RELATION OF INSECTS TO THE PARASITIC WORMS 67 



those commonly used in arguments for the necessity of fly eradication. 

 The possibility is also not excluded that flies may introduce Habronema 

 larvae into human beings, in whose tissues they may perhaps Le able to live 

 for a time and do considerable damage. Though there is no evidence 

 that this ever occurs, the possibility is one that deserves consideration 

 from those who have opportunity to investigate the relation of flies to 

 wounds and other lesions of the skin and mucous membranes. 



Habronema microstoma (Schneider, 1866) Ransom, 1911 



Hill (1918) and Bull (1919) have shown that Habronema microstoma, 

 which, like H. muscce, occurs in the adult stage in the stomach of the 

 horse and other equines, has a life history similar to that of H. muscce. 

 Both of these writers have occasionally observed the presence of H. 

 microstoma in Musca domestica under experimental conditions but find 

 that the usual intermediate host is Stomoxys calcitrans. As they 

 repeatedly failed to infect S. calcitrans with the larvae of H. musca it is 

 probable that the forms from S. calcitrans reported by Johnston (1912) 

 and othe-rs as H. muscce were H. microstoma. Bull (1919) is of the 

 opinion that the larvae of H. microstoma may sometimes be concerned in 

 the production of cutaneous granulomata of horses and that presumably 

 they are introduced into the skin by the proboscis of an infested fly. 



Habronema megastoma (Rudolphi, 1819) Seurat, 1914 



Habronema megastoma in its adult stage occurs in tumors in the 

 stomach of horses and other equines. Hill (1918) and Bull (1919) have 

 found that its life history is similar to that of H. muscce, the house fly 

 (Musca domestica) acting as intermediate host in both cases. Attempts 

 to infect Stomoxys calcitrans with this species failed. Bull (1919) be- 

 lieves that the larvae of H. megastoma introduced by infested flies are 

 the usual cause of habronemic granuloma of horses. So far as the normal 

 life history of H. megastoma is concerned he thinks that the presence of 

 the larvffi in the skin or mucous membranes of horses is to be considered 

 accidental and that it is unlikely that they can reach the alimentary tract 

 from such locations and become mature. According to his view, there- 

 fore, which is shared by Hill (1918), H. megastoma and also the other 

 species of Habronema reach the stomach of the horse as a result of the 

 animal's swallowing infested flies. 



Acuaria spiralis (Molin, 1858) Railliet, Henry and Sisofi^, 1912 



The adults of this nematode have been recorded as parasitic in the 

 esophagus and stomach of the domestic fowl. Insects have not been 



