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THE CATTLE GRUBS OR OX WARBLES : 9 
several larval stages of H. lineatwm from the Punjab. He also fur- 
nished data showing an infestation of shghtly over 35 per cent of 
some 41,000 head of cattle which he examined in different parts of 
the Punjab. C. W. Howard has written that he has never seen 
Hypoderma larve in southern China, except in cattle that were be- 
ing imported. C. P. Clausen made some inquiry regarding the oc- 
currence of Hypoderma in Manchuria in 1923. He informed the 
writers that although cattle in that Province were not infested, those 
from Mongolia were heavily infested. Clausen’s informant stated 
that although many infested cattle were brought into Manchuria 
from Mongolia, they became free from grubs in one year. Clausen 
also learned from Dr. H. Okamoto that near Sapporo, Japan, there 
is a small locality in which this pest has become established, prob- 
ably through introductions of cattle from America. Doctor Mat- 
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Fie. 1.—Distribution of Hypoderma lineatum in the United States. Hach dot repre- 
sents a locality where this species has been collected during this investigation 
sumura also informed Clausen that 7. bovis occurs on cattle in the 
vicinity of Akita. 
Through correspondence and by personal examinations by agents 
of the bureau, the distribution of the cattle grubs in the United 
States and their relative abundance have been determined with fair 
accuracy. A summary of the information on this subject was pub- 
lished by one of the writers in 1915 (4), and Mote (69) has made a 
valuable contribution regarding the distribution of Hypoderma in 
Ohio. A study of the accompanying maps (figs. 1 and 2) will best 
illustrate the distribution of the two species of Hypoderma in the 
United States. It is apparent that H. lzneatwm is much more widely 
and generally distributed in this country than is 77. bovis, in fact, the 
entire area wheze 7. bovis occurs is also infested with H. lineatum. 
The former species had never been recorded in the United States up 
to 1910 (0). Riley (84), basing his information on a number of 
collections mainly from the Central and Southern States, concluded 
that probably H. bovis did not occur in this country. Hadwen (32) 
