IP
42 BRITISH BLOOD-SUCKING FLIES
wood ; it is the only species of the genus reported in this country from such
a habitat, except that at Snailwell C. obsoletus was associated with it. (But
see also p. 146.)
Culicoides vexans Staeger
This species may be recognised by its uniformly mouse-grey thorax, blackish
abdomen, dark legs and creamy-white wings without definite markings. The
wings are uniformly and rather densely clothed with hair which is for the most
part creamy-white ; most (but by no means all) specimens have a patch of dark
hair covering the radial cells, so that to the naked eye the wing may appear to
have a blackish spot in the middle of the costa, though this is never as obvious
as in C. stigma ; the area of the dark hair may extend below the radial cells,
but only to a slight extent. C. vexans is a medium-sized midge, a little smaller
than the average C. pulicaris, with a wing-length of about 2 mm.
In many of the LONDON suburbs, both north-west and south, C. vexans is
a very abundant species, in some places and seasons far outnumbering the
other species of the genus ; it has also been found abundantly in the NEW
FOREST and at OXFORD, and there are specimens in the British Museum from
HERTS., BEDS., HUNTS., CAMBS., and GLAMORGAN, but confirmation of its
occurrence in the North of England and Scotland is desirable. The adults are
to be found chiefly at the end of April and during May ; the latest date of capture
noted in the British Museum is July 6th
C. vexans is a troublesome species where it is abundant, biting even during
the day-time, though chiefiy in the evening. The bite is often painful. It is
most troublesome out of doors, but will also enter houses to bite, which other
Culicoides rarely do ; Staeger records it as troublesome in houses in Denmark.
The life-history of C. vexans has been investigated by Jobling, who thus
summarises his findings :
" It breeds in damp earth round bushes and under big trees, where
desiccation of the ground is prevented by overhanging branches. The
midge has only one generation a year. From eggs laid in June and kept
in the open, the first-stage larvae hatched in October. Further observations
on these larvae were then made in the laboratory, and in the following
March many midges of both sexes were hatched. The pupal stage is of
very short duration, lasting only a few days."
Culicoides albicans Winnertz
This is a dull-coloured insect resembling C. vexans in having the thorax
uniformly mouse-grey and the wings creamy-white ; the only entirely satisfactory
means of distinguishing the two species is by the structure of the male
genitalia, but the legs and abdomen of C. albicans are paler than those of
C. vexans and the hair on the radial cells is less obviously dark, or even all pale.
The scanty records at present available of the occurrence of C. albicans in
Britain indicate that it may largely replace C. vexans in the west and north.
The following specimens are in the British Museum :
NEMATOCERA—CERATOPOGONIDAE 43
DEVON : Dartmouth, vi. 20, I ? {F. W. E.). YoRKS. : Skipwith, vii. 26,
I C? {P- w. £.). LANGS. : Cringle Fields, Manchester, 3 (J, I 31 v. 20
( f f . Britten). WESTMORLAND : Witherslack, vi. 29, I $ {F. W. El). DuNBARTON
: Luss Glen, vi. 09, 1 ( ^ , 1 ? (/. /. F. X. King). ARRAN : Catacol
V . 19, I ? {F. W. E.).
Culicoides brunnicans sp. n.
(Fig- 13)
A study of the male genitalia of the British Culicoides, undertaken in
connection with this volume, has revealed that, in addition to the true C. vexans
and C. albicans Winn., two other distinct species have hitherto been confused
under the name C. vexans. For one of these no name appears to be available
and the above designation is proposed for it.
C. brunnicans is externally extremely similar to C. vexans, which it resembles
in its mouse-grey thorax, dark abdomen and legs, and creamy-white wings
clothed rather densely with pale hair. The only external differences between
the two species at present discovered are in the wings ; in C. brunnicans the
area of dark hair in the middle is more obvious and extensive and not only
covers the radial cells but extends below them in a patch spreading nearly
half way across the wing ; moreover there is a faint and diffuse dark band on
the basal half extending from the costa nearly half way across the wing, this
FIG. 13.—Culicoides brminicans sp. n. Wing of
band being most evident when the wing is viewed under a strong pocket lens
very obliquely against a dark background. For description of genitalia see p. 141.
In Britain C. brunnica^is will probably be found to be common and widely
distributed. It certainly occurs commonly in the London district, as well as
in some other localities. Specimens from the following places are in the
British Museum collection :
MIDDLESEX : Harrow, Stanmore, Northwood, Ealing. HERTS. : Bushey,
Knebworth. OxoN. : Oxford. SALOP : Snailbeach. N. DEVON : Buck's
Mills. Dates of capture range from April 27th to June 8th.
C. brunnicans is found associated with C. vexans in the London district and
IS probably equally annoying ; two of the specimens in the Museum are
definitely labelled as taken in the act of biting. On Stanmore Common in
May, 1916, females were found in swarms at the source of a small stream,
which was probably their breeding-place