186 Psyche [December 
This apparently led to some confusion as to the species concerned 
and the use of the term “nose fly” led to further confusion. It 
should be remembered that this vernacular name is applied with 
few exceptions to G. hemorrhoidalis by horse breeders and farmers. 
These men write of the presence of the insect in Alberta as well as 
Manitoba and Saskatchewan, and it probably occurs still farther 
west. 
The dates of first appearance in the different sections as reported 
by correspondents agree quite well with what has been found by 
inquiry by Mr. Dove and the writer. The earliest date given was 
1883, by a correspondent in western North Dakota, and a cor- 
respondent in central Montana (Fergus County) states that they 
were there in 1898, and another slightly farther west in Montana 
gives 1890 as the date of appearance. Wyoming and Minnesota 
seem to have been invaded during the last seven years, Nebraska 
within the past six years, Iowa about five years ago, and the other 
states more recently. 
Just why G. hemorrhoidalis did not come into prominence as a 
pest of horses years ago it is difficult to tell. It seems almost cer- 
tain that the species was brought into this country at an early 
date with shipments of horses from Europe. Failure to establish 
itself may have been due to conditions surrounding the imported 
animals after arrival here; such as adverse climatic conditions. 
It is possible that climate may have a marked influence on the 
perpetuation of the species in any region and that it will not thrive 
in the more humid area east of the present area of great abundance 
in the Dakotas. It is also barely possible that the species may 
have been present in parts of this country years ago and then be- 
came extinct or nearly so, but this is hardly plausible. Certainly 
our investigations indicate a comparatively recent establishment 
of the insect in the United States, and that the point of first es- 
tablishment was in western North Dakota or eastern Montana, or 
possibly in southern Saskatchewan. 
The habits of the insect indicate that its dissemination is largely 
brought about by the movement of horses. The long time which 
the larvee spend within the host and the rather extended period 
during which they normally leave the animal add to the danger of 
spread by shipping or driving horses from infested to uninfested 
territory. The great number of horses recently shipped from in- 
