INDIRECT INJURIES CAUSED BY INSECTS. 147 



those that have the care of horses are accustomed to clean 

 their mouths and throats with a particular kind of brush, 

 by which method they free them from these disagreeable 

 inmates before they have got into the stomach, or can be 

 at all prejudicial to them a . 



Providence has doubtless created these animals to an- 

 swer some beneficial purpose; and Mr. Clark's judicious 

 conjectures are an index which points to the very kind 

 of good our cattle may derive from them, as acting the 

 part of perpetual stimuli or blisters : yet when they ex- 

 ceed certain limits, as is often the case with similar ani- 

 mals employed for purposes equally beneficial, they be- 

 come certainly the causes of disease, and sometimes of 

 death. 



How troublesome and teasing is that cloud of flies 

 (Musca meteor ica, L.) which you must often have no- 

 ticed in your summer rides, hovering round the head and 

 neck of your horse, accompanying him as he goes, and 

 causing a perpetual tossing of the former b ! — And still 

 more annoying in Lapland, as we learn from Linne c , is 

 the furious assault of the minute horse-gnat, {Culex equi- 

 71US, L.) which infests these beasts in infinite numbers, 

 running under the mane and amongst the hair, and 

 piercing the skin to suck their blood. — An insect of the 

 same genus is related to attack them in a particular di- 

 strict in India in so tremendous a manner as to cause in- 

 curable cancers, which finally destroy them d . — But of 

 all the insect tormentors of these useful creatures, there 

 is none more trying to them than the forest-fly Hippo- 



a De Geer, vi. 295. b Amcen. Acad. iii. 358. 



c Linn. Flor. Lapp. 376. Lack. Lapp. i. 233, 234. 

 «* Life of General Thomas, 186. 

 L 2 



