Le as Carriers of Trypanosoma pecorum. 353 
and also, in large numbers, in open swampy areas where few or no trees 
grow. The rank grass, which grows waist-high in these swamps, appears to 
satisfy what need they may have for shade. Another very favourite locality 
for these flies is a road or ford crossing streams and swamps. The fly is 
absent from dry, open, grass-covered hill tops. 
Habits—The hours of greatest activity, and the feeding times of this 
genus, correspond to those given above for the Tabanide. They have a 
sluggish flight, and attack man more readily than do the Tabanide. When 
they settle on their victim they rarely bite at once, but usually walk about 
slowly for a few seconds before inserting their probuscis. They will follow 
cattle or man for a mile or two. : 
Sex.—No male fly was ever captured by the Commission during the time 
these observations were taking place. 
The Chrysops and the Lhinomyza. 
These flies were comparatively scanty in the neighbourhood, and no 
accurate observations were made of their natural history. All were caught 
at the ford on the Kasala stream, at the foot of Mpumu hill. Rhinomyza 
perpulcra appeared to be very localised in its distribution, as it was never 
seen elsewhere in the vicinity. It was usually captured whilst sunning 
itself on stones in the stream, or whilst it was biting natives washing 
clothes at this ford. Its habitat appeared to be the densely forested banks 
of the ford. Mr. Austen informs us that it is a new African species. 
3. EXPERIMENTS TO ASCERTAIN IF TABANUS SECEDENS (WALK.), TABANUS 
FUSCOMARGINATUS (RICARDO), OR TABANUS THORACINUS (PAL. DE 
BEAUV.), ARE CAPABLE OF TRANSMITTING TRYPANOSOMA PECORUM FROM 
Sick TO HEALTHY OXEN. 
The experiments were carried out between March and August, 1910. The 
above-named species were used, as they were the most common among the 
Tabanide during this period. Only wild flies were employed, as the Commis- 
sion never succeeded in finding the eggs or larvee of these flies. ‘The species 
of Tabanus used in any experiment, and the duration of the experiment, 
were thus entirely dependent on the seasonal incidence of the fly in the 
neighbourhood. 
Endeavours were at first made to carry out the experiments in the 
laboratory on Mpumu hill. Cages, some 12 inches square, were made, with 
sides of wood, the top and bottom consisting of wide-meshed mosquito 
netting. The captured flies were placed in these cases—about 50 flies per 
cage—the cages being kept over water in the laboratory when the flies were 
VOL. LXXXIII.—B. 2 D 
