GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 9 
erenous and the source of the offensive odor. From the pharyngeal 
walls 12 or 15 larvee were removed, 6 of which the present author 
obtained. Three of these larvee were determined as G. nasalis, and it 
is reasonable to believe that the other larve, which were not suffi- 
ciently developed for identification, were of the same species. 
The larve of G. haemorrhoidalis, “the nose-fly,’ as is shown in 
Table I, may be found in the stomach, duodenum, or rectum, and 
also attached about the margin of the anus, where they change in 
color from pink to a greenish, become accustomed to the atmosphere, 
and later drop to the soil for pupation. During the early stages 
they attach within the stomach and duodenum, but later loosen them- 
selves and reattach in the rectum, from which they gradually move 
to the anus. The attachment of clusters of these larve in the rectum 
has been known to stop the passage of excreta and to cause abnormal 
protrusions accompanied by much suffering. 
About June 1, 1915, a horse breeder in Montana experienced a case 
of obstruction of the rectum in a yearling colt. On three different 
occasions within one week the animal was observed lying down in 
the pasture with the rectum greatly protruded. Each time it was 
washed with warm water and replaced, but the larve causing it were 
not observed until the third time. The exact number of bots removed 
by hand was not ascertained, but upon their removal and replace- 
ment of the rectum the animal gradually recovered. 
Table I records a maximum of 1,032 bots removed from a 2-year- 
old colt. The infestation consisted of 695 G. intestinalis, 248 G. 
nasalis, and 89 G. haemorrhoidalis. This was the greatest number 
obtained during any of the autopsies. Colts are always the most 
heavily infested, especially when they come from summer pastures, 
and in this case the animal was greatly emaciated, possessed a dull 
coat, and, in spite of a good appetite and an abundance of food dur- 
ing the previous winter, failed to grow or fatten. It had suffered 
from a broken shoulder, the result of a kick, which ordinarily would 
have healed promptly at this age, but instead it remained for months 
a cripple. The owner, believing that it would never thrive, caused 
the animal to be killed, and the post-mortem examination revealed 
no abnormal condition, except the bot infestation and the broken 
shoulder. It appeared that so much vitality was sapped through the 
inroads of bot infestation that the colt had no recuperative surplus. 
At the date of the post-mortem examination 89 G. haemorrhoidalis 
larve had migrated to the rectum and attached. They were not sufli- 
ciently developed to pass out and were attached at this point with 
lesions characteristic of those usually found in the stomach. 
In Table I many of the infestations noted were comparatively 
small when the post-mortem examination was made, and attention 
should be called to the fact that all of these examinations were made 
11216°—18—Bull. 597 2 
