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 denned 

 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. Living- 

 stone : " 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 colour, 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 goats 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 rattle- 

 snake. The colour 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 Asilidse, 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 Tabanidse. As with the preceding 

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



The family of the Syrphidse, 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 coloured 

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

 distinguish between them. 



