The weather, from the 14th to the i8th, was wretched; it rained sometimes for twelve hours in succession, not heavily, but in a steady drizzle, such as we are familiar with in our English climate.We landed at several places on the coast, Penna to trade as usual, and I to ramble in the forest in search of birds and insects.In one spot the wooded slope enclosed a very picturesque scene: a brook, flowing through a ravine in the high bank, fell in many little cascades to the broad river beneath, its margins decked out with an infinite variety of beautiful plants.Wild bananas arched over the watercourse, and the trunks of the trees in its vicinity were clothed with ferns, large-leaved species belonging to the genus Lygodium, which, like Osmunda, have their spore-cases collected together on contracted leaves.On the 18th, we arrived at a large fazenda (plantation and cattle farm), called Jatuarana.A rocky point here projects into the stream, and as we found it impossible to stem the strong current which whirled around it, we crossed over to the southern shore.Canoes, in approaching the Rio Negro, generally prefer the southern side on account of the slackness of the current near the banks.Our progress, however, was most tediously slow, for the regular east wind had now entirely ceased, and the vento de cima or wind from up river, having taken its place, blew daily for a few hours dead against us.The weather was oppressively close, and every afternoon a squall arose, which, however, as it came from the right quarter and blew for an hour or two, was very welcome.We made acquaintance on this coast with a new insect pest, the Pium, a minute fly, two thirds of a line in length, which here commences its reign, and continues henceforward as a terrible scourge along the upper river, or Solimoens, to the end of the navigation on the Amazons.It comes forth only by day, relieving the mosquito at sunrise with the greatest punctuality, and occurs only near the muddy shores of the stream, not one ever being found in the shade of the forest.In places where it is abundant, it accompanies canoes in such dense swarms as to resemble thin clouds of smoke.It made its appearance in this way the first day after we crossed the river.Before I was aware of the presence of flies, I felt a slight itching on my neck, wrist, and ankles, and, on looking for the cause, saw a number of tiny objects having a disgusting resemblance to lice, adhering to the skin.
This was my introduction to the much-talked-of Pium.On close examination, they are seen to be minute two-winged insects, with dark coloured body and pale legs and wings, the latter closed lengthwise over the back.They alight imperceptibly, and squatting close, fall at once to work; stretching forward their long front legs, which are in constant motion and seem to act as feelers, and then applying their short, broad snouts to the skin.
Their abdomens soon become distended and red with blood, and then, their thirst satisfied, they slowly move off, sometimes so stupefied with their potations that they can scarcely fly.No pain is felt while they are at work, but they each leave a small circular raised spot on the skin and a disagreeable irritation.
The latter may be avoided in great measure by pressing out the blood which remains in the spot; but this is a troublesome task when one has several hundred punctures in the course of a day.Itook the trouble to dissect specimens to ascertain the way in which the little pests operate.The mouth consists of a pair of thick fleshy lips, and two triangular horny lancets, answering to the upper lip and tongue of other insects.This is applied closely to the skin, a puncture is made with the lancets, and the blood then sucked through between these into the oesophagus, the circular spot which results coinciding with the shape of the lips.In the course of a few days the red spots dry up, and the skin in time becomes blackened with the endless number of discoloured punctures that are crowded together.The irritation they produce is more acutely felt by some persons than others.Ionce travelled with a middle-aged Portuguese, who was laid up for three weeks from the attacks of Pium; his legs being swelled to an enormous size, and the punctures aggravated into spreading sores.
