In December 1888 I took two horses to the Falls, and rode one of them all along the narrow strip of open ground between the Rain Forest and the edge of the chasm into which the river falls. It seemed strange not to see a single "fly" in this district, where these death-dealing insects had literally swarmed only eleven years earlier.
Farther westwards, however, tse-tse flies continued to haunt the southern bank of the lower Chobi river in great numbers long after the buffaloes had ceased to live there constantly, though these animals still visited the district during the rainy seasons. At such times they probably grazed down the river in great numbers to within a few miles of its junction with the Zambesi.
A letter I have lately received from my old friend Mr. Percy Reid, who has made many hunting trips to the Chobi and Zambesi rivers, the last two of which were undertaken, the one the year before and the other three years after the epidemic of rinderpest had killed off all the buffaloes on the lower course of the Chobi river, throws a great deal of light on the disputed question as to whether or no there is or has ever been any connection between the buffalo and the tse-tse fly in South Africa.
In the course of his letter Mr. Reid says:
I was at Kazungula (the junction of the Chobi and Zambesi rivers) in 1885, 1888, 1895, and 1899. In 1885 I did not take my oxen beyond Pandamatenka, as it was not considered safe to take them to Kazungula; but even in that year I saw no "fly" between Leshuma[9] and the junction of the rivers, though I remember that a few were said to still exist there at that time. There were no buffalo there then, and the fact that the "fly" still lingered in this district was put down, though I do not know with how much truth, to the great number of baboons which, as you will remember, always frequented the bush near Kazungula.
[9] Leshuma is ten miles south of Kazungula.
In 1888 and subsequent years I sent oxen and horses backwards and forwards from the river to Leshuma at all hours of the day, and never lost any from "fly" bites.
In 1895 there were plenty of both fly and buffalo up the Majili,[10] and swarms of fly up the Chobi, but I did not go very far, and saw no buffalo there.
[10] A river running into the Zambesi from the north, not far above its junction with the Chobi.
In 1899, only three years after the rinderpest had swept off all the buffaloes, I went along the north bank of the Chobi right past Linyanti, and, crossing above the swamps, came back along the south bank. There was not a fly to be seen where, only four years before, I had counted thirty or forty on a native's back at one time, and we had actually to light fires and sit in the smoke to protect ourselves from them. On the whole trip we saw no buffalo, and only got fairly old spoor of one very small lot on the north bank. I certainly always understood that in a very few years after the buffalo disappeared from any district the "fly" followed suit. All the old hunters up on the Zambesi were agreed on that point, and I recollect George Westbeech[11] saying the same thing.
[11] An old Zambesi trader of great experience.
This letter conclusively proves that although tse-tse flies continued to swarm along the southern bank of the Chobi to within a short distance above Kazungula for some years after the buffaloes had ceased to live all the year round in this district (as they used to do up to the early 'eighties of the last century), and only spent the rainy season there, these insects absolutely disappeared within three years after the final destruction of the buffaloes by rinderpest in 1896.
Mr. Reid's letter also seems to show that if buffaloes live in great numbers all along the bank of a certain river where tse-tse flies also swarm, and that if through persecution the buffaloes should be driven far up the river at certain times of year, only returning to their old haunts during the rains, when all hunters have left the country, a large proportion of the tse-tse flies do not migrate backwards and forwards with the buffaloes, but remain constantly on the section of the river where they first appeared as perfect insects, not appreciably decreasing in numbers as long as the buffaloes come amongst them periodically, but gradually dwindling in numbers, and at last altogether disappearing within a few years of the final extinction of those animals, in spite of the continued presence of other kinds of game.
Although Mr. Reid saw no "flies" between Leshuma and Kazungula either in 1885 or in 1888, there were still a few lingering there in the latter year. There were so few in the early part of 1888, however, that probably none were to be seen during June and July, when the nights were very cold, but later on in this same year they increased very rapidly in numbers, as I think, owing to the fact that my own and Mr. Reid's cattle deposited a great deal of dung all along the waggon track leading down to Kazungula. It was in June of that year (1888), after I myself had crossed the Zambesi on an expedition to the north, that Jan Weyers, an old Dutch hunter, took my waggon by night through the old "fly" belt between Leshuma and Kazungula in order to trade with the natives living on the Zambesi, sending the oxen back to Leshuma the following night. In the same month, or a little later, Mr. Percy Reid and his party brought their waggons to Leshuma, and their oxen pulled them backwards and forwards several times between that place and Kazungula. There was thus a great deal of cattle dung, which is, of course, precisely the same as buffalo dung, all along this short stretch of waggon road. For some reason this driving of cattle backwards and forwards between Leshuma and the Chobi caused an extraordinary increase in the number of tse-tse flies. All the natives who travelled the road remarked upon it, and both they and Jan Weyers assured me that they had thought the "fly" was almost absolutely extinct in this district, as in the previous year, even in the hot weather before the rains, very few had been seen.
However, when I went down to the river in August (1888) on my way to the Barotse country, I found a good many tse-tse flies along the track, and by November they had become very numerous. As Mr. Reid and his party did not return to Pandamatenka by way of Leshuma, but went along the southern bank of the Zambesi to the Falls, they were unaware of this sudden increase in the numbers of the tse-tse flies.