204 



Marvels of Insect Life. 



knowledge had rendered it possible to open up Africa, and to cut the Panama 

 Canal." 



Among the obscure maladies which have baffled medical skill for more than 

 a century is the strange skin disease pellagra, which is endemic in Italy and 

 Roumania, and is in some respects similar to elephantiasis. As in the case of 

 cancer, all sorts of theories have been promulgated as to its origin ; and of late the 

 accepted doctrine has been that it is due to eating mouldy maize. Recently several 

 cases have made their appearance in Britain ; and careful investigations by 

 Dr. Sambon have shown that it has appeared in parts of Scotland during the last 

 half century, and in the Shetland Isles, in addition to the few cases that have 



Photo by] 



Crcesus Bird-wing. 



[E. Step, r.i..s. 



On page 197 will be fourirl ;i photograph of the male of this magnificent butterfly. Here we give a portrait of the more soberly coloured 

 female. The specimen photographed measured six and a half inches across the fore-wings. 



occurred in the South of England. Dr. Sambon has now satisfied himself that the 

 disease follows on the bite of a fly ^ to which no definite English name attaches, 

 but which may well be known in future as the pellagra-flv. In some localities 

 it is called the black-fly, and in other countries certain species are known as sand- 

 flies and buffalo-gnats, the latter owing to their bison-like hump. One species 

 or another is found pretty well all over the world, wlu're there are fast-flowing 

 streams. 



They are dark-coloured flies of small size, stout of bodv, with the appearance 

 of being hump-backed, and having rather short legs and broad wings. They are 

 blood-suckers, like the gnats and midges, and in seasons when they are specially 



^ Simulium reptans. 



