GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 5 
DISTRIBUTION IN THE UNITED STATES AND PROBABLE 
DISPERSION. 
Recently Mr. F. C. Bishopp, in communication with a large num- 
ber of horse breeders, has determined some facts on the distribution 
_and other points, especially in regions adjoining the district where 
G. haemorrhoidalis is known to occur. This information will be 
published later. It will suffice to say here that G. haemorrhoidalis 
occurs in sufficient numbers to warrant the adoption of control 
measures in the Dakotas, Montana, and northern Wyoming. Accord- 
ing to Dr. C. Gordon Hewitt, Dominion Entomologist, the species 
extends over a considerable area in the Dominion of Canada. Two 
of the species, G. intestinalis and G. nasalis, are found throughout 
the United States where horses are present. G. pecorwm is not 
known to occur in the United States. 
The constant migration of the larve of G. haemorrhoidalis to the 
region of the anus and their dropping, which occurs over a long 
period, indicates that the principal means of dispersion is through 
the movement of infested horses. During the past few years 
large numbers of horses, which have been purchased in _ the 
infested district for European 
army purposes, were concentrat- 
ed at certain points until more 
could be assembled for shipment. 
This occurred at times when 
larve were normally dropping 
and allowed ample time for this 
species to become established. 
Although the adults may not 
have appeared in sufficient num- 
bers to attract attention in new 
districts, this will undoubtedly 
occur in the near future. 
The comparatively short dura- 
tion of adult life and the func- 
tions of the adults restricted to 
depositing eggs indicate that ‘"~ “@ naemorrhoidets and hair removed 
little dispersion takes place by with root ; b, G. intestinalis; ¢, G. nasalis. 
actual flight. In the nose-fly ae aga 
district there has been a slow but gradual spread of the species each 
year, as verified by hundreds of statements from farmers and horse 
breeders. 
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3 
LARVAL COLLECTIONS AND REARING TECHNIQUE. 
An insectary was located in Aberdeen, S. Dak., where all types 
of farm and city operations concerned with the use of horses could 
