8 BULLETIN 597, U. S. DEPARTMENT OF AGRICULTURE. 
horses that conclusions can be drawn, and these may be erroneous if 
one is not familiar with the various species, their usual points of at- 
tachment, and phenomena peculiar to each. 
SPECIES IMPLICATED. 
Gastrophilis intestinalis, “the common bot,” attaches ordinarily 
in the stomach, has been taken in the duodenum, but has never been 
found permanently attached in any other regions (Table I, p. 10). 
Rarely it may become temporarily attached in the rectum, but is not 
present with an alveolus or lesion. 
G. nasalis, “the throat bot,’ attaches by preference in the duo- 
denum, is often found in the stomach, and is the only known species 
which attaches in the pharynx. Due to the attachment in the throat, 
it not only becomes a species of vital importance when the bots 
congregate in sufficient numbers to hinder or cut off the breathing or 
the horse or cause an infection, but in this location they can not be 
removed by an internal treatment. In the duodenum the infestation 
may be sufficient to hinder or stop the passing of excreta. Table I (p. 
10) shows the comparative abundance in the stomach and duodenum 
during the period that larvee are well developed and naturally drop 
from the-host. 
Various cases are on record in which this species has been removed 
from the pharynx, in all of which the authors considered it a serious 
detriment to the horse. While larvee which were not sufficiently de- 
veloped to be determined with authenticity have frequently been 
removed from the pharynx, 8 larve of G. nasalis were collected in 
the throat of a dray horse by J. L. Webb at Reno, Nev., on August 
29, 1916. In numerous cases, both at Aberdeen, S. Dak., and at Dal- 
las, Tex., the author has found iesions present in the pharynx, indi- 
eating that the larve had become fully developed and had passed out 
of the horse. In making post-mortem examination of horses to de- 
termine the attachment of young larve in the pharynx extreme 
care should be exercised, as young meat-infesting larvee may be con- 
fused with Gastrophilus. Upon hatching they migrate from the 
light into the nostrils and may be found in the pharynx and other 
locations in the throat. 
Dr. Buffington (1905), of Brooklyn, Iowa, gives a valuable history 
of a case in which a mare died as the result of an infestation of 
G. nasalis in the pharynx. This animal had experienced difficulty 
in eating for more than a month, and was unable to take food for a 
week prior to November 26, 1903. At this time she would drink 
water, but after masticating food a very little, would drop it out. 
The symptoms were those of paralysis of the muscles of deglutition 
and there was a very offensive odor about the head. Four days later, 
when the animal died, the nasal, pharyngeal, laryngeal, and upper 
portion of the cesophageal mucous membranes were found to be gan- 
