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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 shining 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 night of September." (Packard) Walsh
has shown that in its larval state the Horse-fly is useful to man as it feeds on snails and prob-
ably 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 Vomitoriæ.
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 occasionally becomes a pest in the South or South-West States of America.
The stable fly, Stomoxys Calcitraus.—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.
The Tsetse-fly, Glossina morsitans, is a member of this family. It is allied to Stomoxys,
the species of which bite very sharply.
S. caltricaus has a well developed proboscis, enabling it to bite severely.
The " Warega-fly " of Brazil, which is said to be a " pest of both men and animals", is a
species of Musca and is said to lay its eggs in the skin; large and painful swellings are
formed.
The " Tdia Bigoti," according to Coquerel and Mondiere, produces a disease in the natives
of Senegal, probably by ovipositing on the skin, thus giving rise to hard red fluctuating
tumours in which larva of this fly reside.
The family of mosquitoes or gnats (culicidæ) have the mouth parts very long and slender;
the mascillæ and mandibles are free and lancet-like. The females alone bite, for in the males
the piercing mouth structures are not well developed, and they are, therefore, not capable of
sucking blood, but spend their lives in the retirement of the swamps and jungle.
"This genus is too well-known, from the blood-sucking propensity of the female, to re-
quire any particular notice. It is plentiful in all countries, whether arctic or tropical, which
abound in wood and water. The female lays about 300 eggs ; nearly a month intervenes
between the egg-state and the fly-state, and there are several successive generations in one
year. Gnats emit no sound when flying early, before their thirst for blood is awakened.
The warmer the weather, the greater is their thirst for blood, the more forcible their flight, the
motion of their wings more rapid, and the sound produced by that motion more intense ".—
(Walker.)
Ixodes, popularly known as Ticks and wood mites, are more or less flat when fasting
globular when replete.
The Ixodes are found in every country, but there is no constant correspondence between
the species of host and that of the parasite ; the specific determination of the different forms
is rendered difficult by the great confusion that prevails. The male and females of the same
species have often been mistaken for different species, and the same species has received distinct
specific names because individuals belonging to it were observed on different hosts. Animals,
however, as a general rule do not appear to suffer from their presence. " In Guadeloupe the
Ixodes of Senegal are supposed to play an important part in the development of a serious
affection known there as Farcy and which is witnessed in horses, cattle and mules; the
ulcerous wounds just referred to are the starting-point of the disease. Nocard has recently
demonstrated that this farcy of the ox is a malady of microbic origin ; and it can be conceived
that the Ixodes may be the agents of inoculation of the micro-organism that determines
such a disease "—(Neumann).
G. I. C. P. O.—No. 60 I. G., C. V. D.-23-12-97.—300.-G. R
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