^6 ANIMALS OF LAND AND SEA 



alights upon the human skin the maggots emerge and enter 

 the puncture made by the mosquito. Various animals are 

 also parasitized by this fly. 



The warble-flies of cattle and the horse bot-flies sometimes 

 live as maggots beneath the skin of man, and the larvae of 

 the sheep bot-fly occasionally infest man, particularly the 

 cavities of the head. In tropical Africa there are several flies 

 related to the blow-flies of which the maggots live under the 

 skin of man as weU as under the skin of various animals. The 

 best known of these is the tumbu fly. 



There is one very interesting fly the maggots of which suck 

 blood after the manner of the leeches. This is the adult of 

 the Congo floor maggot, which occurs throughout tropical 

 Africa. The maggots live in the dust and cracks of the floors 

 of houses and come out at night to suck the blood of the 

 sleeping inhabitants. It is not known to trouble any of the 

 animals, but similar maggots live in the burrows of hairless 

 mammals. Similar flies live in the nests of birds and suck 

 blood from the nestlings. 



The maggots of a considerable number of different flies if 

 swallowed wiU live in the intestinal tract of man, but in the 

 case of most of the species which have been recorded, infesta- 

 tion is rare and purely accidental. House-fly maggots occasion- 

 ally enter the body and cause trouble. Much more common is 

 infestation by the lesser house-fly and the cheese-skipper, which 

 may lead to serious consequences. Bot-fly larvae and the 

 larvae of the large gray flesh-fly have been found in man. 



Strange as it may seem the worst of all man's enemies in 

 the insect world are the mosquitoes, the commonest and most 

 widely distributed of the blood-sucking flies. More than 500 

 species of these have been described, and many of these species 

 under suitable conditions occur in absolutely incredible abun- 

 dance. In the little island of Carriacou there is a musical 

 swamp which at the proper season you can hear humming for 

 a long distance. A road passes through this swamp, and as 

 you approach you soon learn why it hums. On entering you 



