i i 8 BRITISH BLOOD-SUCKING FLIES
habit, when present in numbers, of clustering around tlie bases of the horns
of cattle. Outside the British Isles its range includes Europe and North
America, where it is known under the name of Haematobia serrata R.-D.
The life-history is very similar to that of Stomoxys calcitrans except that
the eggs are laid on fresh cattle droppings. The larvae develop in the " cowpat
" and when mature pass into the soil beneath and pupate there.
Family
HIPPOBOSCIDAE
The flies composing this Family are parasitic upon mammals and birds,
and are probably descended from ancestors belonging to the Muscidae, which
underwent modification in structure as a consequence of a parasitic mode of life.
The body in all cases is flattened and leathery ; the feet are provided with well,
developed claws to enable the insect to cling to the hair or feathers of the host ;
and while some of the species are fully winged, others show a progressive
reduction in this respect reaching the completely wingless state in the Sheep
Ked. But even in the fully winged forms, since the flies are true parasites,
the wings, as a rule, are made use of merely in order to reach the host, or, in
the case of the males, in order to find an individual of the opposite sex, and
thereafter it is only in exceptional circumstances, such as the death of the host,
or too active pursuit by the human hand, or when taking a short flight from
one host to another, that these flies are ever seen upon the wing. The proboscis
in the Hippoboscidae is curved, extremely slender, and protrusible, but it is
composed of the same parts as that of the Muscidae mentioned above. It is
very doubtful if any authentic records of these insects actually biting man exist.
Their presence on a human being is probably in all cases accidental.
The Hippoboscidae are viviparous. The egg hatches within the body of
the female and the larva is retained within her body and nourished there till it
is fully grown. Only one larva is carried at a time and when it is eventually
extruded it pupates at once. The puparium is a rounded body usually of a
brown or reddish colour and very smooth, superficially resembling a berry or seed
rather than an insect pupa. Little is known of the life-histories of these insects
with the exception of the Sheep Ked {Melophagus ovinus L.) which, as an
insect of economic importance, has been the subject of investigations.
Where their life-history is known it appears that the adults are fairly long
lived (four months in the case of Melophagus ovinus). The insects probably
survive the winter almost entirely in the pupal stage, lying in the disused nests
and lairs of their hosts. Melophagus ovinus, the Sheep Ked, is an exception
to this in that it breeds throughout the year on the infested sheep.
The British species may be separated by the use of the following key : —
1. Wings functional and normally developed 2
Wings reduced, non-functional, broken off or absent 5
2. Wings with only three well developed longitudinal veins ; common on deer (Plate 44)
Lipo-pteria cervi L.
Wings with 7 or 8 well developed longitudinal veins 3
CYCLORRHAPHA—HIPPOBOSCIDAE I 19
3. Anal cell closed by a cross vein ; ocelli present ; usually on birds (Plates 40, 41) {Ornithomyia)
8
Anal cell not closed by a cross vein ; no ocelli 4
4. Wing membrane wrinkled, claws bidentate, head not obviously " fitting " the thorax.
On horses, cattle, etc (Plate 39) Hippobosca equina L.
Wing membrane not wrinkled, claws tridentate, head definitely "fi t t ing" the thorax; on
the heron and its allies Ornithopo?ius ardeae Macq-
5. Halteres present, wings reduced or broken off 6
Halteres absent, wings completely aborted ; on sheep (Plate 45, fig. 2) Melophagus ovinus L.
6. Wings absent, i.e. broken off, claws single ; common on deer (Plate 45, fig. i)
Lipoptena cervi L.
Wings merely reduced in size and non-functional, claws tridentate; on swifts, swallows and
martins 7
7. Ocelli present, wings strap-like, seven times as long as broad and almost as long as the legs ;
usually on martins (Plate 42) Stenepieryx hirtmdinis L.
Ocelli absent, wings twice as long as broad and only about half the length of the legs;
usually on swifts (Plate 43) Crataerhina pallida Latr.
8. Palpi uncoloured, medio-cubital cross vein (m.-cu.) 4 times the length of the radio-median
cross vein (r.-m.), last (anal) vein shorter (see fig. 46) (Plate 40) O. avicularia L.
Palpi dark brown, medio-cubital cross vein twice the length of the radio-median cross vein,
last (anal) vein longer (see Figs. 47 & 48) 9
9. Underside of the head and thorax with dark markings ; usually on grouse and moorland
birds (Plate 41) O. lagopodis Sharp
Head and thorax without such markings O. fringillina Curtis
In addition to the characters given in the key it will be found that the species
of Ornilhoniyia show distinctive hair patterns on the wings. The nature of
these may be appreciated by reference to figs. 46, 47 and 48.
Genus LIPOPTENA Nitzsch
Lipoptena cervi L.
(The Deer Fly; the Deer Ked) (Plates 44 and 45, fig. i)
This species is parasitic on several species of deer including the roe, red
and fallow deer in the British Isles. On emerging from the pupa both sexes
possess wings, which, in the case of the female at any rate, as soon as the
insects reach the host, appear to break off close to the base, leaving stumps only
where the wings had been before. Specimens of both sexes found upon a
deer are usually in this wingless condition, in which case they resemble the
sheep ked {Melophagus ovinus) closely, but from which they may be distinguished
by the presence of actual wing stumps and halteres. In the autumn
months, however, winged males are sometimes met with in woods inhabited
by deer ; these diifer considerably in appearance from the wingless males
found in company with the females amongst the hair of the host, being paler
in colour and more slender in the abdomen, while the males that have lost
their wings are more like the females, and are darker in colour with a broader
and stouter abdomen. Both sexes have been taken in flight around a dead
deer, but the females shed their wings on being killed.
Lipoptejia cervi is found throughout Europe, and appears to be generally