360 Annals Entomological Society of America [Vol. VIII, 
DISTRIBUTION AND ABUNDANCE OF FH ypoderma lineata. 
It appears that this species is to be found in every State in 
the Union, although, as has been indicated, there is consid- 
erable difference in its abundance in different sections. During 
our inquiry into the distribution of ox warbles during the last 
two years, we have obtained specimens from thirty-one of the 
States, but there is no reason to suppose that the species is not 
common in all of the others. A total of about 140 lots was 
obtained during this investigation as a result of personal 
collections and specimens sent in by numerous correspondents. 
In general, it appears that 7. lineata is more abundant in the 
Southern and Central Western States than elsewhere in the 
country. However, the presence of the two species combined 
in Vermont and New Hampshire probably gives a heavier 
infestation there than is to be found elsewhere in the country. 
We have found the species to occur commonly at all alti- 
tudes, from sea level to 9,000 feet. As is-indicated by its 
wide distribution, it is also to be found in the humid, semi-arid 
and arid regions. Our inquiry thus far does not indicate that 
annual rainfall has any material effect on the abundance of the 
species. It is possible, however, that by closer study we shall 
find that the rainfall during the spring and early summer has a 
material effect on the local and annual abundance of the species. 
The north-central part of the United States, including 
portions of the States of Minnesota, North and South Dakota, 
and Montana, seems to be freer from the pest than any other 
region. In fact, throughout considerable portions of this 
region ox warbles are entirely unknown. This is particularly 
true of those portions of North and South Dakota and western 
Minnesota included in the valley of the Red River of the North. 
An explanation for the absence of warbles from these areas is 
not apparent. It has been found that the species is absent 
from wooded regions as well as plains areas, and there is some 
difference in the rainfall within the non-infested region. In 
South Dakota it was observed that the warbles were to be 
found in the hilly region along the divides between rivers. 
Hence, it would appear that there is some relationship between 
the topography of the country and the occurrence of the species 
in that section. Prof. H. C. Severin states that he has observed 
this practical absence of warbles from eastern South Dakota, 
