HUMBOLDT ON BITING DIPTEKA 13 



in the evening the air is filled with mosquiios, which are not, as has been stated 

 in some travellers' stories, of the shape of our European gnats, but of that 

 of a little fly. These are the SimuUums. . . . Their bite is as painful as that of 

 Stomoxys. It leaves a little reddish brown spot which is very excruciating and 

 is the extravasated and coagulated blood where the beak has pierced the skin. 

 An hour before the sun sets these creatures are replaced by a species of small 

 gnat called tempraneros (one which shows itself early) because they appear also 

 at sunrise; their presence lasts one hour and a half; they disappear between six 

 and seven o'clock, or, as they say here, after the Angelus. After some minutes 

 of sleep one is bitten by the zancudos, another species of gnat with very long 

 legs. The zancudos, whose beak forms a piercing sucker, causes the sharpest 

 pain and an inflammation which lasts several weeks. Its song is like that of 

 our European gnat, but it is stronger and more prolonged. The indians claim 

 to recognize the zancudos and the tempraneros by their song; these latter are 

 true twilight insects, while the zancudos are nocturnal and disappear towards 

 sunrise. 



" In the journey from Carthagena to Santa Fe de Bogota we have observed 

 between Mompox and Honda, in the valley of the Rio Grande de la Magdalena, 

 zancudos filling the air from eight o'clock in the evening until midnight, dimin- 

 ishing about midnight and hiding themselves three or four hours, and return- 

 ing in clouds with a devouring appetite about four o'clock in the morning. 

 What is the cause of these alternations of movement and repose? Are these 

 animals tired by a long flight ? On the Orinoco it is very rare to see true day 

 gnats, while on the Magdalena one is bitten day and night except for about 

 two hours at midday. The zancudos of the two rivers are without doubt of dif- 

 ferent species. Are the eyes of one of these species affected by the light of the 

 sun more than the eyes of the other species ? , . . 



" At a time when they had not yet studied the geography of animals and 



plants they often confounded the analogous species of different climates. They 



thought that in Japan, in the Andes and at the Strait of Magellan the pines, 



the Ranunculus, the deers, rats, and the Nemocera were the same as those of 



Europe. Celebrated naturalists have thought that the gnat of the torrid zone 



was the same as the gnat of the European marshes, only more vigorous, more 



ferocious, and more dangerous under the influence of a burning climate. This 



opinion is very erroneous. I have examined and described with care upon 



the spot the zancudos with which one is most tormented. On the rivers of 



Magdalena and Guayaquil there are five very distinct species. Latreille, the 



foremost entomologist of the century, has been good enough to revise the detailed 



description of these little animals, which I will give in a note. 



[Here follow the Latin descriptions of the following new species: Culex cyanopen- 

 nis, C. lineatus, C. ferox, C. chloropterus, and C. maculatus.'\ 



" The species of Culex of South America generally have the wings, the 

 thorax and the feet bluish and striped, giving a metallic effect from the mingling 

 of spots. Here, as in Europe, the males, which are distinguished by their plu- 

 mose antenna?, are extremely rare, and one is never pierced except by the females. 

 The preponderance of this sex explains the immense increase in numbers of in- 

 dividuals, each female laying several hundred eggs. In traveling up one of the 

 great rivers of America, one notices that the appearance of a new species of 

 Culex announces the proximity of a new tributary. To cite an example of this 

 curious phenomenon, Culex lineatus, which belongs to the Canon of Tamalame- 

 que, is noticed in the valley of the Eio Grande de la Magdalena only at a spot 

 north of the juncture of the two rivers. It extends up but not down the Rio 

 Grande. It is in the same way that upon a principal vein the appearance of a 

 new substance in the vein rock indicates to the miner the neighborhood of a 

 secondary vein joining the first. 



