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 

 a few 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 "\zv^ings in 

 a peculiar w^ay, 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 a broad ring. 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 by it, 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 wath 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 maybe summed up as folio v^s: 

 the w^hite egg, 1.5mm. long, elongate and a little curved, 

 turns brownish before hatching. The white and footless 

 maggot, w^hich 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 



