376 
enveloped in a cloud of the Hippelates, and in passing him some 
hundreds of the flies now follow yon. 
If it has been proven that infectious diseases are disseminated by 
mosquitoes, house flies, and other flies, the danger arising from the 
Hippelates as carriers of contagious diseases is perhaps more evident 
than in many other cases on record.* Mr. H. Gr. Hubbard, who has 
passed many summers in Florida, remarked on this point ''that in 
Florida a serious disease of the eyelid is often prevalent. It is known 
as 'sore eye' and becomes absolutely epidemic from time to time. He 
feels certain that this Hippelates carries the disease, since it is well- 
known that even the use of the same handkerchief will convey the dis- 
ease from a sore-eyed person to a healthy one. He has known it to start 
with a single person and run through an entire school or community, 
and he thinks Hippelates alone accounts for the rapid spread. More- 
over, the irritation caused by the flies greatly aggravates the disease, 
which becomes very serious, the patient seldom recovering entirely 
from it, being affected by weak eyes ever afterwards." t This danger 
of diseases being carried by the flies exists not only between man and 
man, but also among domestic animals and between man and animal. 
Geographical distribution. — The Hippelates plague reaches, in my 
experience, its maximum height in Florida, but I also encountered the 
flies in annoying numbers at Selma, Ala., and Columbus, Tex. Mr. 
L. O. Howard observed some years ago swarms of a small fly greatly 
annoying his dog, in the vicinity of Washington, and fortunately col- 
lected and preserved specimens; finally Mr. C. L. Marlatt reports a sim- 
ilar experience near the same place. The meager material thus collected 
was submitted to Mr. Coquillett and was found by him to represent 
three species. The species from the District of Columbia collected by 
Mr. Howard, IT. flavipes Loew (Fig. 37), proved to be identical with 
that observed at Crescent City, Fla., and judging from memory, the 
same species occurs at Selma, Ala. Specimens collected at Bartow, 
Fla., were determined by Mr. Coquillett as H.pusio Loew, while those 
found by the writer at Columbus, Tex., and by Mr. Chittenden at 
Rosslyn, Ya., proved to be M. plebejus Loew (Fig. 38). It is safe to 
assume that other species of the same genus will be found to possess 
the same habit, but since these small flies have never been carefully 
collected nothing definite is known at present regarding the geo- 
graphical extent of any of their species. All that can be said at 
present is that the genus Hippelates seems to be confined to the more 
southern portions of the country, t 
* The literature on the subject appears to be quite extended but is not readily 
accessible. Most of the articles which I was able to consult deal with the dangers 
arising from house flies and mosquitoes, but it is evident that the writers on the sub- 
ject of ophthalmia refer to other species of Diptera, though no names are given. 
t Proc. Eut. Soc. Wash., vol. in, p. 179. 
t Osten Sacken's Catalogue enumerates two species from Texas, one from the Dis- 
trict of Columbia, one from Illinois, four from Cuba, and one from California. The 
latter locality is open to doubt. 
