26 BRITISH BLOOD-SUCKING FLIES NEMATOCERA—CERATOPOGONIDAE 27
pits, which are sharply defined, with their surface smoother than that of the
rest of the thorax ; (2) the absence of a hairy pad (empodium) between the
claws, which are equal in size and without teeth ; (3) the presence (at least in
all the British species) of two types of hairs on the wings—a dense microscopic
pubescence covering the whole surface, and longer and less dense hairs which
are variable in quantity in the different species, sometimes clothing only the
outer part of the wing ; (4) the fact that the costa (the thickened front margin)
ends at about three-fifths of the wing's length. In addition an obvious feature
distinguishing most species of Culicoides from 7iiost other Ceratopogonidae is
the presence of spots or clouds on the wings.
The venation is characteristic of the family. The veins towards the front
margin are much stouter than the others, and enclose two small areas known
as the first and second radial cells ; a larger and more elongate enclosed area
FIG. I.—A biting midge {Culicoides nubeculostis Mg.) in resting position.
extending from the base to the middle of the wing is the basal cell, limited
outwardly by the cross-vein. The more slender veins in the field of the wing
form two forks, the 7nedian fork ending in the wing-tip, and the shorter cubital
fork ending on the posterior margin. These features are illustrated in the
diagram accompanying the key to species (fig. 2, p. 30).
The first description of the life-history of a species of Culicoides was published
as long ago as 1713, by VV. Derham, Rector of Upminster in Essex, in his work
entitled " Physico-Theology : or a demonstration of the being and attributes
of God, from His Works of Creation," and dedicated to the then Archbishop
of Canterbury. This account deserves quotation, and is as follows :
" For an Instance of Insects endued with a Spear, I shall, for its peculiarity,
pitch upon one of the smallest, if not the very smallest of all of the
Gnat-VixiA., which I call Culex minimus nigricans maculatus sanguisuga
Among us in Essex they are called Nidiots, by Mouffet Midges* It is
about i-Q- of an inch, or somewhat more long with short antennae, plain in
the female, in the male feather'd, somewhat like a Bottle-brush. It is
spotted with blackish spots, especially on the wings, which extend a little
beyond the Body. It comes from a httle slender Eel-like Worm, of a dirty
white Colour, swimming in stagnating Waters by a wrigling Motion, as
in fig. S-
" Its Aurelia [pupa] is small, with a black Head, little short Horns, a
spotted, slender rough Belly, Vid. Fig. 6. It lies quietly on the top of the
Water, now and then gently wagging itself this way, and that.
" These Gnats are greedy Blood-suckers, and very troublesome where
numerous, as they are in some places near the Thames, particularly in the
Breach-waters that have lately befallen near us, in the Parish of Dagenham ;
where I found them so vexatious, that I was glad to get out of those Marshes.
Yea, I have seen Horses so stung with them, that they have had drops of
Blood all over their Bodies, where they were wounded by them." |
Exactly two hundred years elapsed before a more precise description than
that of Derham was published of the larva and pupa of any species of Culicoides. %
In the year 1913 Patton published an illustrated account of the life-history of
an Indian species, and at the same time Lutz published some account of his
observations on Culicoides in Brazil. Shortly afterwards descriptions were
published by Rieth (1915) and Goetghebuer (1919) of some of the European
species, and by Carter, Ingram and Macfie (1920) of a number of African
species. More recently Thienemann (1928) and Mayer (1934) have summarised
our knowledge—still rather scanty and incomplete—of the life-histories of the
European species.
The eggs of Culicoides are cigar-shaped or sometimes banana-shaped,
dark in colour, and laid singly or in small groups ; in some species at least they
are capable of withstanding prolonged periods of dryness. The larvae, which
m the larger species attain a maximum length of about 9 mm., are provided
with an oval pale brownish head and a long, smooth, dull whitish or translucent
body which terminates in a few hairs ; they progress with a snake-like motion.
As m all members of this family, respiration is entirely cuticular, spiracles being
absent. Though the larvae of most species of Culicoides are normally aquatic.
It was shown by Ingram and Macfie that even these aquatic larvae can survive
for at least six days in moist situations where no free water is present ; moreover,
some species {e.g. C. vexans) appear to pass their whole existence in moist
soil, and others in moist decaying vegetable matter without any appreciable
content of water ; Tokunaga has recorded a Japanese species (C. arakawae)
as breeding in the dung of the poultry which it attacks. The aquatic species
spend the greater part of their time buried in the fine mud at the bottom, with
This refers to Moufet's Insectorum sive Minimorum Anititalium Theatrum (1634), said to be the
hrst zoological work published in England. On p. 82 of this book Moufet refers to small blood-sucking
gnats popularly known as " midges " in England, but gives no details of interest.
T Quoted from p. 192 of the second edition, dated 1716.
+ Heeger, in 1856, described a larva purporting to be that of C. varius Winn., but inspection of his
hgures shows that he had one of the Cecidomyiidae before him.