།། ། ། ། །
PUBLIC RECORD OFFICE
C.O.
Reference :-
885
20 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- | COPYRIGHT PHOTOGRAPH-NOT TO
72
Entomological Research Committee on the subject of big game and the tsetse fly in Rhodesia.
In reply I forward a copy of a letter, with enclosure, received from the Director of Agriculture, and am to suggest that a reply be sent to the Entomological Research Committee in terms of paragraphs 5 and 6 of Doctor Nobbs's letter.
I am to add that the Medical Director states he has no medical officer whom he could detail to accompany an entomologist in the investigation of the various trypanosome diseases which occur in Southern Rhodesia, and he does not think that anything would be gained by engaging a medical man specially for this purpose.
I am, &c.,
The Secretary,
British South Africa Company,
London Wall Buildings, London, E.C.
COLIN E. DUFF,
For Secretary, Department of the Administrator.
DESTRUCTION OF BIG GAME IN SOUTHERN RHODESIA (E. A. NOBBS).
Office of the Director of Agriculture, Salisbury, 27th April, 1910.
Big Game and Tsetse Fly.
1. Possibly the enquiries suggested by the Entomological Research Committee and outlined in the accompanying report by the entomologist might be combined with the contemplated trip to the junction of the Shangani and Karna Rivers on behalf of the Liebig Company, and the proposed experimental research at Gatooma, regarding which a minute is being simultaneously submitted.
2. I think the question of the association of big-game and tsetse is of less moment to us in Rhodesia than such problems as (1) the transmissibility of fly disease by tsetse or other species of flies; (2) the mapping of tsetse areas; (3) the alleged extension of fly areas; (4) the other entomological researches collectively on which Mr. Jack (entomologist) is engaged.
3. If the Entomological Research Committee desire so urgently to solve the problem they refer to, they might well appoint an entomologist" for the express purpose," but from the national economic standpoint, as distinct from the scientific or sentimental one, I cannot advise that this Administration incur expenditure to this end.
4. The scope of the enquiry suggested in their letter is estimated to occupy the entire time of an entomologist for probably two years-I do not deal with the question of "
a properly-trained pathologist," "on which the Medical Director has reported.
5. I have, therefore, to recommend that the Scientific Secretary be informed in reply to his letter of 10th March to the Secretary of the British South Africa Company, that the question of the occurrence and spread of species of Glossina is receiving the earnest attention of the entomologist attached to the Department of Agriculture, with special reference to fly-borne diseases of cattle, while the trypano- some diseases of stock are being studied by our Veterinary Department and by an There is no Inter-Colonial Trypanosomiasis Expedition at the present moment. reason to doubt the competence of the scientists engaged on these enquiries.
6. These steps, initiated some time ago, and now in progress, are considered adequate to meet the requirements of the case without a third enquiry on parallel
lines.
The Treasurer,
Salisbury.
ERIC A. NOBBS,
Director of Agriculture.
DESTRUCTION OF BIG GAME IN SOUTHERN RHODESIA (R. W. JACK).
Tsetse Fly in Southern Rhodesia.
25th April, 1910.
The importance of investigations into the breeding habits of the tsetse fly, its association with big game, and the factors that restrict it to certain belts, has been constantly in mind in this office, and endeavours have been made to locate a spot where the fly occurs in sufficient numbers to afford an opportunity for study. These
73
have not been successful, the fly being very scarce in all the parts visited, and at all scasons during the past ten months.
The study of the breeding habits, natural enemies, &c., can only be carried out where the insect is really abundant. Southern Rhodesia does not seem to afford facilities for the work, owing to the fact that suitable spots are not to be found within convenient distance of the railway. The "fly area" in the Surisuri River basin has not yielded more than about half a dozen specimens in a day at any season since July, 1909, and so is of no practical use for observations. There are two localities in Southern Rhodesia which reports point to as possibly suitable. The first of these is the Escarpment in Lomagundi, where Mr. Thornton, British South Africa Police, encountered fly in numbers in October, 1909, and the adjacent reach of the Hunyani River, where fly was reported to be plentiful in 1907-8-9. The other spot is the junction of the Umniati and Sakugwe Rivers, north of the Sanyati Reserve, where the fly is reported to have been plentiful during the last five years. Either of these spots is remote, that near the Escarpment being also, I understand, difficult or access to a wheeled vehicle. The study of the breeding habits is a labour that might well occupy several months on one spot, and would very likely need to be prolonged throught the rains. There is no need for me to enlarge upon the limita- tions of both these localitics for this purpose. I think it probable that North- Western Rhodesia may afford greater facilities in providing well stocked fly belts near the railway. Perhaps Dr. Montgomery could furnish information on this point. The investigation of the association of tsetse fly with big game involves visits to a large number of " fly belts," and would undoubtedly occupy an expedition several months travelling through infested country. Reports as to the seasonable prevalence of Glossina morsitans are conflicting, but the trend of opinion seems to point to the hot weather preceding the rains as the period when they are most abundant. They have, however, been reported as abundant in July and August. Owing to the very great difficulties of moving about the veldt in the rains, it would be advisable for an expedition to set out about August, and yet be back by the end of the year. Possibly North-Western Rhodesia would be more suitable than Southern Rhodesia for this purpose, though a tour from Hartley to the Umniati, and thence, if possible, over the Umfuli to Lomagundi, striking northwards near the western border to the Zambesi and eastwards to take in the Hunyani River and the Escarpment, should furnish a good deal of information.
The third point, the question of the factor that causes the fly to restrict itself to defined belts, is intermingled with the study of the breeding habits, and of the association of the fly with big game, and will not be answered until knowledge of one or other, or possibly both, of these is obtained.
I have to point out that the failure to find tsetse fly on several of the farms, &c., where trypanosomiasis has broken out in the Hartley District during the past season has caused the question of the possibility of the transmission of the disease by species of blood-sucking flies other than Glossina morsitans to assume consider- able importance, and at the present time I am of the opinion that investigation of this matter is as pressing as that of the cecology of the tsetse fly. This work is the better suited to the discharge of the duties of my office, as it can be carried out with- out my losing touch with headquarters. It is, of course, very desirable that study along the separate lines should proceed at the same time if possible. Perhaps the South African Trypanosomiasis Commission could be induced to help in the matter. I understand that tsetse fly is to be found along the northern bank of the Zambesi near the mouth, and presume that this spot is readily accessible by boat. It might be possible to carry out investigations there.
1.
To sum up, it is desirable that investigations such as those recommended be carried out, but Southern Rhodesia does not afford great facilities for the study of the breeding habits, &c., of the tsetse fly; investigation of all the points would take up all the time of one man for probably two seasons, during which time there would be the expenses of transport, &c., and finally it is a question whether my time could not be more conveniently employed in the near future in investigating the possibility of the transmission of cattle trypanosomiasis by species of blood-sucking flies other than tsetse.
R. W. JACK, Government Entomologist.
The Director of Agriculture,
Salisbury.