353
(2) Sibone River to Msolozi along North bank of Shangani.
1919-1921. Fly always seen in small numbers (twos and threes).
1922. Only one fly seen.
(8) Msolozi to Main Camp along South Bank of Shangani.
1918-1919. Fly present in small numbers throughout, especially close to Msolozi and in strip of river forest extending about a mile and a-half below the main camp.
1920-1922. No fly present anywhere along this tract (one specimen taken by Mr. Kemp in September this year, had in all probability followed across from the north bank).
(4) Main Camp to Brereton's Camp-South Bank of Shangani.
1919. On the edges of a series of vleis near the river fly was to be met with in small numbers, and in greater numbers in a strip of forest close to Brereton's Camp. 1920. Fly apparently entirely disappeared from strip of forest near Brereton's Camp and only odd specimens seen elsewhere.
1921. Three fly opposite Mzola Junction; none seen elsewhere. 1922.
One fly taken opposite Mzola Junction; none seen elsewhere. (5) Brereton's Camp to Ngondo Salt Vlei: South Bank of Shangani.
1919. Odd fly encountered en route and numerous at Salt Vlei; also along Gusu to Sebasinungu.
1920. Fly numerous at the Salt Vlei and very aggressive; odd fly still to be met with between Ngondo and Brereton's Camp.
1921. Not visited in October, but in June took 10 males and 1 female in
14 hours at Salt Pan, and odd fly seen in vicinity.
1922. No fly seen at Ngondo or in vicinity, or along path to Sebasinungu, or between Brereton's Camp and Ngondo.
(6) - Lubimbi Salt Vlei,
October, 1919-22 males 2 females. October, 1920-18 males 16 females.
October, 1921-12 males 3 females.
October, 1922 3 males ( females.
(7) Between Main Camp and Bira and at Bira River.
October, 1919-Fly present in great numbers.
October, 1920-15 males 15 females.
October, 1921-4 males 2 Females.
October, 1922— 2 males 0 females.
Note. Dr. Nobbs and Mr. de Buys visited the Bira River two days previously
and without a net secured 17 males and 17 females.
(8) Mzola Index No. 1: Applying Fiske's formula for denoting density, i.e.,
number of males caught, expressed in net hours:
149
Note. More fly were present below the pan on the banks of the Kana than in 1921, but the camp had been deserted for months in 1921 and has been tenanted throughout the operations this year. It is difficult to dissociate the fly on the river banks from those at the pan itself, which is only a few hundred yards away, as natives going for grass and water carry them to the pan. Only one fly was seen on the river in 1921, and some half-dozen were taken this year (2 males and 4 females). The reduction of fly in the vicinity during the past few years has, however, been very great indeed.
(11) Kana River.-Fly caught at the crossing near Bondo Camp
15 males 8 females (2 crossings).
1920 1921
1922
nil nil
Note. The general reduction of the fly on the Kana between Bondo Camp and Upper Kana Pan (Kana Index) is very marked indeed. Some parts of this stretch were very heavily infected before the operations, but I have no exact figures. I went up the river to collect some figures in October, 1918, but was forced to turn back on account of influenza amongst my carriers. In 1916, however, tsetse fly swarmed for several miles below the Kana Index on the north bank of the river.
Conclusion. The reduction of tsetse in the area of operations has in general continued, and is even more marked than last year. In view of the increase and spread of "fly" on either side of the area and the general tendency to spread else- where in the territory, which has occasioned much correspondence recently, there can be no reasonable doubt that the shooting of the game has been responsible for the very great decrease of tsetse fly in the area. The results might have been even more striking were it not for the great influx of game during the present season, apparently occasioned by the unprecedented drought and other factors mentioned earlier in this report.
Recommendations.-It appears to me desirable that the operations should be continued this season until the general onset of the rains removes the special attractiveness of the area to game and scatters the fly..
.
A detailed survey in regard to tsetse fly of the area and adjacent country might with advantage be made about next August with a view to obtaining final results from the experiment. From the practical standpoint the experimental area should undoubtedly be included amongst the other "concession areas wise increase and further spread of the fly is to be anticipated.
next season, other-
R. W. JACK,
Chief Entomologist.
Male Density.
October, 1918
20
October, 1919
14
October, 1920
5.5
October, 1921
.75
October, 1922
3.25
(9) Mzola Index No. 2.
1920
38 males
36 females.
1921
10 males
6 females.
1922 (a)
7 males
(b)
6 males
4 females. 2-females.
Female Percentage.
16.6
44
50
77.5
23.5
Note. The above figures are, not strictly comparable for reasons already given. The catch (b) for the present year was made over a larger area of ground and over a longer period of time.
(10) Kana Index.
"
1919
· 41 males
17 females..
*1920
19 males
13 females.
1921
0 måles
1922
0 {?) males
( females. Pr(?). females.
563
(No. 38.)
SIR.
No. 47.
GOLD COAST.
THE SECRETARY OF STATE to THE GOVERNOR.
[Answered by Nos. 56 and 60.]
Downing Street, 12th January, 1923.
I HAVE the honour to acknowledge the receipt of your despatches No. 600 of
the 30th of August,* and Nc. 789 of the 20th of Novembert on the subject of the distribution of tsetse-flies in the neighbourhood of Accra.
2. These despatches have been brought to the notice of the Director of the Imperial Bureau of Entomology, who has now had an opportunity of discussing with Dr. J. W. S. Macfie the interesting report forwarded in the second despatch. The opinion which the Director has formed is that in present circumstances there is no reason to suppose that the occurrence of tsetse-flies in the low hills to the north-west of Accra constitutes any real menace to that town, and that, in con- sequence, the expenditure which would be involved in attempting to get rid of this flv-belt would hardly be justifiable.
* No. 44.
61076: not printed.
PUBLIC RECORD OFFICE
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