THE DISTRIBUTION AND ABUNDANCE OF THE OX 
WARBLES, HYPODERMA LINEATA AND H. BOVIS 
IN THE UNITED STATES. 
By F. C. BisHopp, 
Bureau of Entomology.} 
Considering the importance of the ox warbles as pests of 
cattle, it is odd that so little is known by entomologists regarding 
their distribution and relative abundance. It is well known 
that H. lineata is widely distributed in this country, but. the 
fact that there are areas where this species is GLEES or entirely 
absent has not been recognized. 
That the so-called European ox warble, H. bovis, is to be 
found over a considerable area in the northern portion of the 
United States has just been determined through investigations 
conducted by us during the past two years. In fact, this 
species has not been reported to occur in the United States 
except in a single instance. In this case, Prof. C. W. Johnson? 
reared this species from larve collected at Manchester, Ver- 
mont, in June, 1910. In the early work of Prof. C. V. Riley,’ 
in which a considerable number of larvee from various parts 
of the country were examined, not a single specimen of H. bovis 
was obtained. In 1905, Prof. Aldrich‘ states that H. bovis is not 
positively known from North America. In 1912, Dr. S. Hadwen® 
announced the common occurrences of H. bovis at Agassiz, B. C., 
and in 1914 Dr. C. Gordon Hewitt® reported that he had seen 
specimens of this species from Nova Scotia, Quebec, Ontario, 
Alberta, and Saskatchewan, thus indicating a distribution 
from the Atlantic to the Pacific in Canada. 
1Published by permission of the Chief of the Bureau of Entomology. 
2Johnson, C. W., 1910, Psyche XVII, p. 231. December. 
SRiley, ©. Ve, 1892; Insect Lite, TVG pp: 302-317, 12 Pigs. 
2Atdrich, |). M., 1905, A Catalogue of North American Diptera. Smithsonian 
Miscl. Coll. XLVI, No. 1444, p. 416. 
5Hadwen, S., 1912, Bull. 16, Health of Animals Branch, Canada, Dept. Agr. 20, 
pp. 9 pls. 
®Hewitt, C. Gordon, 1914, Can. Ent., XLVI, pp. 1-2. 
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