93 



I have just shown, from my own observations, 

 how muoh the geographical distribution of veno- 

 mous insects varies in this labyrinth of rivers 

 with white and black waters. It were to be 

 wished, that a learned entomologist could study 

 on the spot the specific differences of these 

 noxious insects*, which in the torrid zone, in 

 spite of their littleness, act an important part in 

 the economy of nature. What appeared to us 

 very remarkable, and is a fact known to all 

 the missionaries, is, that the different species do 

 not associate together, and that at different 

 hours of the day you are stung by distinct spe- 

 cies. Every time that the scene changes, and, 

 to use the simple expression of the missionaries, 

 other insects "mount guard," you have a few 

 minutes, often a quarter of an hour of repose. 

 The insects that disappear have not their places 

 instantly supplied in equal numbers by their 

 successors. From half after six in the morning 

 till five in the afternoon, the air is filled with 

 moschettoes ; which have not, as we find related 

 in some travels*^, the form of our gnatsj, but 



* The mosquitos bovos or tenbiguai ; the fneteros, which 

 always settle upon the eyes j the tempraneros, or putchiki ; 

 the jejenes ; the gnat rivau ; the great zancudos, or matchdki; 

 the cafaji, &c. 



+ Kalrn, Reise in Nord-America, torn, ii, p. 268. 



X Culex pipiens. This difference between mosquito (little 

 fly, simulium) and zancudo (gnat, culex) exists in all the 



