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B68
A HANDBOOK
OF
BRITISH MOSQUITOES
BY
WILLIAM DICKSON LANG, M.A., Sc.D.
Assistant attached to thr Department of Entomology
LONDON •
PRINTED BY ORDER OF THE TRUSTEES OF THE
BRITISH MUSEUM
AND SOLD BY
Longmans, Green & Co., 39, P.1- ;kk Row, E.G. 4 :
B. Quaritch, Lid., ir, Grafton Street, New Bond Street, W. i :
Di-lau it Co., Ltd., 34-36, Margaret Street, Cavendish Square, W. i
and AT Till.
British Museum (Natuxai History), Cromwell Road, S.W. 7.
1920
[All rights rtsenxJ.]
PRESENTED
BY
The Trustees
OF
THE BRITISH MUSEUM.
A HANDBOOK
OF
BRITISH MOSQUITOES
BY
WILLIAM DICKSON LANG, M.A., ScD.
A SISTANT ATTACHED TO THE DEPARTMENT OK ENTOMOLOGY
LONDON :
PRINTED BY ORDER OF THE TRUSTEES OF THE
BRITISH MUSEUM
AND SOLD BY
Longmans, Green & Co., 39, Paternoster Row, E.C. 4 ;
B. Quaritch, Ltd., u, Grafton Street, New Bond Street, \\ . i;
Dulai ,\: Co., Ltd., 34-36, Margari r Street, Cavendish Square, W. i
AN 1 1 A I I HI.
British Museum (Natural History), Cromwell Road, S.W. -.
1920
[ . / 7 rights reset 1 1 d. |
%
MAR ^ ly/g
£|fr/ry of TO^t
*V
LONDON I
PRINTED BY WILLIAM CLOWES AND SONS, LIMITED,
DUKE STREET, STAMFORD STREET, S.E. I, AND GREAT WINDMILL STREET, W. I.
fi
PREFAC1
Owing to the important part played by mosquitoes of
in the communication of disease, an increased amount of attention h
been given to the study of these insects in recent But if the
study of any particular species of insect, no matter from what point
of view, be it purely scientific or altogether practical, is to be of real
value, it is essential that the species should be exactly identified.
Twenty-one different species of mosquitoes have been found
occur in the British Islands ; and it is by no means easy to distinguish
every one of these species from all the rest.
It is hoped that this Handbook, prepared with that end in view,
will make it possible for the student to identify all the British species
without much difficult}-, and not only in their adult flies, but.
far as present knowledge of them will permit, in their larval and
pupal stages as well.
The author of the book, Dr. W. D. Lang, has taken great pains in
its preparation, and has neglected no source of information that
would help to make it <»f value for the pur] for which it
intended.
CllAkl ES J. G \H.\\.
A"
British Musi um (Natui u. History),
Man ■':, 1920.
C0NTEN1 S.
I. INTRODUCTORY.
A. Gnats, or Mosquitoes, and other fi
B. The Life-historv of Mosqui ro
C. Structural: the nomenclature of pab
i. Imago ......
2. Larva ......
II. IDENTIFICATION.
A. Imago—
i. To distinguish the sexes
2. To identity the genera —
a. Males
b. Females
3. To identify the species —
a. Anopheles
b. Ochlerotatus
c. Culiceila
d. C 11 lex
B. Larva —
1. To identity the genera
2. To identify the species and instar
a. Anopheles
b. Ocldcrotaius
c. Fin I ay a
d. Theobaldia
e. Culiceila
f. C it lex
III. SYSTEMATIC ACCOUNT.
I. Anopheles —
1.
A.
maculipennis
2,
A.
biftircatus
3-
A.
plumbeus
11. Aides
ciuereus .
11. Ochlerotatus—
1.
0.
caspius ■
2#
0.
curriei .
3-
0.
vexans .
4-
0.
waterhousei
5-
0.
annulipes
6.
0.
detritus .
7-
0.
nemorosus
8.
0.
rusticus
I
I I
14
$5
44
45
7'
"i
1
84
■ ,i
VI
III. SYSTEMATIC ACCOUNT— continued. page
iv. Finlaya genictdata ......... 95
v. Taeniorhynchus richiardii . . .... 98
VI. Theobaldia annulata . . . . . . ... 100
vii. Culicella —
1. C. /nor si /ans .... 102
2. C.fumipennis ...... . . 104
viii. Culex —
1. C./'ifttcns .... ..... 105
2. C. afiicalis . . . . . . .' . . .108
ix. Orthopodomyia albionensis ....... 109
IV. REPUTED, DOUBTFUL, AND FOSSIL BRITISH SPECIES . n 1
V. EVOLUTIONARY AND CONCLUDING REMARKS . . 113
LIST OF PLATES.
The Plates, drawn by E. Ter/.i, are reprinted from K. E. Austen's
British Blood-sucking Flics, British Museum (Natural History), 1906.
Plate I. — Anopheles maculipennis Meigen. Female.
The common malaria-conveying mosquito of Europe. Abundant
in Britain.
Plate II. — Anopheles bifurcatus (Linnaeus). Female.
Has been known to convey malaria in Italy. Abundant in
Britain.
Plate III. — Anopheles plumbeus Stephens. Female.
Has been artificially infected with malaria, but not known to
convey it under natural conditions. Widely distributed id
Britain, but restricted during larval life to a sylvan habitat.
Outside the genus Anoplulcs, no mosquito is known to convey
malaria.
Plate IV. — Ochlerotatus caspius < Pallas). Female.
Plate V. — Ochlerotatus nemorosus (Meigen). Female.
BRITISH MOSQUITOES.
I. INTRODUCTORY.3
A. GNATS, OR MOSQUITOES, AND OTHER FLIES.
THE object of this handbook is to render as easy -sible the
identification of British Mosquitoes.'- Anti-malarial measures, rendered
necessary by the introduction of large numbers of malarious soldiers,
have drawn attention to mosquitoes in Britain ; and it is desirable that
everyone should be able to distinguish a gnat capable of conveying
malaria {Anopheles) from a non-malarial kind Again, diseases other
than malaria are known to be gnat-borne, though fortunately not in
this country; and it is at least of interest, if not of immediate u
that our few British species should be known, in case these should be
found to be concerned in conveying an)- di It is in some of
the non-malarial species that difficulties of determination arise, but in
most cases, with the help of reasonable magnifying power, the species
are easy to distinguish ; and with clear directions and figures there i-^
no reason why everyone should not readily identify most, if not all,
the different kinds.
That such help is needed is clear from a consideration of the
specimens frequently sent to the Museum in answer to requests for
mosquitoes from various localities. Often these are true mosquitoes,
but often they are not, or are a mixed bag of mosquitoes and other
flies. It is evident, then, that what is first needed is to distinguish a
true mosquito, or gnat from flies belonging to other groups.
1 All the text-figures, drawn for this work by Mr. E. ferzi, are very considei
magnified. It has not been considered necessary to give the exact magnification in e.ich
case. The Plates are reprinted from Major E. E. Austen's British I king Fli
British Museum, 1906.
-The terms "gnat " and " mosquito'' are u>L"i indifferently in this work. A
mosquito, and a mosquito is a gnat.
1;
The most telling feature of a mosquito is its proboscis (fig. 6.)
Other gnat-like flies may have an elongated face, even ending in a
more or less pointed projection ; but a gnat has a proboscis several
times longer than the whole head, and easily visible on a near view of
the gnat at rest. When once the proboscis is seen, there can be no
doubt as to the nature of the insect, if it is gnat-like in general appear-
ance. For there are other flies with a long proboscis ; but the general
build of these is so different from a gnat's build, that no confusion is
possible. To describe, however, a gnat as a gnat-like fly is obviously
inadequate. But for lack of any other popular word designating this
type of fly, it must do duty while an attempt is made to indicate a
gnat's general features. A glance at the figures (e.g., fig. 6 and
Plates I.-V.) of more-or-less complete gnats will give a better
idea than any description. Delicacy, probably, is the quality
that best describes the general build of a gnat. The body is
slender and lightly built, and the legs are very long and thin ; the
wings also are narrow (figs. I, 6), and the antennae long and
thread-like, though densely-plumed in the male (fig. 13).1 Another
character, and one diagnostic of a gnat, is the presence of scales
thickly clothing the head, legs and the "nervures" or "veins" of the
wings (figs. 67, 68) ; and they even form a fringe round the whole
margin of the wing (since the wing is limited by a " vein ") ; and in
man}- cases cover the abdomen (fig. 16). But these scales are often
thin and hair-like ; and, since many flies are clothed with hairs where
i-he mosquitoes have scales, this character cannot so easily be used as
a criterion without a fairly high magnifying power. In those forms,
however, in which the abdomen is densely-scaled (the Culicine gnats),
the scales are broad and can be more readily seen. Finally, it must
be borne in mind that hairs as well as scales are often present upon
the thorax and abdomen of gnats ; also that the scales of gnats are
readily rubbed away, so that a bad specimen may appear naked.
A gnat, or mosquito, then, may be known at sight as a fly (that is, a
two-winged insect) of delicate and siender build, with a long proboscis
capable of use by the female for sucking blood, and having thread-
1 Densely-plumed antennae are very noticeable in the males of some flies nearly allied to
gnats, and must not be considered as peculiar to, but only as a characteristic feature of all
gnats.
like antennae with whorls of sparsely-distributed hairs in the female
(fig. 14) and of dense hairs in the male (fig. 1 j), giving the antenna of a
male gnat a plumose appearance. Further, viewed under a moderately
strong magnifying power, the head, legs, veins of the wings, and often
the abdomen, are seen to be densely clothed with scales. If a gnat
caught, so that the venation of the wings can be examined, it may be
known by arrangement of the veins. This is shown in tig. 1,
and the most characteristic feature is the presence towards the
tip of two parallel forked veins (longitudinal veins 2 and 4) with an
unforked vein (longitudinal vein 3) lying between them and also parallel
with them. The stalks of the two forked veins are continued back-
wards, the lower one to the base of the wing, the upper to a point on
longitudinal vein 1 where it branches from that vein. The middle,
costal vein supernumerary cross vein
subcostal vein
6th long.vei
posterior cross vein 5th long, vein
anterior or mid cross vein
. 1. — Wing of Mosquito : Citlex pifiens (Linna
11: long. vein
2n:1long.
vein
3rd long,
vein
ong.vein
4th
unforked vein abuts against cross-veins joining the stalks of the two
forked veins.
Thus, even if a specimen is so rubbed that the scales are removed,
a gnat may be known at once from other flies (except Mochlonyx and
Cluiobonts — allied genera which have no long proboscis) by the wing-
venation. And this, as well as the presence of a proboscis, is a useful
test when a gnat is compared with other flies that are frequently
mistaken for true mosquitoes or gnats. Three of these will be
mentioned. First, there are numerous species ^\ Chirotwmtis and
allied flies that are often noticeable for occurring in immense numb
in the neighbourhood of water, and have a very gnat-like appearance,
especially the males with their densely-whorled antennae. The
flies have no proboscis and are not covered with scale The
B 2
wing-venation is shown in fig. 2, and is seen to be simpler than that
of a gnat. The larvae of some of the commonest species of Chiro-
nomus live in water-butts in company with larvae of Culexpipiens — the
Common Gnat ; but their appearance is very different from the gnat
larvae, and some are bright-red and popularly known as Blood-worms.
The}- make a more-or-less coherent case of slime and dirt, and live in
it on the bottom ; while Cu /ex-\a.rva.e swim freely at all depths and
Fig. 2" — Wing of Chironomus plumosus (Linnaeus).
frequently rest at the surface. The Chironomus-fiy is interesting for its
habit of raising a pair of legs and waving them in the air like feelers
when it is resting and when danger threatens. Mosquitoes have the
same habit, but while Chironomus raises its fore-legs, mosquitoes raise
their hind-legs. Doubtless correlated with this habit is the great length
of the fore-legs in CJiironomus and of the hind-legs in mosquitoes.
Fir.. 3. — Wing of Trichocera regelationis (Linnaeus).
Other flies constantly mistaken for true gnats are certain gnat-like
kinds of the family Limnobidae, for instance, species of the genus
Trichocera. These are familiar for dancing in small swarms in
sheltered situations throughout the winter, and are, consequentlv,
sometimes known as Winter-gnats. The build of a mosquito was
described as delicate ; that of a Trichocera mav be called flimsv, so
fragile are these flies even compared with gnats. There is, of course,
no long proboscis ; and the bodies are bare or but slightly hairy.
The wings arc broader than mosquitoes' wings, and the venation is far
more complex (fig. 3). The larva- are not aquatic.
Rhyphus fenestrate is a very common fly frequently mistaken for
a mosquito. It is found in houses, outhouses, etc., often in company
with Anopheles maculipennis. Having spotted wings (fig. 4), at
sight it superficially resembles that species. The wings, however, are
wider, and the spots consist of the pigmented wing-membrane ;
whereas, in Anopheles maculipennis ; they are formed by scales ma
more thickly there than elsewhere along the veins. Besides, Rhyphus
has no scales, no long proboscis, and its build is more thick-set than
that of a mosquito.
. 4.— Wing of Rhyphus fmtstralis Scopoli.
B. THE LIFE-HISTORY OF MOSQUITOES
The eggs of British mosquitoes are laid during the warmer parts of
the year generally on water, either singly (by the genera Anophel
A'c'dcs, Ochlerotatus and Finlaya), or glued together in floating masses
called rafts (by Taeniorhynchus, Theobaldia, Culicella and Culex). As
far as they are known, the eggs of all species float, and .ire several
times longer than wide. In most species the}' remain from one to
several days before hatching, and the length of time is pro! .abb-
more determined by the temperature than by any Other cause The
emergent larva (figs. 10 and 11 show a full-grown larva) is an
elongate, limbless grub with a wide thorax and head, and wit
variously-shaped and often tufted hairs symmetrically arranged along
its whole length. Some of the most remarkable of these hairs .ire a
pair of very dense tufts called brushes (figs. 10. 11 and [2), lyii
the underside of the head in front of the mouth, and resembling v
moustache. These the larva continually moves backwards and
forwards, and thereby entangles in them the particle nic
matter on which it feeds. These particles arc then combed out of the
brushes by some hairs which grow on the mandibles, and passed into
the mouth. Other particles are swept by the current created by the
brushes on to the other mouth-parts and entangled in them.1 Thus
the larva feeds and grows, and in a few days undergoes ecdysis, that is,
its skin splits, and a second larval form, or instar, emerges, resembling
the first in general features, but differing in detail. In all the British
species of which the first larval instar has been examined, the group
of hairs (fig. II, FIN) lying medianly and ventrally on the last
abdominal segment, and forming the fin-like organ characteristic of
mosquito larvae, is absent, but is assumed at the first ecdysis or moult
by the second larval instar. There is also a minute tooth or egg-
breaker'1 on the surface of the head of the first instar, having a vertical
motion produced by muscles attached to its base, and used for forcing
an exit from the egg. The third and fourth larval instar closely
resemble the second, but are progressively larger and are of longer
duration. Indeed, some forms {e.g., Anopheles bifurcatus) spend the
whole winter in the third or fourth larval form, but otherwise the stages
are generally run through within a few weeks. The larva moves in
wriggling jerks, and an Anophe/es-\a.rva can dart backwards with great
nimbleness. The larva frequently rests just beneath the surface, and
there can breathe by means of a pair of stigmata placed one on
each side of the mid-line of the penultimate segment (the eighth
abdominal), and placed in the Culicine gnats at the end of a long tube
— the siphon. While thus floating, the larva explores the lower side
of the surface-film and its neighbourhood for food, often bending its
body sideways to reach a favourable spot. Owing, presumably, to
the action of the brushes, it is kept gently moving forward while
feeding, whether it is floating on the surface or browsing on the bottom
as it sometimes does, especially in certain species ; and when a
Culicine larva on the surface curves round as just described, it takes
on a rotary motion, circling round the axis of its siphon. Should the
stigmata tend to become clogged, or breathing be otherwise obstructed,
the larva bends round and passes the siphon through the brushes,
1 Set '■. II. V. Nuttall and A. E. Shipley, 1901, Journal of Hygiene, vol. i., p. 57.
2 See Y . YV. Edwards, 1919, Annals and Magazine of Nat. Hist., Series 9, vol. iii.,
pp. 372-6. It is shown below in figs. 98-99a (p. 55), in the mid-line of the head and just
1 ior to the centre.
apparently to clear away the obstruction, just as a cat uses its te
to clear its fur. This action is one of the first signs of distn
exhibited by the larva in an unfavourable environment, even when it
brings no relief, as when the surface of the water is i | with
paraffin. Four finger-like, delicate processes, the analgills (figs. [O, i i >,
project from the end of the last (ninth) abdominal segment, and
probably allow the larva to remain longer beneath the surface than
FlG. 5. — Pupa of nereus.
would be the case if it were dependent for breath upon its stigmata
alone. This accessory breathing-apparatus would also explain how a
hibernating form can remain alive in the mud while the water above
is frozen at the surface.1 Again, the larva of Taeniorhynchu
1 It has been shown that certain mosquito larvae can remai
aerated water for a considerable time after I f the anal gi
ably, through the general integument. See J. VV. S( ' M , i ". Bull. !
vol. vii., pp. 277
continually on the bottom, and has a siphon modified for piercing
submerged plants and obtaining from them the air it needs.
The instar succeeding the fourth larval instar is a pupa. It does
not eat, and, except when disturbed, floats just beneath the surface of
the water. Like the larva, it can swim by wriggling jerks, but is far
more nimble and restless when alarmed. It is also more buoyant
than the larva, and this buoyancy becomes progressively greater as
the time for emergence approaches. The pupa has a very different
aspect from the larva (fig. 5). Generally speaking, it resembles a
comma with a gigantic dot. The dot of the comma is the head and
thorax of the pupa, and the tail its abdomen. The abdomen ends in
a pair of lobe-like fins ox paddles. The outline of the sheath covering
the rudimentary wings can be seen on the sides o( the thorax as in
the chrysalis of butterflies, and the sheathes protecting the future
legs, mouth parts and antennae of the fly are prominent on the surface
of the pupa. As in the larva, there is a single pair of large stigmata
or breathing pores, but in the pupa they are placed on the thorax,
and prolonged into expanding funnels standing out from the thorax
like ears.
The pupal instar is of short duration, generally lasting but a few
days. Before emergence the pupa begins to acquire a silvery look,
due to air that is forced between the pupal integument and the
enclosed imago. This air causes a greater buoyancy of the pupa,
which is increased as more air is forced in, and the pupa appears more
silvery. It is then with difficulty kept from the surface and sometimes
fails to retain its equilibrium, temporarily rolling over to one side or
the other. It rides so high in the water that finally the dorsal surface
of the thorax projects and remains dry. This dry patch then splits
along the mid-line, and very quickly the thorax of the imago is pushed
out. The gnat thus emerges in a humped attitude, with its head sunk
on its breast, the antennae, palps, proboscis, and legs still held in their
pupal sheathes, and the abdomen but little outpushed from the pupal
skin. The imago still continues to move vertically upwards, with the
dorsal surface of the thorax foremost, the antennae and proboscis closely
appressed to the thorax, and the legs, with their tips still in their pupal
sheathes, lying along the emergent abdomen, the tip of which is also
still encased. In this condition the floating insect appears most
unstable, with the thoracic mass high above the cenl gravity of
the system. But, in fact, its equilibrium is by no means easily
disturbed, as may be proved by gently blowing upon it, when it
spins round most readily, like a weather-cock, but does not capsize.
Indeed, an upset in this stage would be fatal, as, once wet, the ins
could not resume its vertical position, and would drown. The pupal
skin, split open and completely emptied of the air that forced out the
imago within, no longer rolls to this side and that, but li<
the surface without rocking. Gradually the emergent fly draws its
limbs free, the wings harden, and it flies away.
The habits of various species differ, but generally British mosquib
hide away during the day and in chilly weather, and fly forth in the
evening if the weather is warm enough. It is mostly then that the
females bite and the maies swarm. The males do not suck blood, but
some have been observed feeding upon flowers. It is the habit of the
males to dance in swarms in the evening at definite sheltered spots,
sometimes in company with the males of other species of gnat or of
gnat-like flies. The females wander about sing!}-, and when one
approaches the neighbourhood of swarming males, the swarm becomes
very agitated and the dance a frenzy. The stimulus exercised by the
frenzied swarm breaks down any inhibitions controlling the female,
who, throwing away reserve, darts into the swarm, is seized by a
partner, and the couple fall out of the dance. The swarm then
resumes its normal motion and awaits the arrival of another female.
It thus appears that the swarming of the males is no aimless
behaviour, but has a bionomic significance, producing the requisite
stimulus that, reacting on the female, leads to her attraction and capture,
thus unlocking a whole chain of consecutive stimuli which produce an
orderly sequence of reproductive proces
But the stimulus of the male swarm may not in all the
only unlocking action. There is some evidence to show that in certain
species of Anopheles, the female requires a meal of blood before she is
ready for pairing' ; and, after pairing, a second meal before oviposition.
1 H. E. Anncti, E. E. Austen and R. K«>~>, 1002. k ' aria 1 \
being .Memoir II. of the I-;- ol of Tropical Medicine, p. 21. I
the absence of conditions suil tble for swarming and not the a
cause of the females' failure to oviposit. Th nothing in I
experiments to negative this possibility.
Imi sindhi cai'SPSs, tinem)„ aim mmnffed femmale will be imidinleiremitt to a swaimm off
--. i - - _ amid time cSaain of reprodnactivie
- - amly t ■ omitrerpojsitiiom) of amrc»tlmeir ©mgamilsmin
:i>e miecessairy sttinmnnliins. TTmis iimfaodmKctiioim of a
.-(tor inn trine life-cycle eviden:
-..3ne comilrirmiiiiiatriioim of ttftnc - - jmmplicator
.md wc . It Imave Saeer
mmeasmnre to mmee - . mneinge: : ~ If it <c©nnld foe slno^ 1
■:m mm trlnose trlnatt coponlalte icadily, Mood-simckiiE g ~Jne
repircadluBdL - ."aere a laimitt footln as to b
tBne olood-snodldiimg Una": : : toeem casual amid mrnoire e i
gemeo - evesm mie: . - ' n s It
- :'.r :.2jmse off estinTKdtiomu For it seemms clear trlaat tfc e
:vofced to snack platmtt-jimices. Bottfln sexes of :
- jaTe foeemi ©toseirwd sancMrr ffloweas^ amid tine femmi
i'areigmi species seldomm or nue^er smtelk Mood. Iff mmdnVndci:-
£„ pHaimfr-^amrTlriiinrj nmKDsqniitoES appealed w. ~jl -z ;
BnaSjottofc' - arMmig rniarniFi-Wooded aTmiwrmgls, aimd -
stiinmmillattmnig lepirodmicttiionn mm tBne ffemmale, it is ewEetmt ((smmce sanelm
mnals wobdM mm©ie leadnlly irepnToxdronce)) ttlnat tikis InaMt, iff Ine:
3smmittfied at ami acceleiiattiffi^' irate mumtil tine wllnc
- trlniirstty for Wood! — as mmamry
i is a ffact ttfinatt dniSeiremitt degrees off strimnnmllmts aire mieetc e
- dinleiremitt species off sjimalL. Gennenalliy we mma tnre
res - _ :Jn degme; • - -•...- stmdm a :- ~
"ffsBflfliHy ~ somme neqaimre trine swatrmmmmg off the nroalle- . • -
--amine, like trine Jbmig • 1 mmemitrioimed,
- ime a mnwaall ©ff Mood as well as trine swar"
I" l gienBeiral! wiew off Sine amnkmal kmntgdomm,, trMs samme di-- 1
i mmTTriTrnffy iresgtmr i : 'isen^Tafole. Tlie sntanatfikaiii mi
~. a s — Inn ceirtraimi : a camise mnmkic : ahe
jcttuwe " -":'-.-:" loot Ine:
rue weire ami imicireasiinng' imiMM:
-; annate win : i^'opeicommeomiL
. ae mmaDe. If tflnrls Mttcfln ire : .-
. - inn tt .
1 1
as a block caused by factors inhibiting the read: f the f
increases as the race evolves, and generation succe
there will come a point at which no i onding t on th
of the male will overcome the female's reluctance, and the i will
perish. Such a process may be in action among m
The swarming of the males at first removes inhibiting fad tut
later the meal of blood is needed as well ; should the inhibiti
continue to accumulate, a new device must be found, or the race will
become extinct.1
Some British mosquitoes hibernate as impregnated fee
and issuing forth in spring, lay eggs, and thus start a new c ■ ith
the new season. Others hibernate as larvae (or, in some
eggs), and the imagines of these species die • ff at the end of autumn.
In some species there appear to be but one or two broods in the year ;
while in others, brood succeeds brood throughout the summer ; but
the rate at which the life-stages are run through, and consequently
the number of broods produced in a season is probably primarily
determined by the temperature. Hot weather sometimes . . in
Ochlerotatits netnorosus) has the effect of checking the life-h by
drying up the breeding-places ; but as a rule the warmer the weather.
the faster the progress o\ the life-cycle.
C. STRUCTURAL: THE NOMENCLATURE OF PARTS
i. THE IMAGO 1
It is impossible to identify mosquitoes without a nomenclature of
their parts. But it is not intended to discuss their morph much
further than is necessary for purposes of identification.
Figure 6 shows the parts of an imaj fly. The the
antennae, the eyes and the mouth-parts. Most of the last i ite
the proboscis ; but the maxillary palpi (generally referred to simply
as the palps) are a pair of jointed, I tructures, lyii
one on each side of the proboscis, usually very short in the f
but long in the male and with tufts >'t" V w^ hairs in
1 Of course it may be argued that the
stimulate the male, such stimulation
precedes in the male. Such a contention would not inval
merely shift the point of its application.
[2
figs. 18-21). The rest of the mouth-parts compose the proboscis..
The mandibles and maxillae are pairs of long, flattened, thread-like
organs lying within the proboscis sheath and concerned with piercing
the skin during biting. The proboscis sheath is formed by the labium,
and has the form of a very much curved gutter or a tube not quite
complete above, and does not enter the skin when the mosquito bites,
but abuts against it, bending ventrally as the piercing mouth-parts are
thrust deeper into the host. Almost at its tip it bears a pair of little
lobed pieces — the labclla (fig. 6) which project beyond the tip and
serve to guide the piercing parts. The channel of the labium is closed
above by a similar, but far more slender gutter open ventrally, called
the epiphafynx — an extension of the labntm. This terse description
by no means exhausts the structure of the proboscis, nor explains the
complex mechanism whereby the gnat simultaneously sucks blood
from its host and injects into him saliva and whatever the saliva
contains. Such description is beyond the scope of this work.
The thorax (fig. 6) bears the wings, the halters (vestigial hind-
wings) and the legs, and is constricted posteriorly by a groove which
cuts off a narrow, posterior strip — the scutellum. Projecting from the
posterior end of the thorax, beneath the scutellum, and overhanging
the first abdominal segment is a dome-shaped prominence — the meta-
notum, or, better, the postscutellum.
The details of the wing-venation are shown in. fig. 1. The vein
forming the margin of the wing is called the costal vein ; that
immediately succeeding it, and meeting the costai vein about half-
way between the base and tip of the wing, is called the sub-costal
vein. Succeeding this, and running from the base nearly to the apex
of the wing, is the first longitudinal vein. The second longitudinal
vein branches from the posterior side of the first longitudinal vein,
and forks into an anterior and a posterior branch near the tip of the
wing. The third longitudinal vein rises from the second longitudinal
vein, and runs unbranched to the margin of the wing between the
posterior branch of the second and the anterior branch of the fourth
longitudinal vein. That short part of it, from where it branches from
the second vein to where it turns towards the margin, is called the
supernumerary cross-vein. The anterior, or mid cross-vein, joins the
end of the supernumerary cross-vein to the fourth longitudinal vein,
■3
which rises near the base of the wing, and is divided into an ant
and posterior branch shortly before it reaches the margin. The fifth
longitudinal vein also rises from near the base of the wing, and
ANTENNA
HEAD
EYE
THORAX
SCUTELLUM
METANOTUM
HALTER
ABDOMEN
HIND LEG
Fir.. 6.— Generalised diagram of n show the nomenclature of •
14
divides about half-way along its course into a curving anterior branch
and a straighter posterior branch. A stout vein, the posterior cross-vein,
joins the anterior branch of the fifth to the fourth longitudinal vein.
The legs (fig. 6) are divided into the following joints, namely
from base to apex, the coxa, trochanter (a very short " corner " joint)
femur, tibia, tarsal joint I, tarsal joint 2, tarsal joint 3, tarsal joint 4,
tarsal joint 5. Tarsal joint 1 is often, in fact generally, spoken of as
the metatarsus ; but I abandon this term as incongruous. The last
tarsal joint ends in a pair of ungues or claws, which may or may not
be toothed. The junction of the femur and tibia is the knee.
The abdomen consists of ten segments, but only the first eight are
readily seen. The last two are modified for reproduction, and are
more or less telescoped into the eighth segment. Generally, all that
can be seen of them are the cerci of the ovipositors (fig. 6), borne on the
tenth segment of the female, and consisting of a pair of short leaf-like
projections ; and, in the male, the great forceps, with their proximal
joints or side-pieces, and their distal joints or claspers (see fig. 59),
terminating in a claw . Smaller accessory organs, harpes and Jiarpagones,
occasionally are present, lying between the large forceps (see fig. 59).
2. THE LARVA (FiGS. 7-12).
The head of the larva bears several pairs of hairs, sometimes so
arranged as to form transverse rows. On the upper surface of the
head these hairs mostly occur on what is generally called the clypens,
a chitinous plate occupying the whole width of the head anteriorly,
but narrowed posteriorly by two converging sutures, which separate
the clypeus from lateral plates of chitin carrying the eyes, and in front
of the eyes the antennae. These clypeal hairs are of great importance
in Anopheles, and it is as well that their nomenclature should be
straightened out. Typically, the clypeal hairs fall into four rows.
The most anterior row is on the anterior edge of the clypeus, and
consists of two pairs of hairs. These two pairs may be called the
inner anterior pair and the outer anterior pair (fig. 7, i.a. and o.a.).
They are present in Anopheles (fig. 7), and have been generally
described simply as " clypeal hairs"; but they are absent in all other
British genera. (A pair of short hairs occurs in front of the clypeal
edge in both Anophelines and Culicines, and may be termed the
<5
pre-clypeal pair (figs. 7, 8, 9. //■.<-.). The second row consists of a
single pair of pre-antennal hairs (figs. 7, 8, g,pr.a.), lying, in AnopJu
(fig- 7). Just anterior to the level of the antennae, but rather in-
differently placed in the Culicines (figs. 8, 9) with regard to this le\
In Culicines, too, the)r are often extremely small and inconspicuous.
The third row consists of three pairs of hairs, the inner, mid, and
outer post-antennal pairs (figs. 7, 8, 9, i.pb.a., mpo.a., o.po.a.), lying
just posterior to the level of the antennae. The row tends to have a
m.po. a
Fig. 7. — Distribution of
hairs on head of Ano-
pheles larva.
Fig. 8. — Distribution of
hairs on head of Tluo-
baldia larva.
FlG. 9. — Distribution of
hairs on hi
li>\ rva.
posteriorly-directed curve. In Ochlerotatus (fig. 9), owing, apparel
to the forward and inward displacement of the mid post-antennal pair,
the second and third rows are confused in arrangement, and the inner
post-antennal pair lies nearly directly behind the mid post-antennal
pair. In the first instar of Ochlerotatus at least, in the sp<
nemorosus, and in Finlaya geniculate the mid post-antennal pair is in
a line with the others. The mid post-antennal pair has a somewhat
intermediate position in Taeniorhynchus, while in Ae'des, Tfuobaldia
(fig. S), Culicella and Culex, their position i- normal. The fourth 1
1 6
STIGMA
Fig. io. — Larva of an Anopheline gnat {i.e., of the genus Anopheles). Dorsal, view. The
ninth abdominal segment is twisted round so as to present a lateral view, to show
the fin.
ANTENNA
EYES
TERZt i
IX™ ABDOMINAL
SEGMENT
BRUSH
HEAD
ABDOMEN
SIPHON
ANAL GILLS
TUFTED HAIR
STIGMA
FlG. ii. — Larva of a Culicine gnat (/.*., one of a genus ol
species figured is A nereus). Dorsal view. The eighth and ninth ab i
segments are twist ! so as to present a lateral view to show I
comb and fin.
i8
consists of a single pair, the vertical hairs (figs. 7, 8, 9, v), which are
always very small. In a row with them and just across the suture is
another pair of very small hairs, which may be called the trans-sutural
pair (figs. 7, 8, 9, tr.s.) ; while a third small hair, the ocular hair (figs. 7,
8, 9. 0), lies in the neighbourhood of the eye. The hairs on the lower
surface of the head have not been used to distinguish the species, and
consequently are not described in detail.
On the head (figs. 10, II, 12), laterally, is a pair of antennae, and
Maxilla
Triangular
plate
Labial
sclerite
Fig. 12. — Ventral view of head of Anopheles.
posteriorly to these a pair of eyes. Each eye is divided by a constric-
tion into a larger anterior portion and a smaller posterior portion,
which may be completely detached. Ventrally and anteriorly (fig. 12)
the head bears a pair of brushes on lateral lobes of the labrum called
flabellae; a median lobe-like pala turn also bears a tuft of hairs (omitted
to save obscurity in fig. 12). In the middle of the ventral surface
of the head are mouth-parts, of which'the most prominent are the
heavily-chitinised teeth of the mandibles, and the labial sclerite of the
labium, against which the mandibles appear to bite. The maxillae
19
are more or less flat, inconspicuous organs with fringed edges. It is
difficult to see that the maxilliary palp is connected with its maxilla ;
on the contrary, it appears at first sight to be an independent organ.
It is often minute in Culicine larvae, bill larger and somewhat
prominent in Anophelines. The labium is a complex structure, con-
sisting of four members placed one upon the other in dorsal-ventral
sequence, like the leaves of a book. Ventral-most and outermost is a
plain, wide, tongue-shaped chitinous flap, the labial flap. Next a
this is a more or less triangular plate, feebly chitinised, with toothed
free edges and often fringed with long hairs. Dorsal to this triangular
plate is the heavily-chitinised labial sclcriU\ also triangular, and in
shape very closely resembling a shark's tooth. Lying dorsal to the
labial sclerite is the labium proper, a peculiar structure more or less
shaped like a hollow cube, with the posterior and lateral faces repre-
sented only by a framework and the ventral face narrowed to a bar.
On the dorsal and anterior faces are numerous chitinous teeth.
The thorax and abdomen (figs. 10 and 1 1) of the larva are character-
ised by numerous hairs of various shapes- simple, branched or tufted.
The eighth abdominal segment bears a pair of stigmata dorsally, and
laterally an arrangement of flattened hairs or scales called a comb.
Each scale is posteriorly directed, fringed with minute cilia-like hairs,
and often terminates in a stout spine or bristle. Primarily, the comb
appears to consist of a dorsal-ventral row of flattened hairs or scales
lying parallel with one another. In the Anophelines the scales retain
their primitive parallel condition, but are united at their bases by a
broad band of chitin so as to form a comb-like structure (fig \;.
89-91, 95-97). Moreover, the band is continued dorsal-wards, and.
passing posteriorly to the stigmata, is continuous with its fellow on the
other side. A second comb-like structure, lying somewhat anteriorly
and ventrallv to the comb, is present in the first instar in Anopk
(figs. 100, 101, ioitf). In most adult Culicines the primitive single row
of parallel comb-teeth becomes broken up into a more or less confused
group, though the teeth tend to remain parallel and directed posteriorly.
Finlaya geniculata, however, and the first instar of those Culicines in
which this stage is known, retain the primitive single-row arrangem-
of their comb-teeth.
In the Culicines the stigmata opening on the eighth segment
2
20
carried up to the end of a long median projection called the siphon
(fig. u). This is heavily chitinised on the distal half only in the first
instar, but throughout its length in succeeding instar. It carries one
or more pairs of tufted hairs (simple in the first instar) ; and on each
side, on its proximal half, a row of flattened toothed scales somewhat
resembling those of the comb. Each of these rows is called a pecten,
each scale composing it is a pecten-tooth, and each projection on a
pecten-tooth is a denticle. The anus is situated at the end of the
ninth abdominal segment, and is surrounded by four thin-walled
papilliform processes, the anal gills. Ventrally, the ninth segment
carries a series of tufted hairs arranged in an antero-posterior row
approximately in a median plane, but actually alternately a little to
left and right of the mid-line. They are inserted on chitinous trans-
verse bars, which viewed from the ventral side of the larva have a
gridiron-like aspect. Collectively, these median hair-tufts form a
rudder-like fin, which probably steadies the floating larva by pre-
venting a rocking motion, and adds power to a sweep of the tail for
purposes of motion. In those forms in which the first instar has been
observed this fin is absent, and its place is taken by simple posteriorly-
directed appressed bristles.
II. IDENTIFICATION.
A. IMAGO.
i. TO DISTINGUISH THE SEXES.
In identifying British gnats it is necessary first to distinguish the
sexes. When a specimen is secured, the question whether it is a male or
a female must be determined before the following keys can be used.1
Luckily, to determine the sex is a simple matter, for there are two
easily-seen characters which afford infallible tests, namely, the structure
of the antennae and the shape and appearance of the distal end of the
abdomen.
1 The keys for identification here used are founded upon those given by F. W. Edwards,
1^12, The Entomologist, vol. xlv., pp. 191, 217, 260 ; moreover, further information
given in these and other papers by the same author has been freely used, and much help has
been rendered me by Mr. Edwards in correspondence and conversation, for which I take
this opportunity of tendering him my best thanks.
2 I
In both sexes there are whorls of hairs on the greater part of the
antennae, a whorl at each joint, except distally. But, while in the female
the hairs forming these whorls are scanty, so that to the unaided eye
the antennae are inconspicuous; in the male these whorls are so dense,
and the hairs composing them so long, that the antenna as a whole
appears as a thick plume, and the pair of antennae form, with the
palps, the most conspicuous feature of the head. Figs. 13 and 14
show, respectively, the antennae of a male and a female gnat.
T1£I=I.Zt ,
Fig. n. — Antenna of male Aides ciiu
Fie. 14.— Antenna of femal-
The abdomen of the male gnat (fig. 15) is, on the whole, club-
shaped. It is somewhat narrower anteriorly, swell- rather quickly
towards the posterior end, begins to taper rapidly, and then is
truncated. It terminates in a pair of rod-like bodies bearing many
long and stiff hairs, and generally lying side by side, but sometimes
somewhat diverging. These are the side-pi< f the forceps
22
largest pair of clasping organs, and each bears distally and jointed
with it a long thin bristle-like clasper, hardly visible to the naked
eye, and generally bent at least at a right angle to the stout side-
piece.
The abdomen of the female (fig. 16) is widest near the middle,
tapers very slightly anteriorly, more decidedly in a posterior direction
to more or less of a point, and ends in a pair of small leaf-like cerci,
sometimes called ovipositors. Ventrally there is a median, lobed
Fig. 15. — Abdomen of i Anopheles
maadipennis.
Fig. 16.— Abdomen of 9 Culex
pipiens.
unpaired piece. The ovipositors cannot be mistaken for the forceps of
the male, being of a far smaller size as well as of a very different
shape.
It should also be noted that in every British form, except Aedes
cinereus, the palps of the male are longer than the proboscis ; and in
every British genus, except Atwpheles, those of the female are much
shorter than the proboscis.
2. TO IDENTIFY THE GENERA.'
a. Males.
When the sex of a specimen has been determined, it is possible to
discover its genus by means of the following instructions. If the
specimen is a male, the palps afford the greatest help for this
determination. At'des is at once known by its palps which resemble
those of female Culicines, being less than one-sixth the length of the
proboscis (fig. if). Aides may also be known by the wide distribution
of broad, flat scales on the head (fig. 29). In most gnats the flat-lying
(as opposed to the up-standing) scales on the head are nearly all
narrow, the few broad ones being confined to the lower and posterior
Fl<;. 17. — Head of male Aides cinerais, from the side, to show the short palp.
parts of the sides of the head. In Aides, the broad scales invade the
crown, and the narrow scales on the top of the head are confined to
a median crest. This is so in both sexes.
In all British gnats other than Aedes, the palps in the male> are
longer than proboscis, and, lying on each side of that organ, appear
as feeler-like structures, thickly scaled, and with certain areas of their
distal parts densely clothed with long, fine hairs. They are five-
jointed, though the scaling and tufts of hair often obscure the
boundaries of the joints. In Anopheles (fig. 18), the last two joints
are short and thick, and together form a hairy head to the long
slender stalk formed by the proximal joints. The whole palp some-
what resembles a golf-club. Anopheles is also distinguished from all
1 The diagnostic characters do not necessarily hold outside the British species.
24
other British gnats by the abdomen (see fig. 15) which, except for
numerous outstanding hairs, is naked, and has none of the scales
which densely clothe the Culicine abdomen in both sexes (see fig. 16).
The scutcllum, too (see figs. 42, 43), is narrow, and not markedly
trilobed as in Culicine genera (fig. 22).
1
y
m
Ilk '.I r'i
18
20
■wz
TEFIZI—I
21
Fig. 20. — Palp of male Och-
krotatus caspius. (Xote :
the palp of male Tae-
?i iorhynch us rich ia > < Hi
is of this type.)
Fig. 18. — Palp of male
A ncpheles maculipennis
(from above).
Fig. 19. — Palp of male
Calex pipiens (side view).
Fig. 21. —Palp of male T/ieo-
baldia annulata. (Note :
the palp of male Culi-
cella is of this type.)
The male Culex has very distinctive and easily-distinguished palps
(fig. 19). The terminal two joints, though hairy, are thin, taper
distally, and are curved upwards through an angle of nearly 90°.
The remaining genera have palps very much alike. The last two
joints are long compared with those of Anopheles, and do not turn
upwards through an angle of 90 like those of Culex. In Ortlio;
myia the last joint is about as thick as, but only about a third as long
as the last but one. In Tlieobaldia (fig. 2i), and Culicella the
Fig. 22. — Scutellum of a Culicine gnat.
joint is somewhat thicker than the last bu"t one, while in 0 elder otatus
(except in 0. rnsticus), Finlaya and Taeniorhynchus it is slightly
thinner (fig. 20). The hairs, however, render this difference somewhat
FlG, 23. — Male genitalia of Cuh
obscure, and the genitalia are a more convincing guide. If the end of
the abdomen is cut off, boiled for about five minutes in a fairly sti
solution of caustic potash, placed on a microscope-slide, and th -
pieces separated with needles, even a fairly low-power lens will n
26
the remarkable difference in type between the genitalia of Theobaldia,
Culicella and Orthopodomyia on the one hand (fig. 23), and Ochlerotatus,
Finlaya and Taeniorhynchus on the other hand (figs. 59-66). Theo-
baldia annulata (the only British species of Theobaldia) may at once
be known from Culicella and OrtJiopodomyia by having spotted wings ;
Orthopodomyia albionensis (fig. 130) is a black form with thin, white
Fig. 24. — Femur, tibia and tarsus of hind-leg of male Taeniorhynchus richiardii.
lines on the thorax ; and Taeniorhynchus richiardii can be dis-
tinguished from Ochlerotatus by the first hind-tarsal joint which has
a median pale band (fig. 24). In Ochlerotatus, too, both the claws of
the fore- and mid-feet are toothed in both sexes ; while in Taenio-
rhynchus the smaller claw on these feet is simple (figs. 25 and 26).
Fig. 25. — Claws on fore-foot of male
Ochlerotatus caspius.
Fig. 26. — Claws on fore-foot of male
Taeniorhynchus richiardii.
Finlaya geniculata, the only British species of the genus, differs from
the British species of Ochlerotatus in the pattern of the abdominal
segments. The light portions of the abdomen consist of a lateral
pair of brilliant white triangular spots on each abdominal segment
(fig- 58) ; while each segment in Ochlerotatus has a more or less
complete pale band (figs. 51-57).
- /
The following key summarises the generic differences detailed
above : —
Mai es.1
A. Abdomen without scales (fig. 15). Last two joints of the palps
short, and together form the head of a club-shaped palp
(fig. 18). Scutellum narrow and not markedly trilobed
(rigs. 42, 43) I. Anopheles.
B. Abdomen densely clothed with flat imbricating scales [fig. I
Scutellum wider and distinctly trilobed (fig. 22 .
/ 1. Palps not one-sixth the length of the proboscis (fig. i-
Flat-lying scales on the crown of the head nearly all wide «
(fig. 29) II.
II. Palps about as long as the proboscis. Flat-lying scales
on the crown of the head all narrow (fig. 28) ; wide scales
confined to a few at the sides of the head posteriorly.
a. Last two joints of the palps tapering and upturned through
an angle of nearly 90 degrees (fig. 19) . . . .VIII. Culex.
b. Last two joints of the palps not upturned.
1. Terminal joint of the palp slightly thicker than the
last but one (fig. 21). Genitalia of male of the type
shown in fig. 23.
' a. Wings spotted. Posterior cross-vein nearly in a line
with mid cross-vein (fig. 33). Second abdominal
segment with a pale median stripe (fig. 36) .
< (3. Wings plain. Posterior cross-vein, though near mid
cross-vein, yet not nearly in a line with it (fig. 34 .
Second abdominal segment without a pale median
stripe (fig. 37)
Terminal joint of the palp slightly thinner than the last
but one (fig. 20), except in Ochlerotatus rusticus.
( Genitalia of male of the type shown in figs. 59-66.
a. Smaller claw on fore- and mid-feet simple (1
Firsthind-tarsal joint withmedian pale riny ii^.24 V*. Taeniorhynchus.
/3. Both claws on fore- and mid-feet toothed tig. 25
First hind-tarsal joint without median pale ring.
1 i. .More or less complete, pale, abdominal band- :
palps slightly longer than proboscis
ii. Brilliant, white, triangular lateral abdominal
spots (fig. 58) ; palps slightly shorter than
proboscis .....-•
Terminal joint of the palp about as thick as, and only
a third as long as the last but one. Genitalia of the
type shown in fig. 23 IX. Ortkop
(O. albioncnsis a black species with thin white lines
on thorax.)
VI. Theoba
VII. Culicella.
V
III. Ochlerotatus.
1 V. / in
1 See also characters of Stegon a p. 112.
28
/;. Females.
To determine the genus of a female mosquito, the palps are not
conspicuously useful, except in Anopheles and OrtJiopodomyia. The
female Anopheles has bristle-like palps about as long as the proboscis
(fig. 27), in OrtJiopodomyia (fig. 130) they are little more than a third
as long, while in all the other female British Culicines the palps are
not one-fourth as long as that organ (figs. 28, 29).
The females oiA'e'des, Ochlerota tns, and Finlayahave long-tapering
abdomens, and the first two have long cerci (figs. 51-58) ; while in the
Fig. 28. — Head of female
Ochlerotatus c as phis.
Fig. 27. — Head of female
Anopheles maculipcnnis .
Fig. 29. — Head of female
Acdes cinereus.
female Taeniorhynchus, Theobaldia, Culicelta, and Culex, the abdomen is
blunt, and has short cerci (fig. 16). The claws of the fore- and mid-feet,
too, are toothed in the three first-named genera (fig. 30) ; and those of
the last four genera plain (fig. 31). As in the males of Aides and
Ochlerotatus, the scaling of the head distinguishes also the females of
these genera ; for broad, flat-lying scales nearly cover the crown in
Ai'des, while in Ochlerotatus they are confined to small patches at the
sides posteriorly (figs. 28, 29) ; and again, the brilliant, white,
triangular, lateral, abdominal spots of Finlaya geniculates separate
this species from the British species of Ochlerotatus, which have more
or less continuous pale abdominal bands (figs. 51-58). Taeniorhynchus,
Theobaldia,and Culicella differ from Culex in the first hind-tarsal joint,
which is shorter than the hind tibia (fig. 24), while in Culex it is
about as long or longer (fig. 32).
The fork, too, of longitudinal vein 2 in Culex is decidedly 1<
Fig. 30.— Claws of fore-foot of
Ochlerotatits caspius female.
FlG. 31. — Claws of fore-foot of female
Culicclta morsitan .
FlG. 32. — Hind-leg of Culex pip;
l'!''- 33~ Distal [>:irt of wing of
and its stalk (that is, the part of the vein between the fork and the
cross-veins) correspondingly short (fig. 1 » ; while both fork and stalk
of longitudinal vein 2 in Taeniorhyncfius, Tkeobaltlia, and
moderately long (fig. $$).
In Tfieobaldia, the cross-veins of the wing are nearly in a line
(fig. 33), the wings spotted, and the second abdominal segment has
a median pale stripe (fig. 36) ; in Culicella, the posterior cross-vein is
distant from the mid cross-vein not more than its own length (fig. 34),
the wings are plain, and the second abdominal segment has no median
pale stripe (fig. 37) ; while in TacuiorJiyiicJnts the posterior cross-vein
Fig. 34. — Cross-veins and parts of veins
2, 3, 4 and 5 in wing of Culicella
morsitans.
Fig. 35. — Cross-veins and parts of veins
2, 3, 4 and 5 in wing of Taeniorhyn-
chus richiardii.
FlG. 36. — Second abdominal segment
of female Theobaldia annulata.
Fig. 37. — Second abdominal segment of
female Culicella morsitans.
FlG. 38. — Scales from third longitudinal
vein of wing of TacniorJiynchus richiardii.
Fig. 39.- — Scale from third longitudinal
vein of wing of Culicella morsitans.
is distant at least its own length from the mid cross-vein (fig. 35),
the wings are speckled with light and dark scales, and there is no
median pale stripe. Besides, the wing-vein scales of Taeniorhynchus
(especially the lateral wing- vein scales) are much wider than
those of Theobaldia or Culicella (figs. 38, 39).
31
The following key summarises these female charact-
l'l MALES.1
A. Abdomen without scales (fig. 15 . Scutellum narrow and not
markedly trilobed fig. 42). Pali rly as 1 the
proboscis (fig. 27) ... . \. Anophel
B. Abdomen densely clothed with imbricating scale 16).
Scutellum markedly trilobed (fig. 22). Palps not one quarter
the length of the proboscis (figs. 28, 29).
' I. Abdomen long-tapering and pointed (figs. 51-58 . Fore-
and mid-feet with toothed claws (fig. 30).
( a. Flat-lying scales on crown of head mostly broad . . II. .
\ b. Flat-lying scales on crown of head all narrow.
( i. More or less complete pale abdominal bands ; ceni long \W.Ochlerotatus.
\ ii. White, triangular, lateral abdominal spots ; cerci short IV. Fin lava.
II. Abdomen slightly tapering and blunt (fig. 16). Fore- and
mid-feet with untoothed claws (fig. 31).
a. First hind-tarsal joint shorter than the hind-tibia fig. 24 .
Second longitudinal vein with moderately long stalk and
fork (tig. 33).
' 1. Posterior cross-vein separated from, mid cross-vein by
at least its own length (fig. 35). Wings speckled with
dark and light scales. Wing scales broad (fig. 38 .
Second segment of abdomen without pale median
stripe ........ Y. Taeniorhynchus.
. Posterior cross-vein separated from mid cross-vein by
less than its own length (fig. 34). Wings plain.
Wing-scales narrow (fig. 39). Second segment of
abdomen without pale median stripe (tig. 37) . VII. Culicella.
. Posterior cross-vein nearly in a line with mid cross-
vein (fig. 33). Wings with spots. Wing-scales narrow.
Second segment of abdomen with a median pale stripe
(fig. 361 VI. Theobai
b. First hind-tarsal joint as long or longer than the hind-
tibia .fig. 32 . Second longitudinal vein with long fork
and very short stalk (fig. 1) . . . . .VIII. Culex.
C. Abdomen and scutellum as in B. Palps a little more than
one third the length of the proboscis (fig. 130) . . IX. O/t/io/
In addition to the points above mentioned, a character at the
distal end of the hind-tibia is sometimes useful in distinguishing the
genera, and is applicable to both sexes. In Ochlerotatus ami A
for instance, there is a straight row of numerous bristles nearly at the
apex of the hind-tibia. This is nut apparent in Cu/ex, Culicella
Theobaldia.
Jee also c . • 1 1 -•
32
3. TO IDENTIFY THE SPECIES.
When the genus of a specimen has been determined, it is possible
to go on to consider the particular species. There is only one
British species in each of the genera Acdes, Taeniorhynchus, Finlaya,
Theobaldia and Ortho-podomyia ; so that these genera do not at
present concern us. On the other hand, Culicella and Culex each
have two; Anopheles three, and Ochlerotatus eight, British species;
and each of these genera will now be dealt with in turn.
&>
a. Anopheles.
Generally speaking, the three British species of Anopheles are
easily distinguished, and it is only occasional specimens that give
trouble. A . maculipennis is known at once by its spotted wings ;
and A. plumbeus is smaller and darker than A. bifurcatus, besides
having a blackish thorax and ashy-grey streaks, instead of the brown
thorax with pale streaks of A. bifurcatus. In some characters (e.g., the
breadth of the scales of the wings) A. bifurcatus is intermediate
between A. maculipennis and A. plumbeus, so that doubtful specimens
lie between A. maculipennis and A. bifurcatus on the one hand, and,
on the other, between A. bifurcatus and A. plumbeus. Thus, the
spots in A. maculipennis may be feebly developed, while the wing-
scales of a specimen of A. bifurcatus may be particularly abundant,
and tend to be massed at those parts of the wing where the aggregated
scales of A. maculipennis form spots. (The same tendency may be
observed in Culicella morsitans and C. fumipennis, thickly-scaled
specimens of which show a tendency to a spotted condition, owing to
the scales being more thickly crowded in places where in Theobaldia
anuulata they are aggregated to form spots.) Or a small, dark
specimen of Anopheles bifurcatus may appear very much like
A. plumbeus. It is useful, therefore, to notice one or two other points
of difference between the three species of Anopheles.
I. In the middle of the anterior end of the thorax, on its upper
surface, is a tuft of thin, hair-like scales. In A. maculipennis these are
straw-coloured, very thin, and tend to be somewhat loosely distributed
(fig. 40;. 1 In A. bifurcatus and A. plumbeus they are decidedly whiter,
; In fig. 40 the scales are rather too closely aggregated.
broader, and more densely aggregated (fig. 41 >. In A. plumbeus they
are even whiter in colour and broader than in A. bifurcates ; but the
character of this scale-tuft is of more use in distinguishing A. maculi-
pennis from A. bifurcates, than A. bifurcatus from A. plumbeus.
2. The posterior outline of the scutellum of A. maculipennis and
A. bifurcatus is a fairly regular curve, convex posteriorly (fig. 42). In
FlG. 40. — Fore-part of thorax of Anopheles FlG. 41. — Fore-part of th
maculipennis , viewed from above and bifurcatus, viewed from al ! in
in front. front.
A. plumbeus it is somewhat flattened or even slightly concave at the
sides (rig. 43). The whole scutellum is slighter in A. plumbeus, and.
the median tubercle smaller and more compact. In A. maculipennis
the median tubercle is more diffuse and swollen than in A. bifurcatus
and the lateral tubercles smaller. But the characters of the scutellum
. 42. — Scutellum of Anop
bifurcatus.
Fig. 43.
are more useful in distinguishing A. plumbeus from ./. bifurcatus than
A. bifurcatus from A. maculipennis.
3. The male genitalia differ considerably in the three species, not
only in the details of the smaller parts, but in the forceps them-
selves. If one of the stout basal joints or side-pieces ol the forceps is
isolated, besides the rather limp curved hairs with which especially
D
the distal end is plentifully provided, a single, straight, stiff bristle
will be seen projecting from the inner edge of the side-piece ;
and a pair of stouter bristles arise from the ventral surface of the
side-piece near its base. In A. maculipennis and A. plumbeus (figs. 44
and 46) the single bristle springs from near the middle of the inner
side ; and in A. bifurcatus (fig. 45) from near the apical end of the
side-piece. In A. maculipennis the paired bristles (especially that on
the inner side) are borne on a projection or lobe of the side-piece
(fig. 44) ; in A. plumbeus they are inserted directly on the side-piece
(fig. 46). In A. bifurcatus (fig. 45) the inner one is borne on a slight
Fig. 44. — Left forceps of Fig. 45. — Left forceps of Fig. 46. — Left forceps of
genitalia of Anophcks genitalia of Anopheles genitalia '[ of Anopheles
maculipennis, from be- bifurcatus, from beneath. plumbeus, from beneath,
neath.
projection, but the outer one is directly inserted ; moreover, this outer
bristle is double, flattened, and frayed distally into several branches.1
These differences may be tabulated as follows : —
Anopheles.
Obvious Characters—
' A. Wings spotted
B. Wings plain.
/ I. Thorax brown, with pale longitudinal bands ; larger
species ........
1 1. Thorax blackish, with ashy-grey longitudinal bands ;
1. A. maculiperuiis.
smaller species
2. A. bifurcatus.
3. A . plumbeus.
1 This has been noticed and figured by S. R. Christophers, 1915, Indian Journal of
Medical Research, vol. iii., p. 378, pi. xx., fig. 1. Christophers, following Felt, calls
the paired bristles " claspettes."
35
Less obvious Characters —
A. Wino-scales less crowded and narrower; hair-like scales
of thoracic tuft very narrow, less densely aggri tnd
straw-coloured (fig. 40); posterior outlin< utellum
forming an even curve: median tubercle of scutellum
very diffuse and tumid ; lateral tubercles small . 1. A.maculip
B. Wing-scales more crowded and less narrow ; bair-like
scales of thoracic tuft not so narrow, more densely
aggregated, and white (fig. 41 ; posterior outline of
scutellum forming an even curve (fig. 4: ; median
tubercle of scutellum tumid, but not so diffuse as in
A. maculipennis ; and lateral tubercles larger . . 2. A. bij
C. Wing-scales more crowded and rather broad : hair-like
scales of thoracic tuft broad, more denser) aggregated,
and white ; posterior outline of th( - ''Hum flattened,
or even slightly concave, laterally (fig. 43: : median and
lateral tubercles small and well-defined . . .3. A.plunv
Characters of the Male Genitalia —
A. Single bristle is near the apical end of the side-piece. The
inner one of the paired bristles carried on a small pro-
jection : the outer inserted directly, double, flattened and
much frayed distally (fig. 45) . . . . .2. A. bifurcatiis.
1 B. Single bristle is near the middle of the side-piece.
I. Paired bristles (especially the inner one) carried on
projections or lobes of the side-piece (fig. 44) 1. A. maculipennis.
II. Paired bristles inserted directly on the side-piece
tig. 461 . . . . . . . .3. A.plnmbt
b. Ochlerotatus.
\
I
The eight British species of Ochlerotatus fall readily (for purpos
of identification) into two groups, one (figs. 47 50), including 0. easpius,
0. curriei, 0. vexans, O. waterhousei and 0. annulipes, having white
bands on the hind-tarsal joints ; and the- other, represented by the
species 0. detritus, O. nemorosiis, 0. rustiats, having uniformly dark
hind-tarsi. Apart from the white banding, the tarsi and le_;s genera
in both groups may be speckled with light scales, giving a pepper-
and-salt appearance to these structures ; and the wings in both
groups may have dark scales only or with but very (c\v white sea
(O. vexans in the first, and all except 0. detritus in the second grot;
or may have mixed light and dark scales, so as g< nerally to ha\ a
speckled look. The chief remaining characters for diagnosing the
species are those exhibited by the abdominal pattern- 5
and the male genitalia (figs. 59 65).
D 2
3^
FlG. 47. — Right hind-leg of 0. caspius.
Fig. 48. — Right hind-leg of 0. vexans.
FlG. 49. — Right hind-leg of 0. water Aottsei.1
Fig. 50. — Right hind-leg of 0. annulipes.
Fig. 51.— Abdomen Fig. 52. — Abdomen Fig. 53.— Abdomen Fig. 54. — Abdomen
of female 0. cas- of female 0. of female O. water- of female 0. annu-
pins. vexans. housei, //pes.
1 The sprinkling of dark scales on the proximal and ventral parts of the femur should
be a little more pronounced in fig. 49.
In the first group, O. Crispins and 0. curriei arc at on< vn by
the white bands embracing the distal end of one tarsal ; the
proximal end of the next (fig. 47). In the other speci<
band occupies only the proximal end of each joint. O. caspi
easily recognised by the bright chestnut-orange colour of the th
with whitish stripes, and by the same sharply-contrasted ci on
the crown of the head. Thus, even a very much rubbed specimen m
V
.K?
I
,
! 55. — Abdomen Fig. ^,6. — Abdomen Fig. 57. Abdomen Fig. 5S.—
of female O. of female O. nemo- female O. >v.
detritus. ro.'
often be identified with certainty. 0. curriei, on the other hand, has
the top of the thorax dullish brown, with a pale band <>n each side.
O. caspi/ts has broad, mixed light and dark scales on the win:
the male genitalia are shown in fig. 59 ; while (\ curri i ha- 1
wing-scales, and the scales on longitudinal veins 3 and 5. and en the
forks of 4, are mostly dark.
In O. vexans the white bands at the proximal en the tai
joints are very narrow (fig. 48) ; while in 1
Fig. 59. — Genitalia of male Ochlerotatus
caspius. a.l. Apical lobe. b.l. Basal
lobe. c. Clasper. cl. Claw. h. Harpe.
ho. Harpago. s. Side-piece.
Fig. 60. — Genitalia of male 0. ve.xans.
ho. Harpago.
Fig. 61. — Genitalia of male 0. waterhousei. FlG. 62.— Genitalia of male 0. annidipes.
FlG. 63. — Genitalia of male 0. detritus.
Fig. 64. — Genitalia of male 0. nernoro
1 1 . 65. — Genitalia of male 0.
. — ( lenitalia
40
G. annulipes (fig'. 50) the bands of the last four tarsal joints are
wide, occupying nearly half the joint in the latter, and about a
third in the former species. 0. vexans^ too, has only dark scales
on the wings, while the wings of the other two species have the
pepper-and-salt appearance due to a mixture of light and dark scales.
Its genitalia, too, have a remarkable form (fig. 60). Again, the
undulating posterior border of the pale abdominal bands is character-
istic of O. vexans (fig. 52).
O. waterkousei and 0. annulipes are not so easy to distinguish.
The males are best distinguished by the genitalia, which are markedly
distinct (figs. 61 and 62). And there is a difference in the coloration of
the thoracic scales of the females, though it is not easy of application
(see F. W. Edwards, 191 2, The Entomologist, vol. xlv., p. 194). In
both, the ground-colour of the thoracic scaling is deep golden brown,
and on this there are pale longitudinal markings of a brassy colour.
In the females of 0. annulipes the ground-colour is richer, and the
lighter brassy lines yellower and brighter ; so that the thorax of
( '. annulipes looks yellower and that of O. waterkousei browner.
But the best general characters are in the hind-femur, and in the
pattern beneath the abdominal segments. The outer surface of the
hind-femur is fairly evenly sprinkled with dark scales in O. waterkousei
(fig. 49), though proximally and ventrally they are not so numerous
as distally and dorsally. The outer side of the hind-femur of
0. annulipes is similar distally and dorsally, but proximally and
ventrally it is almost destitute of dark scales (fig. 50). This difference
is more pronounced in the females than in the males. On the under-
side of the abdomen of O. annulipes the dark markings form a
continuous median stripe with slight lateral projections ; while in
O. waterkousei they form transverse stripes, and the median stripe is
generally obscure or absent. The proboscis, also, in O. annulipes is
yellow on the underside except at the base and tip ; while in 0. water-
kousei it is merely pale.
In the second group O. detritus is unique for having mixed light
and dark scales on the wings (figs. 67 and 68). Otherwise it very
closely resembles O. nemorosus (which may have some white scales
on the sub-costal vein), but there is generally a sprinkling of white
scales on the dark portions of the abdomen above (fig. 55), and the
4 J
legs are more plentifully sprinkled with white scales than I
nemorosus ; moreover, the male may be known by its genita
In 0. detritus, 0. nemorosus, and O. rusticus, the abdom< n is .irk
above, with more or less continuous transverse pale bar the
proximal end of each segment. As has already been
O. detritus may be known from the other two s by the pale-
scales on the wings as well as by the sprinkling of pali the
dark parts of the abdomen. 0. nemorosus differs from I
chiefly in the paler, almost white tint of the abdomin and
their tendency to widen laterally rather than in the mid-lin
In O. rusticus, the pale abdominal bands are yellower, and, in the
female, tend to widen medianly to form a continuous line I t; In
the male this median line appears only on the second nent.
The male genitalia are shown in fig. 65 ; and even to the
0. rustic us may be distinguished by the dense clothing of hairs
on the side-pieces.
Fig. 67. — Stalk of fork of second
Ions', vein of Ochlerotatus detritus.
of fork o!
long, vein in Ochlerotatus >.
The following tables summarise these differed
Ochlerotatus. — General characters.
A. Hind-tarsi with pale bands.
t I. I 'ale bands embrace ends of contiguous tarsal join!
Tale bands on abdomen overlap the junctions of the
segments and are continuous with a median longitudinal
band (fig. 5 1 .
a. Wings speckled with broad, light and dark
bright cliestnut-orange with pale longitudinal mark 1
. Wing scales narrower, wings speckled, but
and fifth, and forks of fourth chief!)
dark; top of thorax brown in the n tnd pal<
the sides .....-•■
.
42
II. Pale bands only at proximal ends of tarsal joints (figs. 48-
50). Pale bands of abdomen chiefly at proximal ends of
abdominal segments, and no median abdominal stripe
(figs. 52-54).
'a. Tarsal pale bands very narrow (fig. 48). Only dark scales
on the wings ....... 3-0. vexans.
/>. Tarsal pale bands occupying one third to half of each
tarsal joint, except the first (figs. 49, 50). Wings
speckled with light and dark scales.
1. Outer side of hind-femur sprinkled with black scales
on the proximal and ventral part (fig. 49). Pale
markings on thorax whitish in female. Basal lobe
of side-piece in male with a tuft of strong bristles
basally, and a long, hairy, lobe-like basal extension
(fig. 61). Proboscis in both sexes pale beneath in the
middle ........ 4. O. ivatcrhousei.
2. < Hiter side of hind-femur without black scales on the
proximal and ventral part (fig. 50). Pale markings
on thorax of female bright yellowish. Basal lobe
of side-piece in male without a tuft of strong bristles,
and without a long, hairy lobe-like extension
rig. 62). Proboscis of both sexes yellow beneath in
the middle ....... 5. O. aniutlipcs.
B. Hind-tarsi entirely dark.
I. Wings speckled with light and dark scales (fig. 67).
Dark portions of abdominal segments sprinkled with
white scales (fig. 55) ...... 6. O. detritus.
II. Wings with dark scales only (fig. 68) — a few light scales
on the sub-costal vein in V. ncmorosus —
' a. Abdominal bands whitish, widening laterally, but not
medianly (fig. 56) ..... 7. O. nemorosus.
/. Abdominal bands yellowish, widening medianly in the
female, so as to tend to form a pale median line
tig. 57). In the male a median line only on segment 2.
The genitalia are very hairy (fig. 65) ... S. O. msticus.
W
\
2. Ochlerotatus and Finlaya. — Male genitalia (figs. 59-66).
The most obvious structures of the male genitalia of Ochlerotatus
are the proximal joints of the outermost pair of grasping organs, or
forceps. Each of these large proximal joints, or side-pieces (fig. 59, s.)
has hinged to its distal end a more or less slender hook, the clasper
(fig. 59, c), which itself is terminated by a thin claw (fig. 59, ci). On
the inner side, each side-piece is more or less divided- longitudinally
into a dorsal and ventral flap. The dorsal flap generally has a more
or less straight edge, but the ventral flap generally has pronounced
apical (fig. 59, a.l.) and basal lobes (fig. 59, b.l). The apical lobe is
r3
Ki v to Male Genitalia in British Spe< ies 01 Ochlerotatus and Finldya.
A. Claspcr much flattened and becoming wider distally : apical
lobe very small ; basal lobe very wide and projecting but
little. Harpago with somewhat globular apex . . 3.
B. Clasper narrow and tapering distally ; apical joint of harp, 1
more or less strap-shaped or expanded, but never globuli
I. Outer and inner edges of side-pieces nearly parallel, and
strongly and regularly curved, the whole side-piei
narrow and forming the arc of a circle ; apical lobe
ventral flap hardly existent; only the distal part of the
basal lobe developed, and this is prolonged into a narrow
arm-like projection with expanded hand-like end ; the
bristles of the tuft at the base of the basal lobe are ex-
ceedingly long, and extend along the ^dge of the ventral
flap as a dense fringe of very long hairs ; claw of clasper
undulating; distal joint of harpago spatulate . . O.rusticu
II. Outer edge of side-piece neirly straight or slightly curved ;
inner edge of dorsal flap more or less undulating ; lobes of
ventral flap variously developed.
Apical lobe of ventral flap very slightly developed : distal
joint of harpago strap-shaped.
1. Basal lobe of ventral flap projecting abruptly and bear-
ing a few specially large bristles basally ; three small
notches on outer side, and one on inner side of
clasper, near its tip — a hair springs from each . I. O. casj,
2. Basal lobe of ventral flpp forming but a slight, rounded
prominence, and has no specially large basal hairs ;
clasper without any hair-bearing notches near its tip,
or with but one .... 9. Finlaya geniculata (fig. 66).
b. Apical lobe of ventral flap prominently developed, even if
small ; basal lobe abruptly prominent.
1. Basal lobe carried on a broad base ; near the tip of the
clasper, and on its outside, four or rive little hair-
bearing notches— on the inside, none ; distal joint
( of harpago strap-shaped ; one large bristle at base
of basal lobe ~. U. >:
Basal lobe, if prominent, carried on a comparatively
narrow base and more or less conical in shape.
a. Edge of dorsal flap sharply undulating ; basal lobe
not prominent, and not distally produced; distal
joint of harpago flattened, about twice as loi
wide, with a rather narrow, delicate, rounded,
selvedge-like expansion ... 5. 0. ami:,.
ti. Edge of dorsal flap nearly straight; basal lobe with
a prominent tuft of long bristles, and distally drawn
out into a spatulate expansion ; distal joint of
harpago not much flattened, but with a very deli-
cate flag-like expansion on one side • 4- O. a
■y. Hdge of dorsal flap nearl) straight : a few extra-
large bristles at proximal end of the basal lobe ;
no apical extension of basal lobe, distal jo
harpago strap-shaped ....
44
generally covered with short, small hairs ; but the basal lobe, as a rule,
has a tuft of long, stiff bristles at its base, and, distally, is covered with
little mammilliform projections, each of which bears a small, but stiff,
hair. The dorsal flap of the side-piece is covered with very long
coarse hairs, and often with a fair sprinkling of scales.
Between the side-pieces, and about a half as long as them, is
another pair of hook-like structures, the harpagones* (fig. 59, 60 ho).
Each harpago has a rod-like, more or less curved, basal joint, and a
limp, hook-like, distal joint, which may be much flattened or expanded.
A third and fourth pair of hook-like organs, the harpes (fig. 59, Ji) and
unci lie within the harpagones. Each harpe is more basally placed
than the corresponding harpago of each side, and consequently, though
nearly as long, does not project nearly as far. Their shape varies but
little in Ochlerotatus.
69
FlG. 69. — Proboscis of female Culicella
mors 1 'tans.
FlG. 70. — Proboscis of female Culicella
fumipennis .
c. Culicella.
Culicella morsitans and C. fumipennis are nearly alike ; in fact, the
flies of the two species are very difficult to distinguish in both sexes.
The larvae, however, are quite distinct. The proboscis in both species
is black, but the female of C fumipennis has a few white scales on the
proboscis, especially at the sides (figs. 69 and 70).'- The males may be
distinguished by the comparative length of the first fore-tarsal joint
and the remaining four joints. In C. morsitans the first fore-tarsal
joint is decidedly longer than the remaining four joints, while in C
fumipennis it is about as long. (See F. W. Edwards, 19 12, The
Entomologist, vol. xlv., pp. 261-2.) In practice, however, I have
1 These structures have often been termed "harpes "in descriptions, and vice versa, the
harpes have been termed "harpagones."
2 These differences are somewhat exaggerated in the figures.
found this test hard of application, owing to the difficull uring
no fore-shortening of these structures in viewing them. The
side of the abdomen of both sexes al ts a diflfei i
fumipennis (fig. 72) the lower side of the mure distal segments of I
abdomen, especially segments six and seven, have a well-defin
pattern of darker scales upon a light background. 1 he lighter
form a pair of triangular patches at the base of the segment, and th<
is a median triangular patch at the apex of the segment. In
morsitans (fig. 71) the lighter scales arc s< tl d more irregularly
over the segment beneath, and there is only a tendency to the pattern
formed in C fumipennis} This is specially marked in segment six.
' {!<-. ■
V
' * .. I
FlG. 71. — Underside of sixth
abdominal segment of male
Culicclla mors it,:
72. — Underside of sixth
abdominal segment of ma
Culicclla fumipennis.
Key to the Gi 'ulicella.
1 - per surf;,
sixth abdominal segment of
female (
A. In female, proboscis black (fig. 69) with no -ibly om
two white scales at sides. In male, first fore-tarsal joii
decidedly longer than the remaining four joints ; segments
four to seven of the abdomen (especially segment six ben<
with a diffuse pattern, chiefly of lighter scale 1 .
!'.. In female, proboscis blackwith a few whit< at the si
(fig. 70). In male, first fore-tarsal joint is hardly longer than
the remaining four joints ; segments six and seven ol
abdomen especially segment six) beneath with a clear
pattern of lighter and darker scales (fig. 72 ...
('. Culex.
Onlv one specimen of Culex apicalis has been taken in Britain.
But since this is an authentic capture (the specimen i> in the museum
of Cambridge University), ami there are no obvious circun
pointing to its introduction, the species must be regarded as Brit
and a comparison made with Culex pipiens, the Common Gnat.
1 These difference- are somewhat i ted in ih
46
The transverse pale bands on the abdomen of Citlcx pipiciis are
basal (fig. 1 6), while those of C. apicalis are apical (fig. J$). They
are cream-coloured in C. pipiens and whitish in C. apicalis. The
general coloration of C. pipiciis is a rich golden brown, while that of
C. apicalis is a very dark grey. It is hardly necessary to put these
three diagnostic characters in a tabular form.
*t>*
B. THE LARVA.
i. TO IDENTIFY THE GENERA.1
It is not possible in the present state of our knowledge to make
a complete scheme for the identification of the pupae of British
Mosquitoes. Doubtless in time this could be accomplished, and
already some distinctions have been published (e.g., F. V. Theobald,
1901, A Monograph of the Culicidae or Mosquitoes, vol. i., pp. 51-2).
But generally the differences are not readily seen, and often would be
extremely minute. Moreover, for the practical purposes of identifi-
cation, there is comparatively little loss in being unable to identify a
pupa. For where pupae are found, larvae, as a rule, are also abundant;
and, since the pupal instar persists but a few days, it is often possible
to keep the pupa and thus rear the fly. The distinctions, therefore,
of the larvae will be next considered.
Aia phc/cs-\ax\-3.Q may at once be known by the absence of a siphon
(figs. 10 and 11). Their tracheae open by a pair of spiracles, or stig-
mata dorsally placed on the eighth segment, and nearly flush with the
general surface. In all the other genera — called collectively Culicines
-the spiracles are borne on the end of a long, straight, horn-like
prominence of the eighth segment, the siphon, heavily chitinised in
all instar except the first. When a larva is at rest just beneath the
surface-film, the horizontal position distinguishes Anopheles from a
Culicine ; the latter hangs from the surface by its siphon at an angle
of about 45 degrees. When disturbed, A ?wp/ie/es-\a.rva.e jerk themselves
backwards with great swiftness, and slowly sink ; while Culicine larvae
jerkily wriggle directly towards the bottom.
Taeniorhyuchus has a siphon curiously modified for piercing the
stems of aquatic plants. It is wide proximally, but suddenly narrows
into a long tapering point. There is no pecten (fig. 74).
1 The diagnostic characters do not necessarily hold outside British species.
\7
Fig. 74. — Siphon of 7 aeniorhynchus richiardii. Fig. 75. — Siphon of
Fig. 76. — Siphon of Theobaldia annulate } ~ Siphon of
48
podomyia has a normal siphon, but no pecten (fig. 152, p. 1 1 1).
Aedes, Ochlerotatits, Finlaya, Theobaldia, and Culicella have a single
pair of tufted hairs on the siphon {Ocfilerotatus rusticus has a second
Siphoi • - ■
Fig. 70. — Siphoi
minute tufted hair), while O/A-.r (rig. ;o> has several such hairs in
scattered positions on the very slender siphon.
In Aides (fig the siphon is comparatively slender, nearly four
times as long as wide ; the pecten extends to about the middle of the
siphon, and the few most distal teeth are separated by wide gaps.
The tufted hair lies in a line with the pecten, between tl th
and the distal end of the siphon, and, consequently, con
beyond the middle of the siphon. The scales of the comb 1 it-
transverse line.
In Ochlerotatus and Finlaya (figs. 105 1221 the siphon is con
tively stout, not more than thrice as Ion • ; the pecten
not extend as far as the middle of the siphon, except in (
and O. rustiais ; and the tufted hair lies near the distal end of the
pecten, either in a line with it or just ventral to it. The antennae
the larval Finlaya are without the appressed spines that are
over the antennae in Ochlerotatus (fig. 1 04).
In Theobaldia (fig. 76,1 and Culicella (figs. 77-8) the tufted hair '.
ventral to the pecten near its proximal end. In Theobaldia the siphon
is stout, and the pecten-teeth end in long hair-like threads. In Culicella
the siphon is very slender and the pecten-teeth normal.
In addition to the above characters, Mr. F. W. Edwards has
pointed out to me that the hairs of the second pair above the anus
are tufted in the genera TacniorhyncJuts, Theobaldia, and Culicella, like
those of the first pair ; but simple in Aides, Ochlerotatus, and Fiula
In Culex they are bifid.
Key ro Genera of Larva .
A. Siphon absent 'fig. 10 . . . . . I. A>;
B. Siphon present.
. I. Pecten absent. Siphon short with wide base and pointed
apex 1 fig. 74 .... V. Taen
II. Pecten present. Siphon more or less cylindrical, tapering
somewhat di stall y.
fa. Siphon with a single pair of tufted hairs (a. second
minute pair in Ochlerotatus ntsticio , or <»f simple hairs
in the first instar.
' 1. Tufted hair near the distal end of the ;
iphon slender ; tufted hair well beyond the middle
of the siphon ; pecten extending t'j about the
middle of the siphon ; the last :i-teeth
widely spaced . • ■ • • II.
■i. Siphon stout ; tufted hair general': die
1 of the siphon, and the pecten ni the
middle: if the tufted hair »nd the
middle, the last few
widely-spaced than the r* 105- 12.
$ i. Antennae with scattered a] • I-'
J Antennae without scattered apj
E
;o
2. Tufted hair near the proximal end of the pecten, or
about at the middle of the pecten in the first larval
instar.
fa. Siphon stout ; pecten-teeth drawn out terminally into
long hair-like filaments (rig. 76) .... VI. Theobaldia.
I ;i. Siphon slender ; pecten-teeth normal (figs. 77-78) . VII. Culicclla.
Siphon with several pairs of tufted hairs (of simple hairs
in the first instar) (figs. 79, 126-8) . . . . VIII. Culcx.
III. Pecten absent. Siphon as in II. In fourth instar,
abdominal segments 7 and 8 with heavily chitinised
V dorsal plates (fig. 132) . . . . . IX. Orthopodomyia.
2. TO IDENTIFY THE DIFFERENT SPECIES AND (AS FAR AS THEY
ARE KNOWN) THE DIFFERENT INSTAR OF EACH SPECIES.
a. Anopheles.
a. The Fourth (last) Larval Instar.
In A. maculipennis and A. bifurcatus (figs. 80, 81) the six post-
antennal hairs are large and pinnately branched, while in A. plumbe?is
(fig. 82) they are very small, and simple. In A. plumbeus the
anterior clypeal hairs are simple, or nearly so. In A. bifurcatus they
are simple, or, at most, split at the ends into two or three branches.
In A. maculipennis, the outer hair, lying over the brush, is branched
repeatedly, while the inner hair has a few branches arranged pinnately.
The palp in all three species bears a branched hair near the apex,
apically and internally a pair of small, sub-equal spines, and apically
and externally a second pair of spines, which in A. plumbeus are sub-
equal, but unequal in the other two species, especially in A. bifurcatus.
The apex of the palp also bears three chitinous laminae, which are
very thin and exceedingly difficult to see at their distal ends.
The float-hairs of A. maculipoinis have about twenty-two leaflets,
with their bases arranged on an elongate capitulum, which is sessile
or with a short, thick stalk. In A. bifurcatus the leaflets are about
sixteen in number, and are inserted on a more club-shaped capitulum
with a more slender stalk. In A. plumbeus about fourteen leaflets
are crowded at the apical end of a club-shaped capitulum with a
rather thick stalk.
The antenna of A. maculipennis and A. bifurcatus has a branched
hair towards the base in the former, and near the base in the latter
species. In A. plumbeus this hair is simple, and. nearer the middle of
the antenna which is short and has no scattered hairs (figs. 80-82 >.
The comb of A. maculipennis (fig. S$) has about twenty-six to
Fig. 80.— Head of fourth Fig. 8 1.— Head of fourth I ; . 82.— Head of fourth
larval instar of A. macu larval instar of A. bifur- larval instar o( .!.
fcjini-. catus.
thirty teeth of at least three sizes ; about seven large, and betv
each of these one or two of medium size, and between each medium-
1 2
52
sized tooth one or two small teeth. In A. bifurcatus (fig. 84) the comb
has about twenty to twenty-five teeth in all, of which about ten are
large, and between each of these one or two smaller teeth. But the
difference in size between the larger and smaller teeth of A. bifurcatus
is less than that between the larger and medium teeth of A. maculi-
pennis. In A. plumbeus (fig. 85) the comb consists of about sixteen
teeth, most of which are large, but a few slightly smaller ones
occasionally occur.
Fig. 83. — Comb of fourth
larval instar of A. maculi-
pennis.
Fig. 84. — Comb of fourth
larval instar of A. bifur-
catus.
Fig. 85. — Comb of fourth
larval instar of A. plum-
beus.
/3. The Third Larval Instar.
The differences between the three species shown by the anterior
clypeal and post-antennal hairs are the same in the third larval instar,
except that in A. plumbeus the anterior hairs are more branched than
in the fourth instar (figs. 86, 87, 88).
The palps of the third larval instar resemble those of the fourth
instar, but the hair towards the apex of the palp of the third instar,
A. plumbeus, is simple, or almost so.
The float-hairs of the third larval instar show differences similar to
those of the fourth instar, but they have fewer leaflets throughout than
those of the fourth larval instar.
The antennae of the third instar are similar to those of the fourth
instar.
The comb of the third instar, A. maculipoinis, has about sixteen
teeth in all ; generally seven larger teeth, and between them oni
two considerably smaller teeth, which, however, vary somewhat in
Fig. 86.— Head of third Fit;. 88.— Head of third FlG. 87.— Head of third
larval instar of A. maculi- larval inst.ir of A. plum- larval in>tar of ./.
pennis. kits.
size (fig. 89). In A. bifurcatus there are about eighteen teeth ; eight
or ten large teeth, and between them an occasional and somewhat
smaller one (fig. 90). In A. plumbeus, the comb consists of about
twelve sub-equal teeth (^fig. 91).
7. The Second Larval [nstar.
The second larval instar in all three species may be known from
the third and fourth by the palp, which has no sub-apical hair. The
ie difference
1
The
-
The comb of ^4. «ra r seven large teeth, and
teeth between each large on-
there are also six c . larger teeth alt- a ith
-
V
•
4
-
E -Head 94. — B :
larval .: ■ - larv:
as ma the difference in the size of the
jd than it is in A - fig. 96). In
:hs there are about ten sub-equal teeth {fig. o"
8. The First Larval Instar.
The first larval instar of A. maculipennis, A. bifurcatus, an
pliimbeus so closely resemble one another that they arc not easy to
distinguish. In all three species the first diners very considerably fn >m
the second instar. All hairs of the head above are simple, except
that one or more of the post-antennal hairs may be forked in the first
\VV
Fig. 95. — Comb of second Fig. 96. — Comb of second 1 J -Comb of second
larval instar of A. maculi- larval instar of ./. bifur- larval instar
■'"/'->"• caius.
two species ; in some specimens of A. maculipennis one or both of the
outer anterior pair is forked (figs. 98, 991; and in A. plumbeus all
the anterior clypeal hairs are more or less branched (fig. 99a). The
float-hairs have but a single leaflet. The comb (figs. ioo. 101. 101a)
has no alternation of teeth of different sizes, though they graduate some-
what in size from the middle towards the dorsal end, and considerably
Fn;. 98. — Head of first Fn;. 99. Ilea . 99a. — Head ol
larval instar of .-/. macu larval instar of. .' larval instar of A.
from the middle towards the ventral end. The number of teeth varies
considerably in different specimens, so that in any individual it is not
safe to use the number as diagnostic of the species ; but generally
there are six in A. maculipennis and eight in A. bifurcatus, but vary
from five to nine in A. maculipennis and from eight to ten in A.
bifurcatus ; and there are about seven in A. plum
1 The large bifurcate (n te) hair lying <>ut>ide the antenna ha> I
omitted.
56
second comb-like arrangement of teeth lying rather anterior and
ventral to the primary comb. There are generally five teeth in this
secondary comb, but the number varies considerably in different
individuals. One or two of the teeth are often of a minute size
compared with the rest, which are approximately equal in size
101 a
Fig. ioo. — Primary and secondary comb Fig. ioi. — Primary and secondary comb
of first larval instar of A. maailipennis. of first larval instar of A. bifurcatus.
Fig. ioia. — Primary and secondary comb
of first larval instar of A. fihtmbeus.
Fig. 102. — Appressed
bristles on ventral surface
of ninth abdominal segment
of first larval instar of A.
tnaculipennis .
Fig. 103. — Appressed
bristles on ventral surface
of ninth abdominal segment
of first larval instar of A.
bifurcatus.
Fig. 103a. — Appressed
bristles on ventral surface
of ninth abdominal segment
of first larval instar of A,
plumbcus.
1
(rigs. 100-ioia). A good character (besides the sub-antennal hair)
for the first instar of the three species is that of the appressed
bristles that lie on the ventral side of the ninth (last) abdominal
segment ; they form a wider group, and there are four or five larger
pairs in A. bifurcatus ; while in A. maculipennis they form a
narrower group, and there are only about three larger pairs | figs. 102 -
103) ; and in A. plumbeus, the group is very narrow indeed, has feu-
bristles and has only two larger pairs (fig. 103a).
Key to rui. Larvae of the British Species of Anophel
A. The six post-antenna] hairs are prominent.
I. The six post-antennal hairs arc pinnately-branched ; fin
of ninth segment present.
a. Outer anterior clypeal hair dendroid in shape ; leaflet -
float-hairs spring from an elongate capitulum which
sessile, or has a very wide stalk ; the difference in size
between the larger and smaller teeth of the comb con-
siderable ; smaller bristle of the outer pair at the apical
end of the palp about three-quarters the length of the
larger one 1. A. maculipennis.
Palp of maxilla with a sub-apical branched hair.
a. 25-30 teeth in comb ; three, four or even five
secondary and tertiary teeth between each of t lit-
seven primary teeth ; about 22 leaflets in each float-
hair (figs. 80, 83) . . A. maculipennis, fourth larval instar.
\ #. About 16 teeth in comb ; one or two secondarv.
and sometimes tertiary teeth between each of the
seven primary teeth ; about 14 leaflets in each float-
hair (figs. 86, 89) . . A. maculipennis, third larval instar.
Palp of maxilla without a sub-apical hair; one or two
secondary teeth between each of the seven primary
teeth of the comb (figs. 92, 95) A. maculipennis, second larval instar.
b. Outer anterior clypeal hair simple, or once or twice split
at the end ; leaflets of float-hairs spring from a clavate
capitulum which has a short narrow stalk : the difference
in size between the larger and smaller teeth of the
comb is but slight ; smaller bristle of the outer pair at
the apical end of the palp about half the length of the
larger one . • . . • . . • 2. A. bifurcatus.
1 1. Palp of maxilla with a sub-apical branched hair.
a. About 25 teeth in comb ; one or two secondarv
teeth between each of the ten primary teeth ; about
16 leaflets in each float-hair tigs. 81, 84)
/ A. bifurcatus, fourth larval ins
( ,± About 18 teeth in comb ; one or two secondary teeth
between each of the eight primary teeth : about 10
leaflets in each float-hair fij A. bifurcatus, third larval ii
Palp of maxilla without a sub-apical hair : about 14
teeth in the comb, alternately larger and smaller
s. 93, 96) .... A. bifurcatu s, second larval instar.
58
II. The six post-antennal hairs simple, or, at most, forked ; a
bunch of appressed bristles occupies the place of the fin
of the ninth segment ; a secondary comb present.
a. About 6 teeth in primary comb ; appressed bristles form
a narrower group, and there are about three pairs of
larger bristles (figs. 98, 100, 102) A. maculipennis, first larval instar.
b. About 8 teeth in primary comb ; appressed bristles
form a broader group, and there are about five pairs of
larger bristles (figs. 99, 101, 103) . A. bifurcatus, first larval instar.
B. The six post-antennal hairs are very small . . . .3. A.plumbeus.
I. Ninth abdominal segment with a fin.
( a. Maxillary palp wiih a sub-apical hair.
( 1. All four anterior clypeal hairs simple or merely split once
or twice ; sub-apical hair of palp freely branched ; about
16 teeth in the comb (figs. 82, 85) . A.plumbeus, fourth larval instar.
/ 2. All four anterior clypeal hairs freely split, especially
the inner pair ; sub-apical hair of palp simple or
merely split at the end ; about 12 teeth in the comb
(figs. 88, 91) .... A.plumbeus, third larval instar.
b. Maxillary palp without a sub-apical hair ; outer pair of
anterior clypeal hairs twice forked, inner pair pinnately
branched ; about 10 teeth in comb (figs. 94, 97)
A. plumbeus, second larval instar.
II. A bunch of appressed bristles occupies the place of the fin
of the ninth segment ; a secondary comb present (figs. 99a,
101a, 103a) ...... A. filumbeus, first larval instar.
b. Oclrferotatus.
It is unfortunate that the Museum Collection contains no larvae
of Aedes cii/ercus, except in the fourth instar. The younger stages
of this species, therefore, have yet to be described. The next genus is
Ochlerotatus, with its eight British species ; and the differences
between the species, and, where known, between the different larval
instar, will now be considered. The first instar of all the species (as
far as it is known, see figs. 108, 116) can be distinguished from the
succeeding instar by the following characters. There is no fin on the
ninth segment ; only the distal part of the siphon is heavily chitinised ;
the pecten has but six teeth, most of which are very wide, and with
the main denticle not very much larger than the rest ; the tufted hair
of the later instar is represented by a simple hair ; the scales of the
comb form a single row ; there is an egg-breaking tooth on the upper
59
surface of the head ; all the post-antennal hairs lie approximately in a
slightly-curved line, and the pre-antennal hairs arc apparently
absent. In the second to fourth instar there is a fin on the ninth
segment ; the whole, or the greater part, of the siphon is heavily
chitinised ; the pecten has more than sixth teeth, of which the main
denticle is so much larger than the rest that it forms the greater part
of the tooth; the tufted-hair of the siphon has from two to six or
more branches; the scales of the comb form more than one row, or
are irregularly arranged ; there is no egg-breaking tooth on the upper
surface of the head ; the mid post-antennal hair has shifted forward
and inward, and so comes to lie directly in front of the inner post-
antennal hair ; and the pre-antennal hair is present and often highly-
branched, but minute.
It is thus more easy to distinguish the first instar from the
succeeding instar than to distinguish one species from another.
Therefore, it is convenient to consider first the differences between the
species in their second, third, and fourth larval instar, and then again
in their first instar. With regard, then, to the second, third, and fourth
larval instar, O.rusticus (fig. 112) and O.vexans (fig. icoj can be
separated from the remaining five species with no difficulty, by their
having the last one or two teeth of the pecten widely separated from
the rest of the pecten and from each other. (The last tooth is slightly
separated from the rest of the pecten as an occasional variation in
other species of Ochlerotatus, especially 0. caspius.) 0. rusticus
(fig. 112) has, moreover, three or four pairs of long simple hairs on
the dorsal surface of the siphon, a second tufted-hair dorsal to, and
about mid-way down the pecten, and the main tufted-hair
decidedly ventrally with regard to the pecten. The second and third
instar of O. rusticus and I . ins have not been 1 ibserved — moreover,
the larval characters of 0. vexans have been taken from the figure in
Dyar, Howard and Knab (1912, The Mosquitoes of North and
Central America, vol. ii., pi. lxvi.) of O. sylvestris, which is n
considered to be the same species as the European 0.
The larvae of the six remaining species are much more difficult
distinguish. 0. detritus is perhaps the m I ited owin§
the anal gills which are very short and nearly -lobular, and the
blunt comb-scales which are merely fringed and have not a lai
6o
terminal spine (figs. 121, 122). It requires, however, a high magnifying
power to see this clearly. The conspicuously paler bases of the
antennae in the fourth instar and the pecten-teeth with their com-
paratively small, evenly graded denticles (figs. 121, 122) are also
Fig. 104. — Antenna of Finlaya geiticulata.
TEFIZI—,
Vic. 105. — Siphon, pecten-teeth, and comb-
scale of O. caspins, fourth larval instar.
Fig. 106. — Siphon, pecten-teeth, and comb-
scale of O. casfiius, third larval instar.
characteristic. The differences between the second, third, and fourth
instar of 0. detritus (and this is applicable to other species as well) are
seen in the numbers of the pecten-teeth and comb-scales, and in the
greater complexity of the post-antennal hairs and tufted-hair of the
6i
siphon. But since these numbers and this complexity ha.
considerable range of individual variation, the characb
not strictly diagnostic, but should be applied with the i
FIG. 107. — Siphon, pecten-teeth, and comb- FlG. 108.— Siphon, pecten-teeth, and 1
scale of O. caspius, second larval instai scale of 0. caspitts, first larval instar.
FlG. 109. — Siphon of O. vexans, fourth
larval instar (after Dyar, Howard and
Knab, as Aides is).
110. — Siphon, pecten-teeth, a:
scale of t'
instar.
that in any one specimen any character may vary beyond the
prescribed limits. With this caution, it may be said that the third
instar of 0. detritus has ten to fourteen pecten-teeth, two or three
62
branches in the tufted hair, three or four branches in the outer post-
antennal hair, and the other post-antennal hairs simple ; while the
fourth instar has eighteen to thirty pecten-teeth, four to nine
branches in the tufted hair, more than four branches in the outer
post-antennal hair, and the inner with two branches.
FlG. hi. — Siphon, pecten-teeth, and comb-
scale of O. annulipes, fourth larval instar.
Fig. 112. — Siphon, pecten-teeth, and comb-
scale of O. nistiats, fourth larval instar.
No satisfactory difference has yet been found between the larvae
of O. caspius and O. curriei. The shape of the comb-scales and
pecten-teeth shown in figs. 105-107, 113-115, iio-in, are the best
means of distinguishing O. caspius, O. nemorosus, 0. waterJiousei, and
O. annulipes. In O. nemorosus the terminal spine of the comb-scales
is very large indeed, and the lateral spines form merely fringing
bristles (figs. 113-115) ; in the other three species the terminal spine
(or, in O. caspius two or three spines) is the largest, but not so much
larger than the lateral spines. There are comparatively few denticles
in the pecten-teeth of O. caspius (tigs. 105 107), and 0. annulipes
(figs. 1 10-11 1), while there are many in those of O <tsei.1
FlG. 113. — Siphon, pecten-teeth. an 1 comb-
scale of O.nemorosu s, fourth larval instar.
114. — Siphon, p
le of c '. n . third larval insl
The antennae are conspicuously paler at the base in the fourth
instar of O. caspius, less so in O. waterhousei and 0. annulipes,
and uniformly pigmented in 0. nemorosus. Generally, in 0. caspius
the tufted hair lies decidedly beyond the middle of the pecten. In
O. nemorosus the anal gills are large and generally lunger than the
segment.
1 The examination of more material has shown that ihe>
and a satisfactory distinguishing character for larvae of 0 am
yet to be found.
64
The second and third instar of 0. waterhousei and 0. annulipes
have not been examined, but the earlier stages of 0. caspius and
0. nemorosus are known (figs. 106-107, n4-n5)- The pecten-teeth
number nine to thirteen, fourteen to seventeen, and nineteen to twenty-
six in the second, third, and fourth instar of 0. caspius, and twelve to
fourteen, twelve to sixteen, and eighteen to twenty-six in 0. nemorosus ;
the tufted hair has three to four, four to five, and five to six branches
in 0. caspius, and two to three, three to five, and four to six in
0. nemorosus ; the outer post-antennal hair has two, five, and eight
branches in 0. caspius, and two, three, and five to eight in 0. nemorosus ;
the mid-hair is simple in all instar of both species, except the fourth, of
0. nemorosus, when it generally has two branches ; the inner hair has
"^^
FlG. 115. — Siphon, pecten-teeth, and comb-
scale of O. nemorosus, second larval instar.
Fig. 116. — Siphon, pecten-teeth, and comb-
scale of 0. nemorosus, first larval instar.
generally two branches in 0. caspius, except in the fourth instar, when
it is simple, and in 0. nemorosus it is simple in the second instar,
sometimes forked in the third, and generally forked in the fourth
larval instar.
The first larval instar has been observed in 0. caspius and
0. nemorosus only, and the shape of the comb-scales affords the
best character for separating them. Generally speaking, the same
differences separate the comb-scales of the first instar as those of the
succeeding instar. Thus, in O. nemorosus the terminal spine is
considerably bigger than the lateral bristles ; and in O. caspius the
terminal spine, though larger than most of the lateral spines, is hardly
larger than its neighbours (figs. 108, 116).
These differences arc expressed in a tabular form in the following
keys : —
Key to thk Larvae of British Species of Ochlerotat, rth
[nstar only.
A. The last one or two teeth separated by wide gaps from each
other and from the rest of the pecten.
I. Tufted hair lies more or less in a line with the pecten ; no
small second tufted hair dorsal to the pecten ; nor any
simple hairs on the dorsal surface of the siphon [&g. [09 ;. 0.
II. Large tufted hair lies ventral to the pecten ; a small tufted
hair lies dorsal to and about half-way along the pecten ;
three or four pairs of long, simple hairs on the dorsal
surface of the siphon (fig. 11: . . . . . 8. O. rusticus.
B. Pecten-teeth evenly spaced ^except that sometimes the last
tooth is a little further removed from the penultimate tooth
than the penultimate from the anti-penultimate .
/ I. Antennae paler at the base ; anal gills shorter than the last
segment.
/ a. Comb-scales blunt, ending in several sub-equal bristles :
pecten not half as long as the siphon tig. 121) . . 6. O. detritus.
. Comb-scales sharp, ending in one or two teeth somewhat
larger than the rest (or sometimes in one decidedly
larger than the rest : pecten generally half as long as
the siphon (fig. 105) . . . . 1. O. caspius, and 2
; c. Comb scales sharp, ending in one spine conspicuou>l\
larger than the rest ; pecten not half as long as the
-.iphon.
<i. Pecten teeth stouter with more denticles fig. no)1 4. O. waterhou
I2. Pecten-tceth more slender with fewer denticles (fig. 1 1 1 5. 0.autittliA
II. Antennae uniformly pigmented : anal gills very large and
tapering, usually longer than the last segment ; comb-
scales ending in a terminal spine so large that the otL
appear as mere hairs or bristles fringing the base of the
terminal spine (fig. n . . . . .7.
Key id the Larvae of Brim>h Species 01 Ochlerotatits, includii
ALL THE INSTAR HITHERTO OBSERVED.
A. Fin of the ninth abdominal segment present : more than six-
teeth in pecten ; main denticle of pecten-tooth so much
larger than the rest that it forms the main part of the tooth :
tufted hair with from two to six branches ; no egg-break
tooth on the dorsal surface of the head ; mid pair of ] .
antennal hairs lying nearly directly anterior to the inner pair.
Second, third, and fourth instar 1
I. No small second tufted hair on siphon dorsal to pecten, nor
pairs of simple hairs on the dorsal surface ot the ^Mihon.
1 See footnote on p. 63.
66
a.
b.
6. O. detritus.
The last one 01 two pecten-teeth separated by wide yaps
from each other and from the rest of the pecten (rig. 109) 3. O. vexans.
Pecten-teeth evenly spaced (except that sometimes the last
tooth is a little further removed from the penultimate
than the penultimate from the ante-penultimate).
1. Scales of comb blunt, ending in several sub-equal
bristles ......•••
a. Pecten-teeth 1H-30; four to nine branches in tufted
hair ; outer post-antennal hair with more than four
branches; inner with two branches ; antennae con-
spicuously paler at the base (fig. 121) O. detritus, fourth larval instar.
S. Pecten-teeth 10-14 ; two to three branches in tufted
hair ; outer post-antennal hair with three to four
branches : other antennal hairs single ; antennae
uniformly pigmented (fig. 122) . . O. detritus^ third larval instar.
I 2. Scales of comb pointed, ending in one or two spines
slightly larger, or one spine conspicuously larger than
the other spines or bristles.
/ a. Terminal spine or spines of comb-scales, though
slightly or conspicuously larger than the fringing
spines, not so much larger that these appear as mere
: bristles, but rather as smaller spines of similar nature.
\ / i. Tufted hair generally decidedly beyond the middle
of pecten. Comparatively few denticles on pecten-
O. curi iei.
of pecten. Comparatively few denticles on pecten-
teeth . . . . .1.0. Crispins and
a. Pecten-teeth 19-26; five to six branches in tufted
hair : outer post-antennal hair with about eight
branches, the others generally simple ; antennae
conspicuously paler at the base (fig. 105)
O. caspius, fourth larval instar.
b. Pecten-teeth 14-17 ; four to five branches in tufted
hair: outer post-antennal hair with about five
branches, the mid generally simple and the inner
generally with two branches : antennae hardly
paler at the base (fig. 106) . . O. Crispins, third larval instar.
c. Pecten-teeth 9-13 ; three to four branches in tufted
hair ; outer post-antennal hair with two
branches, the mid-hair simple and the inner
generally with two branches ; antennae uni-
formly pigmented (fig. 107) . O. Crispins, second larval instar.
ii. Tufted hair at about the middle of the pecten ;
antennae hardly paler at the base.
a. Pecten-teeth stouter and more numerous, with
Mime minute denticles at the base, and others
often between the larger denticles (fig. no) ' 4. 0. waterhousei.
1 b. Pecten-teeth more slender and fewer, without
minute denticles occurring between the larger
denticles (fig. in)
5. O. an nn !i pes.
See footnote on p. 63.
i. Terminal spine of comb- than
the others that these appear as mere li lirs or lit:-'
fringing the base of the terminal spine; anteni
uniformly pigmented; anal gills than the
lasl th of pecten with the last denticle
nspicuously the largest ....
i. Pecten-teeth iS-26; four to six branches in tin
hair: outer postrantennal hair with t
branches, the others generally bifid ; coml
generally arranged in about four irregular i
of seven or eight fig. 113 . O. nemon , fourth larval ii
ii. Pecten-teeth 12-16; three to five branches in tufted
hair: outer post-antennal hair with ti
branches, the others simple or sometimes the inner
hair is bifid; comb-scale* generally arranged in
three irregular rows of about eight each fig. 114
O.nemorosus, third larval insl
iii. Pecten-teeth 12-14: two to three branches in tufted
hair ; outer post-antennal hair with two brand
the others simple; comb- generally
arranged in two irregular rows of seven each
115) . . . . r/«, second larval ins
II. A second small tufted hair lyingdorsal to and about half-way
along the pecten ; three or four pairs of long simple hair-
on the dorsal surface of the siphon : the main tufted hair
lies ventral to the pecten ; the last one or two teeth of the
pecten are widely separated from each other and from the
rest of the pecten rig. 112 .
B. Km of ninth abdominal segment absent : six teeth in pecten :
main denticle of pecten-teeth no: so 1 onspicuously larger than
the rest that it forms the main part of the tooth : tutted hair
of third and fourth instar, simple in first instar : an <
breaking tooth on the dorsal surface of the head ; all post-
antennal hair* approximately in a curved line. First larval inst.i>
O. nemorosns, and probably the other I'>riti>h
I. Scales of comb with terminal spine hardly larger than it*
neighbours (tig. 10- . . . O. caspius, first larval i:
1 1. Scales of comb with terminal spine considerably larger than
the fringing spines (fig. 11 . . U. nan larval ii
V
8. O. ru
<-. Finlaya.
The larva of Finlaya ^eniculata is known from those of the
different species of Ochlerotatus by the antennae- which are snv
and have not the scattered appressed spines usual in gnat-larvae
(fig. 1041 ; and in all the instar but the first by having the coi
scales arranged in a single line. The very large anal gills, too,
sausage-shaped instead of tapering as in Ochlerotatus. '1 he larva
1 J
68
F inlay a geniculaia shares with exotic species of this genus the habit
of living in tree-holes like Anopheles plumbens and OrtJiopodomyia.
With the reservations already made with regard to the larvae of
Ochlerotatus in their different instar, it may be said of F. geniculata
that the pecten-teeth in the second, third and fourth larval instar
Fig. 117. — Siphon, pecten-teeth, and comb-
scale of F. geniculata, fourth larval instar.
Fig. 118. — Siphon, pecten-teeth, and comb-
scale of F. geniculata, third larval instar.
120
Fig. 119. — Siphon, pecten-teeth, and comb-
scale of F. geniculata, second larval instar.
Fig. 120. — Siphon, pecten-tooth, and comb-
scale of F. geniculata, first larval instar.
have, respectively, eight, twelve and fourteen to eighteen teeth ; the
comb seven, twelve and fourteen scales ; the tufted hair, two, four and
four or five branches (see figs. 117-119) ; the outer post-antennal hair
has two or three branches in the third, and three or four branches in
the fourth instar ; and the mid and inner post-antennal hairs are simple,
though in the fourth instar the inner pair sometimes has two branches.
69
The first instar may be known by possessing no fin on the
segment; about six pecten-teeth ; a simple hair on the siphon
egg-breaking tooth on dorsal surface of head ; and all the i
antcnnal hairs forming a single row (fig. 120).
i!^^^^^^
^~*^T
^7
122
FlG. 121. — Siphon, pecten-teeth, and comb-
scale of O. detritus, fourth larval instar.
Fig. 122. — Siphon, pecten-teeth, and 0
scale of O. detritus, third larval instar.
I I
Key to Larval Instar ok Finlaya geniculata.
Fin of ninth abdominal segment present ; more than six teeth
in pecten ; tufted hair with two to six branches ; no eg
breaking tooth on dorsal surface of head : mid pair of post-
antennal hairs lying directly anterior to the inner pair.
Second, third and fourth larval ins
I. Pecten-teeth 14-18; four to five branches in tufted hair ;
outer post-antennal hair with from two to four branche- ;
middle and inner simple or with two branches ; about
fourteen scales in comb fig. 11 . . F. geniculata, fourth larval ii
11. Pecten-teeth about 12; four branches in tufted hair :
outer post-antennal hair with two or three branches :
middle and inner simple : about twelve scales in comb
(fig. 118) ..... F. geniculata, third larval insl
Pecten-teeth about 8; two branches in tufted hair;
about seven scales in comb (fig. 119) . /•". geniculata, second larval ii
70
B. Fin of ninth abdominal segment absent ; about six teeth in
pecten ; hair on siphon simple ; an egg-breaking tooth on
dorsal surface of head ; all post-antennal hairs simple and
lying in a single row (fig. 120) . . . F. geniculate/., first larvaL instar.
\?4.
Fig. 123. — Siphon, pecten-tooth, and Fig. 124. — Siphon, pecten-tooth, and
comb-scale of Theobaldia annulata, comb-scale of TlieobalJia annulata,
third larval instar. second larval instar.
Fig. 125. — Siphon, pecten-tooth, and comb-scale of Theobaldia annulata, first larval instar.
FlG. 126. — Siphon, pecten-
tooth, and comb-scale of
Culex pipiens, third larval
instar.
FlG. 127. — Siphon, pecten-
tooth, and comb-scale of
( 'ulex pi pims, second
larval instar.
FlG. 12S. — Siphon, pecten-
tooth, and comb-scale of
C 'ulex pipiens, first larval
instar.
d. Theobaldia.
The four larval instar of Theobaldia annulata differ in much tl
same manner as the instar of the different species of I
namely, in the number of pecten-teeth and comb-scales, and in the
complexity of their post-antennal hairs and tufted hair. The
differences are best tabulated a- follows: —
A. At least inner and outer post antenna! hair compound : tufted
hair with from three to eight brandies, and situated near
the proximal end of the pecten : comb-scales in more than
one row, or irregularly arranged ; pecten-teeth more than
seven in number ; no egg-breaking tooth on upper surface of
head ; a tin present on ninth abdominal segment.
Second, third, and fourth larval in:
I. Outer post-antennal hair with about twelve branches, mid
with from one to four branches, and inner with about six
brandies ; tufted hair with about eight branches : comb-
scales, about sixty in number, in several irregular rows:
pecten-teeth about thirty in number, of which about t he-
last six are widely-spa< ed and many are hair-like (fig
Theobaldia an nit lata, fourth larval instar.
II. Outer post-antennal hair with about live branches, mid
post-antennal hair simple, inner with three branches :
tufted hair with seven branches : comb-scales, about fifty
in number, arranged in several irregular rows : pecten-
teeth about seventeen, of which about the last mx are
widely-spaced and hair-like (fig. i .
Theobaldia annulata, third larval ins!
III. Outer post-antennal hair with about three branches, mid
post-antennal hair simple, inner with two branches : tufted
hair with about three or four branches ; comb-scales, about
twenty in number, in two irregular rows ; n teeth
about fourteen in number, of which about the last thn
widely-spaced and hair-like (fig. 124 .
theobaldia annulat
B. All the post-antennal hairs simple ; tufted hail
fourth instar is a simple hair in first instar, and situated
ventrally to and about half-way down the pecten ; comb-
;les about ten to twelve in a single row ; pecten-teeth six
to seven in number, and not hair-like ; an egg-breaking
tooth on the upper surface of the head : no tin on the ninth
abdominal segment fig. 12; . Theobaldia annulata. first \ 1
e. Culicella.
The two species of Culicella can be more readily determim
their larval than by their adult characters. In C tnorsi
the axis of the pecten is mcfrc or less parallel with that of the sipl
7^
and the siphon has no scattered single spines on its surface. In
C. fumipennis (fig. 7S), the axis of the pecten lies obliquely with
regard to that of the siphon, and there are scattered single spines on
the rest of the siphon.
The earlier larval instar have not been observed.
/. Culex.
The larva of Culex apicalis has a more slender siphon (fig. 129)
than C. pipiens. The species ranks as British only on the strength of
an isolated capture. In Culex pipiens (figs. 79, 126-8) there are on the
siphon four pairs of tufted hairs (three only in first instar), called so
because in the second to fourth instar in other British Culicines they
have at least two branches. They are often simple in the earlier instar
of Culex pipiens, generally double, and in the last two instar may have
three or even four branches. They lie more or less in a line, with the
Fig. 129. — Siphon pecten toolh, and comb-scale of Culex apicalis, fourth larval instar.
pecten, but the first pair (tufted hair 1). lying near the distal end of the
pecten, is generally more or less ventral to the pecten ; and the third
pair (tufted hair 3) generally lies dorsal to the line of the rest. The
following key gives in tabular form the differences between the instar,
but it must be borne in mind that the numbers of the pecten-teeth,
comb-scales and branches in the hair have a considerable margin of
variation, and so those given in the key are only approximate.
A. No tin on ninth segment ; three pairs of simple (not tufted
hairs on siphon : about four teeth in pecten ; comb-scales
in a single row of about eight to ten ; all post-antennal hairs
simple : an egg-breaking tooth on dorsal surface of head
(fig. 128 ....... Culex pipiens, first larval instar.
B. A nn on ninth segment; four pairs of hairs (simple or
tufted on siphon ; more than four teeth in pecten ; comb-
scales in at least two rows or irregularly arranged ; post-
antennal hairs at least double ; no egg-breaking tooth on
dorsal surface of head.
1 1
Comb-scales in two irregular rows of about ten scales in
each row ; live to seven teeth in pecten ; all four pail
tufted hairs on siphon may have two branches, but
numbers three and four may be simple ; outer p<
antennal hair with two or three branches, mid and inner
with two branches (fig. 127) . . Culex pipiens, second larval instar.
Comb-scales in at least three irregular rows, tending
form a triangular patch containing thirty to fifty teeth.
". Ten teeth in pecten ; tufted hairs 1 and 2 generally
double, 3 and 4 often double but may be simple :
outer post-antenna! hair with from three tosix branches,
mid with two or three branches, and inner with three
branches ( tig. 126) .... Culer pipiens, third larval in
Twelve to fifteen teeth in pecten; tufted hair 1 generally
with three branches, 2 with three or even four
branches, 3 generally with two branches, and 4 generally
with three branches : outer post-antennal hair with from
seven to nine branches, mid with three or four branches,
and inner with four or five branches (fig. 79).
Culex pipiens, fourth larval instar.
III. -SYSTEMATIC ACCOl'XT.
1.— ANOPHELES, Meigen.1
Anopheles; J. W. Meigen, 1818, Systematische Bcschrcibun^ der bekanr.ten
Europaischen zweiflugeligen Insekten, vol. i, p. 10.
( ienosyntypes, Culex bifurcatus Linnaeus and Anopheles maculipennis
Meigen.
Genolectotype, Culex bifurcatus Linnaeus. See D. W. Coquillett, n>io.
Proc. United States National Museum, vol. xxxvii, p. 5 ~
1. Anopheles maculipennis Meigen.5
Plate I., and figs. 7. 10, 12, 15, 18, 27, 40, 44, So, 83, S<<. 89, 92,
98, 1 00, 102.
Anopheles maculipennis, Hoffmgg. ; Meigen, 1818, op. cit., \>. 11. [Note:
Meigen's ascription of the name maculipennis tu Hoffmani probably
refers to an MS. label.]
1 For an account of the distribution of Anopheles in Britaii G II. 1 Nut tad I,
L. Cobbett and T. Suangeways-Pigg, 1901, Journal of Hygiene, v.. I. i, pp. 4 4 •
W. D. Lang, 1918, A Map showing the known distribution in England and Wales ••(" the
Anopheline Mosquitoes, British Museum (Natural History) : and I E.
Annals of Applied Biology, vol. vi, pp. 40 7.
'-' For a full account of the anatomy and life-history of this G. H. F. N'ottall
and A. E. Shipley, 1901-1913, Journal of Hygiene, vol. i, nos. . and 2, \ , ii,
no. I, and vol. iii, ii". 2.
74
The spotted wings are generally enough to distinguish A.
macnlipennis, not only from the other British species of Anopheles,
but from all other British gnats, except Theobaldia annulata • and
even if only the rubbed wing is available, the relative positions of
the cross-veins, as described above, will distinguish these two forms
(fig- 33)- If the wings are rubbed, or if for any other reason there
is doubt, the best characters for distinguishing A. maculipennis from
A. bifurcatus and A. plumbeus are those of the thoracic scale-tuft
(see above, p. 33, figs. 40 -41). The difference between the scutella
of A. macnlipennis and A. bifurcatus is too slight to be of much
value ; and to compare the breadth of the wing-scales, it is
necessary to have already the wings of the two species as standards.
In the case of a male, the characters of the genitalia (fig. 44) are
absolutely diagnostic.
The larvae of A. maculipennis are most easily recognised, especially
when alive, by the dendroid outer anterior clypeal hair (figs. 10, 80, 86,
92). This lies over the brush, and, in the living larva, is seen at once
with a hand-lens when the larva even momentarily retracts its brushes.
A. maculipennis appears to be common all over England and
Wales wherever breeding conditions are suitable. Its abundance in
any district depends, apparently, partly upon the locality itself, but
also varies from year to year. Its distribution in Scotland and Ireland
has not been worked out at all fully ; but since the species has been
found in both countries, it is probably widely distributed where there
are the requisite breeding conditions. The favourite breeding-places
seem to be the shallow margins of weedy, but not foul, calm, open1
water ; and there is also required a certain degree of warmth. That
A. maculipennis does not avoid brackish water is shown by its
abundance, observed by Dr. Davidson, in the brackish-water dykes
in the neighbourhood of Sandwich, Kent.
The eggs are first produced when the flies emerge from hibernation,
in March, in mild seasons, but generally in April. The}- are laid,
probably during the night or early morning, and singly, not, as in
1 Mr. F. W. Edwards has observed that, even when found in the same water. ./.
maculipennis prefers an open station, while A. bifurcatus prefers a shaded station. His atten-
tion was also drawn to the fact by Dr. Penrose of Bournemouth. See also J. Feytaud and
E. Gendre, 1919, Bull. Soc. Path. Exot. Paris, vol. xii, pp. 178-182.
Culex, in rafts formed of numbers glued together; though they often
take up definite positions of equilibrium with regard to one an
and often form regular patterns. Within a few days the larvae
hatched, and within a few weeks emerge as flies, having pa rough
their four larval instar as well as the pupal instar. The advent of th<
newly-emerged flies in a district is announced by the presence
males as well as females; for the hibernating flies are females on
During the day-time and in inclement weather the flies
prefer to shelter in buildings and similar situations : but i illy in
the evenings in calm weather the females fly forth and bite, ;vm\ the
males gather in swarming companies. Fresh broods of eggs continue-
to be laid throughout the summer, until about the end mber.
By the middle of October no more larvae or pupae are found in fr<
waters nor male flics in the land. The female flies shelter in
buildings, and are especially fond of occupied cowsheds, pigstyes and
stables, where they keep comparatively warm, and in the milder spells
of winter always have a meal hand)*. In these situations they may
be found in immense numbers, and are particularly fond of settling
upon cobwebs. A wholesale destruction of these hibernating femali
promises to be an effective means of reducing the numbers
-/. maculipennis in a district in the following season.
Towards the end of summer the flies are often found with larval
water-mites attached to the bodies, wings or legs.1 These mites have
been observed to suck and weaken the flies. They ar arativi
rarely found on the larvae : and how they obtain a hold on die fly is
not known. Nor is it easy to understand how they return to the
water. There is no reason why a male fly should approach water ;
and a female weakened and finally dying under the attack of a mite
would in the majority of cases collapse far (from the mi: int of
view) from any water. A mite on A. maculipennis captured, by
Mr. D.J. Scourfield during August was submitted to Mr I - . who
kindly determined it forme and pronounced it to be th : a
species of Arrhenurus. Larval Trombidinm (possibly the same mite
under another name) have also been recorded from the fli
Anopheles maculipennis and A. bifurcatus. Again, J Curt 4.
British Entomology, explanation of pi. 210) quotes Haliday .1- saying
1 SeeC. Wesenlier^-Lund, 191S, \ iilensk. Mo risk naturh. 1
76
that A. maculipennis ''are very much infested by a small reddish
parasite ( Ocypete rubra ? ) ; I have found ten of these attached to the
abdomen of a male."
A larva collected by Major A. Macdonald in Kew Gardens was
found to be full of the diatom Fragilaria sp., probably F. virescens
(kindly determined for me by Mr. F. B. Taylor, of Bournemouth).
Occasional diatoms occur in larval mosquitoes, but it is not usual to
find them in large numbers ; and, since diatoms must often abound
where the larvae of A. maculipennis are feeding, it appears probable
that the diatoms in the case described were eaten deliberately.
2. Anopheles bifurcatus (Linnaeus).
Plate II., and figs. 41, 42, 45, 81, 84, S7, 90, 93, 96, 99, 101, 103.
Ciilex bifurcatus ; Linnaeus, 1758, Systema Naturae, Regnum Animale,
editio decima, p. 603.
As a general rule, the unspotted wings of A. bifurcatus readily
distinguish it from A. maculipennis and the coloration of the thorax
from A. plumbeus. But in doubtful cases the characters of the
thoracic scale-tuft are the most useful criterion to distinguish
A. bifurcatus from A. maculipennis (figs. 40- 1) ; and the shape of the
scutellum to distinguish A. bifurcatus from A. plumbeus (figs. 42-3).
In the case of a male, the characters of the genitalia are absolutely
diagnostic of the three species (figs. 44-46). These points of difference
have been described in detail above, as also have the larval characters,
the most useful of which are the simpler outer anterior clypeal hairs
(seen best in the live larva above the brushes) to distinguish it from
A. maculipennis, and the large, branched post-antenna! hairs to
distinguish it from A. plumbeus (figs. 81, 87, 93).
A. bifurcatus is as widely distributed as A. maculipennis in
England and Wales, and is probably equally common. In a few
localities it has been recorded as commoner. But the numbers of
A. maculipennis vary considerably from year to year in a given
district, while those of A. bifurcatus remain more constant. A.
maculipennis, however, is the more noticeable species, owing to
its fondness for entering houses and its habit of hibernating as a
female fly.
A. bifurcatus hibernates as a larva (probably, as a rule, if not
always, in the third instar), which, as soon .is the spring-weather
comes, completes its development and emerg a fly. I
quently, male A. bifurcatus arc found earlier in the sea- mi than m;
A. maculipennis, which have to undergo their whole life-history from
the egg at the beginning of each season, while A. bifurcatus starts
a three-quarter grown larva. In 19 1 8, A. bifurcatus appeared
early as February.
The habit of hibernating as a larva probably explains the more
constarit numbers of A. bifurcatus from year to year. For a few
warm days in early spring, followed by cold weather, will tempt forth
the hibernating females of A. maculipennis into the open, and they
will stand the chance of being overtaken and destroyed by the
suddenly returning cold. Whereas the larva in the water remains
under for more uniform conditions, and can live in or under ice.
The general habits of the two species are similar. A. bifurcatus,
however, prefers the shelter of foliage to buildings, and thi i^
comparatively uncommon in houses and more common in wooded
country ; and it will bite more readily by day than A. maculipennis.
Adult A. bifurcatus, however, have been observed by Mr. F. W.
Edwards resting under the raised floor of a bungalow at Wood
Walton Fen, Hunts, preferring cobwebs for their settling places. In
one case only was a mosquito observed to have been caught by
a spider and shrouded in silk. In the Sandwich district, where
it was remarked that A. maculipennis flourished in brack ish
water, the evidence shows that A. bifurcatus prefers the fresh, if
it does not actually avoid brackish water. In the same district
A. bifurcatus has also been found in a wooden vessel in a farmyard
— practically a " water-butt," which is a most unusual situation
for an Anopheles, and unknown to harbour the genus in town
areas. In Palestine during 191S, Major E. E. Austen, D.S.O., -
A. bifurcatus breeding in wells and underground cisterns, and
mentions it especially as abundant in wells of the 1 rar irdcns
near Jaffa.
Larval mites are found on A. bifurcatus towards the end ol the
summer, as they are on A. maculipennis. Remarks on these will be
found in the description of the latter sped*
73
3. A. plumbeus Stephens.
Plate III., and figs. 43, 46, 82, 85, 88, 91, 94, 97, 99a, 101a, 103a.
Anopheles plumbeus; J. F. Stephens, 1828. Zoological Journal, vol. hi,
P- 5°3-
Anopheles nigripes, n. sp. ; C. Staeger, 1839. Kroyer's Naturhistorisk Tid-
schrift, vol. ii, p. 552.
The small size and dark colouring of A. plumbeus with the
ashy-grey longitudinal thoracic markings will generally distinguish it
from A. bifurcatus. But, in a case of doubt, the shape of the scutellum
(fig. 43) and, in the male, the genitalia (fig 46) afford the best
criteria. It is unlikely that A. plumbeus and A. maculipennis will be
confused, but the differences described above (pp. 34-5) should obviate
all difficulties. The larva of A. plumbeus has a more stumpy look
than that of A. maculipennis and A. bifurcatus, and may be most
easily distinguished from the larvae of both species by the post-
antennal hairs, which are exceedingly small, difficult to see, and
simple, instead of pinnately branched. The outer anterior clypeal
hairs are simple, or nearly so (figs. 82, 88, 94).
A. plumbeus appears to be widely distributed in England and
Wales, and is common in some localities. It also occurs in Scotland
and Ireland. On several occasions it has been taken in houses,
though essentially a sylvan species; and, as far as is known, confined
during its larval and pupal life to water-filled holes in trees.1 The
larvae of Finlaya geuiculata are often found sharing these holes with
A. plumbeus'} A. plumbeus larvae have been found during the winter
(1918) by F. \V. Edwards, and I have kept in captivity from
September, 1918, till April, 1919, larvae of A. plumbeus captured
during August, 191S, by Angus Macdonald, jun., at Culross, Fifeshire.
A curious point with regard to the breeding of A. plumbeus is the
apparent scarcity of the larva compared with the frequency of the
imago. In more than one district where the fly is common, a search in
likely tree-holes has failed to reveal the larva, or no tree-holes have
been discovered. Observers report that A. plumbeus bites more viciously
1 Beech-trees as a rule, but it has been taken from Chestnut (24, iii, 1919 ; Botanical
Gardens, Cambridge : 1". W. Edwards), and probably occurs in any trees providing suitable
holes. See also under OchlerotaUis geniculates. Theobald records A. plumbeus from a
peat-cutting.
- Hoth species have also been taken with Orthopodomyia and Stegomyia, see pp. 109-10.
than the other two British Anopheles, and by day as well as by night.
It has quite lately been established that A.plumbeus can be inf< I
with malaria; see B. Blacklock and II. i\ Carter, [919, Ann. '
Medicine and Parasitology, vol. xiii, p. [87.
II. AEDES, Meigen.
Aedes, Hoffmgg. j J. W. Meigen, 1818, Syst. Beschr. bekannt. Eui :tl.
Insekten, vol. i, p [3. Genotype, Aedes cinereus, Miegen.
Meigen's ascription of the name to Hoffmannst e r> to an MS.
by that collector on the material Meigen was describii
1. Aedes cinereus Meigen.
Pigs. 5, 11. 13, 14. 17, 29, 75.
? Ctdex ciliaris : Linnaeus, 1 7 ' > 7 - Systema Naturae, editio • ma
reformata, vol. i, part 2, p. 1002.
Aides cinereus, Hoffmgg. ; J. W. Meigen, 1 Syst. Beschr. bekannt. Eur
zweifl. Insekten, vol. i, p. 13. [Not' . - above under the genus Ak
Aedes ru/us, mini. : 1!. A. Gimmerthal, 1845, Bull. ^,,c- I n 1 j >. Nat. Moscow,
vol. xviii, p. 295.
Culex nigrituhis ; J. W. Zetterstedt, 1850, Diptera Scandinaviae. i\.
P- 3459-
non Culex nigritulus, Zetterstedt : Y . V. Theobald, 1901, .\ Monograph of I
Culicidae or Mosquitoes, vol. ii, p. 140, which is Culex pipiens, I. inn.
var. doliorum, F. W. Edwards, q.v.
Aedes fziscus, h. sp. ] C. R. Osten Sacken, [877, Bull. United States G
and Geogr. Survey, vol. iii, p. 191.
./ .-' . leucopygus, n. sp. ; .\. Eysellj 1903. Abhandlungen und Bericht d
Vereins fur Naturkunde zu Kassel, vol. xlviii. p. 285.
The male 1 if Aedes cinereus may at once be known by its very
short palpi. The female at first sight Looks like an obscure Ochlerotatus,
since it has the pointed abdomen of that genus. The marked contra
however, in the female, between the reddish ground-o >li air < if the th< >ra\
and the almost black head and abdomen, sufficient!) uish it
a glance from the various species of Ochlerotatus, and an examinati
under a high-power lens or microscope show- the wid< in the
crown of the head in both sexes. In the male the thorax is bla
The larva generally resembles those of the various 5|
Ochlerotatus, but is distinguished from these by the com pa
slenderness of the siphon and by the position of the ban- tuit
decidedly beyond the middle of the siphon (fig. ; -
8o
F. W. Edwards considers the North American A'cdes fuscus to be
identical with the European A. cinereus. In America A. fuscus is
believed to pass the winter in the egg. We have no records of A'cdes
cinereus during the winter, and it may be that it winters as an egg in
Britain as it is supposed to do in America.
A. cinereus in Europe has been recorded from Norway, Sweden,
Austria, Hungary and Italy (see F. V. Theobald, 1901, Monograph of
the Culicidae or Mosquitoes, vol. ii, p. 234, and 1907, vol. iv, p. 539) ;
from Germany (Habichts-Wald, W. of Cassel, Hessen, see A. Eysell,
1903, Abh. Ber. Ver. Naturk Kassel, vol. xlviii, p. 285) ; from
Holland (see J.-C. H. de Meijere, 191 1, Tidschr. o. Entomologie,
vol. liv, p. 148) ; Denmark ; and from Russia (see under A'cdes
rufus).
Though widely distributed, A'cdes cinereus does not appear to be
very common in Britain ; or, at least, not often observed. The general
situations indicated in the British records suggest that it is mainly a
river-haunting species. I have gathered the following records : —
Cambs. — Baitsbite, N.E. of Cambridge, Chippenham, N. of New-
market, and Wicken, S. of Ely. See F. IV. Edwards, 19 12,
The Entomologist, vol. xlv, p. 260.
Dorset. — Studland. See F. IV. Edwards, under Cambridgeshire records.
Hants. — Bournemouth ; flies and larvae; 10 and 11, vi, 1908 ; colld.
H. J. Waddington. British Museum Collection.
Brockenhurst ; flies and larvae; 11 and 26, vi, 1906; colld.
C. O. Waterhouse. British Museum Collection.
Herts. — Radwell, near Letchworth. F. W. Ed-wards colld.
Hunts.— Wood Walton Fen, W. of Ramsey ; 13, vi, 191 3 ; colld. Hon.
N. C. Rothschild. British Museum Collection.
Middlesex— -Harefield, N. of Uxbridge ; 21, viii, 1916 ; colld. F. W.
Edwards. British Museum Collection.
Stanmore ; 10, viii, 1918 ; colld. K. G. Blair. British Museum
Collection.
Norfolk. — Ormesby, N. of Great Yarmouth. See F. IV. Edwards, under
Ca m bridgeshire records.
Suffolk.— Tuddenham, N.E. of Newmarket ; J. E. Collin. See F. IV.
Edwards, under Cambridgeshire records.
Wales.— Crymlyn Bog, S.W. of Neath, Glamorganshire ; 14. vi,
colld. Lt.-Col. Yerbury. British Museum Collection.
Scotland. — Edinburgh. See F. IV. Edwards, under Cambridgeshii
records.
III. OCHLEROTATUS, Arribalzaga.
Ochlerotatus, nov. gen. ; 1. I. Arribal/.aga, [891, Dipterologia Argentina.
Revista del Museo de La Plata, vol. i, p. 374, and vol. ii, p. 1 j.3.
Genosyntypes, Culex albofasciatus Macquart, and Ochlerotatus confirmatus,
n. sp. Genolectotype, 0. confirmatus ; see 1). \V. Coquillett, 19 10, Proc.
United States National Museum, vol. xxxvii, p. 577.
1. Ochlerotatus caspius (Pallas).
Plate IV., and figs. 20, 25, 28, 30, 47, 51, 59, 105 108.
Culex caspius ; P. S. Pallas, 177 1, Reise durch verschiedene Provinzen des
Russichen Reichs, p. 475.
Culex punctatus ; J. W. Meigen, 1804. Klassifikazion und Beschreibung der
europaischen Zweifliigligen Insekten, vol. i, p. 6.
Culex dorsalis; J. W. Meigen, 1830, Systematische Beschreibui ig
bekannten Europaischen zweifliigeligen Insekten, vol. vi, p. 212.
Culex penicillaris N. ; C. Rondani, 1872, Bull. Soc. lint. Ital., vol. iv, p. 31
(fide]. Villeneuve, 1919, Bull. Soc. Ent. France, p. 56).
Culex pulchripalpis ; F. V. Theobald, 1901, A Monograph of the Culicidae or
Mosquitoes, vol. ii, p. 16 {non Rondani, 1872, bull. Soc. Ent. Ital.,
anno, iv, p. 31).
It is impossible, since the type specimen is not available, to be absolutely
certain that Pallas' Culex caspius is the species generally known as
Ochlerotatus dorsalis ; but the probabilities are so great that there is
justification for reviving this ancient name ; and specimens oi rsalis
from the Caspian are in the British Museum Collection.
The brilliant coloration of the head and thorax, the white bands
on the hind tarsi each embracing two tarsal joints, and on the
abdomen each embracing two abdominal segments, make 0. caspius
one of the most easily recognisable of British mosquitoes. The gr
breadth of the light and dark scales of the wings also are characteristic
of this species. The larva is to be known from those of other species
of Ochlerotatus by the length of the pecten, which is about half as long
as the siphon, the tufted hair lying beyond the middle of the siphon.
82
O. caspius appears to be abundant in southern England, and the
larva occurs both in inland waters and in brackish water near the
sea. In the latter situation it is generally found in company with
O. detritus. The larvae are found in spring and early summer, and
the flies soon appear. In mid-summer neither flies nor larvae are
generally seen, and often the breeding-pools are dried up ; but when
rain)- weather fills the pools again, both larvae and flies quickly re-
appear, and the flies are often noticed in great abundance at the end
of summer and in early autumn. It is not known in what stage O.
caspius spends the winter. Flies of this species are often found far
from any likely breeding-haunts ; for instance, one was taken in my
garden in Chelsea in August, 1918, at least half-a-mile from any water
such as a pond, and nearly a mile from any pond likely to afford a
suitable breeding-place. Mr. F. W. Edwards tells me that O. caspius
has been observed biting indoors. It is seldom that any species of
Ochierotatus enters houses.
H. Dyar, L. Howard and F. Knab (1917, The Mosquitoes of North
and South America and the West Indies, vol. iv, p. 634.), in discussing
the possible identity of two American species, Q. onondagensis (Felt) and
O. curriei (Coquillett) with O. caspius (as O. dorsalis), suggest that the
sea-side specimens of O. caspius are of a different species from those that
breed inland in fresh waters, and that an examination of larvae from
salt and fresh waters respectively will reveal differences comparable
with those of the larval O. onondagensis and O. curriei in America.1
Specimens of larval O. caspius (probably third instar) from brackish
water of Millbrook Common, Southampton, and specimens of the
third larval instar from Mitcham Common, Surrey, have been
compared by Mr. F. W. Edwards, and some of those from Mitcham
Common have comb-scales resembling the Millbrook Common
specimens, while others have the terminal spine considerably larger.
It is possible that two forms are confused.
O. caspius has been recorded from Scandinavia, Holland, Germany
(Berlin), and Austria (see F. V. Theobald, 1901, Monograph of
Culicidae or Musquitoes, vol. ii, p. 18) ; also Southern Russia (Pallas,
1771, loc cit.) ; it also occurs in Macedonia, whence Major R. A. P.
1 Dyar and Knab now regard these species as one (191 7, Insec. Inscit. Menstruus,
vol. v, p. 122).
■
Hill, R.A.M.G., has sent me specimens, and see J. Waterston, [918,
Bull. Ent. Research, vol. ix, p. 7 ; Palestine; Mesopotamia, and in
Northern Africa (see F. \Y. Edwards, 191 1, Bull. Ent. Research
vol. ii, p. 249) ; also France and Italy.
I have gathered the following British records : —
Essex. — Beckton Marshes, London, E. ; iv, 1919 ; colld. F. \Y. Edwards
see F. W. Edwards, 1917, Bull. Ent. Research, vol. vii, p. 217.
British Museum Collection.
Royal Albert Dock; colld. Dr. Rees. See F. /'. Theobald
1901, A Monograph of the Culicidae or Mosquit .'. ii, p.
(recorded as Culex pulchripalpis Rondani, and it is suggested that
the}- were introduced on some ships coming from Italian port-- —
see, however, p. 112 1.
Hants. — Millbrook Common, N.W. of Southampton ; larvae, 13, ix,
191S, and flies, 13, viii. 1918; colld. Corporal Ryan. R.A.M.C.
Received per dipt. M. Gross, R.A.M.C.
Kent. — Charlton. See F. IV. Edwards, 191 2, The Entojnologist,
vol. xlv,p. 195.
Dartford Marshes ; 29, v, 1902 ; colld. F. W. Edwards. British
Museum Collection.
Lewisham ; 27, viii, 1899 ; colld. R. S. Pengelly. British
Museu m Colh 'ctit >//.
Rochester. See F. IV. Fdwards, 1912, The Entomologist,
-col. xlv, p. 195.
Middlesex. — Chelsea; In garden; Trafalgar Square; 12, viii, 1918
Colld. IV. D. Lang.
Chiswick ; 3. ix. 191 1 ; colld. F. W. Edwards. British Museum
Collection.
Stamford Hill, London. N. ; 30, viii, 1899; colld. A. Milton.
British Museum Collection.
Suffolk. — Aldburgh ; 14 and [9, viii, [895 ; colld. A. Piffard ; s
Entomologists' Monthly Magazine, 1895, series 2. vol. vi, p. 227.
British Museum Collection.
Surrey. — Battersea Park ; 30, vii. [918. Colld. Mrs. W. D. Lan
Camberwell ; ix, 1918 ; colld. Dr. Simpson. British Mus
Collection.
2
§4
Mitcham Common ; larvae colld. Miss L. E. Cheesman, 26, vii,
191S ; pupated 28 and 29, vii, 1918 ; emerged 1, viii, 1918 ; another
emerged (presumably pupating later), 14, viii, 191 8. British
Museum Collection.
Putney; ix, 19 17. Colld. G.J. Arrow.
Worcestershire. — Forest of Wyre. See B. W. Edwards, 191 2, The
Entomologist, vol. xh\ p. 195.
Wales. — Tal-y-bont, N. of Barmouth, Merionethshire ; reared from
larvae; vii, 1914 ; colld. F.W.Edwards, 1917 ; see Bull. Ent.
Research, vol. vii, p. 217. British Museum Collection.
2. Ochlerotatus curriei (Coquillett).
Culex Curriei, new species ; D. W. Coquillett, 1901, Canadian Entomologist,
vol. xxxiii, p. 259.
Ochlerotatus curriei closely resembles. 0. caspius, but the brown
coloration of the thorax is not nearly so bright, and the whitish
markings form a pair of broad bands instead of taking the form of
narrow lines. The wing scales, too, are narrower than those of
0. caspius, and the light and dark scales are more segregated along
separate veins or parts of veins, than uniformly mixed as in O. caspius ;
thus, longitudinal veins 3 and 5, and the forks of longitudinal vein 4,
have dark scales for the most part in 0. curriei. No British specimens
of the larva have been found ; but it closely resembles the larva
of O. caspius — indeed, no difference between the larvae of these
species is discernable from the evidence of the published figures of
O. curriei.
This species has been added to the British fauna only since last
September, when Dr. Hugh Scott took it in numbers in swampy
hollows on the heaths S.E. of Wareham, Dorset. On the 15th Sept.,
1919, it occurred on Stoborough Heath, " in numbers, biting fiercely,
at about 4.30p.m. (summer time) on a cool, dull, hazy afternoon";
and on 23rd Sept., Middlebere Heath, "biting, between 12 and 3 p.m.
(summer time), in spite of high, rather cold wind, and clouds alter-
nating with hot sunshine." Dr. Scott also noted that none occurred
near the coast north of Studland, between Littlesea Merc and the
Specimens are in the Cambridge University Museum and in the
British Museum. It also occurs in Denmark. Sweden and X. .V
3. Ochlerotatus vexans (Mcigeni.
Figs. 48, 52, 60, 109.
Culex vexans; J. W. Meigen, 1830, Systematische Beschreibung der bekann-
ten Europaischen zweifliigeligen Insekten, vol. vi, p. 241.
Culex sy/vestris, n. sp. ; F. V. Theobald, 1901, A Monograph of the British
Culicidae or Mosquitoes, vol. i, p. 406, pi. xx.w, fig. <
Ochlerotatus vexans is known by the very narrow white bands at
the basal ends of the hind tarsal joints (fig. 48) ; otherwise it resembles
O. waterhousei and O. annulipes, but has only dark scales on the
wings, and the posterior border of the pale abdominal bands is
undulating (fig. 52) ; the male genitalia, too. are very distinctive ( fig. 60).
I have not seen a larva, but it has been described and figured by
H. Dyar, L. Howard, and F. Knab (Mosquitoes of North and Central
America and the West Indies, 1917, vol. iv, p. 695, and [912, vol. ii.
pi. lxvi) as Aides sylvestris, and may be known from other British
species of Ochlerotatus, except O. rusticus, by the two distal-most teeth
of the pecten being widely spaced ; and from O. rustic/is by the tufted
hair, which is in a line with the pecten (fig. 109).
0. vexans occurs in Scandinavia, Russia, Austria, Germany anil
Holland (see F. V. Theobald, 1901, A Monograph of the Culicidae or
Mosquitoes, vol. i, p. 405), China, Japan, India, Ceylon, Philippines,
Borneo, and perhaps Fiji (see F. \Y. Edwards, i-ii;. Hull. Ent.
Research, vol. vii, pp. 218-9), an^ (described as Aides sylvestris) in
North America, where it is referred to as a woodland species. It is,
apparently, rare in Britain ; but F. YV. Edwards I Entomologist, 1
vol. xlv, p. 195) records it from Mildenhall, Suffolk, colld. C. <i.
Lamb, vii, [894 ; and since then he tells me he has seen specimens
from Shotover, near Oxford (colld. A II. llamm. 5, viii. [918, two
males), and from Coe Fen, Cambridge (colld. F. Jenkinson, one
female
There are, in the British Museum Collection, some specimens from
the Clifton Collection, which, though without information ility,
are probably British.
86
t
4. Ochlerotatus waterhousei (Theobald).
Figs. 49. 53, 61, no.
Culex Waterhousei, sp. n. : F. V. Theobald, in C. O. Waterhouse, 1905,
Annals and Magazine of Nat. Hist., series 7, vol. xvi, p. 674.
Ochlerotatus waterhousei and O. annulipes are very much alike,
and the differences given in the tables above (pp. 40,42-3), and in figs.
49-50, 61-2, must be referred to for distinguishing them. The larva
of O. waterhousei may be distinguished from that of O. caspius by the
length of the pecten ; from O. rusticus by the position of the tufted
hair ; from O. vexans by the spacing of the last two teeth of the
pecten ; from O. detritus by the number of teeth in the pecten ; from
O. nemorosus by the length of the anal gills ; and from O. annulipes by
the length of the pecten-teeth (fig. 1 10 ; see, however, footnote on p. 63).
O. waterhousei has been so confused with O. annulipes (see under
that species) that it is not possible to determine its range with
certainty. Probably it is not so common in continental Europe as
0. annulipes (which is the common form in France, see J. Villeneuve,
1919, Bull. Soc. Ent. France, p. 56, as Culex cantans). In England, F. W.
Edwards (191 2, The Entomologist, vol. xlv, p. 218, as Ochlerotatus
inaculatus) refers to it as widely distributed and probably common.
The larvae are found in early summer (in shadiest pools in thick
woods — F. W. Edwards) ; and the fly generally towards midsummer.
It is not known in what stage the winter is spent. The following are
some records of its occurrence : —
Bucks. — Burnham Beeches ; 7, v, 19 12, colld. F. W. Edwards ; 10 and
28, vi, 1907, 18, vi, 1908 (larvae and pupae) ; colLd. C. O. Water-
house. British Museum Collection.
Essex. — Epping Forest; larva colld. Miss L. E. Cheesman, v, 191 8 ;
pupated 15, v, emerged 19, v; fly colld. H. Main; v, 1918 ; see
p. no.
Hants. — Brockenhurst ; 5 and 16, v, 1904; 5 and 7, v, 1905 ; pupae
and flies ; colld. C. O. Waterhouse. British Museum Collection.
Herts. — Bushey Heath ; 27, vii, 191 2 ; colld. F. W. Edwards. British
Museum Collection.
Felden, S. of Boxmoor ; 7, v, 1899 ; colld. A. Piffard. British
Museum Collection.
Knebworth; iv, 1919 ; larvae; colkl. F. W. Edwards, British
Museum Collection.
Hunts. — Wood Walton Fen, W. of Ramsey ; 15 15. iv, [914; colld.
F. W. Edwards. British Museum Collection.
Kent. — Hever, W. of Tonbridge ; 8, vii, 1907 ; colkl. Lt.-Col. Yerbury.
British Museum ( 'ol lection.
Middlesex. — Novver Hill, Tinner ; i, v. [914; colld. V. \V. i. irards.
British Museum Collection.
Norfolk. — Merton, S. of Walton ; 31, v, 1908 and io, vi, 1900; colld.
Lord Walsingham. British Museum Collection.
Shropshire. — Longner Hall, S.E. Shrewsbury ; in garden ; v. 1
vi, 1908 and 12, x, 1912 ; colld. R. F. Burton. British Museum
Collection.
Suffolk. — Barton Mills ; v, 1916 ; colkl. F. W. Edwards. British
Museum Col lectio?/.
Sussex. — Angmering Ponds, S.F. of Arundel; I and 27, vii, [9 7;
colld. Rev. A. E. Eaton. British Museum Collection.
Fridge, S. of Tunbridge Wells, Kent; 11. vi, [886; colkl.
G. H. Verrall. British Museum Collection.
Goring Woods, X.W. of Worthing ; 20, 24 an
colld. Rev. A. E. Faton. British Museum Collection.
Scotland. — Dingwall, Ross; 29, v, 191 1; colkl. Lt.-Col. Yerbury.
British Museum Collection.
5. Ochlerotatus annulipes (Meigen).
Figs. 50, 54, 62, 111.
Cutex annulipes; J. W. Meigen, 1830, Systematische beschreibung der
bekannten Europaischen zweirkigeligen Insektcn, vol. vi, p. 241.
? Culex variegatus ; F. de P. Schrank. [781, Enumeratio Insectorum Austriae
indigenorum, p. 482.
ICulex maculatus ; J. W. Meigen, 1S04, Klassifika/.ion und Beschreibung
europaischen Xweiflugligen [nsekten, vol. i, p. 4.
? Culex cantans, Hoffmgg. ; J. W. Meigen, 1818, Syst( matische Beschreibung
der bekannten Europaischen /weiilugeligen [nsekten, vol. i. p. <>.
Meigen, in ascribing this species to Hofftnannsegg, is probably only
quoting an MS. label of that collector's writing.]
88
Mr. F. W. Edwards has kindly pointed out to me that Meigen's
description of Culex cantans agrees far more closely with his later
description of Culex amuilipes than with Ochlerotatus waterhousei, the
species generally hitherto considered as identical with Meigen's Culex
cantans. Probably, then, Culex annulipes and Culex cantans are the
same species. Now, Meigen states that his Culex maculatus is
identical with his C. cantans ; in fact, is only the male of that species
(1830, loc. cit.) ; but since, the name maculatus has the priority over
cantans, this species must be known as OcJilcrotatus maculatus, Meigen,
with the synonymy given above ; and the species which has generally
been called Ochlerotatus maculatus must be called 0. waterhousei,
Theobald. But, until the identity of Culex annulipes with C. cantans
is proved, it is best to retain the former name and drop C. maculatus.
O. annulipes is unlikely to be mistaken for any other species except
0. waterhousei, which it so closely resembles, that the differences
described on pp. 40, 42-3 must be looked for. The larvae, too, are so
similar to those of 0. waterhousei, that a satisfactory difference
has yet to be found. Note, too, the relative situations in which
the larvae are found ; those of 0. waterliousei in the shadiest pools of
thick woods, and those of 0. annulipes in open pools. 0. annulipes is
probably common on the European continent ; in England it appears
to be local. Specimens have been found in the following places :—
Hunts. — Wood Walton Fen, W. of Ramsey. 29, v, 191 3 ; colld.
Hon. X. C. Rothschild; and 13-15, iv, 1914, and 17, iv, 1919,
larvae, pupae and flies ; colld. . F. W. Edwards ; the larvae were
taken from " clear pools under birch and sallow trees " and " clear
puddles among reeds" (see F. W. Edwards, 1917, Bull. Ent.
Research, vol. vii, p. 215). British Museum Collection.
Norfolk.— Rollesby, N. of Great Yarmouth ; colld. G. H. Verrall.
See F. W. Edwards, 1912, The Entomologist, vol. xlv, p. 217.
Shropshire. — Longner Hall, S.E. of Shrewsbury ; one specimen ;
vi, 1 91 8 ; colld. R F. Burton. British Museum Collection.
Sussex. — Angmering Ponds, S.E. of Arundel ; 1 and 27, vii, 1907 ;
colld. Rev. A. E. Eaton. British Museum Collection.
Rotherfield, S. of Tunbridge Wells, Kent; 6, vi, 1886; colld.
G. H. Verrall. British Museum Collection.
6. Ochlerotatus detritus 1 1 laliday)
FiSs- 55. 63, 67, i2i, 1
Culex detritus ; A. H. Haliday, 1833, Entomological Magazine, vol. i, p. 151.
Culex sahnus, sp. n. ; E. Ficalbi, 1896, Bull. Soc. Entomologica Italia:
anno xxviii, p. 29.
Culex Tcmci, n. sp. ; F. V. Theobald, 1903, A Monograph of the (
or Mosquitoes, vol. iii, p. 193.
Ochlerotatus detritus is distinguished by the white scales that
freely scattered over its wings, abdomen and proximal parts of the
legs ; otherwise, it has a blackish ground-colour with pale basal
abdominal rings. The light-and-dark speckled wings distinguish it
from O. nemorosus, which it otherwise closely resembles and wh<
wings are nearly entirely dark-scaled (figs. 67-8) ; the speckling of
light scales on the darker parts of the abdomen above and the rows of
black spots beneath1 also distinguish it from 0. nemorosus (fi|
and the male genitalia of the two species are very different in detail
(figs. 63-4). The larva is remarkable among the species of Ochlerotatus
for the shortness of its siphon and the numerous small denticles on
the proximal part of the pectcn-teeth (figs. 12 1-2). Other details are
mentioned in the former section.
O. detritus occurs in Italy (see reference above), and there are in
the British Museum Collection specimens from Majorca and Algeria.
It is abundant in brackish water in the South of England, and h
been taken in Wales and Ireland ; and 0. caspius is nearly al 1
found in company with it ; on the other hand, it does not accompany
O. caspius where that species is found breeding inland. It ibable
that 0. detritus winters as a larva or an egg, since larvae are found
early in the year, and after that the flies. "The species is, at lea
double-brooded, for larvae and emerging flies have been taken in
September. Probably, as with O. nemorosus, in summer droughts the
shallow waters where they breed dry up, and the impregnated t
flies tide over the dry period among vegetation. In Maw 1918, at
Great Wakering, Essex, an interesting obs >n was made by
1 The "ventre trifariam fusco-puncl H I
sea-side habitat make it possible to identify certain II
go
Mr. A. J. Grove, who found males of this species swarming in company
with males of Anopheles bifurcatus.
The following are British records of OcJderotatus detritus : —
Cornwall. — Sheviock, S. of St. Germans ; 7, ix, 191 2 ; colld. Lt.-Col.
Yerbury. British Museum Collection.
Devon. — Tor Point, S. Devon; 19, iv, 1889; colld. Lt.-Col. Yerbury.
British Museum Collection.
Essex. — Beckton Marsh, near Royal Albert Dock ; 16, iv, 1914 ; colld.
F. W. Edwards. British Museum Collection.
Great Wakering, S.E. of Rochford ; v, 191 8 ; males swarming
with males of A noplieles bifurcatus. Colld. A . J. Grove.
Walton-on-Naze ; 4 and 5, v, 1907 ; colld. Lt.-Col. Yerbury.
British Museum Collection.
Hants. — Millbrook Marsh, N.W. of Southampton ; larvae and flies ;
8 and 13, viii, 1918, and 13, ix, 1918 ; colld. Corporal Ryan. Per
Capt. M. Gross, R.A.M.C
Kent. — Dartford ; 14, vi, 1912 ; colld. Lt.-Col. Yerbury ; also the type-
locality of Culex terriei (a synonym of Ochlerotatus detritus), see
F. V. Theobald, 1903, A Monograph of the Culicidae or Mos-
quitoes, vol. iii, p. 194. British Museum Collection.
Sheerness district; larvae ; 22, iii, 191 8, and 2, iv, 1918 ; and
flies, 8, v, 1918. Colld. Major A. Macdouald, R.A.M.C
Sussex. — Worthing; 16 and 26, v, 1907, and 8, vi, 1907 ; colld. Rev.
A. E. Eaton. British Museum Collection.
Wales. — Tal-y-bont, N. of Barmouth, Merionethshire ; larvae (in
puddle behind shingle bank) and flies; vii, 1914 ; colld. F. W.
Edwards. British Museum Collection.
Scotland. — Arrochar, Dumbarton; ix, 191 5 ; larvae in brackish water
pools, full of decayed seaweed, reached on occasions by the tide ;
colld. Miss L. H. Huie. British Museum Collection.
Brodrick, Arran ; v, 1919 ; brackish pools. Colld. F. IV.
Edivards.
h -eland.— Holywood, Co. Down, N.E. of Belfast ; colld. A. H. Haliday.
See original description.
Sutton, near Dublin. Per Dr. R. F. Scharjf.
7. Ochlerotatiis nemorosus (Meigen).
Plate V., and figs. 9, 56, 64, OS, [13 1
Culex nemorosus; J. W. .Meigen, 1818, Systematische B
bekannten Europiiischen zweifliigeligen tnsekten, vol. i, p. \.
Culex sylvaticus ; J. W. .\reigen, 18 18, op. cit. p. 6 (non Cul 'tic us ;
J. F. Stephens, 1825, Zool. Journ., vol. i, p. 454, which is Culex pip\
see F. W. Edwards, 1912, The Entomologist, vol. xlv. \>. j;
Culex domesticus (parti m) ; J. F. Stephens, 1825, Zoological Journal, vol. i,
p. 455; from Hertford {non Culex domestieus : E. Germar, 181 "
nach Ualmatien und in das Gebeit von Ragusa, p. 290). The specimens
so named in Stephen's collection in the British Museum an -sens,
and one C. nemorosus.
? Culex concinnus ; J. F. Stephens, 1846, Illustrations of British Entomok'-
Supplement, p. 19, pi. xliii, fig. 1. (See F. W. Edwards, [912, The
Entomologist, vol. xlv, p. 277.)
? Culex fusculus ; J. W. Zetterstedt, 1S50, Diptera Scandinaviae, vol. i\,
P- 3459-
? Culex nigripes, Zetterstedt, var. sylvae ; F. V. Theobald, A
Monograph of the Culicidae or Mosquitoes, vol. ii, p 9^6.
Culex concinnus of Stephens is either a variety of Ochlerotaius nemOTi
(Meigen) or, probably, a distinct species. The general ground-colour of
the type-specimen is darker, the dorsal surface of the thorax isgi I the
sides, the colour of the abdominal rings is paler, and it is of a smaller
size than O. nemorosus. Culex nigripes var. sylvae of Theoba
closely with Culex concinnus.
Ochlerotatus nemorosus resembles O. detritus, but has few, if any,
pale scales on the wings and on the darker parts of the abdomen
above, and the abdomen is not spotted beneath. The pale transvei
bands on the abdomen are whitish rather than yellowish, and do not
tend to spread medianly to form a longitudinal band in the mid-line.
as in O. rusticus. The male genitalia also are very peculiar (see
fig. 64). The larva is remarkable for the great size of the anal gills,
which taper to a fine point and are not sausage-shaped, as in Fin/aj
gem'cu/ata,wh.ich also has very large anal gills ; their size, h< '\\ ever, var:
Hermaphrodite specimens have been described by Edwar 17.
Hull. Ent. Research, vol. vii. p. 2 1 6), taken on Harrow V.
Common, and first noticed by him because apparently he w
bitten by a male.
92
Ochlerotatus nemorosus is a more or less sylvan species, frequenting"
the neighbourhood of woods and copses, and biting freely by day. It
is found throughout central Europe. The Algerian record (F. W.
Edwards, 191 1, Bull. Ent. Res., vol. ii, p. 248) is O. detritus. It is
common in Britain. The larvae appear to occur especially in shallow
pools on commons and heaths near woody places, where the bottom
is composed of rotting leaves. In such waters they are found in
spring, having hibernated in this stage ; and, since these pools readily
dry up, the larvae are not met with in fine summers, and do not
appear again until the rainy weather at the end of summer or in the
early autumn. Then the pools are quickly re-stocked with larvae.
But if, as in 191 8, the dried-up pools are re-filled at mid-summer, a
brood of larvae are soon produced (see evidence of records in 191 8
and Edward's observations, 1917, Bull. Ent. Research, vol. vii, p. 216).
It is almost certain that the impregnated females tide over the
droughts among the herbage in woods.
Some British records are as follows : —
Bucks. — Burnham Beeches ; 7, v, 191 2 ; colld. F. W. Edwards. British
Museum Collection.
Farnham Common, near Burnham Beeches ; 7, v, 191 2 ; colld.
F. W. Edwards. British Museum Collection.
Dorset. — Littlesea, Studland ; 31, vii, 191 1 ; colld. Rev. A. E. Eaton ;
S, 12, 1.8, and 21, v, 1907, and 2, vi, 1912 ; colld. Lt. -Col. Yerbury.
British Museum Collection.
Rempstone Heath, W. of Studland ; 30, v, 1907 ; colld. Lt.-Col.
Yerbury. British Museum Collection.
Essex. — Coopersale Common, N.E. of Epping ; larvae; 6, viii, 1918.
Colld. D. J. Scourfield.
Epping Forest ; larvae ; emerged, 21 and 22, iv, 191 8 ; another
larva pupated, 25, iv, and emerged, 29, iv, 191 8 ; colld. Lt.
Tickner Edwardes, R.A.M.C. ; also 4 and 6, v, 191 8. Colld.
K. G. Blair ; also 30, vii, 19 19. Colld. F. W. Edivards.
Epping Forest, Chigwell Row Recreation Ground ; larvae ; 1
viii, 1 91 8. Colld. D.J. Scourfield. .
Epping Forest, Monk Wood ; 31, iii, 1918. Colld. A. Bacot.
Loughton ; larvae from sheltered pool, full and teeming with
larvae of 0. nemorosiis at beginning of May, then dried up, and
again teeming at end of July when again filled
Colld. Miss L. E. Cheesman.
Hants. — Southampton ; larvae and Hies ; received 2. v, i Id.
Major A. C. Parsons, R.A.M.C.
Lyndhurst ; colld. Lt.-Col. Yerbury. British Museum Collection.
Middlesex. — Hampstead Heath ; larvae, in company with larvae of
Culex pipiens, in temporary pool under trees, with leaves at
bottom ; 28, vii, 191 8. Colld. K. G. Blair.
Harrow Weald Common; 21, iv, 1912 (see F. \V. Edwan
1917, Bull. Ent. Research, vol. vii, p. 216); colld. F. \Y. Edwards.
British Museum Collection.
Stanmore ; larvae; 20, iv, 1918. Colld. K. G. Blair.
Stanmore Common ; 18, v, 1916 ; colld. F. W. Fduards. British
Museum Collection.
Shropshire. — Longner Hall, S.E. of Shrewsbury; 1, v, [912, and
v, 1918 ; colld. R. F. Burton. British Museum Collection.
Surrey. — Oxshott ; 28, v, 1902 ; colld. C. O. Waterhou<e. British
Museum Col lee t ion.
Putney; 16, v. 1906; fly and larva; colld. C. O. Waterhous
British Museum Collection.
Sheen Common; larvae in a pool recently rilled after being dry
since the spring, when larvae of this species were present in it ;
21, vii, 1918. Colld. R. //. Thomas.
Scotland. — Nethy Bridge, S.W. of Grantown, Aberdeen-hire ; colld.
Nuttall. British Museum Col lee t ion.
North Sutor, Cromarty ; 12, vi, 1894 ; colld. O. Grant.
Museum Collection.
The Mound, N.W.of Dornoch, Sutherland ; 4, viii. [900 ; colld.
Lt.-Col. Yerbury. British Museum Collection.
Pitlochry ; Perthshire; 4, ix, [91 5 ; colld. P. A. Buxl
Cambridge University Museum Collection.
Torphins, Aberdeenshire, \\" "f Aberdeen and N 1 : >yne
colld. J. M. Wright, P.M. British Museum <
94
8. Ocklerotatus rusticus (Rossi).
Figs. 57, 65, 112.
Culex rusticus ; P. Rossi, 1790, Fauna Etrusca, vol. ii, p. 333.
Culex ornatus (partim) ; J. F. Stephens, 1825, Zoological Journal, vol. i,
p. 454. (non Culex ornatus, Hoffmgg. ; J. W. Meigen, 1818, Systema-
tise-he Beschreibung der bekannten Europaischen zweifliigeligen Insekten,
p. 5. See F. W. Edwards, 1912, The Entomologist, vol. xlv, p. 277.)
Culex pungenst R.D. ; J. B. Robineau-Desvoidy, 1827, Mem. Soc. Hist.
Nat., Paris, vol. iii, p. 407.
Culex quadratimaculatus, Nob. ; M. Macquart, 1834, Histoire Naturelle
des Insectes ; Dipteres, vol. i, p. 34.
Culex diversus, n. sp. ; F. V. Theobald, 1901, Monograph of the Culicidae
or Mosquitoes, vol. ii, p. 73, pi. xxvii, fig. 107.
Culex nemorosus, Meigen, var. luteovittata, mihi. ; F. V. Theobald, 1901. torn.
cit., p. 85.
Ocklerotatus rusticus, though generally resembling O. nemorosus,
is really a very distinct species. The yellow colour of the pale
abdominal markings, and their tendency to spread medianly so as to
form a line down the middle of the abdomen (fig. 57), readily
distinguishes 0. rusticus from O. nemorosus. But the male genitalia
of O. rusticus (fig. 65) differ so much from,those of the other British
species of Ochlerotahis, that they may often be distinguished by the
naked eye, mainly owing to their dense hairiness. The siphon of the
larval 0. rusticus differs from that of its British congeners in the
position of the tufted hair, in the possession of a minute second tufted
hair, and in having several single hairs scattered over its dorsal surface
(fig. 112). It also shares with O. vexans the peculiarity of the widely-
spaced last two pecten-teeth. 0. rusticus does not appear to be a
well-known species. It was originally described from Tuscany, and
specimens from Ghent are in the British Museum Collection. It
occurs in Denmark (C. Wesenberg-Lund) and Macedonia (J. Waterston ).
In Britain it seems to be widely-distributed, and replaces O. nemorosus
in some districts. The following are some records of O. rusticus
from Britain : —
Hants. — Brockenhurst ; 1, v, 1905 (type of Culex nemorosus var.
luteovittata); larvae and flies, 26, 27 and 29, iv, 1905 ; fly, 5, v,
1904 ; colld. C. O. Waterhouse. British Museum Collection.
Lyndhurst; 21, v, 1904; colld. G. II. Verrall. British Mm um
Co/lection.
Herts— Felden, S. of Boxmoor ; 7, v, 1899 ; colld. A. Piffard. Britx
Museum L ollection.
Kent. — Hy 'the ; 13, vi, 1S99 ; colld. A. Piffard. British Museum
Collection.
Sheerness district; iarvae ; 20, iii, 191 S. Colld. Ma;
Macdonald, R.A.M.C
Tunbridge Wells ; 5, vi, 1886; colld. G. H. Verrall. Britx
Museum Collection.
Norfolk.- Merton, S. of Walton ; 30, vi, 1907 ; colld. Lord Walsingham
British Museum Collection.
Shropshire. — Longner Hall, S.E. of Shrew-bury ; in garden, vi. 190
£ $ , lurking among Scilla nutans, 5, v, 191S ; ? 9, 13. v. [918 ;
colld. R. F. Burton. British Museum Collection.
Sussex. — Goring Woods, N.W. of Worthing ; 24 and 2y. \ i.
colld. Rev. A. E. Eaton. British Museum Collection.
Tilgate, Sussex; 23, v, 1897; colld. G. II. Verrall. Brit.
Must 7/ m Collection.
Warwickshire. — Brinkk;\v, N.W. of Rugby ; 30, vi, 1902 ; colld. Ma
E. E. Austen, U.S.O. British Museum Collection.
Wales. — Porthcawl, S.W. of Bridgend, Glamorganshire; 31, v, 1
colld. Lt.-Col. Yerbury. British Museum Co/lection.
Locality not specified. — See G. H. Verrall, 1901, A list of British
Diptera, second edition, p. 13 (as Culex rusticus).
IX. E IN LAY A, Theobald.
Fiulaya, now gen. ; I . X . Theobald, 1903, A Monograph of the Culicidae
or Mosquitoes, vol. iii, p. 281. Genosyntypi ilia, n. sp., and
Culex Kochi, Donitz. Genolectotype, Fiulaya ; 1
H. Dyar, L. Howard, and F. Knah, 1 «> 1 7, The Mosquitoes North and
South America and the West Indies, vol. iv. p. (>i
1. Fiulaya geniculates (Oh\i< ;
Figs. 58, ' ''. 104. 1 17 120.
Culex genicuiatus ; G. A.Olivier. [791, Encyclope'die Me'thodique, Histoire
Naturelle, Insectes, vol. vi, p. 134-
96
Culex lateralis, Meg. : J. W. Meigen, 1818, Systematische Beschreibung der
bekannten Europaischen zweifliigeligen Insekten, vol. i, p. 5. [Note :
" Meg." = Megerle von Muhlfeldt, and is but the author of the name
in MS.]
Culex ornatus (partim) ; J. F. Stephens, 1825, Zoological Journal, vol. i,
p. 454; Hertford. (no?i Culex ornatus, Hoffmgg. ; J. W. Meigen, 1818,
op. cit., p. 5. See F. W. Edwards, 191 2, The Entomologist, vol. xlv,
p. 277.)
Culex guttatus ; J. Curtis, 1834, British Entomology, vol. viii, p. 537, pi. 537
(but not fig. 9) ; Cobham, Surrey.
Culex albo-punctatus, N. ; C. Rondani, 1872, Bull. Soc. Entom. Italiana,
anno iv, p. 31.
Finlaya geniculates, is an easily recognised species. Its black ground-
colour, with brilliant white knee-spots and triangular lateral spots on
the abdomen, as well as the very pale greenish-yellow markings on
the thorax, mark it distinctly from other British species. The larva,
too, is very distinct if the " comb " of the eight abdominal segment
can be seen ; for the scales of which it is composed form a single line,
as in all the larval instar of the British species of Anopheles and A'edes
and in the first larval instar of TJieobaldia annulata, Culex pipiens,
Ochlerotatus caspius, O. nemorosus and, probably, of all Culicines. In
the species of Ochlerotatus the scales of the " comb," in all but the
first instar, are irregularly arranged. The teeth of the pecten of
Finlaya geniculata are comparatively few, and straighter than in the
species of Ochlerotatus. The pecten is comparatively short ; and the
anal gills are very long and sausage-shaped.
Finlaya geniculata is a thoroughly sylvan species, and its larva
lives, like that of Anopheles plum dens (and often in company with it),
in water-filled holes in trees.1 Mr. Burton, of Longner Hall, Shrews-
bury, has kept through the following winter, in a wooden tub, eggs
which were laid in the autumn of 191 7 ; also a few larvae which hatched
before the winter survived. In the spring of 191 8 the eggs hatched,
and the larvae, with those that had passed through the winter,
completed their metamorphosis and emerged as flies in April. This
species, therefore, passes the winter as a larva or in the egg ;
1 Generally Beech trees, but it has been found in Hornbeam, Chestnut, Sycamore, and
Ash (F. W. Edwards), and probably occurs in any tree having suitable water-filled holes.
It is found also with Orthopcdomyia and Stegomyia, see p. no.
"7
and it is probable that the species of the allied genus Ochlerotatm "li-
the same. It is also probable, judging from the respective at
which the flies and larvae of various sizes have been found, and from
the observations (though few) on the slow rate of growth of the lan
that normally there is only one brood of Finlaya geniculate, in the
year. Such is not always the case in Ochlerotatus, for 0. caspius, < '.
detritus and 0. nemorosus, except in dry years, have at least t
broods.
Finlaya geniculata is recorded from Austria, Russia, and Switzer-
land (see F. V. Theobald, A .Monograph of the Culicidae or Mosquito.
1901, vol. ii, p. 53, and 1903, vol. iii, p. 191, as Culex lateral*
specimens, too, from France (Alpes Maritimes) are in the British
Museum Collection; it also occurs in Denmark and Macedonia.
The following are some British records : —
Bucks. — Burnham Beeches; (1) 10 and 28, vi, 1907; colld. C. O.
Waterhouse ; (2) larvae and pupae associated with larvae of
Anopheles plumbeus in holes in beech trees, 4, iv, [916; pup
i8, iv, emerged 24, iv ; pupated 24, iv, emerged 30, iv ; pupated
28, iv, emerged 4, v ; pupated 30, iv, emerged 4, v ; colld.
F. W. Edwards. See F. W. Edwards, 1917, Bull. Ent Research,
vol. vii, p. 212. British Museum Collection.
Cambs. — Cambridge, in bathroom of Livingstone Hotel ; 20, viii, 191
colld. C. B. Holman-Hunt. Cambridge University Museum
Collection.
Cornwall. — Poltesco, N. of Ruan Minor, Lizard district ; 27, v. 19]
colld. Rev. A. E. Eaton. British Museum Collection.
Scilly ; vi, 19 19. Colld. K. G. Blair.
Essex. — Epping Forest; (1) Epping Thicks; larvae in hollows on
tree-bases; viii, 191 8 ; colld. D. J. Scourficlii :
larvae; colld. A. IV. Baeot ; 10, iv. 191 S. pupated 1, v.
emerged 9, v ; (3) Monkswood ; larvae in hollows on tree-ba
colld. D. J. Scourfield. viii, 1918.
/A?///.s\— Gosport ; 22. vii, [892; colld. M. K Thomas. British
Museum Collection.
Herts.— Bushey Heath ; 27. vii, 191 2 ; colld F. W. Edwards. B
Museum Collection.
11
98
Cassiobury Park, N. of Watford ; young larvae associated with
larvae of Anopheles plumbeus in hole at base of beech tree ;
21, viii, 1 91 6; colld. F. \Y. Edwards. See Bull. Ent. Research,
1 91 7, vol. vii,pp. 201, 2*12.
Kent, — D art ford ; 14, vi, 1912 ; colld. Lt.-Col. Yerbury. British
Museum L olfaction.
Middlesex. — Bedford Park, Chiswick ; 17, vi, 19 18. Colld. Dr. C. 'J.
Gahan.
Harrow ; 17, vi, 1914 ; colld. F. W. Edwards. British Museum
Collection.
Regent's Park, London, N.W. ; 4, viii, 191 5; colld. F. W.
Edwards, British Museum Collection.
Oxon. — Stokenchurch ; 13, viii, 1907; colld. G. H. Verrall. British
Museum Collection.
Shropshire. — Longner Hall, S.E. of Shrewsbury; 31, v, 1908, and
5, viii, 1918 ; flies; see also record above of eggs and larvae;
colld. R. F. Burton. British Museum Collection.
V. TAEXIORHYNXHUS, Arribalzaga.
Taeniorhynchus, nov. gen. ; F. L. Arribalzaga, 1891, Dipterologia Argentina, 1 ;
Revista del Museo de la Plata, vol. i, p. 374, and vol. ii, p. 147.
Genosyntypes, Culex taeniorhynchus ^ Arribalzaga, non Wiedemann,
Taeniorhynchus confinnis, n. sp., and Taeniorkynchus fasciolatus. n. sp.
Genolectotype, Culex titillans F. Walker, in J. E. Gray, 1848, List of the
specimens of Dipterous Insects in the collection of the British Museum,
part i, p. 5 ( = Culex taeniorhynchus Arribalzaga, non Wiedemann).
1. Taeniorhynchus richiardii (Ficalbi).
Figs. 24, 26, 35, 38, 74.
Culex Richiardii, n. sp. ; E. Ficalbi, 1889, Bull. Soc. Ent. Italiana, vol. xxi,
P- 5°-
Taeniorhynchus richiardii is easily distinguished from all British
gnats except Theobaldia annulata by having a pale ring in the middle
of the first tarsal joint of the hind leg. And the wings, speckled
with very broad scales, dark mixed with light, render it very easily
distinguished from Theobaldia annulata. The most remarkable feature,
however, in Taeniorhynchus richiardii is th< >n of the larva, which
not only has no pecten, hut is of a peculiar shape, the true sip
being exceedingly short, and its apparently pointed tapering end b<
formed of the ventral pair of the valves that in a normal siphi i
the aperture. The siphon is adapted for piercing the of sub-
merged plants,1 and for exploiting the air contained in them and thus
obviating the necessity of periodic journeys to the surface for breath.
Edwards has observed that this species spends the winter as a n< arly
full-grown larva.- The pupa also is adapted to a submerged life, and
pierces the roots of grass with its pointed thoracic trumpets. The fly
appears about midsummer, and though widely distributed, does not
seem to be very common. It was originally described from Italy ;
specimens from Palestine are in the British Museum Collection ; and
Waterston records it from Macedonia (Bull. lint. Research, i
vol. ix, p. 8). British records are as follow
Cambs. — Wicken, N.E. of Cambridge; 2, vii, ioi;; colld. F. W.
Edwards. British Museum Collection.
Dorset. — Littlesea, Studland ; 2, viii, [911 ; colld. Rev. E. A. E;
British Museum Collection.
Durham. — Gibside, S.W. of Gateshead ; 10, viii, 19 16 ; colld. R. S.
Ba<mall. British Museum Collection.
Hants. Church Farm, near Hook, E. of Basingstoke, Hants. ; 17, vii,
1 91 2 ; colld. F. W. Edwards. British Museum Collection.
Herts. — Letchworth ; larvae. Colld. /•". //'. Edzvards ; Jan. [9]
Kent. Dymchurch, S.W. of Ilythc ; in an outhouse, with female
Anopheles maculipennis , 25, vii, [918. Colld, G. Walt
Wye, N.E. of Ashford ; indoors ; colld. Theobald. F. I '.
Theobald, 1903, A Monograph of the Culicidae or
vol. Hi. p. 269.
Middlesex. Ealing; 26. vii. [912; colld. II. Campion. Bn
Museum Collection.
1 Glyceriafluitans',xx F. W. Edwards, 1919,
and Typha; see C. Wi senberg-Lund, 1918,
- For a detailed account of this Ian
Monthly Magazin 5, vol. v, 1-. 83. Also, C. Wes(
belige Meddelelser fra Dansk Naturhi ing in Kjppenhavn, ■■
II 2
IOO
Norfolk. — Norwich and the Norfolk Broads ; obs. Dr. Long. See
F. V. Theobald, 1903, A Monograph of the Culicidae or Mos-
quitoes, vol. Hi, p. 269.
Shropshire. — Longner Hall, S.E. of Shrewsbury ; 30, vii, 1918. Colld.
R. F. Bur ton.
Sussex. — Angmering Ponds, S.E. of Arundel ; colld. Rev. A. E.
Eaton. See F. IV. Edwards, 19 12, The Entomologist, vol. xlv,
p. 261.
Patching Pond, N.W. of Worthing; 9, ix, 1907; colld. Rev.
A. E. Eaton. British Museum Collection.
Warwickshire. ^-Sutton Coldfidd ; colld. R. C. Bradley. See F. W.
Edwards^ 191 2, The Entomologist, vol. xlv, p. 261.
VI. THEOBALDIA, Neveu-Lemaire.
Theobaldia, nov. gen. ; M. Neveu-Lemaire, 1902, Comptes Rendus Heb. des
Se'ances et Memoires de la Soc. de Biologie, vol. liv, pp. 133 1-2.
Genotype, Culex annulatus, Schrank.
1. Theobaldia annulata (Schrank).
Figs. 8, 21, 33, 36, 76, 123-5.
Culex annulatus; F. v. P. Schrank, 1776, Beytriige zur Naturgeschichte,
p. 97.
Culex affinis, Mihi ; J. F. Stephens, 1825, Zool. Journ., vol. i, p. 452;
Hertford ; in June.
Culex calopus ; J. F. Stephens, 1825, loc. cit. ; near London (non Culex
calopus, Hofifmgg. ; J. W. Meigen, 1818, Systematische Beschreibung
der bekannten Europaischen zweifliigeligen Insekten, vol. i, p. 3).
Specimens thus labelled in Stephens' Collection in British Museum.
Theobaldia annulata is one of the commonest and most easily
distinguished of British gnats. Its great size, boldly-contrasted black
and pale-cream colouring, as well as its domestic habits, force it upon
the attention. With Anopheles maculipennis it is known from all other
British species by having spots on the wings. They are formed by
the aggregation of dark scales. From A. maculipennis it may be
known by its burly build, as well as by its banded legs and abdomen.
Culicella morsitans and C. fumipennis also have a tendency for the
aggregation of wing-scales into spots, but this is only a tendency,
and the characters given on p. 30 indicate how these two species can
easily be distinguished from Tlteobaldia annulata. The larvae of the
two species of Culicella, and that of Theobaldia annul at a, differ from
the larvae of other species of British gnats in the position of the tufl
hair at the proximal end of the siphon instead of near the m
And the pecten-teeth of T. annulata% produced into hair-like termii
tions, distinguish the larva of this specie- from those of Culicella
morsitans and C. fumipennis (figs. 76, [23 -5).
Theobaldia annulata, like Anopheles maculipennis, and i ule* /\r.
(and often in company with these), winters as a female fly in cell..
outhouses, etc. ; and may be troublesome in mild weather in the
winter, by becoming active owing to the warmth and biting in the
house. It is possible that in exceptionally mild winters some lan
may survive, since they have been recorded at dates very late in the
year. Some eggs which hatched in captivity in the British Museum
2nd Sept., 1918, passed through several instar, but most died
before the fourth instar was attained, and none pupated. Their death,
however, may have been due to unnatural conditions or unsuitable
food. On the other hand, some very young larval Anoph
plnmbeus, taken in Epping Forest and Culross, Fifeshire. in late-
summer, 191 8, having attained the fourth larval instar are still alive
at the present time (Feb. 1919). Larval Theobaldia annulata is some-
times found with Culex pipiens in water-butts ; and. as far as I am
aware, these are the only British species which are found in what may
be called domestic waters.
Theobaldia annulata occurs throughout Europe, in X. Afri
and in Mesopotamia there is a variety apparently adapted to desert
conditions, the white scales becoming yellow, and the black-
brown. The American records probably refer to /'. maccrack .nil
T. dugesi (see H. Dyar, L. Howard and F. Knab, [915, Mosquit
\. of Central America and the West Indies, vol. iii. pp. 404 and |
Specimens in the British Museum Collection have been obtained from
Norway, Switzerland, Southern France, Cyprus, and Moroco Miss
A. L. Lang has sent me a specimen from M< nastir ; Mr V. I .n
records it from Mikra in the Salonica district Bull. Ent. R ch,
1918, vol. ix, p. 91 ; and Major E. E. Austen, 1 tells me h<
with one specimen in Palestine.
In Britain the species has been collected from soman]
102
that it would serve no purpose to enumerate them. But it is worth
noting that specimens from as far north as Inverness-shire and
Aberdeen are in the British Museum Collection.
VII. CULICELLA, Felt.
Culicella, n. gen.; E. P. Felt, 1904, New York State Museum Bulletin 79,
p. 39 1 C. Genotype, Culex dyari, Coquillett.
I. Culicella morsitans (Theobald).
Figs. 23, 31, 34, 37, 59, 69, 71, 77.
Culex morsitans, n. sp. : F. V. Theobald, 1901, Monograph of the
Culicidae, vol. ii, p. 8, pi. xx, fig. 79.
? Culex dyari, sp. nov. ; D. W. Coquillett, 1902, Journ. New York Ent. Soc.
vol. x, p. 192.
Culicella morsitans and C. funtipennis are very similar species
hardly to be distinguished as flies, but having quite distinct larvae.
The blunt abdomen, the short first hind-tarsal joints, and nearness of
the posterior cross-vein to the other cross-veins characterise these two
species of Culicella and separate them from the other British gnats
except Theobaldia annuldta. That species, however, besides having
spotted wings, has a median pale longitudinal band on the
second abdominal segment and the posterior cross-vein almost in a
line with the mid cross-vein, characters not possessed either by Culicella
morsitans or C. fumipennis. In C. morsitans there are very few, if
any, white scales on the proboscis of the female (fig. 69), and in the
male the first foreJtarsal joint is decidedly longer than the remaining
four joints ; the pattern, too, on the underside of the male abdomen
is generally diffused rather than clearly marked (fig. 71). In the larva
(fig. 77) the axis of the pecten is nearly parallel with that of the
siphon, and there are no single scattered spines on the siphon as there
are in C. fumipennis, the axis of whose pecten is oblique with that
of the siphon. (Note : The siphons of the two species are figured by
F. W. Edwards, 19 12, The Entomologist, vol. xlv, p. 262, figs. 3, 4,
but, unfortunately, the names have been transposed in the legends.)
According to F. W. Edwards, the larvae of both British species of
Culicella feed mainly at the bottom and prefer open pools. When
disturbed they wriggle beneath the leaves. Evidently they shun the
surface, and may well be on the way to developing similar habits to
Taeniorhynchus. Mr. Edwards suggests that it is even possible thai
that genus may have been derived from Culicella.
C. morsitans appears to be mainly a British . and in Britain
to be somewhat commoner than C. fumipennis. The type-sp< is
from Eridge, Sussex. There are specimens in the British Museum
Collection from Ghent and Southern France, and de Meijere • it
from Holland (Tidschrift v. Ent., nil 1. vol. liv, p. [38). It occurs
in Denmark and Macedonia. British records are as follow
Bucks. — Burnham Beeches; 10, vi, 1907; colld. C. O. Waterhouse ;
6. v, 19 1 4 ; colld. F. W. Edwards. British Museum Collection.
Essex. — Epping Forest; larvae; 21, iv, 1918 ; one pupated 24. iv,
and emerged 1, v; and another pupated 23, iv, and emci
29, iv ; colld. Lt. Tickner Edwardes, R.A.M.C. ; pupa, 13, v, 1
emerged 16, v. 191 8 ; colld. Miss Cheesman.
Rochford ; 11, 12, and 15, vi, 1907 ; colld. Rev. A. I'.. Eaton.
British Museum Collection.
Hants. — Brockenhurst ; 30 and 31, iv. and 9, 15, and 28, v.
colld. C. O. Waterhouse. British Museum Collection.
Lyndhurst ; colld. Lt.-Col. Yerbury. British Museum Collect:
Hunts.— Wood Walton Fen, E. of Ramsey; 13-15, iv, [914; colld.
F. W. Edwards. British Museum Collection.
Middlesex. — Harrow Weald Common; pupa; 28. iv. 1913 ; olid.
F. W. Edwards. British Museum Collection.
Norfolk.— Ormesby. N. of Great Yarmouth ; 25. vi. [918 ; colld «".. II.
Yerrall. British Museum Collection.
Shropshire. — Longner Hall, S.E. of Shrewsbury ; in garden, i6,vi,
5, vii, 191 8; colld. R. F. Burton. British Museum ion
S,^;/^— Newmarket ; 26. viii, 1908; colld. G. II. Yerrall. B
Museum Collection.
.S///7T/.— Mitcham Common ; larvae; 3, v. [918, pu| Il8,
emerged 15, v, [918 ; pupa collected 3, v. 1918, emerged '• \ . :
Colld. Miss L. E. Cheesman.
Woking. See /■'. W Edzvards, 1912, /'■
vol. xlv, p. 262.
Sussex— Angmering Ponds, S.E. of Arundel ; 4, vii, 1
A. E. Eaton. British Museum Collection.
104
Eridge, S. of Tunbridge Wells, Kent ; type-specimen of C?ilex
morsitans ; colld. G. H. Verrall. British Museum Collection.
Patching Pond, N.W. of Worthing ; 10, ix, 1907 ; colld. Rev.
A. E. Eaton. British Museum Collection.
Wales. — Llanidloes, Montgomeryshire; 24, vii, 1918. Colld. R. F.
Burton.
2. Culicella fumipennis (Stephens).
Figs. 70, 72, 78.
Cukx fumipennis, Mini. ; J. F. Stephens, 1825, Zoological Journal, vol. i,
P- 453-
Culicada Theobaldi, n. sp. : J. C. H. de Meijere, 1911, Tidschrift voor
Entomologie, vol. liv, p. 142, pi. ix, figs. 10-16. See F. W. Edwards,
1 91 2, The Entomologist, vol. xlv, p. 277.
The white scaling at the sides of the proboscis in the female
(fig. yo), and the length of the first fore-tarsal joint and the pattern of the
underside of the abdomen in the male (fig. 72) are the only characters
hitherto observed whereby the imago Culicella fumipennis can be
distinguished from C. morsitans (see pp. 44-5). And since these
differences are matters of degree, they are by no means as certain
guides for determination as is desirable. I have not been able to
discover any differences in the male genitalia. The larvae, however,
have very different siphons (see figs. 77-8), and can be distinguished
at a glance under sufficiently high magnification. It would be of
great interest to determine by numerous experiments if these two
species always bred true, and that they were not one species with a
dimorphic larva. Also, since the genitalia are so similar, whether they
would interbreed, and in that case whether the siphons of resulting
larvae would exhibit dominance or mixed characters ; and in the
former case whether the 3 : 1 Mendelian proportion would occur in
the second generation.
Culicella fumipennis appears to be nearly as common as C. morsitans
and as widely distributed. De Meijere records it (as Culicada TJieobaldi)
from Holland, Noe from Italy, and Waterston from Macedonia.
British records are as follows : —
Bucks. — Burnham Beeches; larvae and flies; 6, v, 1914; colld. F. W.
Edwards. British Museum Collection.
Dorset.— Burton Mere; 27, v, 1910; colld. Rev. A E. Eaton 6 itish
Museum Colli xtion.
Littlesea, Studland ; 2, viii, 1 « # 1 1 ; colltl. Rev. A. E. 1
British Museum Collection.
Studland; 21, v, 1912 ; colld. Lt.-Col. Yerbury.
Museum C ollection.
Hants. — Brockenhurst ; flies and larvae ; 15, v. [904 ; 3, IO, 12.
vi, 1905 ; 15, vi, 1906; colld. C. 0. Waterhouse. British May
Collection.
Middlesex. — Harrow-on-the-Hill ; 14, v, 1905; colld. W. D. I.
British Muse inn Collection.
London, British Museum (Nat. Hist), Diptera Room ; 4. ix,
1916 ; colld. F. W. Edwards. British Museum Collecti
Shropshire. — Longner Hall, S.E. of Shrewsbury ; in garden. [<
1908; colld. R. F. Burton. British Museum Collection.
Shrewsbury ; on windows in Board Room, Shrewsbury Infirmary ;
3, ix, 1910 ; colld. R. F. Burton. British Museum Collecti
Surrey. — Ripley, N.E. of Guildford ; type-specimen ; colld. I F
Stephens. British Museum Collection.
Wales. — Llanidloes, Montgomeryshire; 24, vii, [918. Colld. R. F,
Burton.
Scotland. — Dingwall, Cromarty ; 31, v, 191 1 ; colld. Lt-Col. Yerbury.
British Museum Collection.
Invcran, Sutherland ; 17, vii, [886; colld. (i. H.Verrall. B
Museum Collection.
VIII. CULEX, Linnaeus.
Culex; Linnaeus, 1758, Systema Naturae, Regnuni Animate, editio
p. 602. Genpsyntypes, C. pipiens, C. hi fur cat us, C /•■
C. reptans and C. stercorals. Genolectotype, C. pip D. W.
Coquillett, 1910, Proc. United States National Museum, vol. xxxvii,
P- 5-9-
1. Culex pipiens Linnaeus.
Figs. 1, 16, 19, 22, 32, 79, 121
Culex pipiens ; Linnaeus, 1758, Systema Naturae, Regnum Anin
decima, p. 60 2.
Culex bicolor; J. F. Stephens, 1825, Zool Journal, »
from Hertford. (Probably Culex J. W. Meig
io6
Svstematische Beschreibung der bekannten Europaischen zweifliigeligen
Insekten, vol. i, p. 9. See F. W. Edwards, 1912, The Entomologist,
vol. xlv, p. 277.)
Culex lutes cms ; }. F. Stephens, 1825, loc. cit.; from Darenth. (non Culex
lutes cens ; J .C. Fabricius, 1775, Systema Entomologiae, p. 800. See
F. W. Edwards, 1912, The Entomologist, vol. xlv, p. 277.)
Culex punctatus ; J. F. Stephens, 1825, loc. cit. ; no locality is recorded, (non
Culex punctatus ; J. AW Meigen, 1818, Systematische Beschreibung der
bekannten Europaischen /.weirliigeligen Insekten, vol. i, p. 9. See F. W.
Edwards, 191 2, The Entomologist, vol. xlv, p. 277.)
Culex marginalis, Mihi. ; J. F. Stephens, 1825, op. cit. p. 455 ; one female ;
London See F. W. Edwards, 191 2, The Entomologist, vol. xlv,
p. 277.
Culex rufus ; J. F. Stephens, 1825, op. cit., p. 456 ; from Hertford (common).
(non Culex rufus, Hoffmgg. ; J. W. Meigen, 18 18, Systematische
Beschreibung der bekannten Europaischen zweifliigeligen Insekten, vol. 1,
p. 7. See F. W. Edwards, 1912, The Entomologist, vol. xlv, p. 277.)
Culex domesticus (partirh) / J. F. Stephens, 1825, op. cit., p. 455 ; from Hertford.
(Probably Culex domesticus ; E. F. Germar, 18 17, Reise nach Dalmatien
und in das Gebiet von Ragusa, p. 290.) Three specimens under this
name in Stephens' collection in the British Museum are Culex pipiens
and one Culex nemorosus.
Culex sylvaticus ; J. F. Stephens, 1825, op. cit., p. 454; one specimen, in June,
from Coombe Wood, (non Culex sylvaticus; J. W. Meigen, 18 18,
Svstematische Beschreibung der bekannten Europaischen zweifliigeligen
Insekten, vol. i, p. 6, which is Ochlerotatus nemorosus, q.v.)
The male Culex pipiens may be known at once from other British
gnats, except C. apicalis, by the pointed palpi which curl upwards
through an angle of about 90 (fig. 19). The female ma}' be known
from Ae'des and Ochlerotatus by the blunt abdomen (fig. 16) and simple
claws ; and from Taeniorhynchiis, Theobaldia and Culicella by the long
first hind-tarsal joint (fig. 32). The long fork and short stalk of
vein 2 of the wing is also an easily seen character distinctive of Culex.
The creamy colour of the pale abdominal bands and their basal
position distinguishes both sexes of Culex pipiens from C. apicalis.
The larva is known by its long slender siphon (less slender than that
of C. apicalis) and several scattered hair-tufts with few hairs.
Culex pipiens is quite the commonest British gnat, and is abundant
everywhere. It is the more noticeable, as it frequents houses and,
with Anopheles maculipennis and Theobaldia aunulata. spends the
winter as an impregnated female fly in the shelter of buildings.
Any collection of water that is not too foul serves as a breeding-place.
Water-butts and zinc cisterns, as well as pond.-, in various situatii
in fact, any stagnant water appears to satisfy the larv
pipiens. One unusual situation is recorded by A. Macdonald, jun..
from Culross, Fifeshire. He found larvae in collections of water in a
disused saw-pit in what had been a copse situated on a m<;or ; but the
trees had lately been cut down, so that where the water was there
was now no shelter at all. The water was dark-coloured, but cle;
Foreign records show Culex pipiens larvae to be still less particular in
their breeding-places. H. Dyar, L. Howard and F. Knab (1915,
Mosquitoes of North and Central America and the West Indies, vol. iii,
p. 367) say that the larvae are able to thrive in highly polluted water,
and quote catch-basins of sewers and water highly charged with the
refuse from slaughtered animals as localities for them. They
quote Ficalbi as recording the larvae of Culex pipiens from fonts
consecrated water in churches and in sulphurous water ; and J.
Waterston (1918, Bull. Ent. Research, vol. ix, p. 10) found them in
Macedonia in an artificial washing-pool amid soap-suds, and in
extremely foul-smelling, but quite clear, rocky pools of a sewaj
effluent. It is probable, then, that in England Culex pipiens is
more particular in its breeding-places, but for lack of observation it is
not credited with such foul propensities.
C. pipien s occurs throughout Europe, in northern Africa. E. Afri
Madagascar, and restrictedly in X. America. From the last-mention
fact, Dyar, Howard and Knab consider that the species has been
introduced into X. America from Europe. It is worthy of n< I
that Culex fatigans. a species so much resembling Culex pipiei
the only satisfactory characters for distinguishing the two sped
in details of the male genitalia, has a very wide geographi tri-
bution in the warmer parts of the world, and has been records I 1 ■'. V.
Theobald, 1901, A Monograph of the Culicidae or Mosquitoes, vol. ii.
p. 154) from Spain and Portugal. Now it is evident that, since the
two species are so much alike that it needs a microscope-preparati
before their differences can be seen, it may easily happen that •
fatigans maybe present in a country without being detected.: for il
C. pipiens is common. C. fatigans will not be sought
possible that if C fatigans were to extend its range it mij
ioS
long time be unnoticed. The practical interest of C. fatigans is that
it conveys (and presumably can transmit) the worms that cause
filariasis and the organism that causes dengue fever. It is desirable,
therefore, that C. pipiens should be closely watched in case C. fatigans
extended its range ; and the possibility should not be forgotten of C.
pipiois acquiring the disease-bearing habits of C. fatigans where the
range of these species overlap, and by this means spreading the
diseases concerned over its own range.
Culex pipiens, Linnaeus ; var. doliorum, Edwards.
Culex pipiens, var. doliorum (nov.); F. W. Edwards, 191 2, The Entomo-
logist, vol. xlv, p. 263.
Culex nigritulus, Zetterstedt ; F. V. Theobald, 1901, A Monograph of the
Culicidae or Mosquitoes, vol. ii, p. 140.
non Culex nigritulus ; J. W. Zetterstedt, 1850, Diptera Scandinaviae, vol. ix,
P- 3459-
Edwards describes as a variety of Culex pipiens a form which is
much smaller, darker, and having a thorax without any reddish tint,
and recognises it as identical with British specimens referred by
Theobald to Culex nigritulus, of Zetterstedt. Theobald's specimens
were from larvae living in water-butts, but the locality is not mentioned.
Edwards' type-specimen of his variety doliorum was also reared from
a larva which with others was " swarming in water-barrels at Kings-
wear, S. Devon." They were found in October, 191 1. A single
specimen from Bushey Heath, Herts, and collected by F. W. Edwards,
27, vii, 191 2, is in the British Museum Collection.
2. Culex apicalis, Adams.
Figs. 73, 129.
Culex apicalis, n. sp. ; Adams, 1903, Kansas Univ. Sci. Bull., vol. ii, p. 26.
Culex pyrenaicus, n. sp. ; Brolemann, 1919, Ann. Soc. Ent. France, vol. lxxxvii,
p. 427.
Culex hortensis, Ficalbi ; F. W. Edwards, 191 5, Entomologist's Monthly
Magazine, ser. 3, vol. i, p. 167.
non Culex hortensis; E. Ficalbi, 1889, Bull. Soc. Ent. Italiana, vol. xxxi,
p. 217.
Culex apicalis resembles the more southern and eastern species
C. hortensis, but has broader wing-scaling and. no white spot at the
distal end of the tibia. A single specimen of this species was taken
109
by F. Jenkinson at Logie, Elgin, X.B., n, ix, [911, and is now in th<
Cambridge University Museum. The type-specimen came from
N. America, and that of C. pyrenaicus from the Pyrennee . and I
latter form has also been taken at Rambouillet and la Creuse in
France (see J. Ville'neuve, 1919, Bull. Soc. Ent. France, p. 5$
IX. ORTHOPODOMYIA, Theobald.
Orthopodomyia^ nov. gen.; F. V. Theobald, 1904, I Entomolog
vol. xxxvii, p. 236. Genotype, O. alipes, n. -p.
I. Orthopodomyia albionensis, MacGregor.
Figs. 1 30- 1 2.
Orthopodomyia albionensis, sp. nov.: M. E. MacGregor, 1919, Journ. k
Army Medical Corps, vol. xxxiii, p. 451, and plate.
? Culex pulchripalpis, X.; C. Rondani, 1872, Bull. Soc. Ent. Ital., anno
P- 3i.
? Culex pulchripalpis, Rondani (1872) ; E. Ficalbi, 1899, Bull. Soc. Ent. Ital.,
anno xxxi, p. 220.
non Culex pulchripalpis ; F.V.Theobald, 1901, A Monograph of the Culicidae
or Mosquitoes, vol. ii, p. 16, which is Ochlerotatus ca spins, q. v.
Orthopodomyia albionensis is easily distinguished from all other
British gnats by the long palps of the female (fig. 130) and by the
fourth tarsal joint of that sex (fig. 131 ) which, at least in the fore-l<
is not longer than broad. The general black ground-colour with
brilliant white (not creamy) markings also distinguish both sexes from
all the British forms except Finlaya geniculates and Stegomyia fascia
(added to the British list while this work was in the pr \>. 112.
The complete white abdominal bands and white-banded tarsi
distinguish it from the former, and its larger size and three pairs
(instead of two pairs) of white longitudinal stripes on the dorsal
surface of the thorax distinguish it from Stegomyia fasciat ell as
the absence of the silvery-white lateral row of abdominal s
species, and the larva has no pecten on an otherwise norma n
(fig. T32).
In July of this year ( 1 9 1 9 ) , Major A. Macdonald collected some
larvae in Epping Forest from a tree-hole from which he had forn:
■obtained the larvae of Anopheles plum be us. They were reared by
I IO
Capt. M. E. MacGregor at Sandwich, Kent, and the emergent flies
were mosth- Finlaya geniciilata. Among them, however, appeared
four Ortkopodomyia, described by MacGregor as a new species. But
Rondani's original diagnosis of Culex pulcliripalpis, and Ficalbi's later
more detailed description do not leave the matter free of doubt ; and
it may be that the Epping Forest specimens are of Rondani's species
Until it is possible, therefore, to compare Italian with the English
material, it is better to accept MacGregor's name for this form.
rEKzr-
FiG. 130. — Head of female Ortkopodomyia
albionensis, showing the rather long
palps.
Fig. 131. — End of fore-tibia and fore-tarsus
of female of the same species, showing
short fourth tarsal joint.
Through the kindness of Major A. Macdonald and Capt. M. E.
MacGregor, a specimen of each sex of Ortkopodomyia albionensis is in
the British Museum. On the 31st July, Mr. F. W. Edwards and
Capt. MacGregor visited the tree-hole and collected a good deal of
material. That brought back by Mr. Edwards yielded only Finlaya
geniculates ; but from Capt. MacGregor's material emerged a few
Ortkopodomyia and two specimens of Stegomyia fasciata, a second
mosquito new to Britain from this tree-hole. On another visit, on
nth August, to the same tree-hole, Mr. Edwards secured a single
larva of 0. albionensis in the fourth iristar, and five pupae, three of which
he reared to the imago-stage. Again, in September, Mr. 11. Main I
three more larvae, one in the second and two in the third instar, i
to the spot in Epping Forest whence the others were obtain* d. These
are still (Jan. 1920) alive, one in the third and the other two in the
fourth instar, and it is likely that will hibernate in this condition.
It is a great encouragement to collectors that, while this work v
in the press, this and two other species new to Britain, namely,
Ochlerotatits curriei (see p. 84) and Stegomyia fasciata (see p. ii2>
have been discovered.
Fig. 132. — Siphon ;ind comb-scale of the fourth-instar of larva of same S]
IV. REPUTED, DOUBTFUL, AND FOSSIL
BRITISH SPECIES.
Stephens (1825, Zoological Journal, vol. i. pp. 452-456) re<
as British several of Meigen's species which have not since been found.
Fortunately, Stephens' collection is in the British Museum, and his
determinations have been revised by Mr. F. W. Edwards (see The
Entomologist, 1912, vol. xlv, p. 2771. All are referable to known
British species. References to these are included in the synonymy
under the account of the species to which they refer.
Besides these there are the following n of foreign
Britain : —
Cuhx lutescens; J. C. Fabricius, 1775- Systems Entomologii
Recorded as British l.y F.V.Theobald, 1901, A Monograpl < the
I 12
( ulicidae or Mosquitoes, vol. ii, p. 168, from Kingston-on-Thames, in
1S85 ; but the specimen no longer exists. Also by G. H. Verrall, 1888,
A List of British Diptera, p. 10.
Stegomyia fasciata (Fabricius). Culex fas ciatus : J. C. Fabricius, 1805, Systema
Antliatorum, p. 36. Two specimens of this mosquito emerged from the
pupal material (otherwise Finlaya geniculata) collected by Capt. M. E.
MacGregor from the tree-hole in Epping Forest from which the larvae
and pupae of Orthopodomyia albionensis had already been obtained (see
above). Stegomyia fasciata is the mosquito concerned in conveying
Yellow Fever; and, being a ready breeder, is reared extensively in
research laboratories in England. It would not, therefore, be a matter
for surprise had escaped specimens of the fly been taken from the
neighbourhood of laboratories. But to find it in the larval and pupal
stages in Epping Forest is another matter, and it appears likely that, if
no mistake has been made, this is a genuine case of the introduction of
a foreign species. It will be interesting to note whether the species will
survive the winter in the locality where it appears to be established.
Stegomyia fasciata differs in general appearance from all other British forms,
except Finlaya geniculata and Orthopodomyia albionensis, \x\ being a black
species with brilliant white markings ; and from the two species mentioned
in being much smaller and having a pair of sickle-shaped white bands on
the thorax, a second pair of straight, yellowish, longitudinal lines between
these, and a lateral row of silvery-white spots on the abdomen in addition
to the usual banding. Orthopodomyia albionensis has three pairs of very
narrow, white, longitudinal lines on the thorax, Finlaya geniculata has a
median, pale, greenish-yellow line and a pair of similar lateral lines on
the dorsal surface of the thorax, and lacks the white tarsal bands of the
other two species (see M. E. Macgregor, 191 9, Bull. Ent. Research,
vol. x, p. 91).
' Before leaving- the subject of reputed British species, it is worthy
of remark that there is a widespread belief in the occurrence of foreign
gnats (" mosquitoes " they are generally called in this connection) intro-
duced into this country by means of ships. The belief appears in
letters written to the Museum, in entomological literature (see the case
of the "Norway Mosquito" recorded in the Entomological Monthly
Magazine, 1895, p. 227, which was merely Ochlerotatus caspius), and
finds perennial expression in the Press; there is an echo of it in
Theobald's remark on Culex pulchripalpis (see under Ochlerotatus
'13
caspins, p. 83); and it is a possible explanation of the remarkab
and isolated occurrence of Culex apicalls, an Ai in and Medit
ranean species, in Elgin (see p. 10S), and the single case of Stegi m
fasciata quoted above. But. apart from the fact that, th
means impossible, such introduction is uhlikely,1 there is n ve
evidence that any gnat taken in Britain was introduced, and all sup-
cases (except the two last mentioned) that have been in
proved to be ordinary British species. Such rumours, then, should
treated with scientific scepticism, and conclusive evidence demand
Though beyond the original intention of this work, it is of inter
to observe that at least three species of gnat are found sils in
Britain. These are from the Oligocene of Gurnard Bay, W. of C< ro
Isle of Wight, and are described by T. D. Cockerell. 1915, Pi
United States National Museum, vol. xlix, pp. 488-9, pi. Ixi, fig. 12.
and pi. lxii, figs. 1 and 2. They are named as follows : —
Culex protolepis, Cockerell, op. fit., p. 488, pi. lxii, fig. 1.
Culex pro for Ainus, Cockerell, op. cit., p. 48S, pi. lxii, fig
Culex petrifactellus, Cockerell, op. cit., p. 4S9, pi. Ixi. fig. 12.
From the figures and descriptions of these forms it is evident th
they are Culicidae, but a more exact determination is not possible.
To assign them to the genus Culex is but conjecture.
Gnats have also been described from the Baltic amber, which
probably is also Oligocene in age. And since Baltic amber is
frequently picked up on our eastern coasts, it is possible that
gnat-fauna may be found in Britain.
V. EVOLUTIONARY AXI) CONCLUDING
REMARKS.
It is evident from the foregoing account that there is much yet
to be found out about British Mosquitoes. About their structure,
for there may be many other differences than those given in the
diagnostic tables, and these mav be more definite and more
seen than those characters which are given ; besides, the first two
ept in the case of the "cultivated
U4
larval instar of Ochlerotatus detritus have not been described ; and
only the last larval instar of Taeniorkynchus richiardii, Aedes cinereus,
Ochlerotatus vexans, 0. ivaterhousei, 0. auuulipes, 0. rusticus, Culieella
morsitans, C. fumipeuuis and Orthopodoiuyia albionensis ; and no larval
stasre of Ochlerotatus curriei. And about their habits, both as flies and
larvae ; the times of appearance of the former, their distribution, the
stations they mostly frequent, their enemies and other adverse circum-
stances affecting them, the kind of prey they prefer (for instance, Culex
pipiens is said especially to attack birds), and their mating habits ; and,
in observing the larvae, the kind of water they like best, the amount
of impurities they can stand, the nature of their food and of their foes,
and the behaviour in the winter of those that hibernate, are instances
of what needs to be done. The remarks on pp. 5-1 1 illustrate the
directions and scope of some of the conclusions to be drawn from the
habits of mosquitoes. And, though a knowledge of the structure of
each instar of even' species is of immediate use for identification, it is
of still greater interest if it points to possible conclusions concerning
the evolution of gnats. The study of post-embryonic growth-stages
as affording evidence of the phylogeny of any group is becoming more
widely pursued by biologists, and has been applied with encouraging
results especially by those whose work lies among fossil organisms.
And one of the commonest occurrences met with by palaeontologists
is that of homceomorphy both in convergent and in parallel evolution
— homoeomorphs being organisms closely resembling one another, yet
having a different ancestry manifested in differing post-embryonic
growth-stages. Hence, if two gnats resemble one another so closely
that their separation is a matter of considerable trouble, it is not surpris-
ing to find their larvae differing considerably, as in Culieella morsitans
and C. fumipennis. Again* it is probable that such larvae, in common
with other more distantly-connected species, will resemble one another
more closely in the earlier instar. Thus, a larval difference (unless, as
in Taeniorkynchus, the larval peculiarity is obviously the result of direct
adaptation to a peculiar environment) is probably of more significance
than a difference in the imago. This principle has been recognised as
fundamental by American authors, notably by Dyar and Knab, and
they accordingly classify mosquitoes primarily with regard to their
larval characters.
H5
A glance at the British forms will show the value of some of th<
larval characters. It is evident that the genus Anopheles differs more
from the other genera of gnats than these d<» among themselves : but
the larval differences are more striking than those of the imago. And
even the first larval instar of Anopheles differs considerably from the
first larval instar of a Culicine — notably in r> [ng no siphon, in
having anterior clypeal hairs, float-hairs and the scaler of the comb
united basally. It is even possible that the " secondary comb " of the
first instar Anopheles with its separated scales is the homologuc of the
comb of the Culicines. It is likely, then, that Anopheles diverged from
the main stock before this had divided into various Culicine lineages.
The first instar (as far as it is known) of the various Culicine genera
have the hair on the siphon approximately in the position of the hair-
tuft in the later instar ; and this renders it likely that the genera A
Finlaya and Ochlerotatus diverged along one line, Theobaldia, Culicella,
and possibly Taeniorhynchus along a second line, and Cnlex alon
third line. It is evident from an examination of the first larval instar
of various species that the arrangement of the comb-scales in a single
disconnected row is a primitive one. This primitive condition is re-
tained in Aides, Finlaya and Taeniorhynchus throughout their larval
life. It is of interest to note that this primitive line has apparently
independently broken up into a triangular patch with the scales
irregularly arranged in Ochlerotatus, in Theobaldia (and presumably
Culicella) and in Cnlex. From the first instar, too, it is seen that the
arrangement of the post-antennal hairs is approximately in a line.
In the second, third and fourth larval instar of Ochlerotatus, the mill
post-antennal hair has moved forward and inward, showing that in
this character Ochlerotatus has advanced beyond the other allied
genera.
The arrangement of the larval hairs has been considered from an
evolutionary point of view. What of their form ? Culicid larvae are
remarkable for the extraordinary variety of form displayed in the
hairs springing from the integment. These may be apparently
simple, split at the end, slightly branched, once or twice bifurcate,
pinnately branched or feathered, dendroid, tufted, with flattened
laminae forming rosettes (as in float-hairs) or fringed scales (as in
the comb), stiffened so as to be bristle-like or hardened into a spine
i :
n6
or tooth. It is reasonable to suppose that these are all modifications
of a simple hair, and that various degrees of branching (from mere
splitting of the end to a fringed scale or a tufted hair consisting of
several sub-equal branches united at the base, and themselves having
tiny secondary and pinnately-arranged branches) have been imposed
upon the simple hair during evolution, and that the general develop-
ment of a hair is an anagenesis from more simple to more complex.
But in certain cases, hairs may be seen to be secondarily simple and
to be in catagenesis or declining evolution. Such are the anterior
clypeal hairs of Anopliclcs plnnibens in the last two instar. Those of
the third instar (fig. 88) are more complex than those of the fourth
(fig. 82), and those of the second (fig. 94) than those of the third
instar. It is probable, too, that the smooth antennae of Anopheles
plumbens, Finlaya genicn/ata, and OrtJwpodomyia is a secondary con-
dition correlated with their life in tree-holes; that is, that the appressed
spines or scales were originally present, but were lost during evolution.
There is, however, no ontological evidence in this case.
It is possible, while in all the cases hitherto mentioned, the h'air,
scale, or tooth is derived from a single hair, the pecten-teeth, on the
contrary, are compound in origin, and that each tooth is comparable
with the comb of the eighth segment. In the first instar of O. neino-
rosus the more distal pecten-teeth may have several smaller denticles
on each side of a larger one, and are reminiscent of the very minute
rows of graduated teeth that cover the siphon and chitinous " saddle "
of the ninth segment.
It is often asked of what use to the organism is the comb or the
pecten. For that matter, what use has been discovered for any of
the marvellously-shaped hairs with which the larva is so abundantly
adorned ? The function of the palmate hairs of Anophe/es, it is true,
is to help the organism to float, and of the brushes to collect and
direct particles of food. But in most cases a use has yet to be found
for the hairs of Culicid larvae. But is it likely that every branch and
every form of hair has an adaptive significance ? I think not. Given
an organ that during evolution begins to vary in a definite direction,
certain variations will be seized upon and adapted to definite uses.
But it often seems that a process in evolution once started continues
with an increasing momentum, and often cannot be checked ; and has
1 17
no relation to Natural Selection, except that it may
by hampering the organism. Such has almost certainly ha
in connection with the skeletal structures of variou
particularly in the matter of calcium carbonate secretion. In the
case of the larval hairs, it is possible that a tendency to branching,
flattening, and otherwise modifying the shape of a simple hair a
in primitive Culicid larvae; and as evolution proceeded this tend
gained in momentum in even- lineage, and has pi to the
extremes now met with in present-day Culicids. Where it could
put to a use this was done, as in the case of the float-hair- But oft n.
if not generally, when confronted with a Culicid larval h are
dealing, not with a complex adaptation, but with a variation which
has got out of hand possibly by the removal of some inhibiting
factor, which made for conservatism in an organ with great potential
variability.1
Before concluding, I would acknowledge, with many thanks, the
ready assistance I have received from the following ; chiefly in the
shape of material, particularly of various larval stages, but Ivice
and information. Without this help the handbook, imperfect as it is,
would be vers- greatly impoverished : —
John Archibald, Esq., late R.A.M.C. ; R. F. Burton, Esq.; M
L. E. Cheesman ; Dr. J. Davidson, late Capt. R.A.M.C : Dr. J. J.
Day, late attd. R.A.M.C. ; Tickner Edwardes, Esq., late R.A.M
M. Gross, Esq., late Capt. R.AAI.C. ; A. J. Grove, Esq., of the I.
Government Board ; Col. S. P. James ; G. II. Lockett, Es . and the
boys of Gresham's School, Holt; Major A. Macdonald, R.A.M
Angus Macdonald, jnr. ; Major A. C. Parsons, R.A.M. C. : Mr. Ryan,
late R.A.M.C. ; Dr. Hugh Scott'- ; D. J. So airfield. Esq. ; C. 1
Esq.; F. B. Taylor, Esq.; A. Vassall, Esq.; and my coll
Major E. E. Austen, D.S.O. ; K G. Blair, Esq.; G. R Brook, !
late R.A.M.C. ; F. W. Edwards, Esq. ; and J. Waterst n, Es
R.A.M.C.
1 C.Wesenberg-Lund (1919, \ idensk. Medd. fra 1 >ansk naturhisl I 1
accounts for the abundance and length of the larval hairs as at
motions in the environment, but he does not aci
- By an oversight on p. 84, no acknowledgment to Dr. H
presenting the Museum with specimens
collected by him near Wareham.
1 [Q
INDEX OF THE TRIVIAL NAMES MENTIONED.
PAGE
affinis Stephens . . . . ioo
albionensis MacGregor vi, 2*6-7,
109-11, ri2, 114, i-5
albofasciatus Macquart . . 8i
albopunctatus Rondani . 96
alipes Theobald .... 109
annulatus Schrank vi, 24, 26, 29,
30, 32, 47, 70, 71, 74, 96> 98,
100-2, 106, 121-5
annulipes Meigen v, 35, 36, 38,
40, 42-3, 62, 63-6, 85-6, 87-8,
114, 122, 124
apicaliS Adams vi, 45, 46, 7--
106, 108-9, 113, 123, l25
bicolor Stephens (1 Meigen) . 105
bifurcatUS Linnaeus v, vii, 6, 32,
33-4, 35> 5°>5'-4 57-8, 73-5,
76-7, 78, 9°, io5> I22~3>
Plate II.
caJopus Stephens {non Meigen) 100
can tans Meigen .... 86-8
caspius Pallas v, vii, 24, 26, 28-9,
35, J^> 37, 38, 41, 43, 49- 59,
60-1, 62-7,81-4, 86, 89,96 7.
109, 112-3, 121-2, 124,
Plate IV.
ciliaris Linnaeus .... 79
cinereus Meigen v, 7, 17, 21,22,
23, 28, 47, 58,79-81, 114,121,
i-3
concinnus Stephens ... 91
confinnis Arribdlzaga ... <»s
confirmatus Arribalzaga . . 8i
eurriei Coquillett v, 35, 37, \\,
62, 65-6, 82, 84 5. in. 114
detritus Hali. lay v, 35, 37,39,
4/, 4: \. 59 '"■ 65 '■• 69*
86. 89 90. 91 2, 97, 1 14, '-1-'-
1-4
diversus Theobald ... 94
doliorum Edwards . . 79i 108
domesticus Stephens, partim
(non Germar) . . • • 91
domesticus Stephens, partim
(and probably Germar) . 106
dorsalis Meigen ....
dugesi Dyar & Knab . . 10 1
dyari Coquillett . . . • 102
equinus Linnaeus . . . . 105
fasciatus Fabricius 10, 27, 51,
109-1 11, 112, 11;
t'asciolatus Arribdlzaga
fatigans Weidemann . . -i°7 :
fenestralis Scopoli . . 5, 121
fumipennis Stephens \ i, 32. 44
r. 72, 100-3, 104 5. 1 11. 123
fusculiis Zetterstedt . .
fuscus Osten Sacken . . :<>. 80
g-eniculatus < Hivier vi, -
26. 28, 17, 39, 43i ■
69, 70. 78, 91, 95 8. 109
112, II". 122, 124
mttatus Curtis ''''
■
hortensis Fi< albi •
kochi Donitz . . ■ •
lateralis Mi igen .
leucopygus Eysell .
lutcovittata Theobald ... "4
lutescens Fabricius . ' ' '
lutescens Stephen •• I >ri-
cius). ...... ,o0
maccrai Dyar >v Knab
macula tits Me
I 20
maculipennis Meigen
28,
PAGE
v, vii, 5,
33-4, 35, 5°,
22, 24,
51-6, 57-8, 73-6, 77-8, 99-
101, 106, 1 2 1-3, Plate I.
marginalis Stephens . . . 106
morsitans Theobald vi, 25, 29-30,
32, 44-5, 4-, 71, 100-1, 102-4,
114, 121-3
nemoroSUS Meigen v, vii, ir, 15,
35, 37, 39, 4°, 4i, 42-3, 62,
63-4, 65, 67, 86, 89, 91-3,
94, 96-7, 106, 116, 121-2, 124
nigripes Staeger .... 78
nigripes Zetterstedt ... 91
nigrittilus Theobald . . 79, 108
nigritulus Zetterstedt . . 79, 108
onondagensis Felt ... 82
ornatus Stephens {non Meigen)
94, 96
81
113
penicillaris Rondani .
petrifactellus Cockerell
pipiens Linnaeus vi, 3, 4, 10. 22,
-V, 29, 45, 46, 48, 70, 72-3,
79, 91, 93, 96, ioi, 105-8,
114, 1 2 1-3, 125
pllimbeus Stephens v, vii, 32,
33-4, 35, 5°, 5*-6* 57-8, 68,
74, 76, 78-9, 96-8, 101, 109,
116, 122-4, Plate III.
plumosus Linnaeus . . 4, 121
poicilia Theobald .... 95
pPOtOlepis Cockerell . .113
protorhinus Cockerell . .113
pulchripalpis Rondani 83, 109, no
pulchripalpis Theobald 81, 109, 112
PAGE
pulicaris Linnaeus. . . . 105
punctatus Meigen .... Si
pinutatus Stephens {non
Meigen) 106
ptmgens Robineau-Desvoidy . 94
pyrenaicus Brolemann . . .108-9
quadratimaculatus Macquart . 94
regelationis Linnaeus . . .^,121
reptans Linnaeus .... 105
richiardii Ficalbi vi, 24, 26, 30,
47- 98-100, 114, 1 2 1-3
rufus Gimmerthal . . .79,80
riifus Stephens {non Meigen). 106
rusticus Rossi v, 25, 27, 35, 37,
39, 4i-3, 48-9, 59, 62, 65, 67,
S5-6, 91, 94-5, 114, 122, 124
. . 89
• • i°5
. . 91
. . 91
salinus Ficalbi
stercoreus Linnaeus
sylvae Theobald .
sylvaticus Meigen .
sylvaticus Stephens
Meigen).
sylvestris Theobald
taeniorh xncJuts Arribalzasa
{non Wiedemann) .
terriei Theobald .
thcobaldi de Meijere .
titillans Walker
variegatus Schrank
vexans Meigen v, 35, 36, 37, 38,
40, 4^-3, 59, 6l> 65~6, 85, 86,
94, 114, 122, 124
waterhousei Theobald v, 35, 36,
37, 38, 4°, 42-3, 6*t ^2-6, 85,
86-7, 88, 114, 122, 124
{11011
106
59, 61, S5
98
89, 90
104
98
87
I 2 I
LIST OF FIGURES.
i. Culex pipiens Linnaeus. Wing, to show nomenclature of veil
_•. Chironomus plumosus (Linnaeus). Wing.
3. Trichocera regelationis (Linnaeus). Wing.
4. J? hyp hus fenes trail's Scopoli. Wing.
5. Aedes cinereus Meigen. Pupa.
6. Diagram of mosquito, to show the nomenclature of the pans.
7. Anopheles maculipennis Meigen. Diagram of larval head to show 1
distribution of hairs.
8. Theobaldia annulata (Schrank). Diagram of larval head to show
distribution of hairs.
9. OcJikrotatus nemorosus (Meigen). Diagram of larval head t<
distribution of hairs.
10. Anopheles maculipennis Meigen. Diagram of larva to sh
nomenclature of parts.
11. A'edes cinereus Meigen. Diagram of larva to show the nomenclat
parts.
12. Anopheles maculipennis Meigen. Diagram of und< i side of larval 1
show nomenclature of parts.
13. A edes cinereus Meigen. Antenna of male.
14. A edes cinerais Meigen. Antenna of female.
15. Anopheles maculipennis Meigen. Abdomen ol male.
16. Culex pipiens Linnaeus. Abdomen of female
17. Acdes cinereus Meigen. Profile of the head of male.
18. Anopheles maculipennis Meigen. Palp 0!' male, from aboA
19. Culex pipiens Linnaeus. Palp of male, from the si
20. Ochlerotatus caspius (Pallas). Palp of male, from abo
21. Theobaldia annulata (Schrank). Palp of male, from aboi
22. Culex pipiens Linnaeus. Scutellum.
23. Culicclla morsitans (Theobald). Genitalia of male.
24. Taeniorhynchus richiardii (Ficalbi). Hind iale.
25. Ochlerotatus caspius (Pallas). Claws ale.
26. Taeniorhynchus richiardii (Ficalbi). Claw
27. Anppheles maculipennis Meigen. H female, from a
28. Ochlerotatus caspius (Pallas). Headoffemal ive.
29. A'edes cinereus Meigen. Head of female, bom ah-
122
30. Ochlerotatus caspius (Pallas). Claws of fore-leg of female.
31. Culicella morsitans (Theobald). Claws of fore-leg of female.
32. Culex pipiens Linnaeus. Hind-leg of female.
33. Theobaldia annulata (Schrank). Venation of distal part of wing.
34. Culicella morsitans (Theobald). Parts of 3rd, 4th and 5th longitudinal
veins to show relative positions of cross-veins.
35. Taeniorhynchus richiardii (Ficalbi). Parts of 3rd, 4th and 5th longitudinal
veins to show relative positions of cross-veins.
36. Theobaldia annulata (Schrank). Second abdominal segment, from above.
37. Culicella morsitans (Theobald). Second abdominal segment, from above.
38. Taeniorhynchus richiardii (Ficalbi). Piece of the third longitudinal vein to
show the broad scales.
39. Culicella morsitans (Theobald). Piece of the third longitudinal vein to
show the narrow scales.
40. Anopheles maculipennis Meigen. Scale-tuft on anterior part of thorax.
41. A. bifurcatus (Linnaeus). Scale-tuft on anterior part of thorax.
42. A. bifurcatus (Linnaeus). Scutellum.
43. A. plumbeus Stephens. Scutellum.
44. A. maculipennis Meigen. Side-piece and clasper of genitalia of male.
45. A. bifurcatus (Linnaeus). Side-piece and clasper of genitalia of male.
46. A. plumbeus Stephens. Side-piece and clasper of genitalia of male.
47. Ochlentalus caspius (Pallas). Right hind-leg.
48. O. vcxans (Meigen). Right hind-leg.
49. 0. waterhousei (Theobald). Right hind-leg.
50. O. annulipes (Meigen). Right hinddeg.
51. O. caspius (Pallas). Abdomen of female, from above.
52. O. vcxans (Meigen). Abdomen of female, from above.
53. 0. waterhousei (Theobald). Abdomen of female, from above.
54. O. annulipes (Meigen). Abdomen of female, from above.
55. O. detritus (Haliday). Abdomen of female, from above.
56. 0. ncmorosus (Meigen). Abdomen of female, from above.
57. 0. rusticus (Rossi). Abdomen of female, from above.
58. Finlaya geniculata (Olivier). Abdomen of female, from above.
59. Ochlerotatus caspius (Pallas). Genitalia of male.
60. O. vcxans (Meigen). Genitalia of male.
61. O. -ivatcrhousei (Theobald). Genitalia of male.
62. O. annulipes (Meigen). Genitalia of male.
63. O. detritus (Haliday). Genitalia of male.
64. O. ncmorosus (Meigen). Genitalia of male.
65. O. rusticus (Rossi). Genitalia of male.
66. Finlaya geniculata (Olivier). Genitalia of male.
67. Ochlerotatus detritus (Haliday). Scales on fork of second longitudinal
vein.
68. 0. ncmorosus (Meigen). Scales on fork of second longitudinal vein.
123
69. Culicella morsitans (Theobald). Proboscis of fem
70. C.fumipennis (Stephens). Proboscis of female.
71. C. morsitans (Theobald). Sixth abdominal segment of m >ro
beneath.
72. C. fumipennis (Stephens;. Sixth abdominal segment of male, from
beneath.
73. Culex apicalis Adams. Sixth abdominal segment of female, from ai
74. Taeniorhynchus richiardii (Ficalbi). Siphon and comb-scale of Ian
75. Aides cinereus Meigen. Siphon, pecten-tooth and comb-scale of larva.
76. Thcobaldia annulata (Schrank). Siphon, pecten-tooth and comb-s<
larva.
77. Culicella morsitans (Theobald). Siphon, pecten-tooth and comb-scale of
larva.
78. C. fumipennis (Stephens). Siphon, pecten-tooth and comb-scale
larva.
79. Culex pipiens Linnaeus. Siphon, pecten-tooth and comb-scale of larva.
80. Anopheles maculipennis Meigen. Head of fourth larval instar.
Si. A. bifurcatus (Linnaeus). Head of fourth larval instar.
82. A.plumbeus Stephens. Head of fourth larval instar.
83. A. maculipennis Meigen. Comb of fourth larval instar.
84. A. bifurcatus (Linnaeus). Comb of fouth larval instar.
85. A.plumbeus Stephens. Comb of fourth larval instar.
86. A. maculipennis Meigen. Head of third larval instar.
87. A. bifurcatus (Linnaeus). Head of third larval instar.
•88. A. plumbcus Stephens. Head of third larval instar.
89. A. maculipennis Meigen. Comb of third larval instar.
90. A. bifurcatus (Linnaeus). Comb of third larval instar.
91. A.plumbeus Stephens. Comb of third larval instar.
92. A. maculipennis Meigen. Head of second larval instar.
93. A. bifurcatus (Linnaeus). Head of second larval instar.
94. A.plumbeus Stephens. Head of second larval instar.
95. A. maculipennis Meigen. Comb of second larval instar.
96. A. bifurcatus (Linnaeus). Comb of second larval instar.
97. A.plumbeus Stephens. Comb of second larval instar.
98. A. maculipennis Meigen. Head of first larval instar.
99. A. bifurcatus (Linnaeus). Head of first larval instar.
99a. A. plumbcus Stephens. Head of first larval instar.
100. A. maculipennis Meigen. Combs of first larval instar.
101. A. bifurcatus (Linnaeus). Combs of first larval instar.
101a. A.plumbeus Stephens. Combs of first larval instar.
102. A. maculipennis Meigen. Tuft of bristles on ventral sui ninth
abdominal segment of first larval instar.
103. A. bifurcatus (Linnaeus). Tuft of bristles on ventral surl I ninth
abdominal segment of first larval instar.
I24
103a. A. plumbeus Stephens. Tuft of bristles on ventral surface of ninth
abdominal segment of first larval instar.
104. Finlaya geniculate. (Olivier). Antenna of fourth larval instar.
105. Ochkrotatus caspius (Pallas). Siphon, pecten-teeth and comb-scale of
fourth larval instar.
106. O. caspius (I 'alias). Siphon, pecten-teeth and comb-scale of third larval
instar.
107. O. caspius (Pallas). Siphon, pecten-teeth and comb-scale of second
larval instar.
10S. O. caspius (Pallas). Siphon, pecten-teeth and comb-scale of first larval
instar.
109. 0. vexans (Meigen). Siphon of fourth larval instar (from fig. of Aedes
sylvestris in Dyar, Howard and Knab).
no. O. wat'erhousei (Theobald). Siphon, pecten-teeth and comb-scale of
fourth larval instar.
in. O. annulipes f Meigen). Siphon, pecten-teeth and comb-scale of fourth
larval instar.
112. 0. rusticus (Rossi). Siphon, pecten-teeth and comb-scale of fourth
larval instar.
113. 0. nemorosus (Meigen). Siphon, pecten-teeth and comb-scale of fourth
larval instar.
114. O. nemorosus (Meigen). Siphon, pecten-teeth and comb-scale of third
larval instar.
115. O. nemorosus (Meigen). Siphon, pecten-teeth and comb-scale of second
larval instar.
116. O. nemorosus (Meigen). Siphon, pecten-teeth and comb-scale of first
larval instar.
117. Finlaya geniculata (Olivier). Siphon, pecten-teeth and comb-scale of
fourth larval instar.
118. F. geniculata (Olivier). Siphon, pecten-teeth and comb-scale of third
larval instar.
119. F. geniculata (Olivier). Siphon, pecten-teeth and comb-scale of second
larval instar.
120. F. geniculata (Olivier). Siphon, pecten-tooth and comb-scale of first
larval instar.
121. Ochkrotatus detritus (Haliday). Siphon, pecten-teeth and comb-scale of
fourth larval instar.
122. O. detritus (Haliday). Siphon, pecten-teeth and comb-scale of third
larval instar.
123. Theobaldia annulata (Schrank). Siphon, pecten-tooth and comb-scale
of third larval instar.
124. T, annulata (Schrank). Siphon, pecten-tooth and comb-scale of second
larval instar.
125. T. annulaia (Schrank). Siphon, pecten-tooth an<l i
larval instar.
126. Culex pipiens Linnaeus. Siphon, 1
larval instar.
127. C. pipiens Linnaeus. Siphon, pecten-tooth and •
larval instar.
128. C. pipiens Linnaeus. Siphon, pecten-tooth and comb-
instar.
129. C. apicalis Adams. Siphon, pecten-tooth and comb I >arth
larval instar.
130. Orthopodomyia albionensis MacGregor. Headoffemal
131. Orthopodomyia albionensis MacGregor. Fore-tai female.
132. Orthopodomyia albionensis MacGregor. Siphon and comb-scali
fourth larval instar.
An< ipheles maculipi i i
i
Anopheles bifurcatu
PLAT
Anopheles plumbeus Stephens. Fern
4
Ochlerotatus caspius I Pall i I
Ochlerotatus nemorosus (Meigen). I
QL
536
B68
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British Museum (Natural
History) Dept. of B
A handbook of Britisl
mosquitoes
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