The mosquito is not the only insect pest of the Amazon valley. Professor Orton says the pium, or sand-fly, is almost as bad as the better-known tormentor. He has two triangular, horny lancets, which leave a small circular red spot on the skin. There are several species, all working by day, and relieving the mosquito from sunrise to sunset. Then there is the maruim, which resembles the pium, and inhabits some, but not all, of the valleys; Humboldt estimated that there was a million of them to a cubic foot of air where he was. There is also the mutuca, which resembles a horse-fly; one variety has a lancet half an inch long, and he knows how to use it to advantage. There is a carapato, or tick, which mounts to the tips of the blades of grass, and attaches himself to any one brushing against them. The carapatas bury themselves so deeply that their heads break off at any attempt to pull them out; their bite is painless, but it often causes sores and ulcers. Happily, their range is less extensive than that of the mosquito, and some parts of the country are wholly free from them. Frank asked Manuel how the natives, who had no nets, managed to get along in the height of the mosquito season. [Illustration: AN INDIAN OF NORTHERN BOLIVIA.] "They get along very badly," was the reply. "One plan is to cover their bodies with oil, which the mosquitoes don't like, but it does not drive them away. Smudging or smoking keeps them down, but then it is almost as bad for the people as for the mosquitoes. Sometimes they bury themselves in the sand, leaving only the head exposed; this they cover with a piece of wetted cloth, either wrapped around the head, or supported above it like a miniature tent. Some of the Indians plaster their bodies with mud, laying it on like varnish, and allowing it to dry, but it has to be pretty thick to keep the mosquitoes from penetrating it. Some of the insects will pierce through any ordinary clothing; I have heard of their going through ordinary shoe-leather, but never saw with my own eyes a mosquito that could do it." Sheltered by their nettings, they passed the night in comparative comfort, and were off early in the morning. In fact, the raft was in motion before the youths had risen; the Indians were so silent in their movements that they did not disturb the slumber of the travellers. Frank made a comparison with the noisy boatmen of the Nile which was very much in favor of the Indians of the Beni. [Illustration: BREAKFAST SCENE ON THE RIVER BANK.] About seven o'clock they stopped for breakfast and the scene was so picturesque that Frank made a sketch of it.