STINGING-FLIES 247 



Sancudos are so frequent that even the Indians consider 

 many districts on the Maranon and Hualiaga as absolutely 

 uninhabitable. During his first sojourn in the Peruvian 

 forests, Tschudi lay for several days almost motionless, with 

 a swollen head and limbs, in consequence of the bite of 

 these intolerable flies ; and although by degrees the skin 

 became more accustomed to the nuisance, and swelling no 

 longer followed, yet their sting never failed to cause great 

 |)ain. During three months of the year they infest the 

 I)rovince of Maynas to such a degree, that even the stoical 

 I ndians utter loud complaints, and the dogs endeavour to escape 

 them by burying themselves in the sand. Breeding cattle in 

 these parts is impossible, for the sancudos would be the in- 

 evitable death of the calves. 



In no season of the year, at no hour of the day or night, do 

 tliey desist from their attacks ; but they are more peculiarly 

 abundant in the second half of the rainy season. One of the 

 most remarkable circumstances of their history is that they not 

 only totally avoid certain limited districts, but even small places 

 in the middle of a village. It is a fact, well known to every 

 traveller on the Maraiion, that certain sand islands or tracts 

 along the banks are deserted by the sancudos, while others, 

 to all appearances quite similar, are infested by them. The 

 so-called hldck water (a still unexplained natural wonder), 

 which resembles a polished surface of black marble, and 

 sometimes even marks the entire course of considerable 

 rivers — as, for instance, the Eio Negro — seem to be par- 

 ticularly unfavourable to them, so that many places in Solimoes 

 are thus converted into a painless paradise. 



Most of the independent tribes of Maynas protect them- 

 selves against the stings of the sancudos by a kind of tent, 

 made of the leaves of the Mauritia palm, and even the 

 poorest Indians of the missions possess cotton toldos, which 

 have an opening only on the ground, and, though insup- 

 portably hot, yet keep off the still greater plague of these 

 tormentors. 



Not content with a passing attack, a South American gad- 

 fly {(Estinis hominis) deposits its eggs under the human skin, 

 where the larvae continue for six months. If disturbed, they 

 penetrate deeper, and produce troublesome ulcers, which some- 



