NATURAL ENEiAIIES 75 



during an early stage in the development of the insects. 

 It is improbable that the worms develop to maturity 

 in the fly, since they have been found only in the larval 

 stage in that host. It might be noted in this connec- 

 tion that Carter erred in identifying certain structures 

 as reproductive organs." 



Other nematodes have been found in the typhoid 

 fly, but it is not as yet determined that they are surely 

 distinct from the one just mentioned. 



The Mite Enemies of Musca Domestica 



Many flies of different species are often noticed to 

 have small red mites attached to their bodies. This 

 has been found to be the case with small flies as well 

 as with large ones — even mosquitoes have enemies of 

 this kind. Some of these mites probably exert a dele- 

 terious effect upon their host and are true parasites, 

 but with others the flies simply act as aeroplanes to 

 carry the mites from one place to another. (A free ride 

 seems to be the only object for which they have at- 

 tached themselves to the fly.) 



Attention was called to these mites in the first place 

 by DeGeer in 1735. Linnaeus wrote of one of them in 

 1758, and other writers have made mention of them 

 and have described several species. Mr. Nathan Banks, 

 an authority upon this group of creatures (Arachnids), 

 has given the writer the following information : 



"Latreille based a new genus and species on mites 

 from the house fly, and he called it At omits parasiticum. 

 This is the young of one of the harvest mites of the 



