Tsetse, the native name of a proboscidian dipterous insect of the genus glossina (Wiedemann), peculiar to Africa, and especially to the tropical portions. This genus comes near stomoxys (Fabr.), and resembles in appearance and habits the gadfly called in Scotland cleg (haematopotapluvialis, Meig.). The best known species, G. morsitans (Westw.), is 5 lines long and 8½ in expanse of wings, a little larger than the house fly; the head is dirty buff, and the eyes are large; thorax chestnut red, with four longitudinal black bars; abdomen dirty buff, with black bristles above, the first segment with a round black spot at each side, and the four following with a broad dark brown band interrupted in the middle; the wings are considerably longer than the body. The bloodsucking apparatus consists of a long horny proboscis, containing a compound bristle or two needle-like piercers, communicating with a poison bulb at the base, and supported on each side by two feathery palpi. It is very active and difficult to catch, except in the cool of the morning and evening, when it is sluggish; it has a loud and peculiar buzz, which does not terrify cattle like that of the gadflies.
This scourge of the African wilderness has no sting in the tail, and deposits no eggs on or under the skin of animals, but introduces its poison into the blood by the proboscis while sucking. The puncture of the tsetse is almost certain death to the ox, horse, sheep, and dog, but is harmless to man, the mule, ass, goat, pig, wild animals, and even calves while sucking; in man it causes a slight itching, like that produced by the bite of the mosquito or flea. It produces no immediate effect in the ox or horse, but in a few days there appears an exudation for half an inch around the punctures, the eyes and nose begin to run, the skin quivers as if from cold, and swellings occur under the jaw; the animal may continue to graze, but by degrees grows thin and weak; this state may continue for months, until purging comes on, and death ensues from exhaustion. The better the condition of the animal bitten, the more speedy often will the death be, accompanied by symptoms of staggering and blindness; sudden changes of temperature hasten the progress of the disease, which goes on to certain death. They occasionally attack a horse like a swarm of bees, alighting on him by hundreds, sometimes causing death in a week.
After death the subcutaneous areolar tissue is found to be injected with air, and the fat is oily and greenish yellow; the heart and muscles are very soft and flabby, the gall bladder distended with bile, the blood much reduced in quantity, with sign3 of disease in the lungs and liver. No remedy is known; the natives pretend to have roots which, pounded and sprinkled on the hair, prevent the bite, but their inability to keep cattle proves their in-etficacy; the droppings of animals mixed with human milk and drugs, and smeared on the hide, often prove a temporary safeguard; an animal slightly bitten and escaping death will fall a victim to the next severe bite. With the destruction of the game, this insect, deprived of its food, may become extinct; and until it does, whole districts are rendered unable to keep cattle, horses, sheep, or dogs. It is found chiefly in the bush or among reeds, and rarely in the open country; it is confined to limited regions, which it never leaves, so that cattle may graze in quiet on one side of a river while the opposite bank swarms with tsetse. When obliged to pass through a country infested by them, the natives select a moonlight winter night, when they are torpid from cold.
The flesh of animals bitten by the tsetse is not unwholesome, if they are killed before emacia-tion and weakness supervene. C. J. Andersson and Dr. Livingstone give extended accounts of the ravages of this insect.
Tsetse (Glossina morsitans), enlarged.