556 THE TSETSE. 



suffered greatly from the bites of the Gad-flies, and was at last obliged to keep a little 

 naphtha in a bottle, and rub it occasionally over my face and hands, for the purpose of 

 repelling these blood-thirsty insects, which selected me for their victim, leaving my 

 companions untouched. I have found the whole of the unprotected space round the 

 neck covered with their bites, and my ears thickly stained with blood from the effects 

 of their weapons. 



To this family belongs the terrible TSETSE, the curse of Southern Africa, which 

 destroys horses, dogs, and cows by thousands, though it causes no harm to man or to 

 any wild animal. Fortunately, it is a very local insect, its boundaries being as sharply 

 defined as if drawn on a map, one side of a stream being infested with this active 

 insect, while the other is perfectly free. 



The following account of its habits and the effects of its bite are given by Dr. 

 Livingstone : " In the ox the bite produces no more immediate effects than in man. 

 It does not startle him as the gad-fly does ; but a few days afterwards the following 

 symptoms supervene : the eyes and the nose begin to run ; the coat stares, as if the 

 animal were cold ; a swelling appears under the jaw, and sometimes at the navel ; and, 

 though the animal continues to graze, emaciation commences, accompanied with a 

 peculiar flaccidity of the muscles ; and this continues unchecked until, perhaps months 

 afterwards, purging comes on, and the animal, no longer able to graze, perishes in a state 

 of extreme exhaustion. Those which are in good condition often perish soon after 

 the bite is inflicted, with staggering and blindness, as if the brain were affected by it. 

 Sudden changes of the temperature produced by falls of rain seem to hasten the 

 progress of the complaint ; but in general the emaciation goes on uninterruptedly for 

 months, and do what we will, the poor animals perish miserably. 



When opened, the cellular tissue on the surface of the body beneath the skin is seen 

 to be injected with air, as if a quantity of soap-bubbles were scattered over it, or a dis- 

 honest, awkward butcher had been trying to make it look fat. The fat is of a greenish- 

 yellow color, and of an oily consistence. All the muscles are so flabby, and the heart 

 often so soft, that the fingers may be made to meet through it, and the lungs and liver 

 partake of the disease. The stomach and bowels are pale and empty, and the gall- 

 bladder is distended with bile." 



The insect which occasions these terrible results is hardly larger than a house-fly, the 

 figure being drawn of the natural size. It is curious that, although horses perish under 

 its bite, mules, asses, and goals escape injury, and it seems that the bite of a single fly 

 is sufficient to cause death. Another curious symptom is, that the blood loses its 

 redness, and hardly stains the hands of the person who dissects the smitten animal. 

 The source of all this mischief is to be found in a little poison-gland at the base of the 

 mouth, not larger than a mustard-seed, and yet infinitely more deadly than the venom 

 of the rattlesnake. The color of the Tsetse is brown, with a few yellow bars across 

 the abdomen. When it bites a man, the pain which it causes is very slight, and the worst 

 results are a trifling irritation not more severe than that caused by the bite of a 

 gnat. 



The large insect on the right hand of the Tsetse is an example of the Asilidae, or 

 Hornet-flies, among which are found the most gigantic specimens of the order. The 

 body of these insects is long, and clothed with stiff hairs. They are fierce and voracious, 

 feeding mostly upon other insects which they catch on the wing, and out of which they 

 suck the vital fluids through their powerful proboscis. One species of this family has 

 been known to capture and carry off a hive-bee, a remarkable instance of a stingless 

 insect attacking and overcoming a creature so formidably armed as the bee. Some of 

 them are said to attack cattle after the manner of the Tabanidag. As with the preceding 

 family, the larvae of the Asili reside under ground, and feed upon the roots of plants. 



The family of the Syrphidag, or Hoverer-flies, is rather large, and contains many 

 interesting insects. Among them may be mentioned the Volucella flies, which feed, 

 while in the larval state, on the larvae of bees and wasps, and, as if to aid them in 

 gaining admission into the nests of those formidable creatures, are shaped and colored 

 so like the insects which they invade, that at a little distance it is almost impossible to 

 distinguish between them. 



