B9 



acute, it would find it next to impossible to lay thirty or forty eggs mthout being killed 

 by the strokes of the ox's tail, for though it has been supposed that the fly is shrewd 

 enough to choose such places as the tail cannot reach, Eeaumur saw a cow repeatedly flap 

 its tail upon a part full of the bumps, and in another instance he saw a heifer beat away a 

 party of common flies from a part where there were seven or eight bumps. He conclud- 

 ed, therefore, with much plausibility, that these two beasts would have treated the ox-flies 

 in the same way if they had given them pain when depositing their eggs. The extraor- 

 dinary efi'ects produced upon cattle on the appearance of one of these flies would cer- 

 tainly lead us to conclude that the pain inflicted is most excruciating. Most of our 

 readers may recollect to have seen in the summer months a whole herd of cattle start off 

 across a field in full gallop, as if they were racing, their movements indescribably awkward, 

 their tails being poked out behind them as straight and stiff as a post, and their necks stretch- 

 ed to the utmost. All this consternation has been known from the earhest times to be pro- 

 duced by the fly we are describing. 



Virgil gives a correct and lively picture of it in his Georgics, of which the following 

 is a translation : — 



Round Mount Albumus, green with shady oaks, 



And in the groves of Siiarns, there flies 



An insect pest (named (Estrus by the Greeks, 



By us Asilus) : fierce with jarring hum 



It drives, pursuing, the afirighted herd 



From glade to glade ; the air, the woods, the banks 



Of the dried river, echo their loud bellowing. 



We might adduce several other instances of similar terror caused among sheep, deer 

 and horses, by insects of the same genus, which are ascertained not to pierce the skin. It 

 is therefore most probable that the fly terrifies the ox by her buzzing, rather than pains 

 him by piercing his hide, her buzz, like the rattle of the rattle-snake, being instinctively 

 understood, and intended it may be to prevent an over population by rendering it difficult 

 to deposit the eggs. 



According to Kirby and Spence, when cattle are employed in agriculture the attack 

 of this fly is often attended with considerable danger, since they then become unmanage- 

 able, and whether in harness or yoked to the plough will run directly forward. At the 

 season when it infests them close attention should be paid, and their harness so constructed 

 that they may easily be let loose. 



The number of bumps to be found on a beast is very variable. Kennie says that on 

 one cow only three or four bumps may be observed, while on another there may be thirty 

 or forty. They are not always placed on the same parts, nor arranged in the same man- 

 ner : commonly they are near the spine, but sometimes on or near the thighs and should- 

 ers. The grub being confined in a tolerably large fistulous ulcer, a part of the cavity 

 must of necessity be filled with pus or matter. This matter appears to be the only food 

 allowed for the grub, for there is no appearance that it lives like the grubs of flesh flies 

 upon putrescent meat. Mandibles indeed, similar to those with which other grubs break 

 their food, are altogether wanting. A beast which has thirty, forty, or more of these 

 bumps upon its back, would be in a condition of great pain and suffering terrible indeed 

 in the extreme if its flesh were torn and devoured by as many large grubs ; but there is 

 every appearance that they do not generally inflict much pain. Indeed so far are they 

 regarded from being injurious, that they are looked on as proofs of the goodness of the 

 animal, since these flies only attack young and healthy animals. It is said also that the 

 tanners prefer those hides that have the greatest number of hot holes in them, which are 

 always the best and strongest. 



Remedies. 



Although these insects do not cause any permanent injury, yet their presence in large 

 numbers may occasion some little inconvenience. 



Mr. Verrill states that they can be pressed out of their burrows with the thumb, care 

 being taken not to crush or burst them in the burrows ; or the openings of the tumours 

 may be enlarged with a sharp knife, and then they can easily be removed, and the wound 

 will soon heal. 



