1917] Bishopp—Nose Fly and other Species of Gastrophilus 183 
it seems strange that more facts regarding their introduction, 
spread and local and seasonal abundance have not beer recorded. 
The common horse bot or nit fly, Gastrophilus intestinalis De 
Geer, on account of its abundance and comparatively slow flight, 
has been most readily observed and most frequently mentioned in 
literature. It was undoubtedly introduced into this country 
many years ago and has become widely spread throughout the 
United States. We have records of its occurrence in nearly all 
‘ 
Fig. 1. Map showing the distribution of the nose fly, Gastrophilus hamor- 
rhoidalis L. in the United States. The large dots indicate localities where this 
insec{ has been reported and the small dots its probable distribution. 
parts of the country though it seems to vary much in local 
abundance. At high elevations it seems to be rare. 
The chin fly, G. nasalis L., also appears to be well distributed 
over the United States. We have rather clear records of its oc- 
currence in practically all states from Texas to North Dakota and 
from New York to California; also in the western part of Canada. 
It occurs, no doubt, in the eastern part of Canada, and in the 
eastern states of the Union. 
The nose fly, G. hemorrhoidalis L., is undoubtedly the most im- 
portant economic species of the three when it is present in abun- 
