224 



THE LOWER AMAZONS 



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 accom- 

 panies 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 resem- 

 blance to lice, adhering to the skin. This was my intro- 

 duction to the much-talked of Pium. On close examina- 

 tion, they were 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 whilst 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. 

 I took the trouble to dissect specimens to ascertain the 

 way in which the little pests operate. The mouth con- 

 sists 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. I once travelled with 

 a middle-aged Portuguese, who was laid up for three 

 weeks from the attacks of Pium ; his legs beingjswelled 



