78
The Tse-tse-fly, Glossina morsitans, is a member of this family. It is allied to Stomoxys, the
species of which bite very sharply.
In 1885 Railliet gave the following resumé of the history of this insect:—
" The fly to which the Negroes give the name of Tse-tse is met with throughout nearly the whole of Central Africa.
It appears to prefer hanging about the borders of marshes and watering-places and in beds of reeds. It makes a loud
buzzing noise, which is easily recognised again when it has once been heard. If Bruce is to be believed, the buzzing of the
Tse-tse is a mixture of dull and sharp sound, which is somewhat discordant. This buzzing causes more terror and disorder
among men and animals than the monster of the countries they inhabit could produce, if they were twice as numerous."
'Many travellers, among them Livingstone and Oswald, have stated that this fly is one of the most redoubtable
scourges of the African torrid zone; nevertheless, the descriptions published with regard to it have, it appears to us, some-
thing of a legendary character. Like the Stomoxes, the Tse-tse attacks man and animals. It darts on the latter, say the
travellers, with the rapidity of an arrow, and prefers biting them inside the thighs or beneath the belly, and a tumour soon
forms at the part attacked.
' It has been said that this insect prefers the uncovered parts of the body; the action of its bite on man is no more
dangerous than that of the gnat; that the domesticated animals, on the contrary, with the exception of the ass, the elephant
and the goat, begin to waste away immediately, and soon succumb ; that dogs resist the bites when they are fed on venison,
but perish when they receive milk; that calves nourished on milk, on the contrary, are exempt from injury, &c. On
autopsy, the heart, lung, and liver are found more or less affected.
'The majority of these descriptions of the older travellers have been contradicted by more recent observations. Thus
a Belgian expedition has lost several elephants ; P. Baur has witnessed several of his asses perish as a result of the stings
of this fly, and he asserts that, instead of preferring uncovered parts, the Tse-tse usually gets underneath the clothing and up
the sleeves of men, and below the tail of animals. Others have observed that those bitten generally succumb as a consequence
of the gradually increasing weakness, which may continue for several weeks, and even months. Finally, the most careful
autopsies have not revealed any lesion of the spleen, liver, lungs or brain.'
"All these contradictory statements show that the action of the Tse-tse punctures is extremely variable, and that, con-
sequently they ought not to be venomous. Besides, Nocard and myself have introduced, without any result, beneath the
skin of the thigh of a sheep, the head and proboscis of a Tse-tse brought from Zanzibar a short time before by Paul
Lervy."
"In reality the Tse-tse can merely be regarded as a carrier of virus, and its bite is only dangerous when its proboscis
has been previously infected. With regard to the virus which it habitually inoculates, it is difficult, in the present state of
our knowledge, to say what it actually is ; but contrary to what Mégnin has advanced, it is impossible to say it is that of
anthrax, at least in the majority of instances. We have already given the opinion that it might well be the virus of various
maladies, and perhaps even of affections peculiar to Central Africa. This manner of looking at it appears the only way by
which to explain the diversity of statements given by travellers."
S. Caltricans has a well developed proboscis, enabling it to bite severely.
The Warega-fly of Brazil, which is said to be a " pest of both man and animals", is a species of
Musca and is said to lay its eggs in the skin ; large and painful swellings are formed.
The "Idia 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
maxillæ 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 require 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 female 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 wit-
nessed in horses, cattle and mules; the ulcerous wound just referred to is 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 micro-organism that
determines such a disease."—(Neumann).
The presence of the trypanosoma of Surra in the body fluids of certain species of flies* caught
near to or on the bodies of animals (horses, dogs) suffering from that disease, were frequently observed
Railliet—Art: Mouches, Nov. Dict. Prat. de Méd Chir-et Hygiene Veterinaires, Vol XIII. Paris, 1885.
* Nawabkhan, the Camel Jamadar of the 3rd Punjab Infantry, has the reputation of knowing more about the camel than
any body else in the district, and he communicated to me the following information as interpreted by Major Money, 4th
Punjáb Cavalry :—
"The prevailing opinion among the natives in this district is that Surra is caused by the bite of a large brown fly (the size
of a small bee) called Bhura dhang. In the month of May that fly comes from the ground in jungle-land that has been under
water. In June and July the flies are very numerous and in full force; about the 15th August they begin to diminish, and