116 INSECTS AFFECTING DOMESTIC ANIMALS. 
from its presence were soon proven to be wide of the truth, while the 
exaggerated tales of death to animals, the destruction of horns, and 
many other wild statements were easily recognized as imaginative. 
That the loss from their presence is very considerable is recognized 
by most practical stock breeders who have everyday association with 
the affected animals, the loss showing in reduced vitality, lack of 
growth, or in loss of milk. 
Mr Fletcher, the entomologist of the Dominion of Canada, estimated 
the loss in Ontario and Quebec at one-half the product. 
The loss is the direct result of the irritation to cattle, which keeps 
them in a perpetual worry and interferes with their feeding and with 
the normal digestion of food, and to some extent from the loss of blood, 
which, when the flies occur by the thousands on a single animal, is an 
item not to be ignored. When at rest upon the horns, at which time 
they are most conspicuous, they are in reality the least harmful, as they 
then cause neither irritation nor loss of blood. 
The larvee are of course entirely harmless and it is only the adults 
that affect the animals. 
Injury to other animals than cattle seems to be very slight, and while 
a number of records have been given of the insect occurring upon 
horses these seem to be exceptional. 
POPULAR NAMES AND POPULAR ERRORS. 
Upon this subject Riley and Howard say: 
The popular name which is here adopted—the ‘‘horn-fly”—has the sanction of 
popular use. It is sufficiently distinctive, and we therefore recommend its adoption. 
The name of ‘Texas fly” and ‘‘ buffalo-fly ” and ‘‘ buffalo-gnat” are also in use in 
some sections and indicate an impression that the insect came from the West. Dr. 
Lintner uscs the term ‘‘cow-horn fly.” Objections may be urged to all of these. 
The most prominent of the popular errors is the belief that the fly damages the 
horn, eats into its substance, causes it to rot, and even lays eggs in it which hatch 
into maggots and may penetrate to the brain. There is no foundation for these 
beliefs. As we shall show later, the flies congregate on the bases of the horns only 
to rest where they are not liable to be disturbed. While they are there they are 
always found in the characteristic resting position, as shown in fig. 60, and described 
later. Where they have been clustering thickly on the horns, the latter become 
‘“flyspecked”’ and appear at a little distance as though they might be damaged, and 
it is doubtless this fact which has given rise to the erroneous opinions cited. 
HABITS AND LIFE HISTORY. 
The adults of the horn-fly are about half as large as the common 
house fly and very much like it in shape and color. The accompanying 
figures will serve to distinguish it, while the following technical descrip- 
tion by Dr. Williston should be used for the exact discrimination of 
the species: 
Male.—Length, 3.5 to4 mm. Sides of the front gently concave, its least width 
equal to one-fourth of the distance from the foremost ocellus to the base of the 
antenne; in the middle a narrow dark-brown stripe; a single row of slender 
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