77
Walker includes Hippoboscidæ under the Eproboscidæ. Loew and Sacken objected to uniting
under the head of Brachycera all those families which cannot be referred to the Nemocera, especially
to the union of the Hipposcidæ with the other Brachycera, since both the history of their development
and their internal and external anatomy essentially differ from them. These authorities include them
under a third section, Coriacea, co-ordinate to the Nemocera and Brachycera, and having the same
systematic value.
"The species of this family pass their egg-like and larva state in the body of the mother, and when
born are pupæ or larvæ just ready to assume the pupa state, as is proved by their size, which nearly
equals that of the parent fly, by their slight motion when first extruded, by spiraculiform points which
run down each side of them, and by their changing into perfect flies. Each female produces a single
egg. The proboscis consists of a pair of hairy coriaceous valves, which include a very slender rigid
tube or siphuncle, the instrument of suction, which is formed by the union of two setiform pieces."—
(F. Walker).
According to Dufour and Leuckart, quoted by Packard, the females of this species have all
irregular uterus-like enlargement of the oviduct, which furnishes a milk-like secretion for the nourish-
ment of the larvæ.
" The flies are parasites living largely upon birds, but sometimes upon animals. The whole body
is depressed or flattened, and birds of prey are most usually affected. It is rare to find a hawk, eagle
or owl upon which several specimens of these peculiar flies cannot be found. They move rapidly, and
their first impulse is always to seek shelter when driven from their original host. A few species are
wingless, and among them is the so-called 'sheep tick,' Melophagus ovinus which is usually looked upon
as a louse, and resembles one in the prominent proboscis, the lack of wings and the strongly developed
legs, on which the claws are very prominent."—(Smith).
The Forest-fly or Horse-tick (Hippobosa equina), is very abundant in the New-Forest, Hampshire
The description given of it by Walker is as follows :—"Nigra, capite thoraceque fulvo flavoque variis
alis sordide hyalinis, pedibus fulvis, tibiis posterioribus et femoribus nigro-subfasciatis, unguibus nigris.
Long. 3-3½ ; alar 8 lin." According to A. E. Omerod, the forest-fly may be taken as a type of the
division. It causes irritation both by blood-sucking, and by creeping, which it can do backwards,
forwards or side-ways, with great nimbleness, on the parts of the animal especially preferred for infesta-
tion.
Another set of troublesome creatures in India are the Gad-flies or Horse-flies, belonging to the
family Tabanidæ. This order, I think, includes the 'Bara Dhang' (Hindustani) and Hmet (Burmese),
which are probably varieties of the species T. lineola the green-head fly and T. tropicus.
"They have short, broad heads, enormous eyes, and short, though many jointed, feelers. The abdomen is oval, a little
flattened, and the body is convex and powerful. The mouth parts are well developed, consisting of a series of five sharp-
pointed lancets, so rigid that they readily pierce the skin and draw blood almost as soon as they touch. These flies appear in
the Summer, chiefly abound in woods, or the edges of woodland, and sometimes in low meadows or marshy places. The
flight is powerful; the males frequent flowers, the females with their sharp mouths, pierce the skins and feed on the blood
of quadrupeds. In England the ox-gad-fly, T. bovinus, is the most common variety ; but in the United States T. Atratus is
a common species, while the T. Cinctus, orange-belted horse-fly, is smaller and less abundant. The T. lineola, as in India, is
the most common American species, —thousands of them appearing in the hotter parts of the Summer, when the sun is shin-
ing on the marshes and western prairies ; horses and cattle are sometimes worried to death by their harassing bites. In
cloudy weather they do not fly and they perish on the cool frosty nights of September.''—(Packard).
Mr. Walsh has shown that in its larval state the horse-fly is useful to man, as it feeds on snails and
probably the larvæ of other root-eating insects. The larvæ of other species are aquatic, living under
submerged objects.
The family Muscidæ is the largest in number of genera and species in the order as well as the most
difficult to classify. The common ' House-fly,' ' the Blue bottle ' and the ' Flesh fly ' are examples and
may be considered as typical forms which most of the species resemble, not necessarily in colour or
markings but in general type of structure.
The Blow-fly.—Calliphora Vomitoria.
The " Screw-worm-fly "—Lucilia macellaria, a common species, usually feeds upon dead or
decaying animal matter. Under some circumstances, however, it attacks living animals, and occasion-
ally becomes a pest in the South or South-west States of America.
The Stable-fly.—Stomoxys Calcitrans. This has the mouth parts formed for piercing, and annoys
animals by alighting upon and sucking the blood of parts that cannot be reached by them with
head or tail.
The Horn-fly.—Hæmatobia serrata. Like the stable-fly is a blood-sucker, and both species are
often found on animals at the same time.
Francis Walker—Insecta Britannica 'Diptera'— 1853, London.
A. E. Packard—Study of Insects—1869, United States, America.
J. B. Smith—Economic Entomology—1896, United States, America.
A. E. Omerod—Agricultural Entomology—1884, London.
H. Loew and Osten Sacken—Monographs of the Diptera of North America—1862 to 1873, Smithsonian Institution, Wash-
ington.
Smithsonian Institution—Bulletin of the United States, National Museum—1886, Washington.
B 2204-20