He had read of a fatal insect that frequented some districts in the interior of South Africa, and the first sight of these flies aroused his suspicions that it might be they.
He communicated his thoughts to the others, who at once shared his alarm.
"Call Swartboy hither!" said Von Bloom.
The Bushman was called, and soon made his appearance, coming up from the spring.

He had for the last hour been engaged in unpacking the wagon, and had taken no notice of the horses or the interest they were exciting.
As soon, however, as he got near, and saw the winged swarm whirring around the horses, his small eyes opened to their widest extent, his thick lips fell, and his whole face yielded itself to an expression of amazement and alarm.
"What is it, Swart ?" inquired his master.
"Mein baas! mein baas! der duyvel um da--dar skellum is da `tsetse!'" "And what if it be the tsetse ?" "Mein baas!--all dead--dead--ebery horse!" Swartboy then proceeded to explain, with a loud and continuous "clicking," that the fly which they saw was fatal in its bite, that the horses would surely die--sooner or later, according to the number of stings they had already received; but, from the swarm of insects around them, the Bushman had no doubt they had been badly stung and a single week would see all five of the horses dead.
"Wait, mein baas--morrow show." And to-morrow _did_ show; for before twelve o'clock on the next day, the horses were swollen all over their bodies and about their heads.

Their eyes were quite closed up; they refused any longer to eat, but staggered blindly among the luxuriant grass, every now and then expressing the pain they felt by a low melancholy whimpering.

It was plain to every one they were going to die.
Von Bloom tried bleeding, and various other remedies; but to no purpose.
There is no cure for the bite of the tsetse fly!.