5* 



Insects and Disease 



skin which the larvae penetrate as soon as they 

 hatch. It has also been suggested that they might 

 reach the subcutaneous tissue by migrating from 

 the alimentary canal as do some of the other bot- 

 flies. A very serious eye disease, Egyptian opthal- 

 ntia, is known to be spread by the house-flies and 

 others. These flies are often abundant about the 

 eyes, especially of children suffering from this 

 disease. It is suspected that certain small flies 

 (Oscinidae) in the southern part of the United 

 States are responsible for the spread of disease 

 known as "sore eye." 



FLEAS 



The fleas used to be considered as degenerate 

 Diptera and were placed with that group but they 

 are now classed as a separate order (Siphonaptera). 

 Within recent years these little pests have come 

 into special prominence on account of their im- 

 portance in connection with the spread of the 

 plague. The fact that they are so abundant every- 

 where and that they will so readily pass from one 

 host to another makes the possibility of their 

 spreading infectious diseases very great. Besides 

 the kinds that are concerned in the transmission 

 of plague, which are discussed in another chap- 

 ter, there are many other kinds infesting various 



