1915] Ox Warbles in the United States 363 
findings in the West. As has been stated, Dr. Hadwen reported 
this species to occur commonly in eastern British Columbia, and 
one would expect this infestation to extend southward along the 
Rockies in the United States. However, only two lots of this 
species were obtained from the West. One of these from 
Waldron, Washington, consisted of one larva of H. bovis and 
five of H. lineata. This place is situated on an island in Puget 
Sound not far from the Canadian line. The other point of 
infestation was located at Garneil, Montana. Our corre- 
spondent there sent in two lots of warbles; the first contained 
one specimen of H. bovis and one of H. lineata; the second, 
three specimens of H. bovis and one of H. lineata. No informa- 
tion was secured regarding the possible mode of introduction of 
this species into Montana, although it 1s wellknown that pure 
blooded stock, particularly of the dairy types is brought in 
from the East. In the North Central States, three points of 
infestation were discovered. A well established infestation was 
found to occur at Davenport, Iowa. A correspondent at that 
point sent in three fourth-stage larve of H. bovis on April 26, 
1915, and twenty larve in the same stage on May 6, 1915. No 
information was gained as to the possible origin of this infesta- 
tion. On May 7, Mr. E. W. Laake and the writer obtained 
twelve fourth-stage larve in the back of a cow in the stock 
yards at Chicago, Ill. Four of these proved to be H. bovis. 
The origin of the infested animal could not be learned. The 
single occurrence of this species in Michigan was established 
through the collection of six larve by Dr. Shafer at East 
Lansing, on April 7, 1914. Two collections of larve from 
cattle at Cadillac, Michigan, by Mr. James F. Zimmer, prove to 
be composed entirely of H. lineata. 
It would seem, therefore, that in the western two-thirds of 
the United States, H. bovis is to be found in rather restricted 
and well separated areas, although no doubt a thorough search 
would reveal a more general distribution than is now supposed 
to exist. In the Northeastern States this species predominates 
over H. lineata, both in distribution and abundance. 
The writer is of the opinion that the European ox warble 
must have some well marked climatic barriers which have 
prevented its general dissemination throughout the country, as 
cattle, many of which are no doubt infested, are shipped annu- — 
