1. The Nzega sub-district of Tabora contains old savannah wooding (mostly Brachystegia), younger savannah wooding (in part Brachystegia, in large part Acacia) and grassy “ culture steppe,” or open settlement. There is also a large, natural, open grassy steppe, uninhabited, on the Wembere.
2. The younger wooding has grown up as the result of depopulation caused by clan and tribal warfare that pre-dated the entry of the Germans, though a little has been produced since by oppressive or unpopular chiefs.
3. The older bush is for the most part infested with G. morsitans, and the younger is in part infested, in part in course of becoming infested, by tsetses that appear to be advancing on several fronts. The largest bush area in the district as yet uninfested is that of Mwambiti, south and west of Gulube.
4. Much of the settled culture steppe being itself still very bushy, the advance of the fly to its borders would appear to constitute a serious threat, and the cattle and their owners are already beginning to be driven by G. morsitans out of culture steppe in north Makarundi and Nzega Ndogo, at a point south-east of Kiguhumo.
5. G. swynnertoni has recently passed into the sub-district from Shinyanga, is spreading, and, being particularly adapted to dry thorn-bush conditions, is probably capable of infesting all portions that are as yet uninfested, as well as all of the culture steppe excepting parts of Makarundi. G. swynnertoni is already in contact with the great thorn-bush area, Arusha to Dodoma, to the east of the Nzega sub-district, for it occupies areas in Mbulu and Mkalama.
6. The advances by G. swynnertoni and G. morsitans into the Mwambiti bush area are of somewhat special interest, for they are representative of what is happening in much of South East Africa.
7. The possibility of dealing with this situation by means of measures against the game has been carefully considered. The only effect such measures could have here would be to accelerate the advance of the fly owing to the movements of man and game that they would bring about and to divert the population from development of their country to hunting. Both these situations are already existing in East Mwanza and are proving difficult to remedy.
8. Means of producing and consolidating cleared barriers are under experimentation, but it would seem that at present the above-mentioned advance can be met, if at all, only by judiciously planned and organised late grass-burning.
9. Grass-fires in any case have for hundreds of years burned off the country. Their discontinuance, unreplaced by settlement and immediate heavy stocking with animals, leads to a vicious thicket growth that gradually suppresses all pasture, continues to harbour tsetse and is clearable only at the greatest expense. As, then, burning does and must take place, surely it is far better that in tsetse areas (not in cattle-areas) the fires should be organised in such a way that they will damage the fly and in a limited number of years replace the patchy, scanty humus of the thickets
with well-distributed manure resulting from the grazing of cattle, than that the present indiscriminate and harmful system of burning should be allowed to continue.
10. The administrative difficulty is a very real one. A man who is over-busy in other directions, or easily imposed on, can never enforce the postponement of burning. Someone should, if possible, be in special charge during the critical months and be aided by legislation, energetic native guards and the co-operation of the headmen.
11. Postponement of burning was effected last year on these lines in nearly the whole Mwambiti-Mwansimba area with success. This area comprises both the advance by G. swynnertoni and two of the three most threatening advances by G. morsitans. The fire, as regards its carrying out, was most successful also. It will take three or more such burnings before the probable effect on the tsetse can be clearly seen, and work on the more extensive thickets may also first be needed.
12. On the west of the area bush-clearing is necessary to hold the fly back. The natives have already carried out a first instalment of this clearing near Kiguhumo and, near “ Stoke's Camp ” and Ndambire's, made a small beginning with the splitting up of the fly-belt on the lines indicated on the map. Their efforts (Ibologelo, Nzega and North Makarundi) that are immediately threatened by G. morsitans.
13. In Nzega, as in Shinyanga, the value of using the tribal organisation was well proved. The natives still follow their chiefs and headmen as their natural leaders, and there can be no doubt that where this system has been allowed to weaken and headmen have lost their prestige, measures against the tsetse are going to be far more difficult to carry out.
14. South Makarundi offers a fine example of what can be done in the way of making culture steppe (and freedom from fly) permanent by getting the natives to dig up stumps for firewood instead of making journeys to the bush.
