306 ENTOMOLOGY 



remain in the thoracic muscles for a time and become larvae, 

 which at length pass through the proboscis of the mosquito 

 into the skin of man. It is possible, though not proved, that 

 other mosquitoes than Culex and indeed other kinds of insects 

 are involved in the transmission of filariasis. 



In Egypt, an eye disease is transmitted by the house fly. 

 There is some evidence that the bubonic plague is spread 

 through the agency of fleas. Anthrax of cattle is carried by 

 gad flies (Tabanidae). A South African disease fatal to 

 horses, cattle and dogs, though not to man, is transmitted 

 from infected to healthy animals by the proboscis of a muscid 

 fly, Glossina morsitans, as has been mentioned. The specific 

 cause of this disease is a blood parasite similar to that of 

 malaria. Finally, the destructive Texas fever of cattle is 

 undoubtedly transmitted by the common cattle-tick, as was 

 discovered by Theobald Smith, though the tick is not, properly 

 speaking, an insect. 



