mosquito-bars in all barracks
and especially in all hospitals.

2. The destruction of the larvse of young mosquitoes, com-
monly known as " wiggletails " or "wigglers, " by the use of
petroleum on the water where they breed.

The mosquito does not fly far, and seeks shelter Avhen the wind
blows ; so it is usually the case that every community breeds its
own supply of mosquitoes, in water-barrels, fire-buckets, or un-
drained puddles, post-holes, etc. An application of one ounce of
kerosene to each fifteen square feet of water once a month will
destroy not only all the young, but the adults who come to lay
their eggs. The Avater in any cistern or tank is not afl'ected in
the least for drinking or washing purposes, if only it is drawn
from below and not dipped out. For pools or puddles of a some-
what permanent character, draining or fiUing-up is the best
remedy. It is recommended that the medical officer who makes

REMEDIES AGAINST 3I0SQUIT0ES 189

the sanitary inspections at each post be charged with tlie super-
vision of the details of these precautions.
Very respectfully,

Your obedient servant,

J. R. Kean,
Major and Surgeon, U.S.V., Chief Surgeon.
By Command of Brigadier- General Lee :
R. E. L. MiCHiE,

Assistant Adjutant- General.

General Orders, No. 6.

Headquarters Department of Cuba,
Havana, December 21, 1900.

The Chief Surgeon of the Department having reported that it
is now Avell established that malaria, yellow fever, and filarial
infection are transmitted by the bites of mosquitoes, the follow-
ing precautions will, upon his recommendation, be taken for the
protection of the troops against the bites of these insects :

1. The universal use of mosquito-bars in all barracks and espe-
cially in all hospitals, and also in field service when practicable.

2. The destruction of the larvae or young mosquitoes, com-
monly known as " wiggletails, " or "wigglers," by the use of
petroleum on the water wdiere they breed.

The mosquito does not fly far and seeks shelter when the wind
blows ; so it is usually the case that each community breeds its
own supply of mosquitoes in water-barrels, fire-buckets, post-
holes, old cans, cesspools, or undrained puddles.

An application of one ounce of kerosene to each fifteen square
feet of water, twice a month, will destroy not only all the young,
but the adult females who come to lay their (.')X,\^i^. The water in
cisterns or tanks is not affected for drinking or washing purposes

190 MOSQUITOES

by this application, if only it is drawn from below and not
dipped out.

For pools or puddles of a somewhat permanent character,
draining or filling-up is the best remedy.

The medical department will furnish oil for the purpose above
mentioned.

Post commanders will carefully carry out these precautions.
By conniiand of Major-General Wood :
H. L. Scott,

A dju taut- General.

Dr. Keed informs me that this order was drawn up by
Colonel J. E. Kean, United States Army, Acting- Chief
Surgeon of the Division of Cuba. Colonel Kean wrote,
under date of January 12th, that he made the interval
between the applications of kerosene twice a month in-
stead of once a month, as he had been unable to find in
Cuba an oil of sufficient diffusive quality over the surface
of the water, which at the same time would be less vola-
tile than the common illuminating kerosene. The lubri-
cating oils experimented with did not spread readily.

Mr. Kerr's Staten Island exi^erience w^as an extensive
one and led to interesting results. He writes me :

While I do not know how long the protection was afforded
by each treatment of the pond-surface, my judgment was that it
covered a period of at least several weeks. I think much depends
upon the surrounding natural conditions. An exposed pond
reasonably clear of weeds and grass and Avith a fairly clean shore-
line, liberally treated with a non-volatile fuel oil, is quickly
covered with an oily scum, which the first wind blows over to one
side. Then with a change of wind it is blown hither and thither,

HEME DIES AGAINST MOSQUITOES 191

so that the pond is thus automatieally treated over its whole sur-
face by the shifting of the wind, so long as there is a surplus of
oil present. If the pond is full of grass and weeds and the surface
once becomes covered, there is, of course, much less shifting, but
the accumulation of oil on the foliage keeps the surface well
covered, and I assume that this is largely due to the oil working
on and off the foliage more or less, due to tlie disturbance of the
wind. In a perfectly sheltered pond ; for instance, in a deep
hollow surrounded by large trees, quite protected from wind and
containing more or less of weeds and grass, I think the oily scum
stays fairly constant, and in thus referring to the surface-coating
I mean that which is plainly visible, and it is possible, even prob-
able, that there remains for much longer periods a minute film of
oil over the whole surface, which is not observable through such
means as I have used.

The twenty-five or more ponds which were treated under my
direction had the oil applied at somewhat irregular intervals,
averaging perhaps once a month, and at no time did I find any
mosquitoes during that whole sunnner in their vicinity. The
mechanical difficulties of oil application, however, led to resort-
ing to drainage, and therefore my experience with the oil meth-
ods ceased. These were hill-top ponds, chiefly in the Avoods,
while the large marsh areas Avere so meagrely treated on the
edges with oil as scarcely to be considered as treated at all, and
therefore with them no real experience was gained.

I have thought— but had no opportunity to try the experi-
ment—of anchoring one or more barrels filled with fuel oil in the
pond ; for convenience perhaps placing them there in the winter
when frozen over and boring small holes in the barrel while the
oil is thick with the chill of cold weather. Then with the sum-
mer's heat this oil will ooze out and maintain the supply in
places not accessible by other means. If on experiment the oil
oozed out too freely, various expedients could be tried— such as

192 MOSQUITOES

making larger holes and filling them with wicking or oakum,
through wliieh the oil would filter slowly. Any such method,
however, would probably meet some difficulties through the
abundant dirty residue which such oil always contains, but I am
very sure that such experiments would result in a method of
automatic distribution of the oil from such anchored barrels. If
the water is deep enough they could be sunk with stones, and
with holes on the upper and lower sides, the oil would press up-
ward by the difference in specific gravity and tlius give a con-
stant pressure on which to issue slowly.

Mr. Matheson's experience at Lloyd's Neck did not
fully coincide wdtli that of Mr. Kerr in regard to the
durability of the surface-film. He states that his experi-
ments with oil upon a five-acre pond indicated that the
fuel oil would maintain a film for about a week, while the
ordinary illuminating- oil, with which he first experi-
mented, would last only half that time, the light fuel oil
being very much heavier in gravity than the illuminating
oil. The periods for which the film persisted varied ac-
cording to the weather. With a high northw^esterly wind
the film w^as broken and the oil driven on the lee shore.
He believes that an application every twenty days would
be perfectly effective, but the cost of a more frequent ap-
plication was so slight that he did not care to take the
chances and treated the pond mentioned about every two
weeks.

Persons who are reading up on th mosquito question
will naturally consult the works of the English and Ital-
ian investigators, and it may be well to suggest that the
word *' kerosene " apparently does not occur in the Eng-

REMEDIES AGAINST MOSQUITOES 193

lish language as spoken by Englishmen, who invariably
term it paraffine or j)araffine oil. To the Italians we are
indebted for a useful expression, which we might just as
well adopt, namely to '' peirolke^' meaning to treat waters
with kerosene. Example : The petrolizatioii of mosquito-
breeding i^ools is one of the most important measures to
be undertaken in the warfare against mosquitoes.

Many of the small-scale experiments which have been
made, notably by the Italians, with a small number of
mosquito larvtB in small jars or puddles, are not so in-
dicative of the results to be ex^^ected as are more natural
and large-scale conditions. Mr. Matheson tells me that
he once took tw^euty-five larvne in a quart jar and cov-
ered it with a thin film of common kerosene oil and no-
ticed that in less than fifteen minutes all larvae were dead.
At the same time he put a film of oil on the surface of a
thirty-gallon tank, and at the end of an hour there w^ere
still some few larvae wriggling. He questions whether
kerosene is as swift a larvicide if put on the surface of
deep ponds, as it is on the surface of experimental jars.
In my owai w^ork I discovered that wdiere the oil was not
distributed equally the larvae clustered in the free places
and were able to support life for hours.

Otlici' Snhdtuiccs Agahist fhe Earhj Stages of
Mosquitoes.

The last paragraph indicates plainly the fact that
laboratory experiments with other substances must not
be accepted as conclusive until the substances used are

194 MOSQUITOES

treated upon a large scale and out of doors, but if a labo-
ratory experiment fails it may be taken for granted that
the outdoor trial will fail even more disastrously. It is
for the reason that the much-quoted experiments of Celli
and Casagrandi were apparently small-scale experiments
that we in the United States have been inclined to give
little weight to them. They experimented with a great
number of products and decided that petroleum, certain
aniline dyes, and vegetable powders made from pyre-
thrum or chrysanthemum plants (which form the so-
called Dalmatian and Persian insect powders) are the
only substances which are to be recommended. Of the
aniline dyes they recommend especially a substance
which they call in their published work " Larycith 3,"
and under this name the writer mentioned it in his Gov-
ernment bulletin. Every effort was made to ascertain
what this substance might be, and it eventually dawned
upon me that it might be a misprint for " Larvicide 3."
Under this apprehension, Mr. Matheson, who, by the
way, is a manufacturing chemist, succeeded in obtaining
samples of the substance and in analyzing it. He finds
that it is nothing but dinitrocresol, which is an insecti-
cide that was formerly highly recommended, but which
is now scarcely used at all on account of its very poison-
ous character. It was used, in a solution of one pound to
fifteen gallons of water, against caterpillars in Bavarian
forests, and has been used to some extent as a germi-
cide in washing down the walls of sick-rooms and also
in washing the outside of brewers' casks to prevent
mould and fungi. Its poisonous qualities would make

BE ME DIES AGAINST MOSQUITOES 195

it dangerous to use as an application to i^onds. The
P3^retlii'um jjowders are exi^ensive and not thoroughly
eifective.

The use of tar was suggested by Dr. Fielding -Ould, of
the English West African Commission, and creosote oil
has been suggested as a probable larvicide of value. Ex-
periments made by the writer in the summer of 1900 with
coal tar showed that this substance is slow in its action,
not perfectly effective, and not at all persistent. Experi-
ments with the two grades of creosote oils (by-products
in the manufacture of illuminating gas) indicated that
they destroy the larvae, but not nearly so rapidly as the
various grades of kerosene. It is possible that the creo-
sote oils ma}" prove to be more permanent than the
lighter illuminating oils, though the}'- are not as rapid in
their effect and not as satisfactory, on the whole, as the
grade known as fuel oil.

A great deal has been said about the value of perman-
ganate of iDotash as a larvicide for mosquitoes. In the
summer of 1898 a paragraph was copied in nearly all of
the newspapers of the country, which was attributed to
the Puhlic Health Journal, and which read as follows :

Two and one-half hours are required for a mosquito to develop
from its first stage, a speck resembling cholera bacteria, to its
active and venomous maturity. The insect in all its phases may-
be instantly killed by contact with minute quantities of perman-
ganate of potash. It is claimed that one part of this substance in
1,500 of solution distributed in mosquito marshes will render the
development of larvae impossiljle ; that a handful of permangan-
ate will oxidize a ten-acre swamp, kill its embryo insects, and keep

196 MOSQUITOES

it free from organic matter for tliirty days, at a cost of 25 cents ;
tliat with care a whole state may be kept free of insect pests at a
small cost. An efficacious method is to scatter a few crystals
widely apart. A single pinch of permanganate has killed all the
germs in a 1,000-gallon tank.

The item is so obviously ridiculous upon its face that
it would hardly seem worth while to make any attempt to
refute its statements. Nevertheless, it has been so widely
read that definite experimentation seems necessary to set
the matter at rest. The unknown author's ig-norance of
the life history of mosquitoes in the openin^^ sentence
need not necessarily imply that he would not know a good
remed}^ if he found one. Careful experiments were under-
taken by the writer in July, 1898, Avith various strengths
of permang-anate of potash, in water containing" mosquito
larvse from one to six days old. It was found that small
amounts of the chemical had no effect whatever upon the
larvae, which Avere, however, killed hy using amounts
so large that, instead of using a " handful to a ten-acre
swamp," at least a wagon-load would have to be used
to accomplish any result. Moreover, after the use of
tliis large amount and after the larvae were killed, the
same water, twenty-four hours later, sustained freshly
hatched mosquito larvae perfectly, so that even were a
person to go to the prohibitive expense of killing mos-
quito larvae in the swamp with permanganate of potash,
the same task would have to be done over again two days
later.

The same conclusion was subsequently reached, after
careful experiment, by Dr. Lederle, of the New York

RE3IEDIES AGAINST MOSQUITOES 197

Health Department, and by the Italians Celli and Casa-
grandi.

After all, we are xiractically reduced to the use of oils
in this larvicidal work. The question will naturally arise,
** Are there any other oils which can be used to better
advantage than the best petroleum oils ? " Mr. Matheson
suggested to me the use of corn-oil, a substance which is
rather extensively made in certain parts of the country and
which, considering the enormous crops of corn grown in
our Western States, which, in fact, are so great that some-
times in years of over-production the grain is burned as
fuel, might reasonably be supposed to be a cheap oil. At
present, however, that does not seem to be the case, and
its price in the ordinary market is prohibitive, as com-
pared with ordinary kerosene. Nevertheless, experiments
were undertaken with samples received from Mr. Mathe-
son. It was found that the corn-oil did not spread readily
and that it gathered together in large patches. Mosquito
larvge rising to the surface of the water, and finding them-
selves under a patch of oil, simply wriggled violently
until they found the s^iaces between the patches, where
they breathed comfortably and lived for several days. In
this experiment the main object was to secure a persist-
ent oil which Avould not evaporate, but would remain for
at least several weeks over the surface of the water. The
non-spreading qualities of corn-oil, however, as well as its
price, remove it from the list of good culicides.

Although a number of proprietary and secret mixtures
for mosquito-breeding pools have been sent to the writer
for experiment, none of them have been found more satis-

198 MOSQUITOES

factory than the cheapest petroleum, and none of them
are recommended. In a work of this kind we need not
only the best but also the cheapest substances. The large
scale on which this Avork is undertaken, and will be under-
taken in the future, demands a cheap substance, and on
the whole there can be no doubt that the kerosene known
as fuel oil will be found to be the most satisfactory. Of
course, the general interest in the subject will induce
future additional experimentation, and it is quite within
the iDOSsibilities that something better will be discov-
ered. Up to the present time, however, nothing definite
is known.

The AhoUiion of Breeding -Places hy Drainage or hy
Filling.

In the chapter on mosquitoes and malaria is given an
account of how, by an expenditure of forty dollars for
drainage in the summer of 1900 in a Maryland village,
malaria practically ceased to exist, although the previous
summer there had been one or more cases in every family
in the village. That meant that the breeding-places of
Anopheles were abolished. And it should be added that
the numbers of mosquitoes of the genus Culex were vastly
reduced by this operation. Those which remained prob-
ably bred in artificial water-receptacles, such as tanks,
tubs, or barrels, not a part of the former permanent supply
of the place. This is probably one of the most striking
instances of the value of drainage with which this section
could appropriately be introduced.

REMEDIES AGAINST MOSQUITOES 199

In the Slimmer of 1900, at a certain army post, about
one-half of the sokliers were ill with malaria. The hospital
was not screened, Anopheles were found upon the walls of
the malarial ward, bit the malarial patients in their beds,
flew out and bit the sentry on guard, and generally be-
haved themselves in a highly indecorous manner. The
early part of the summer was wet, then came a long dry
spell. After the drought had continued for some weeks I
visited the i^ost, and within a few hundred feet of the
door of the hospital found a slight depression in the
ground which had contained a surface-pool of water. The
water had entirely evaporated during the dry spell, but
the drying mud at the bottom was fairly carpeted with
the empty pupa skins of Anopheles. This was the onlj^
trace of the early stages of Anopheles found in the
vicinity. This small depression could have been filled up
with two cart-loads of earth, and had this been done at
the proper time it would not have been responsible for the
birth of a single Anopheles, whereas it had been respon-
sible certainly for several thousands. This is as good an
example as could be desired of the desirability and feasi-
bility, as well as economj^ in many cases, of filling up
breeding-places with earth.

There can be no doubt that there are many cases where
a little drainage-work such as was done in the Maryland
town, or a little filling-in such as was needed at the army
post, will accomplish striking results in the way of reduc-
ing the numbers of mosquitoes. There are also many
other places where drainage or filling-in upon a large
scale would be desirable and necessary. It is difficult in

200 MOSQUITOES

any case, and entirel}^ without reference to tlie question
of mosquito-suppl}^, to see why swamp-land should be
allowed to exist. There are many large tracts of swamp-
land which could be drained with a comparatively slight
expenditure of money, and which, when once reclaimed,
would be of ver}" great value for agricultural purposes.
There is a great deal of this land in the immediate vicin-
ity of many large communities which suffer from the at-
tacks of mosquitoes and which are more or less malarious.
In such instances, community drainage-work should be
undertaken for the health and comfort of the community.
Misguided owners of swamp -land, if they cannot be made
to see that such measures would bring dollars and cents
into their pockets, should be coerced.

In many cases such drainage or swamp-reclamation is
an expensive and a more or less complicated matter. The
swamps, for example, on the borders of the Great Lakes,
and of the smaller lakes which abound in central New
York, in Wisconsin, and at other points, cannot be thor-
oughly^ reclaimed without the expenditure of large
amounts of money. The same may be said for such great
brackish marshes as the Hackensack meadows in the
vicinity of New York Cit}^ and the great stretches of
high marsh- land, occasionally overflowed only b}^ the
highest tides, which exist at man^^ points along the At-
lantic coast. In such cases even large communities will
not be apt to undertake the responsibilitj^ of drainage
and diking measures on account of the expense. This
means that such measures should be adopted by States.
A good practical state drainage law is in these daj^s a

REMEDIES AGAINST MOSQUITOES 201

practical necessity, and the adojition of such laws by many
States should be actively urged and will be furthered in
the immediate future.

In the annual report of the State Geologist of New
Jersey for the year 1899 (Trenton, N. J., 1900), it is shown
that the general drainage laws of the State provide for
the improvement and reclamation of the wet lands of the
State, both tidal or salt meadows and wet fresh-water
lands. " On the application of at least five owners of
separate lots of land, included in any tract of land in the
State which is subject to overflow from freshets, or which
is usually in a low, marshy, bogoy, or wet condition,
the Board of Managers of the Geological Survey is au-
thorized to make survej^s of such tract or tracts and to
ado^Dt a system of drainage for the same." The plans and
surveys are submitted to the Supreme Court, and com-
missioners to do the work are appointed by the court.
Under the head of " The Eeclamation of the Hackensack
and Newark Meadows," in the same report, the improve-
ment of four thousand acres within the corporate limits
of Newark is proposed, that within the corporate limits of
Jersey City and Elizabeth having been handled by those
cities. The extension of the city of Newark over the
marshy tract to the deep water of Staten Island Sound
would be made possible by reclamation-work. The de-
preciation of value and real estate near the meadows, and
the increase which would follow the reclamation, are
strong arguments, aside from the sanitar\' benefits to be
gained. In the case of the Newark meadows, a report by
C. C. Yermeule showed that the cit}^, on advertising for

202 MOSQUITOES

plans and proposals, found that tlie marsh could be ren-
dered suitable for occupation at a contract cost not ex-
ceeding $300 per acre, an amount which, when compared
with the selling- price of city lots in Newark, is very small.
Drainage not for city purposes, however, Mr. Vermeule
shows, can be done for about $93 per acre. This would
put the land in condition for agriculture or grazing. He
shows that in Nova Scotia, drained marsh-lands sell for
$150 to $200 an acre for agricultural i^urposes only, and
that the diked meadows in Salem and Cumberland Coun-
ties in New Jersey have always been worth several times
as much as improved upland. "As much as fifty-five
bushels of wheat i^er acre, and heavy crops of haj^ are
raised on them. A moderate amount of drained tide-
marsh attached to a farm in that vicinity enhances the
value of the farm." He urges that a private corporation,
if it can secure a sufficiently large area to begin opera-
tions, and can drain it and put a small portion under cul-
tivation as a demonstration, could promptly lease the
rest for enough money to give a fair return on the invest-
ment, and the appreciation in the value of the land in
the course of a few years, since it is so near New York,
would undoubtedly make the venture profitable.

An editorial in the New Jersey Adrerfiser of February
9, 1901, advocates work under the Board of Trade against
mosquito-breeding places. The reasons are summed up
well in the following words :

'' There is a sanitary reason for their extirpation. They
injure property for sale, so there is a good economic rea-
son. They afflict the healthy, and torment the sick, and

REMEDIES AGAINST MOSQUITOES 203

the bad name tliey g-ive a locality keeps population away.
A crusade ag-ainst the mosquito plague should go hand in
hand with local enterprise. The abolition of the pest
would be the greatest victory achieved in the whole
career of the Newark community."

They show that Newark has a magnificent water-sup-
ply; possesses a large park area; is about to build a
city-hall, is to cleanse the Passaic Eiver of its filth, and
dredge it to make a larger channel. Finally it is urged
that the meadows be reclaimed, and that the marshes
along the bay be diked.

The Hoboken (N. J.) Observer, \\\\(\en: date of October 8,
1900, says that the draining of the meadows and other
low lands lying between Hoboken and Jersey City, and
between Jersey City and the Passaic Piiver, has become
an urgent matter and has long been agitated from a com-
mercial standpoint, but these fens and meadoAvs are
breeding-places for mosquitoes. Pieports of the bureaus
of vital statistics show that the majority of deaths are
caused by zymotic diseases.

The Roman correspondent of the London Standard of
January 14, 1901, states that the annual parliamentary
report on the measures for improving the sanitary con-
ditions and promoting the agricultural prospect of the
Roman Campagna shows that, while the rural popular
district is constantly increasing, fever becomes more and
more rare. The proportion of fever-stricken land has
been reduced fifty per cent, by these measures. The cul-
tivation of the region under the new conditions has in
many instances yielded splendid results, and a nundjer

204 MOSQUITOES

of private individuals are investing considerable capital
in carrying out further imiirovements.

The question of drainage-work was treated very inter-
estingly and convincingly by Mr. H. C. Weeks, of Bay-
side, Long Island, in the Scientific American Sa-pplement,
January 5, 1901. The following paragraphs are taken
from this imi3ortant article.

There are many causes which militate against reclaiming
marshes, which must be done before the largest factor in the
spread of mosquitoes is eliminated. Generally they are held in
small tracts by a number of owners, and the more the owners,
the greater the difficulty of action. This fact suggests the neces-
sity of every state having, as some places have, drainage laws
that would relieve such a situation. And that leads to the
statement of the necessity of some legislation preventing a small
interest in a tide-stream, owned by a few, and used but little,
overriding the general interest and preventing a drainage scheme
that w^ould improve the health and material interests of a large
territory, as well as relieve it of mosquitoes. In passing — how
often does it occur that a train-load of passengers is held up by
an open bridge over a little stream, and the cause of it all, a
sailor standing on his rights and unconcernedly waiting for the
tide or wind to bear his little craft through the draw. Such
things are contrary to the spirit of the age, and should be rem-
edied.

Another difficulty is found in the fact that owners, as a rule,
are not informed of the financial side of the case, and they are
unwilling, sometimes unable, to invest in a plan for reclamation
that will mean an outlay to them, when there is already an in-
come in the salt hay produced, though generally this is of no
net profit.

There is, too, a great lack of information on the general sub-

REMEDIES AGAINST MOSQUITOES 205

ject of the reclamation of marshes, and their producing- value is
little understood. All know, of course, in a general way, of the
notable instance in the case of Holland ; but that nearly a mill-
ion acres have been rescued from the sea under the greatest dif-
ficulties and expense in that land, and have been made to pay
on the investment, is not fully realized. And the same may be
said on this continent in the upper and middle Atlantic sea-
board, as well as on the Pacific side. Many marshes are of allu-
vial formation, and there are numerous instances of the contin-
uous production of enormous croj^s of almost every kind for
scores of years without the use of any fertilizers. Cases exist,
however, of persons being unwilling to be convinced, and contin-
uing their opposition even after a successful reclamation, as are
seen in the official records of Massachusetts^ where examinations
by the state have shown a great improvement in the sanitary
and agricultural conditions. In the instance of Green Harbor,
in that state, it is shown that the death-rate of the reclaimed
district averages lower than the general death-rate of the
state, that there is a steady increase in summer visitors, and
that many houses are being built. The testimony of persons
of wide knowledge and ample experience in the science and art
of agriculture is adduced, showing the good results in that field,
and yet it fails to silence opposers. Besides mentioning tlie re-
markably heavy crops of hay, much preferred by his horses to
the best from the uplands, also the excellent crops of strawber-
ries and vegetables raised in these lands, one such qualified ob-
server gives his experience as to asparagus in such convincing
words that they are quoted in full : "■ While visiting the Marsh-
field Meadows on April 19, 1807, I found asparagus already up,
very nearly high enough to cut. I was surprised at this, for my
own asparagus had but just appeared above the surface of the
ground, although growing on land so warm that I am usually
first to ship native asparagus to Boston market. I was also sur-

206 MOSQUITOES

prised at the size of the stalks, tliey being much larger than the
first set of stalks that appear on my land. When I consider the
fact that the land on which this asparagus was growing has pro-
duced large crops every year for tw^enty years, without fertilizers
of any kind, and still produces better crops than my land, which
has had $000 worth of fertilizers to the acre applied to it during
the last twenty years, it convinces me that this land, for garden
purposes, surpasses any which I have ever examined. . . .
We realize, in a measure, the great value of the material which
nature has for ages been storing up for man's future use, if he
be wise enough to avail himself of it."

It has been too frequently thought that to throw up an em-
bankment to keep out the waters, and to build sluices and gates
to let the interior water out, were all that was requisite ; and,
under this mistaken view, many instances have occurred greatly
to the loss of the persons interested, and to the prejudice of the
whole subject. An eminent engineer has said of reclamation ;
" What at first sight seems a mere mud and water proposition
really requires, for its proper economic development, the best iDrod-
uct of the latest practice in several fields of engineering and other
sciences. Although the method of reclamation is centuries old,
it may now be worked out by the aid of much that is novel in
methods of construction and operation. ' '

Successful reclamation requires a most careful consideration of
all the conditions existing, w^hicli generally vary in some feat-
ures at every point, and not the least of the difficulties to be met,
and one which to-day accounts for many expensive failures, is
the ravages of the musk-rat, and yet even he can be circumvented
with proper care. Unsuccessful reclamations can all be accounted
for by the neglect of some important point. A partially drained
marsh is, no doubt, in a w^orse sanitary condition — more pesti-
ferous and pestilential — than if not drained at all, and for most
crops it is likewise a failure. Besides, the soils in all marshes are

BE3IEDIES AGAINST MOSQUITOES 207

not suited to the raising of crops, and one reclaiming- failure,
even on that account, seems to offset many successful ones. Care
must be had in allowing for the subsidence of the marsh, which
occurs in more or less degree, depending upon the character of
the soil. Usually, where the marsh-lev^el is sufficiently above
mean low tide, reclamation can be effected without the use of ar-
tificial means to care for the inner water.

The cost of maintaining effective reclamation is slight if tlior-
oughly done in the first instance, but otherwise, becomes expen-
sive and discouraging, and there are many fields once successfully
reclaimed but now overflowed, resulting from the attempt at sav-
ing a few dollars jper acre in the original work.

While it may be argued as against reclamation that there is
plenty of cheap land without spending good money to obtain
more acreage, yet this is not the way to dispose of the fact that
these marshes are the prolific breeding-ground of mosquitoes,
and that mosquitoes — how many kinds is not ascertained — bear
the germs of a disease that, in its great pre valency, does more to
reduce the vigor, which is largely the capital, of a nation, than
any other disease.

Mr. Weeks's mention in this article of the crops that
can be grown upon reclaimed swamp-lands reminds me
that Professor Milton AVhitney, Chief of the Division of
Soils of the United States Department of Ag-riculture, has
told me that the value of drained salt marsh-lands is very
great for meadow purposes, and that when well drained,
so as to prevent any danger of seepage waters coming
near the surface, they are valuable for truck crops, if
situated within easy reach of markets.

In the work wdiich w^as done by the Richmond County
Club of Pongan Hills, Staten Island, under the leader-

208 MOSQUITOES

ship of Mr. W. C. Kerr, of the firm of Westinghouse,
Church, Kerr & Co., New York, to which we have several
times referred, considerable drainage of fresh-water
swami^s above the seacoast bluffs was carried on with
g-reat success and at a minimum of expense. This work,
together with the use of kerosene upon larger pools, re-
sulted in complete relief from the attacks of the fresh-
water moscpiitoes, Avhich during the early summer had
always been numerous and ferocious, but down the bluffs
below the Club there was a large area of salt-marsh, and
in the higher portions of this marsh-land the brackish
water-mosquito of the Atlantic coast {Cuk-x sollicitans)
breeds abundantly and puts in its appearance up to the
end of July in numbers. An attempt by members of the
club was made to buy this land in order to dike and drain
it, with the idea that it could subsequently be let to truck
growers, access to New York markets being easy and
profits for truck farming- in that vicinity being great. In
the attempt, however, they found a singular obstinacy on
the part of the owners of this Avorthless land, and the
attempt was, at least temporarily, abandoned.

A successful effort of this kind, however, has been re-
corded by the writer in a previous publication. It comes
from one of the editors of the Scientific American, who
writes as follows :

In the town of Stratford, Conn., where I have resided for the
past forty-five years, we have been greatly plagued by swarms of
mosquitoes, so great, in fact, that the " Stratford mosquito" be-
came a well-known characteristic of Stratford. We have in the
southern part of our town, bordering on the sound, several acres

REMEDIES AGAINST MOSQUITOES 209

of marsh-land or meadow, which would become periodically
overflowed with water in the summer and a tremendous breeding-
ground for mosquitoes, and this plague to the town continued
until about 1890-91, when a party from Bridgeport, Conn., pur-
chased a large section of the meadows and began to protect them
by a dike, both on the north and south ends, which shut out the
water. In addition to this, numerous drain ditches were made
which helped to carry the water away. The result of this work
made the land perfectly dry and spongy, so that after a rain no
pools collected on the surface of the meadow and the creation of
the mosquitoes was prevented. The transformation was so re-
markable that people outside the town would hardly believe that
it had been effected, and a year or two later tlie town voted a
special appropriation of $2,000 to the party who undertook to
build the dike and render the meadows mosquito-proof. It had
also the effect of placing on the market a large tract of land ele-
vated from the sound, for residences, and as many as twenty- five
sunnner residences have been built upon this land bordering on
the sound, and the number is increasing each year. They are free
from mosquitoes, so that the operation shows the economy and
the benefit that will result by using some means for eliminating
the mosquito-breeding pools.

As has been pointed out on earlier pages, nearly all of
our mosquitoes breed exclusively in fresh water, and none
of the forms which inhabit the United States, so far as
ascertained, will breed in sea-water. Therefore, under
certain peculiar conditions, another remedy is indicated
by this fact, namely, that near the seashore, by a certain
amount of ditching, the water of ponds may be converted
from fresh to salt. A rather large-scale operation of this
kind was conducted a few years ago at Virginia Beach,

210 MOSQUITOES

the well known seacoast resort directlj^ east of Norfolk,
Ya. Behind the hotels at this place, in former days — the
hotels themselves fronted npon the beach — was a large
fresh water lake, which, with its adjoining swamp, was a
source of mosquito-supx^ly, and it was further feared
(although this was before the mosquito-dissemination of
malaria was proven) that it made the neighborhood mal-
arious. Canals were cut, and the water of the lake was
changed from a body of fresh to a body of salt water.
The lake is now supplied with salt water at daily high
tides by an underground feeder. Crabs and small tish
occur in the lake in numbers, and no mosquito larvse
are to be found even in August, even in the swampy
places at the lake border. The water itself is very salt to
the taste, and samples which have been tested at my re-
quest by Mr. E. E. Ewell, a chemist, showed that the
total chlorine contained in the samples, calculated as so-
dium chloride, is equivalent to 22.88 grams of that salt per
liter, or 1,336 grains per United States gallon, or 3.05
ounces (avoirdupois) per United States gallon. The chlor-
ine contained in sea-water is equivalent to 31.15 grams of
sodium chloride per liter. The sam^^les from Virginia
Beach, therefore, contained approximately two-thirds of
the quantity of salt usually i:)resent in the sea-water.

Even where states or communities cannot be induced to
take up the question of marsh drainage and diking, it is
possible for public-spirited individuals of means to do
work in this direction which Avill count. For example, it
is planned by a company of wealthy men who have sum-
mer homes on the north shore of Long Island, in the

REMEDIES AGAINST MOSQUITOES 211

vicinity of Oyster Bay, Cold Spring Harbor, Lloyd's Neck,
and Center Island, to spend several thousand dollars in
this kind of work during' the summer of 1901, with the
sole view of reducing the summer mosquitoes of that
region. This is mentioned as an indication of what might
be done at other points.

Introdadlon of Fish into FishliKj Ponds.

It happens quite often that larger or smaller ponds will
be found which for some reason or other are considered
too valuable to drain, and which the owners will not per-
mit to be treated with kerosene, and yet in which mos-
quitoes breed abundantly. Such ponds will, as a rule, be
found to be milldams, ice-i^onds, or pools artificially con-
structed with rock and cement bottoms for the purpose
of watering stock. Into such ponds it becomes absolutely
necessary to introduce fish that will destroy mosquito
larvae, which will otherwise invariably be found to exist in
them in great numbers.

The subject of the appropriate fish to use for this pur-
pose has been considered in Chapter YII., and to that
chapter the reader is referred.

Remedies Against Adult Mosquitoes.

In regions where mosquitoes abound, all houses must,
as a matter of course, be thoroughly screened, if a meas-
urable degree of comfort is to be gained. The extreme
importance of the careful screening of Avindows and doors

212 3I0SQUITOES

in malarious neig-liborlioods cannot be too strongly in-
sisted upon, wherever there is any reason to suppose that
any work which may have been carried on against breed-
ing-places may not have been so thorough as to be effect-
ive. If mosquitoes of the malarial genus Anopheles
once gain access to a house they will remain hidden
behind curtains or somewhere upon the walls during
the day and at night fly out about the rooms in their
search for iDcrsons to bite. Some observers of tropical
countries say that in unprotected houses, Anopheles
will frequently fly out and hide outside during the day,
returning to the houses at night, but by far the more
usual method seems to be to stay indoors. In addition
to this screening, it is recommended that in tropical
countries all the indoor walls of houses should be
painted white or whitewashed, in order that the dark
bodies of the mosquitoes may plainly" be seen and that
they may easily be caught. However, when the walls are
not white and when the insects are hidden behind hang-
ings or behind old-fashioned beds or elsewhere, they
may be driven oiit of their hiding-places with smoke and
will then settle on the window-panes in the hoi^e of es-
caping.

To kill living Iiiosquitoes in houses, Fermi and Lum-
bao recommend chlorine gas. Pour into a dinner plate
containing four or five spoonfuls of chloride of lime five
to ten cubic centimetres of crude sulphuric acid. This
liberates the chlorine gas, which kills the mosquitoes.
The same w^'iters state that the vapors of chloral act rap-
idly, killing them in a few seconds, though these vapors

REMEDIES AGAINST MOSQUITOES 213

can be used only in rooms which are not inhabited, or in
which the vapors can be permitted to remain for several
hours.

The burning- of pyrethrum powder in such a room,
when done in a proper way, will also kill the mosqui-
toes or, at least, stupefy them. The pyrethrum i^owder
should be moistened somewhat and moulded into little
cones, which are then dried in the oven. When one of
these cones is ignited at its summit b}^ a match it will
smoulder slowly, filling- the room with smoke, which to
most people is not unpleasant, and which smells much
like the sticks of punk w^hicli boys use to light lire-
crackers. This smoke seems to stifle the mosquitoes,
which fall to the floor. Two or three of these cones
burned in a room in an evening- will give relief by stupe-
fying the insects, but on a warm summer night they will
not take the place of screens, since the windows must be
closed in case of any movement of the air, otherwise the
smoke is not efl'ective.

The use of tin cups or inverted can-covers, the shal-
lower the better, nailed to the end of a stick and contain-
ing- a very small quantity of kerosene, is very prevalent in
some iiarts of the country for catching- mosquitoes resting-
on the ceiling. AYliere the ceiling- is white, the mosqui-
toes can readily be observed and the tin cup is pushed uji
under them. When they attempt to fly they are caught
by the kerosene and killed. I have seen dozens of them
caught in this Avay of an evening in a mosquito-infested
house. The first time I ever saw the apjiaratus was al)out
1890, in a New Jersey town. When al)out to retire to my

214 3I0S QUI TOES

bedroom at night one of these stick-cups was given to me
with a description of how it was to be used. I was too
sleepy to experiment, however, and went to bed. On
wakening the next morning I thought of the experiment
and tested it with great success. Eighteen mosquitoes
were caught on the ceiling of the bedroom, but as every
one of them was full of blood, I regretted that the use of
the instrument had come as an after-thought.

Celli and Casagrandi state that the substance Avhich
they call Larycith III, which (if I am correct in suppos-
ing it to be a misprint for " larvicide ") is dinitrocresol
— a yellow aniline color— will when burned in small quan-
tities, kill the adult mosquitoes, and that this method con-
stitvites the most efficacious method of destroying them.
The Chinese use pine or juniper sawdust, mixed with a
small quantity of brimstone and an ounce of arsenic, run
into slender bags in a dr}^ state. Each bag is coiled like
a snake and tied with thread. The outer end is lighted.
Two coils are said to be sufficient for an ordinary room,
and 100 coils sell for six cents.

There have been many substances recommended for
use ujion the skin in order to discourage mosquitoes.
Camphor, rubbed upon the face and hands, or a few drops
upon the pillow at night, will keep away mosquitoes for
a time, and this is also a well-known property of oil of
pennyroyal. The use of oil of peppermint, lemon juice,
and vinegar have all been recommended for use as pro-
tectors against mosquitoes, while oil of tar is also used
in bad mosquito localities. Dr. John B. Smith writes
that in the matter of preventives, in his experience noth-

REMEDIES AGAINST MOSQUITOES 215

ing is equal to oil of citronella. He has used this on the
seashore with great success for three summers, and has
recommended it to guimers and others, who have re-
ported good results. Mr. E. H. Gane, of the firm of Mc-
Kesson & Bobbins, of New York, informs me that the
essential oils which he has found most effective in keep-
ing away mosquitoes have been the oils of lavender, cit-
ronella, and eucalyptus, in the order named. The sub-
stance, however, which he has found to work with most
perfect success is castor oil. He wrote under date of Oc-
tober 3, 1900, " Of course the application of this oil in its
natural state is almost as objectionable as the bite of the
insect, but by dissolving it in alcohol and adding some
kind of essential oil or perfume, a preparation can be
made which is not objectionable to most people and is
very effective as a iDreventive of mosquito bites. The
formula which I have been using with great satisfaction
is : Castor oil, 1 ounce ; alcohol, 1 ounce ; oil of lavender,
1 drachm. The solution should not contain less than fifty
per cent, of the oil, to be satisfactory in all cases.

Eucalyptus.

In addition to the use of eucalyptus oil to keep mos-
quitoes from biting, as mentioned in the previous para-
graphs, the growth of eucalyptus trees is said by certain
persons to drive mosquitoes away, and trees of the genus
Eucaly|)tus have been especially recommended for ]dant-
ing in malarial regions. In 1893, Mr. Alvah A. Eaton, of
California, wrote that in portions of California where the

216 MOSQUITOES

blue gum occurs no other remedy need be sought for.
Further than that, he stated that no matter how plentiful
the mosquitoes are, a few twigs or leaves laid on the pil-
low at night will secure perfect immunity. The same year,
Mr. W. A. Sanders, of California, wrote that he had planted
eucalyptus trees nineteen years previously about his
house and that they had reached, some of them, a height
of 140 feet. An irrigating ditch ran through the grove,
but there was never a single mosquito larva in the ditch
in the grove, although on both sides of the grove larv?e
were plentiful. In the grove, mosquitoes were never
found, though outside they were plentiful. This seems
very strong evidence, but there is also evidence to show
that eucalyptus trees are not at all effective. Dr. Alfredo
Duges, the well known naturalist of Guanajuato, Mexico,
wrote me on September 8, 1900 : " I have received your
very interesting study of the mosquitoes of the United
States, and thank you greatlj^ for it. At the end of the
book you speak of the utility of eucalyptus for driving
away insects. I have had some experience with these
trees. The fresh leaves placed upon the pillow will
attract mosquitoes. Thinking that the mosquitoes loved
this plant, I have placed the branches farther away, but
without result. I have burned the leaves in my chamber,
and the cursed beasts have resisted the smoke." Dr.
Nuttall states that malaria still prevails in certain local-
ities outside of Rome, in spite of eucalyptus plantings.

REMEDIES AGAINST MOSQUITOES 217

The Castor-oil Plant.

A great deal was said in the newspapers during the
winter of 1900-01 about the planting of the castor-oil
plant to prevent mosquitoes. These notes were all based
upon a consular report from Captain E. H. Plumacher,
United States Consul at Maracaibo, Venezuela. The dis-
patch, which was taken from Consular Keport No. 246,
March, 1901, reads as follows :

A simple remedy against mosquitoes has been employed in sev-
eral places in South Africa, and is equally well-adapted to the
temperate zone. It consists in planting the castor-oil plant {Rici-
nus communis), or *'Palma Christi," around the house and
premises.

In cold and temperate climates the castor-oil plant grows to a
height of four or five feet ; in these countries, it becomes a tall
tree and is perennial. It seems that the smell of the plant is dis-
agreeable to mosquitoes and other insects, and it is an acknowl-
edged fact that where these plants grow, few mosquitoes will be
found.

My personal experience bears this out. My residence is sur-
rounded by plantain and banana trees, and I have been much
troubled in the past by the great number of mosquitoes which
gathered between the leaves. Following the example of old
settlers in the country, I planted the castor-seeds, which grew
up in profusion, and there are now no mosquitoes to be
found among the plaintain and banana trees, although I keep
the ground well irrigated. By keeping the branches and the
seeds of the plant in rooms, the mosquitoes are driven awjjy from
the latter.

There are several varieties of the castor-oil plant. In this coun-

218 MOSQUITOES

try there are two — one with brown nuts, and the other white in
color, with a kernel tasting like the fresh almond,

E. H. Plumacher, Consul.

Maracaibo, November 30, 1900.

(Copied from Consular Reports, No. 24G, March, 1901.)

Persons familiar with this phant, and wdio have had it
g-rowino' in their gardens, tell me that altliough they have
heard the idea advanced before, they are convinced that
tliere is nothing in it, and that the growth of this plant
does not drive a^vay mosquitoes.

Remedies for the Bites.

As elsewhere pointed out, different persons differ
greatly in the effects which the mosquito -poison produces.
Some persons are scarcely troubled by the puncture,
while others are quite severely poisoned. It has been my
own experience that if I can only refrain from scratching
after having been bitten, no swelling results, and the irri-
tation soon disappears. Even a small degree of scratch-
ing, how^ever, such as the rubbing of one's cuff, or coat-
sleeve, or collar, increases the irritation and produces
a swelling, and sometimes white spots. Household am-
monia has been found by manj^ persons to give relief, and
others say that a single touch of alcohol stops the irrita-
tion. Dr. E. O. Peck, of Morristow-n, N. J., has ^vritten
me that he has found glycerine a sovereign cure for the
bites. Touch the bite wdth glycerine and in a few minutes
the pain is gone. He says also that glycerine takes the
pain from bee-stings. Dr. Charles A. Nash, of New York

REMEDIES AGAINST MOSQUITOES 219

City, has written me tliat whenever a mosquito bites him
he rubs the spot and marks it with a lump of indigo.
This, he says, instantly stops the irritation, no matter
whether the application is made instantly, or after the
lapse of a day or so. He stated that he has used it since
1878, and has a g-ood opportunity to test it, for he lives in
a locality where mosquitoes are abundant.

IX

H()}r to Collect and Preserve Mosquitoes

Including- an Account of How to Raise Mosquitoes and
Study the Earl}^ Stages.

ADULT mosquitoes are very fragile creatures. Tlie
scales upon tlieir bodies and legs are easily rubbed
off, and the antennae, and especially the legs, break
with the least handling-. Even in their ordinary course of
life the scales rub off, and with certain species an adult
which is two or three weeks old is quite different in ap-
pearance from one which has just emerged from the pupa.
Practically, they can not be handled Avith the fingers, or
their value as cabinet specimens or as specimens for study
is lost. With some forms there are important charac-
ters in the arrangement of the scales on the thorax. AVith
others the scales on the Aving are of importance and if
the front legs are accidentall}^ broken oft', an important
character to which I have referred in the systematic por-
tion of this book as existing in the claws of the fore feet,
is naturally unavailable. In capturing them, therefore,
they must not be handled, and I have found the most sat-
isfactory method of capture to consist in simply placing
a small, open-mouthed vial over the mosquito while at

220

BOJV TO COLLECT MOSQUITOES 221

rest. On the wing it cannot be caught, even with a deli-
cate net, without rubbing or leg-breaking. If a mosquito
lights upon your hand, or upon a twig or a leaf, or upon
a wall of a room, it is quite easy, especially if it be en-
gaged in sucking blood, to cover it adroitly with the vial.
It rises almost instantly, and the mouth of the vial is
plugged with a plug of absorbent cotton. A drop of
chloroform on the cotton will stupefy the specimen almost
immediately and another drop will kill it.

The specimen may be kept permanently in the vial and
when studied, if the study goes no farther than an exami-
nation of the coarser characters in an attempt to determine
the species, it will often suffice gently to slide it out
upon a sheet of white paper and examine it with a power-
ful hand lens. With the one-quarter inch achromatic
triplet lens made by different firms I have found it pos-
sible to distinguish all of the generic and specific char-
acters, even down to the teeth of the tarsal claws. This,
however, is difficult to persons who are not accustomed
to the use of high-power hand lenses, and in such in-
stances one must break off a tarsus and mount it upon a
slide in glycerine or Canada balsam for examination
under a compound microscope.

It is not advisable to mount adult mosquitoes bodily on.
slides in any medium whatever. They should not be pre-
served in alcohol or formalin, but should be kept dry in
vials. Of course they will rattle around somewhat and
there is danger that the legs and the antenna) will be lost ;
therefore, if they are moved from the vial after the col-
lecting and killing, into pill boxes with cotton, they can

222 31 OS QUI TOES

be carried safely or can be sent in the mails. Several of
the pill boxes may be i^laced inside a tight tin or wooden
box and mailed with j)erfect security.

A collection of mosquitoes should, however, not be kept
in this way, provided it is intended as a study collection.
The method which I have adoj^ted and which is the
one customarily used for small insects that are not too
small for hand-lens work, is the triangular-tag- method.
Take a sheet of stiff paper or very thin cardboard and cut
a strip, say, five-sixteenths or three-eighths of an inch
wide. Then from this strij), by slightly oblique cuts,
cut a series of triangles that will be i^ointed at the tip
and a little less than an eighth of an inch wide at the
base. Through the base of the tag maj^ be run an insect
X:>in and to the tip the mosquito should be glued, white or
yellow shellac being the best medium for the gluing. The
mosquito should be glued on its side, just behind one
wing, so that its back is away from the pin. This enables
one readily, by holding the point of the pin in his hand,
to examine with a lens all legs, antenntx^, palpi, one side,
and the back. The tag should be pushed up on the pin
until it is from two-thirds to three-quarters of the length
of the pin away from the point. To the lower part of the
pin should be attached a small label, giving date, exact
locality, and name of the collector, and below this may be
pinned another small label, bearing the name of the
insect.

Those who for some reason do not like the paper tri-
angle method of mounting use very minute pins made by
Miiller in Vienna and known as "minuten insekten na-

IIOJV TO COLLECT MOSQUITOES 223

deln," which are sokl by Queen tt Co., Philadelphia,
and other large dealers in such thing-s. These \)m^ are
so small and delicate that they may be thrust through
the thorax of the mosquito and into a little strip of cork,
the cork strip itself being pinned upon one of the larger
and longer insect i^ins.

Some collectors, instead of using the chloroform meth-
od of killing, prefer the cyanide bottle. The cyanide
bottle is made by taking a wide-mouthed Hask, putting
a small lumi? of cyanide of potassium at the bottom and
covering it with a layer of liquid i^laster of Paris, which,
when allowed to set, makes a complete layer over and
around the cyanide and prevents the water that comes
from the deliquescence of the cyanide from injuring
specimens that are placed in the vial, but which at the
same time is sufficiently^ porous to permit the escape of
the deadly cyanide fumes. Even with the layer of plas-
ter of Paris, however, the cyanide bottle wdll sometimes
become wet, so that a bit of blotting-paper may with
advantage be inserted to cover the plaster of Paris, and
to absorb the superfluous moisture. A mosquito capt-
ured in one of these cyanide flasks or vials dies very
quickly and is in good condition for dry mounting or for
transfer to pill boxes. The c^^anide bottle is preferably
stoppered with a cork stopper, but rubber stoppers are
also used.

In collecting early stages of mosquitoes it is only nec-
essary to have a supply of bottles, a little coftee-strainer
with a handle, and a large reading-glass. Other appar-
atus is cumbersome and unnecessary. I have a large

224 3I0SQU1T0ES

reading-glass four inches in diameter, witli a strong han-
dle, which I find very useful in examining the surface of
water-pools, especially for Anopheles larvae. The dip-
strainer used is an ordinary cheai? coffee-strainer which
has been mounted upon a long handle, so that one can
reach out two or three feet from the shore and cai:)ture
larvae and pup*. Other larger strainers with a fine mesh
are sold at the hardware stores and may be purchased
clieapl}^ In bringing larvae and pupte in from the field,
too much jarring about in a bottle may result in their
death by drow^ning. It is desirable, therefore, to put
moss or water-weed in the bottle with a minimum of
water, provided the insects are transferred to an aquarium
or a still jar wdthin a few hours.

Nuttall, Cobbett, and Strangeways-Pigg, who have done
a great deal of collecting of mosquito larvae in England,
as shown in one of their important papers, entitled
'' Studies in Relation to Malaria," published in the Jour-
nal of Hygiene, vol. i., No. 1, January, 1901, used as their
collecting apparatus some wide-mouthed bottles of me-
dium size with cork stoppers ; a white enamelled dipper
which, when required, can be tied with a jDiece of twine
to a long bamboo rod ; a small pipette with a rubber bulb
and small vials containing dilute alcohol for the preser-
vation of larvae which they did not Avisli to keep alive.
They travelled over England on their collecting trips on
bicycles. When the larvae or eggs a\ ^re captured in the
l^orcelain dippers they Avere removed with a iDipette and
put in bottles, wdiich were half filled with water, wrapped
in cloths, and attached to the bicycle frame. They found

HOJy TO COLLECT MOSQUITOES 225

that they coukl be transported for several hours without
injury. They noted also that the large larvae did not
withstand the shaking as well as the small ones, but that
a sufficient number could always be brought back for
studying iDurposes. On expeditions lasting a couple of
days they took precaution to remove the corks occasion-
ally to give the insects fresh air. White dippers were
used, since they could more easily detect the eggs or
larvae on the white background, and they found that only
rarely could they detect the insects by direct inspection
of the surface of the water.

Larvae and pupae, when it is desirable to preserve tliem
in these stages, and it is always desirable to keep a small
set of each species, may be kept in vials of alcohol or di-
lute formalin (5 to 10 per cent.). Wlien preserved in alco-
hol they should be passed through different strengths,
beginning with a weak mixture, in order that they may
not shrivel ; or, what is still better, kill the larvie or pup.^
suddenly in a cyanide bottle, then bring the water nearly
to the boiling looint in a little porcelain dish over an alco-
hol lamp and drop the insects in, leave them until tbe
boiling point is just reached and then remove them. An
immersion of only a few moments will suffice. Ordina-
rily the larvc^e will sink at once to the bottom of the water
and very soon thereafter rise to the top. This rising is
an indication that the specimen should be removed at
once. The specimen may then be preserved in ordinary
commercial alcohol and will retain perfectly its cokjr and
shape. This method is used successfully with the larvae
of many insects. It is not necessary to mount either

226 MOSQUITOES

larvse or iDupse whole on slides. One of these preserved
specimens can be put in a cell with alcohol or g-lj^cerine
and studied under a low liower with iDcrfect ease, and the
examination of minute details of its anatomy, external
and internal, may readily be accomplished by dissection,
and the parts dissected out mounted permanently on
slides in any of the ordinary media.

In rearing different species of mosquitoes I have had
perfect success in the use of large, cylindrical glass jars
known as battery jars. Thej^ can be bought in almost
any city and of various sizes. The size which I find most
convenient will hold about a gallon of water. A layer
of sand an inch or two deep is placed in the bottom
of the jar and a quart or more of water poured over it.
After the sand has settled and the water has cleared, a bit
of almost any small water-plant may be inserted to ad-
vantage, provided mosquitoes of the genus Culex are be-
ing reared. If the experiment is with Anopheles, how-
ever, some fresh-water alga is introduced, such as
Spirogyra, Mougeotia, (Edogonium, Cladophora, or Os-
cillaria — almost any green scum from stagnant water, in
fact. Over the top of the jar is placed a i^iece of swiss,
or other fine, translucent cloth, held down by a large rub-
ber band.

The eggs of Culex may be had with ease by exposing
a bucket of water out of doors in a mosquito locality on
almost any summer night. If the egg masses be trans-
ferred from the bucket to the prepared breeding- jar the
growth of the larvae can be watched and their transfor-
mations can be observed with perfect ease. Occasional

HOW TO COLLECT 3I0S QUI TOES 227

specimens can be taken out and preserved, to illustrate
variations of different stages of growth. Accurate notes
can be kept as to temperature, i:>eriods of transformation,
and so on. A series of dates, provided several jars are
under observation, can be written from time to time upon
a slip of paper, which may be pinned to the edge of the
cloth- covering of each jar.

AVhere the eggs of Anoi)lieles, for example, have not
been found, females collected at large may be liberated
in such a prepared breeding- jar. They will rest on the
under side of the cloth-covering during the day and at
night will lay their eggs on the surface of the water. It
is desirable to have a stick in the water, or a leaf, or a bit
of cork, floating on the surface. I have had no difficulty
in obtaining the eggs of Anopheles in large numbers in
this way and the eggs of Culex as well, but although as
many as fifty females of Psorophora have been liberated
in breeding- jars prepared in this way, I have not been
able to get the eggs of this genus, which, as a matter of
fact, are yet unknown. It is possible that Psoroj^hora does
not deiDosit its eggs upon the surface of water. This,
however, is unlikely and it is rather to be supposed that
the females used in my ex^Deriments were not old enough
for oviposition and died from the confinement of the jar
before the egg-laying period arrived.

When one wishes to study closely the movements and
intimate habits of the early stages of mosquitoes a great
deal may be observed through the glass sides of the jar,
by using a coarse lens and studying those near the edge.
But when a closer study is desired, individual larva3 or

228 MOSQUITOES

pupic may be lifted out with a strainer and put in a shal-
low porcelain vessel where they can be watched with ease
under a dissecting- microscope. Anopheles larvae may be
studied in this way very easil}^ and no nature study could
be of more fascinating" interest than the observation of
these creatures, lying as they do with the body practi-
cally in a single plane, so that they may be easily
watched, with the mouth-parts in constant action, and
the head occasionally turning upside down and the re-
verse with lightning-like rapidity.

CHAPTER X

The Class}fication of the United States Mos-
quitoes

THE mosquitoes belong* to that order of insects known
as the Diptera. The Diptera are the true flies. They
possess but two wings, the second pair being repre-
sented only by two little projections known as halteres or
poisers. The mouth-parts are formed for sucking and the
transformations are complete, that is to say, the early
stages differ radically from the adult. In the order Diptera
the mosquitoes are separated into a distinct family known
as the Culicidse, the family name being derived from the
name of the typical genus Culex (see Chapter III.), the
generic name Culex being taken from the Latin word
culex, which means a midge or a gnat. The true mos-
quitoes of the family Culicidae are distinguished l)y hav-
ing the antennae furnished with whorls of hairs, which are
very delicate and long in the male, and sparse in the
female. The head is furnished with a long, projecting
beak, which in the female is capable ot piercing the skin
of human beings. The wings are as a rule transparent, but
to the veins, when seen under the compound microscope,
are attached scales of different shapes, something like

229

230

3I0SQUIT0ES

the scales of a butter%'s wing*. The Ciilicid?e that occur
in the United States are divided into nine g-enera and
about twentj'-four recognized species. More species have
been named, but some of them have been shown to be the
same as others which were previously named, so they are
included as synonyms. In the analytical tables which
follow, the characters which disting-uish these different
genera and species are given. These tables have been
drawn up by Mr. D. W. Coquillett, a well-knoAvn writer

Fig. 48.— Claws of Front Feet of Culex stimvlans ; female at right, male
at left greatly enlarged. (Original.)

on insects of the order Diptera, who has made at my re-
quest a study of the North American species of the
family Culicidse. The tables have been made as plain
and as non-technical as possible, but there are a few
points which should i)erhaps be explained. In unrevised
form, these tables appeared in the writer's bulletin on
mosquitoes, published in August, 1900, and I have no-
ticed that some observers have found difficulty with
the characters relating to the teeth of the tarsal claws

CLASSIFICATION OF THE 3I0SQUIT0ES 231

and to the one which is mentioned as the " petiole of the
first submarg-inal cell." In order to study the teeth of
the claws of the front feet, it is necessary for most people
to break off a foot and mount it on a microscope slide, for
study with the compound microscope. One who is keen-
sig-hted and ex^^ert with the hand lens can make them out
pretty well with a rather high i^ower (say a quarter-inch
Tolles triplet) hand lens, but many others have great difli-

FiG. 49.— Claws of Front Feet of Culex jierturhans; female at right, male
at left ; great!}'' enlarged. (Original.)

culty in detecting them in this way. This, curiously
enough, is especially true of those skilled in the use of the
compound microscope. The terminal claws of the front
feet of nearly all mosquitoes possess good characters in
the teeth, and in order that readers may know just what
to look for, the claws of the front feet of two species are
shown on the accompanying cuts, with the teeth plainly
indicated. Whether a claw bears one tooth, or two, or
none, is very important in the classification.

232

MOSQUITOES

CL

The expression " petiole of the first siil)niar£rinal cell "
is, I realize, incomprehensible to anyone not familiar with
the vocabulary of scientific entomology. Therefore on
the accompanying cuts are indicated this first submarginal
cell and its petiole. The petiole is the vein which runs

from the end of the cell back
to the first cross-vein, and
the relative length of this
petiole and of the cell it-
self are of importance in
the classification.

The names used in this
series of tables, and in this
book, as a whole, differ in
some slight degree from
those which have been used
in the previous writings of
the author, and of Mr. Co-
quillett. Oulex tceniatus, for
example, a name which w^as
used in Bulletin 25, has been
decided to be a synonym of
Stegoniyia faseiata. In this
conclusion Mr. Coquillett is
joined by Mr. Theobald, the
English author. Oulex excitans of Bulletin 25, is stated by
Mr. Theobald to be also a synonym of S. faseiata, from a
study of the type specimen. Anopheles argyritarsis has
been added, since, although it is not known to occur in
the United States, it has been found in Qnha by the Army

'iiKummKi

Fig. 50. — Wing of (Julex conso-
briiiua (above) ; and G. pipiens
(below) ; showing petiole of first
submarginal cell; enlarged.
(Original.)

CLASSIFICATION OF THE MOSQUITOES 233

Yellow-fover Commission, and is of some importance to
us, as Cuba is so near our Southern States, and American
citizens have so many interests in Cuba. Another species
of Megarhinus, namely, grandiosa, Williston, has been
added by Mr. Coquillett.

It is unfortunate that this table has to be published be-
fore the monographic work by Mr. F. Y. Theobald, the
English expert, who has had exceptional advantages in
his studies, for tjie British Museum, of the mosquitoes of
the whole world, makes its appearance. From correspond-
ence with Mr. Theobald I learn that his opinions differ in
some respects from those of Mr. Coquillett in regard to the
proper names for some of our mosquitoes. For example,
the brownish, sordid mosquito which we called CuJex
pungeus is, in Mr. Theobald's opinion, composed of two
distinct species, namely, Culex jnpiens (a common Euro-
pean mosquito), and Culex fatnjam, an East Indian
species which he says is identical with Culex pungens, and
which he states occurs abundantly in many parts of the
world, extending north and south of the Equator to about
38^ north and south latitude (just about the range of the
yellow-fever mosquito). Mr. Theobald is also inclined to
think that the Culex impiger of AValker is identical with
the species known to entomologists as Culex ni gripes of
Zetterstedt, and he also has a mosquito from North Amer-
ica which he thinks is Culex aimidatus Meigen, a form
which we have not recognized in the United States. Mr.
Theobald has also received from Canada an Anopheles
which he thinks is a variety of A. lifKreafus. This also
is a species which is unknown to us in the United States.

234 3I0S QUI TOES

It will be noticed in the tables wLich follow, and in the
consideration of mosquitoes and j^ellow fever in Chapter
V. that Mr. Coquillett and the writer have adopted the
generic name Stegomyia for the mosquito which has in
our previous writings been named Culex fasciahis. I have
been induced to adopt this name through correspondence
with Mr. Theobald, who writes me that he has discovered
characters which separate this mosquito from the old
genus Culex, and that he has proposed the name Stego-
myia for the genus. He has given me no clew as to the
characters upon which he has founded this genus, except
that thej- are *' scale characters." A study of the scale
structure of this insect and other mosquitoes of the genus
Culex does not reveal any very important differences, but
Mr. Coquillett, from other characters, has concluded to
adopt Mr. Theobald's generic name, and it is here used
with the characters pointed out in the table. It will be
unfortunate should this use of the name antedate the
publication of Mr. Theobald's monograph, since the genus
should be his and not ours. Two other new generic names
proposed b}^ Mr. Theobald, viz.: Toxorhynchites and Con-
chy Hastes, have been adopted and are characterized in the
tables. It will be noticed that the characterizations are
printed with quotation marks, and that they are followed
by Mr. Theobald's name in parenthesis. This method of
printing will make Mr. Theobald responsible for these
genera as well as for Stegomyia, in the event that this
book is issued from the press in advance of his publica-
tion.

With these words of explanation, the folloAving tables,

GLASSIFICATTON OF THE 3I0SQUIT0ES 235

for which it must be distinctly understood Mr. Coquillett
is responsible, and for which I owe him many thanks, will
probably enable those who are at all in earnest in the
matter to distinguish our species without e^reat difficulty.

I. — Gexertc Syxopsis.

The following: taljle contains all the genera of the long-beaked
mosquitoes known to occur in North America. The males are
readily recognized by the antenna being densely covered with
long hairs ; in the females the hairs of the antennae are short
and very sparse :

1. Palpi in the male at least nearly as long as the proboscis ; in

the female less than one-half as long 3

Palpi in both sexes at least almost as long as the proboscis , 2
Palpi in both sexes less than one-half as long as the pro-
boscis 7

2. Proboscis straight or nearly so, colors of body brown and yel-

lowish AnojjJieles.

Proboscis very strongly curved, colors bluish or greenish.

3fe(jarhimis.

3. Legs bearing many nearly erect scales Psorojyhora.

Legs destitute of such scales 4

4. Colors, black, brown and yellowish, proboscis almost

straight 5

" Colors, green and bluish, proboscis very strongly curved "
(Theobald) Toxorhijnclutes.

5. "Thorax marked with lines of silvery scales" (Theo-

bald) Sttyomyia.

Thorax not marked in this way G

6. " Hind feet black, their apices snow white'' (Theo-

bald) (JonchyJlastes.

Hind feet not marked like this Ciile.v.

7. Upper side of thorax with line of bluish scales. . UranoUvnid.
Upper side of thorax not niarkcci in this way AMes.

23G 3I0SQUIT0ES

II. Genus Uranot^nia.

Our sino:le species is rarely met with ; it is among: the smallest
of mosquitoes and will readily be recognized by the stripe of vio-
let-blue scales on the thorax :
aapphirina O. S.

III. Genus Aedes.

The single species is likewise rarely met with, and like the
preceding, is of very small size ; it is of a brownish color with
golden-yellow scales on the thorax and cross-bands of white ones
on the abdomen :
fuscus O. S.

IV. Genus Conchyliastes.

Our two species are of medium size and of rather rare occur-
rence ; they may be distinguished as follows :

AVith the last two Joints of the hind feet Avhite musicus Say.

With only the last joint of the hind feet white, .jiosticatus Wied.

V. Genus Stegomyia.

Our two species are of rather small size, and may be distin-
guished by the following characters :

Front claws of the female toothed on the under side, the
outer silvery stripes of the thorax greatly widened in

front of the wings fasnata Fabr.

Front claws not toothed, the outer silvery stripes of the thor-
ax very narrow throughout their entire course. si gnif era Coq.
fasciata Fabr.
excitans Walk.
frater Desv.
mosquito Desv.
tceiiiatns Wied-
si gnif era Coq.

CLASSIFICATION OF THE MOSQUITOES 237

VI. — GE2sUS Culex.
{a) RECOGNIZED SPECIES.

Males.

1. Front tarsal claws bearing a distinct tooth near the middle of

the under side of each 3

Front tarsal claws bearing two teeth on the under side of one
claw, and one on under side of the other, proboscis destitute
of a whitish band near the middle 3

3. Feet distinctly white at bases of the joints . mllicitam Walk.
Feet not white at bases of the joints consobrinus Desv.

"3. Proboscis destitute of a whitish ring near the middle 4

Proboscis with such a ring, ends of tarsal joints white

tar.suU.s Coq.

4. Bases of tarsal joints not white 5

Bases of tarsal joints white stimulans Walk.

5. Palpi not dilated 0

Palpi strongly dilated toward the apex invpiytr Walk.

6. Petiole of first submarginal cell at most one-fourth the length

of that cell pipiena Linne.

Petiole at least almost half as long as the cell . pungens Wied.

Females.

1. Front tarsal claws bearing a distinct tooth near middle of

under side of each 3

Front tarsal claws destitute of teeth 7

3. Proboscis destitute of a white ring near the middle 4

Proboscis marked with such a ring, bases of tarsal joints
white 3

3. With a stripe of yellowish scales in middle of the abdo-

men sollieitans Walk.

Without such a stripe taniorltijiK-hus Wied.

4. Bases of tarsal joints distinctly white stimalans Walk.

Bases erf tarsal joints never white 5

238 3fOS QUI TOES

5. Abdomen marked with a cross-band of whitish scales at

base of each se^nuent unpiger AValk.

6. Abdomen never marked in tliis manner, but with a cluster

of whitish scales at front angles of some of the seg-
ments triseriatus Say.

7. Proboscis marked with a distinct whitish ring near the

middle, feet white at sutures of the joints 8

Proboscis destitute of a whitish ring near the middle D

8. Tarsal joints white at bases only ^jerturhans Walk.

Tarsal joints white at both ends tarsalis Coq.

9. Feet white at bases of joints excrucians Walk.

Feet never wdiite at bases of the joints 10

10. Petiole of first submarginal cell about one-eighth the

length of that cell jjlpiens Linne.

Petiole one-fourth the length of that cell. . . .pungens Wied.
Petiole at least almost half the length of that cell.

eonsobrinus Desv.

(&) UNRECOGJ^IZED SPECIES.

aiinulatus Schrank. This European species w^as credited to
our fauna by Osten Sacken.

hoscii Desv. Probably a rubbed specimen of pungens.

nigripes Zett. Black, the legs of the male dark yellow, hairs
of pleura of female gray, a band of white scales at base of each
segment of her abdomen.

rubidns Desv. The description was apparently founded on a
rubbed specimen of Pso?-ophora ciliata.

testaeeus v. d. Wulp. Must closely resemble consohrimis.

incidens Thomson. Is evidently a synonym of impiger
Walker.

bigoti Bellardi. According to the figure and description, the
bands of black scales are at the bases of the abdominal seg-
ments ; in the recognized species these bands are always at the
apices of the segments. In other respects this species must greatly
resemble pungens.

cubensis Bigot. Apparently founded on a badly rubbed speci-
men of pungens.

CLASSIFICATION OF THE MOSQUITOES 239

frater Desv. This name was proposed for the Culex fasciatus
of Wiedemann, under the impression that this is not the same
species as the one described by Fabricius under the same name. It
seems quite certain, however, that the word "proboscis" in Fa-
bricius's description was simply a lapsus for " palpi," and with
this emendation the two descriptions agree very well.

mexicanus Bellardi. Is evidently a synonym of xjostlcatus.

pipiens Linne. A European species recently reported by
Mr. Theobald as occurring in this country.

provocans Walker. Is a synonym of nernorosus Meig., accord-
ing to Theobald.

territans Walker. Is apparently related to pungens.

Our recognized species of Culex and their synonyms may be
listed as follows, the synonyms indented :

consohrimis Desv.

? annulimanus v. d.
Wulp (Anopheles).

impatiens Walker.

inornatus Williston.

pinguis Walker.

punctor Kirby.
impiger Walker.

implaoabilis Walker.

incidens Thomson.

? quinquefasciatus Say.
perturbans Walker.

pipiens Linne.
pungena Wied.

? boscii Desv.

? cubensis Bigot.

'i fatigans Wied.
stimulans Walker.
tceniorhynchus Wied.

damnosus Say.
sollicitans Walker.
tar sails Coquillett.
triseriatus Say.

VII.— Genus Psorophora.

Our single species is of a yellowish color, usually varied with
brown, the bases of the tarsal joints white. It is considerably
larger than any of our other species of yellowish or brown mos-
quitoes :

cillatus Fabr.
molestus Wied.
? rubidus Desv.

240 3I0SQUIT0ES

VIII.— CtEXUS Toxorhynchites.

These are anions: the largest of our mosquitoes, and closely re-
semble those of the following genus. Our single species has all
of the feet marked with white :

rut Has Coq,

IX.— Genus Megarhinus.

Our three species are among the largest in this family, and are
not known to occur north of the District of Columbia. They
may be separated as follows :

Hind feet alone marked with white 1

None of the feet marked with white luTmorrhoidaUs Fabr.

1. Front and middle feet wholly black portoricensi's Roeder.

Front and middle feet yellow, first joint of the front ones
black * grandiosa Will.

X.— Genus Anopheles.

(a) RECOGNIZED SPECIES.

1. With a yellowish white spot near three-fourths the length of

the front margin of the wing 3

Without such a spot 2

2. Scales of last vein wholly black, palpi wholly black

maculipennis Meig.

Scales of last vein white, marked with three black spots, palpi

marked with white at bases of last four joints, crucians Wied.

3. Hind feet wholly brown, scales of last vein white, those at

each end black pnnctipeniii.s Say.

Hind feet largely snow-white on the apical half.

argyritarsis Desv.

* This species, of which I have never seen a specimen, probably be-
longs to the preceding genus. — D. W. C.

CLASSIFICATION OF THE MOSQUITOES 241

{b) UNRECOGNIZED SPECIES.

The following species which have been credited to our country
have not been recognized with certainty ; some of them probably
do not belong to the present genus, while a few were evidently
founded on badly rubbed specimens in which the distinctive
characters were therefore wanting :

anniilijnanus v. d. Wulp. I strongly suspect that this does
not belong to the present genus ; the description applies fairly
well to the male of Culex consohrinus Desv.

ferruginosus Wied. This name was proposed for the species
previously described by Say under the name of Culex quinqiie-
fasciatus, but the description differs so decidedly from the one
published by Say as to give the impression that it is founded on
a different species. I strongly suspect that the type of ferrugi-
nosus is a rubbed example of Anopheles crucians, which was de-
scribed from the same locality. Say's description of his Culex
quinquefasciatus agrees very well with the species which I have
identified as Culex impiger Walker.

inaculipennis Meigen. According to Theobald this European
form is identical with our Anopheles quadrimaculatus Say.

nigripes Staeger. This European species should be readily
recognized by its unspotted wings.

albimanus Wied. Differs from our other species by the snow-
white apices of the tarsi.

pictus Loew. Is evidently closely related to crucians Wied.

Our recognized species of Anopheles and their synonyms may
therefore be listed as follows, the synonyms indented :

argyritarsis Desv. maculipennis Meigen.

crucians Wied. quadrimaculatus Say.

"i ferruginosus Wied. punctipennis Say.

hiemalis Fitch.

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