148 INDIRECT INJURIES CAUSED BY INSECTS. 



passing from the body, having ceased feeding-, they can 

 do no farther injury. In Sweden, as De Geer informs 

 us, they act much more sensibly : 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^. 



Providence has doubtless created these animals to 

 answer some beneficial purpose; and Mr. Clark's judi- 

 cious conjectures are an index which points to the very 

 kind of good our cattle n.ay derive from them, as acting 

 the part of perpetual stimuli or blisters : yet when they 

 exceed certain limits, as is often the case with similar 

 animals employed for purposes equally beneficial," they 

 become certainly the causes of disease, and sometimes 

 of death. 



How troublesome and teasing is that cloud of flies 

 (Musca meteorica, 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 ! — And 

 still more annoying in Lapland, as we learn from 

 Linn^% is the furious assault of the minute horse-gnat, 

 {Culex cquinus, L.,) which infests these beasts in infi- 

 nite 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 district in India in so tremendous a 

 manner as to cause incurable cancers, which finally 



" De Geer, vi. 295. 



'' Linn. Flor. Lapp. 3T6. Lack. Lapp. i. 233, 234. 



