ONE of the most terrible scourges of Africa is the disease known as sleeping sickness, which is caused by a trypanosome, a blood-parasite, carried and spread by two species of tsetse fly. Hence there was a large gathering of the fellows at the meeting of the Zoological Society on March 21 to see the film exhibited by Mr. R. W. Harris, who showed what is being done by the Government entomologists to mitigate, if not terminate, the ravages of this insect. Since this war of extermination has to be carried on over millions of square miles, any such campaign might seem hopeless. But it was made manifest that, in so far as Rhodesia is concerned, a considerable measure of success has been attained. This has been done by the use of an ingenious trap devised by Mr. Harris's father, Mr. R. H. T. P. Harris. The trap is made of canvas; box-like in form, and much wider at the top, it is mounted on four legs, keeping it well off the ground. In bulk it is roughly of the size of, say, a small antelope. The flies are not very discriminating, and on sighting this canvas ‘stalking-horse’ alight on it, and crawl down according to their habit, to reach the shaded under-side, there to suck the blood of their prospective victim. Their exploration is thorough, but fruitless. But presently, they find a long slit through which daylight appears r entering from a special cage at the top. They at once pass through, and upwards, into what they take to be the daylight and freedom beyond. Passing into this light-filled cage they are unable to escape. Enormous heaps of flies were shown which had been taken from this trap. Yet another trap was shown designed to induce the flies to deposit their larvse therein. Millions of pupae are taken in this way.