34 BRITISH BLOOD-SUCKING FLIES NEMATOCERA—CERATOPOGONIDAE 35
numerous localities extending to as far north as Ayrshire. It occurs throughout
the summer .
As might be expected f rom its larger size, the bite of C. mtbeculosus is more
painful (at the time of infliction) than that of most of the other species, and when
numerous it may be a serious pest ; for example, Mr . L . C. Curtis in sending
specimens of this species for identification in Ma y 1930, stated that it was so
troublesome at a sewage f a rm at Burnham, Es s ex, that the f a rm hands were
unable to work. Ac cording to J . S. Steward, it feeds in the largest number s
between 10.30 a.m. and i .o p.m. , and in bright sunshine, but also in smaller
number s at any time of the day. It at tacks horses chiefly on the under side
of the body.
C. nubeculosus was discovered by Steward (1933) to act as host to the worm
Onchocerca cervicalis (Railliet and Henry), the parasite giving rise to fistulous
withers and poll-evil in horses. The development of the worm was followed in
the tissues of the midge.
La r v a e of C. 7iubeculosus have been found in the liquid running f rom farmyard
manure heaps, or in green slime rich in organic matter, but details of its
life-history have not been worked out.
Cu l i c o i d e s r i e t h i Kieffer
Thi s species needs comparison only with C. nubeculosus, which it rather
closely resembles. The main distinctions are to be found in the male genitalia,
but C. riethi ma y also be distinguished f rom C. nubeculosus by the following
points :—Da r k dots on mesonotum smaller and not tending to fuse ; scutellum
mainly yellowish, the dark area in the middle smaller and not including a paler
s p o t ; legs not nearly so dark ; wings less densely hairy, no hairs on the
spa ce below radial cells ; palpi differing in shape, the second segment less
swollen and relatively shorter ; size a little smaller ; average wing-length
scarcely over 2 mm.
C. riethi, as far as known at present, is confined to coastal marshes. British
records of it are as follows :
NORFOLK : Blakeney Point, 19 vii. 1920 ( / . E. Collin) ; Wa xham, viii.
1932 {F. JV. Edwards).
SUFFOLK : Aldeburgh, 17 ix. 1907 ( / . E. Collin).
ESSEX : Gravesend, 20 vii. 1907 ( / . W. Yerbury).
SOMERSET : Burnham-on-Sea ? (W. H. Thorpe, ig^i).
The larvae are recorded by continental observers as occurring in salt water,
presumably on the muddy margins of tidal creeks and pools. On account of
the peculiar habitat, it is probable that the specimen reared f rom a larva found
in a pool near low tide level at Burnham-on-Sea , April 1927, by W. H. Thorpe,
was this species and not C. nubeculosus, as recorded at the time.
Cu l i c o i d e s p u n c t i c o l l i s Becker
(Fig. 5)
Thi s is another close ally of C. nubeculosus, differing f rom that species and
also f rom C. riethi in the better definition of the dark ma rkings of the wings,
which (when seen by reflected light) show up more clearly on the milky-white
background ; the spot at the tip of the wing is well separated f rom the small
one preceding it on the costal margin, as well as f rom the small spot at the tip
of the lower branch of the median fork, whereas in both the other species these
spots are usually more or less connected by a dark suffusion. As in C. riethi
the legs are mainly pale, but as in C. nubeculosus the dark patch in the middle
of the scutellum usually includes a small greyish spot.
FIG. 5.—Culicoides puncticollis Beck. Wing of
C. puncticollis is a common and widely spread species in the Medi ter ranean
region. It cannot definitely be stated to be a British insect, but it may possibly
occur with us ; it is described and figured here because there is a specimen
(without any data as to its origin) in the old Hope-AVestwood British collection
in the Oxford Mus eum.
It may be that C. riethi and C. puncticollis are merely northern and southern
forms of the s ame species, in which case the earlier name puncticollis should be
used.
Cu l i c o i d e s s a l i n a r i u s Kieffer
(Fig. 6)
This species and the closely related C. circumscriptus resemble C. nubeculosus
and C. riethi in having the ba ck of the thorax " stippled " with numerous
dark brown dots, but differ strikingly f rom them in the ornamentat ion of the
wings, which instead of a
suffused grey pattern on a
pale ground are provided
with numerous welldefined
pale spots on a
grey ground, and with
only one spot darker than
the ground colour, this
covering the two radial
cells ; in addition the
wings are hairy right to
FIG. 6.—Culicoides salinarius Kieif. Wing of
the base, whereas in the other pair of species the base of the
or less extensively bare. In C. salinarius the cross-vein is pale (occupying the
centre of a large pale spot), the spot near the outer end of the median fork is