ENTOMOLOGY

.. RELATION OF INSECTS TO THE PARASITIC WORMS 67those ~ommonly used in arguments for the necessity of fly eradication.The possibility is also not excluded that flies may introduce Habronemalarvre into human beings, in whose tissues they may perhaps ~ able to livefor a time and do considerabJe damage. 'l'hough there is no evidencethat this ever occurs, the possibility is one that deserves considerationfrom those who have opportunity to investigate the relation of flies towounds and other lesions of the skin and mucous membranes.Habronema microstoma (Schneider, 1866) Ransom, 1911Hill (1918) and Bull (1919) have shown that Habronema microstoma,which, like H. m'U8ClE, occurs in the adult stage in the stomach of thehorse and other equines, has a life history similar to that of H. m'U8ClE.Both of these writers have occasionally observed the presence of H.microstoma in llf usca domestica under experimental conditions but findthat the usual intermediate host is Stomoxys calcitra'1ls. As theyrepeatedly failed. to infect S. calcitrans with the larvre of H. mUSClE it isprobable that the forms from S. calcitrans reported by Johnston (191~)and othc.rs as H. m'U8cO! ,vere H. microstoma. Bull (1919) is of theopinion that the larvre of H. microstoma may sometimes be conccrned inthe production of cutaneous granulomata of horses and that presumablythey are introduced into the skin by the proboscis of an infested fly.Habronema megastoma (Rudolphi, 1819) Seurat, 1914Habronema megastoma in its adult stage occurs in tumors in theIItomach of horses and other equines. Hill (1918) and Bull (1919) havefound that its life history is similar to that of H. musclZ, the house fly(Jf'U8ca domestica) acting as intermediate host in both cases. Attemptsto infect Stomoxys calcitrans with this species failed. Bull (1919) believesthat the larvre of' H. megastoma introduced by infested flies arethe usual cause of habronemic granuloma of horses. So far as the normallife history of H. megaatoma is concerned he thinks that the presence ofthe larvre in the skin or mucous membranes of horses is to be consideredaccidental and that it is uI,llikely that they can reach the alimentary tractfrom such locations and become n;tature. According to his vie,v, therefore,which is shared by Hill (1918), H. megastoma and also the otherIIpedes· of Habronema reach the stomach of the horse as a result of theanimal's swallowing infested flies.Acuaria apiralis (Molin, 1858) Railliet, Henry and Sisoif, 191~The adults of this nematode have been recorded as parasitic in theesophagus and stomach of the domestic fowl. Insects have not been