In Angola, Dr. Livingstone found the banks of the river Seuza infested by legions of the most ferocious mosquitoes he ever met with during the course of his long travels. ‘Not one of our party could get a snatch of sleep. I was taken into the house of a Portuguese, but was soon glad to make my escape, and lie across the path on the lee-side of the fire, where the smoke blew over my body. My host wondered at my want of taste, and I at his want of feeling; for, to our astonishment, he and the other inhabitants had actually become used to what was at least equal to a nail through the heel of one’s boot, or the tooth-ache.’ ‘He who has never sailed on one of the great rivers of tropical America, the Orinoco, or the Magdalena,’ says Humboldt, ‘can form no idea of the torments inflicted by the mosquitoes. However accustomed the naturalist may be to suffer pain without complaining, however his attention may be riveted by the examination of some interesting object, he is unavoidably disturbed when Mosquitoes, Zancudos, Zejens, and Tempraneros cover his hands and face, pierce his clothes, or creep into his nose and mouth. In the missions of the Orinoco, in these small villages, situated on the river banks and surrounded by interminable woods, this plague affords an inexhaustible subject for conversation. When two people meet in the morning their first questions are--‘How did the Zancudos behave last night?’ ‘How are the mosquitoes to-day?’ At the mouth of the Red River the unfortunate inhabitants lay down at night upon the ground, and cover themselves with three or four inches of sand, so that only the head remains free, over which they spread a protecting cloth. Above the influx of the Rio Arauca into the Orinoco, at the cataracts of Baragnon, the atmosphere up to a height of 15 or 21 feet, is filled with a dense mist of stinging insects. Placing oneself in some dark spot, for instance in one of the deep hollows formed in the cataracts by mounds of granitic blocks and looking towards the opening illumined by the sun, one sees whole clouds of mosquitoes, increasing or diminishing in density as the creatures in their slow and rhythmic motions now draw more closely together, and then again separate. In Esmeralda, at the eastern extremity of the Upper Orinoco, the mosquito clouds are almost as thick as at the cataracts. When the superior of the monastic order to which the mission belongs, wishes to punish a lay brother, he sends him to Esmeralda, or, as the monks facetiously remark, ‘condemns him to the mosquitoes.’