1915] Ox Warbles in the United States 361 
and that a greater number occurs in the western part of the 
State. Dr. W. L. Boyd states that while warbles are rather 
common in southern Minnesota, he has never known an animal 
to become infested at the Experiment Station at St. Anthony 
Park. Dr. Boyd found 39% of two herds of dairy cattle, 
totaling 82 head, to be infested in the vicinity of Duluth. All 
of the specimens obtained from these herds proved to be 
H. lineata. 
Although this species is present in a large percentage of the 
live stock in the central part of the Mississippi Valley, there is 
some indication that it is decreasing in numbers in this region, 
probably owing to the more extensive cultivation of the land 
and better care being given to the live stock. The heaviest 
infestation of this species which we have observed occurred in 
southwestern Texas, although it does not follow that this region 
is in general more heavily infested than others. Probably 75% 
of the cattle in the United States are more or less infested. 
The average number of warbles per animal ranges from one up 
to about one hundred. Many animals even in rather heavily 
infested herds, are entirely free. 
The localities from which we have obtained specimens of 
this species are indicated on the accompanying map. Records 
made by other investigators are not included. These would 
add a large number of localities, including some of the States 
from which we have not obtained specimens. 
DISTRIBUTION AND ABUNDANCE OF [Hypoderma bovis. 
As is shown on the accompanying map, this warble is rather 
widely distributed through the northern part of this country.! 
The north-eastern States have by far the greastet infestation, 
Vermont being the center of this heavily infested region. 
Although a considerable number of specimens of H. lineata were 
obtained from Vermont and New Hampshire, undoubtedly 
H. bovis occurs in greater numbers. This is also true of New 
York, and probably of Pennsylvania. St. Louis, Mo., was the 
1 The counties from which we have obtained specimens of H. bovis are as fol- 
lows: Alabama, Lee; Illinois, Cook; Iowa, Scott; Maine, Oxford; Maryland, 
Garrett; Michigan, Ingham; Montana, Fergus; Missouri, St. Louis; New Hamp- 
shire, Grafton, Merrimac, Rockingham; New York, Oneida, Onondaga, Ontario; 
Pennsylvania, Erie, Washington; Vermont, Bennington, Franklin, Orange, Orleans, 
Rutland, Washington, Windham, Windsor; Washington, Jan Juan. 
