During 1887 some friends and I took four horses and five donkeys into the "fly" country on the Angwa river, in the northern part of Mashunaland. There were a good many buffaloes and a fair number of tse-tse flies in this district at that time, but not one for every hundred of either that I had met with along the Chobi river in the early 'seventies. My own horse cut its career short by galloping with me into an open game pitfall and breaking its back, and the other three, although they were well fed with maize morning and evening, were too weak to gallop after game in a fortnight. After a month they were too weak to carry a man at all, and they were then shot. The five donkeys all got thin, and swelled at the navel, and ran at the eyes, but none of them died, although they remained in the "fly" country for more than a month. By the end of the following rainy season they had quite recovered their condition and were well and strong again. These same five donkeys were taken down to Zumbo on the Zambesi the following year by the late Bishop Knight-Bruce. But they all died from the effects of this journey, during which they must have suffered great hardships and also been exposed to the attacks of thousands of tse-tse flies on the lower Panyami river.
When visiting the old Portuguese settlement of Zumbo on the Zambesi, in 1882, I found the few Portuguese residents as well as the natives living there in the possession of great numbers of pigs. These animals were sent out every morning into the country round the settlement, and called back in the evening—those which belonged to the Portuguese—by a few notes on a horn. A little maize was then scattered on the ground for them to pick up, after which they were shut up for the night in a walled enclosure. As tse-tse flies were numerous along the bank of the Zambesi on both sides of Zumbo, and it was quite impossible to keep cattle there on account of them, or any other domestic animals besides the pigs, except the small native goats, the former must have been equally as resistant to "fly" poison as the latter. These domestic pigs certainly did not owe their immunity to the "fly" disease to the fact that they were fat, for they were miserably thin long-snouted looking brutes. Although the pigs I saw at Zumbo probably did not go very far away from the settlement during the daytime, I feel sure that they must have been constantly bitten by tse-tse flies, as these insects were numerous quite close up to the native village, which is built amongst the ruins of the old Portuguese town.
All the natives living in "fly"-infested districts of South Africa keep small, miserable-looking dogs, as well as goats of a small, indigenous breed, and the natives outside such infested districts also keep goats of the same kind. These goats take no harm from the tse-tse flies; but the large Cape goats, which are descended from European breeds, as well as Angora goats, are not resistant to the "fly" disease. Nor are any dogs of European breeds.
In 1891 my two horses were suddenly attacked by tse-tse flies as I was riding with a companion along the bank of the Revue river, where the local Kafirs had told me these insects did not exist. Luckily, being so well acquainted with the peculiar "buzz" made by a tse-tse fly, I believe I heard the first one that came to my horse, and immediately dismounted. In the next few minutes we caught sixteen flies on the two horses, most of them by pinning their feet with a knife blade, as they are very difficult to catch with the hand. I then made the Kafirs cut branches, with which they kept the flies off the horses until we had got them away from the river, and beyond the "fly" belt. Most of these flies were caught immediately they settled on the horses, but two or three managed to fill themselves with blood. My horses, however, which were in very good condition, were never affected in any way.
Tse-tse flies are most active and troublesome in hot weather. During the winter months in South Africa (May, June, and July) none will be seen until the sun is high above the horizon, but later in the season they begin to bite early in the morning. After sunset in the evening they seem to become lethargic, and will often crawl up between one's legs or under one's coat as if for shelter, and from such positions will often "stick" one long after dark. On cold nights they probably become quite benumbed, and do not move at all, but on warm nights they are sometimes very active and hungry. As before related, I lost twenty-one oxen by driving them backwards and forwards in one night through a "fly" belt ten miles in width. This was in the month of November, and the night was very warm.
On the 25th of August 1874, when returning from the pursuit of a wounded elephant, I struck the Chobi river late at night, and had to walk several miles along the bank before getting to my camp. It was a bright moonlight night, and fairly warm. My only clothing consisted of a shirt, a hat, and a pair of veld shoes, and as I walked along near the water's edge the tse-tse flies kept flying up from the ground and biting my bare legs, and from the loud slaps behind me I knew they were paying similar attentions to my Kafirs. Now, these "flies" were undoubtedly resting on the bare ground, for we were walking, not through bushes, but along the strip of open ground between the forest and the water's edge. The bite of the tse-tse is very sharp, like the prick of a needle, but in a healthy man it causes no swelling or after irritation, like the bite of a midge or a mosquitoe. Speaking generally, the bites of a moderate number of tse-tse flies may be said to have no appreciable effect on a human being. Still, I am of opinion that if one is exposed to the attentions of swarms of these insects for months at a time, the strongest of human beings will find himself growing gradually weaker. Explorers or traders may sometimes be exposed to the bites of great numbers of tse-tse flies for a few days together, but they will soon pass through such districts. Only an elephant hunter, I think, would ever be likely to remain for any considerable period of time in a country where tse-tse flies were very numerous. I cannot think that many Europeans have suffered from tse-tse fly bites as much as I have. In 1874, and again in 1877, I spent the whole of the dry season, from June till November, on the southern bank of the Chobi river, and lived during the greater part of those two seasons in a swarm of tse-tse flies. Up to that time I had had no fever, and my constitution was unimpaired in any way. Towards the end of both those seasons, however, not only I myself but all my Kafir attendants became excessively thin, and seemed to be getting rather weak. The natives, too, who lived in the reed beds where there were no tse-tse flies, but who used to come to the southern bank of the river to collect firewood and look at their game traps, all said that they could not live there because of the tse-tse, which made them thin and weak, or, as they expressed it, the tse-tse "killed them," just as they say in times of famine that hunger is killing them.
In 1882 I met with a curious experience, for which I cannot quite account. During that year I had made an expedition from the high plateau of Mashunaland to Zumbo, on the Zambesi, and had had a somewhat hard time and gone through a severe attack of fever. I had also been very much bitten by tse-tse flies on the lower Panyami and Umsengaisi rivers. Towards the end of the year I got back to the Mission Station of Umshlangeni in Matabeleland, and was given a warm welcome by my old friends the Rev. W. A. Elliott and his wife. I reached the Mission Station late in the evening, after a ride of fifty miles in the hot sun. I was fairly well, having recovered from the attack of fever, but perhaps a little run down.
Soon after I had turned in on the bed Mrs. Elliott had arranged for me, I felt my nose coming on to bleed. Not wanting to disturb any one, I pulled a newspaper I had been reading from the chair by my bedside, and spreading it on the floor, let my nose bleed on to it. It bled a good deal, and the next morning I was surprised to see that the blood which had come from me was not like blood at all, but slimy, yellow-looking stuff. When I showed it to Mr. Elliott, I said to him that it looked to me exactly like the blood of a "fly-stuck" donkey which I had shot some years before at Daka, and I laughingly suggested that I was "fly-stuck" too. That something had affected the red corpuscles of my blood seems certain, but whether innumerable tse-tse fly bites or fever, or both combined, had done it I cannot say. Ever since I received an injury in the head in 1880, I have been rather subject to bleeding from the right nostril, but I have never again lost any blood which bore the slightest resemblance to that which came from me in Mr. Elliott's house after my trip to Zumbo in 1882.