238 OUR HOUSEHOLD INSECTS 



incredible multitudes, and to realise the terrible suffer- 

 ings they are answerable for ; he is inclined to treat the 

 whole matter almost as a joke, and to laugh at the 

 violence of the execrations which have been heaped on 

 the heads of such insignificant offenders. But there can 

 be no question that the plague has been, and is still, in 

 many parts of the world, a most real and serious one, 

 and experience shows that the descriptions travellers 

 have given of the numbers of the insects, and the pain 

 and disfigurement caused by their attacks, highly 

 coloured though they often seem, may yet be accepted 

 as having a solid foundation in fact. The exact effect 

 of a gnat or mosquito bite, however, upon the human 

 body, varies with the species of insect which produces 

 the wound, with the sensitiveness and temperament of 

 the individual attacked, and with surrounding circum- 

 stances. On the borders of the great rivers of the 

 Brazilian forest, where mosquitoes are probably as 

 troublesome as anywhere in the world, the effect is 

 quite different upon Europeans and natives. According 

 to Humboldt, who paid great attention to the subject 

 when he was in the region of the Upper Orinoco, blisters 

 and swelling are not produced upon the skin of the 

 natives, i,e., the copper-coloured Indians, though such 

 results follow in the case of the white man, new settlers 

 being much more severely dealt with than old residents. 

 Speaking of a white man who had had "his twenty 

 years of mosquitoes," he says, "Every sting leaving a 

 small darkish-brown point, his legs were so speckled 

 that it was difficult to recognise the whiteness of his 

 skin through the spots of coagulated blood." That, not- 

 withstanding their immunity from the above secondary 

 effects, the natives still suffer acutely, is manifest from 

 the numerous and energetic devices they adopt to free 



