THE HORN-FLY. 163 
the insect he went, in the dark, to his cattle-yard and re- 
turned soon after with undoubted specimens of horn-flies. 
This would indicate that the insects had been introduced be- 
fore, but had remained unnoticed. 
Owing to a series of very dry summers the insect is no 
longer as common and troublesome in Minnesota as it was 
afew years ago. It is confined to cattle which it torments 
day and night in the stable or in the pastures. The flies 
burrow among the hair, preferring the region about the 
shoulders and the root of the tail, though other portions do 
not escape. While biting the flies spread out their wings in 
a peculiar way, and do not keep them closed as do the 
stable-flies. The flies have still another peculiar habit which 
caused them to be called ‘“‘horn-flies.’’ They cluster about 
the horns, especially their bases, and frequently encircle them 
as abroadring. This position is selected to rest, and not to 
injure the horns, as has frequently been claimed; in fact their 
mouth-parts could not penetrate such hard material, being 
constructed simply to suck blood. This blood-sucking habit, 
the constant irritation caused byit, and their running about 
over the skin, prevent the cattle from feeding, disturb quiet 
digestion, and as a consequence cause a falling off in milk 
and cream. Some cattle suffer less than others; and if 
equally infested with these tormenters some animals will 
quietly remain chewing their food while others become 
frantic. 
The small fly, about 4mm. long (a little over one-sixth 
of an inch), is of a dark ash-gray color with a faint tinge of 
yellow. As the insect is illustrated (fig. 136, plate XII) it 
is not necessary to describe it in detail. 
The life-history of this pest may be summed up as follows: 
the white egg, 1.5mm. long, elongate and a little curved, 
turns brownish before hatching. The white and footless 
maggot, which soon hatches, tapers toward the head and 
terminates abruptly behind, where it is furnished with a pair 
of black spiracles. When mature it measures about three- 
eighths of an inch, and is of a dirty yellowish-white color. 
Like all maggots of this family of insects it moves by 
contracting and extending its body, and is assisted by a 
