INSECTS IN GENERAL. ()9 



c^orniis, gnaw the interior of the trunks of trees : they pierce 

 the wood or sap, mince it, reduce it into saw-dust, and then 

 eat the particles. 



Those of the tipidce, which live under ground, swallow 

 earth, afterwards rejecting all in it that is unfit for nutriment. 

 They prefer the unctuous earth, or soil produced by animal 

 or vegetable decomposition. An immense number of insects 

 live on the excrements of animals ; on dead flesh of all kinds ; 

 on our butcher's meat, as is well known, Avhere flies deposit 

 their eggs, which soon produce voracious larvae. The meat 

 which is gnawed by these larvae rapidly corrupts, which is 

 owing to a kind of fermentation which they occasion, and 

 wliich accelerates tlie progress of decomposition. The dried 

 flesh of animals is also attacked by insects, but of genera very 

 different from those that feed on fresh and soft meat. They 

 are usually coleopterous larvae, and sometimes perfect insects 

 of the same order. They are pretty well known to the 

 amateurs of natural history who make collections of dried 

 specimens. It is scarcely necessary to notice the ravages 

 committed in clothing, furs, &c. by moths and other lepidop- 

 terous insects. 



Other insects subsist upon the living animal, deriving sus- 

 tenance both from its fluids and the substance of its flesh. 

 There is especially a singular larva of the genus oestrus, which 

 lives on the back and under the skin of horned cattle, where 

 it produces tumours and subsists upon the pus secreted from 

 the wound which it has made. Larvae of the same g-enus live 

 in the stomach of horses, round the pylorus, and sometimes in 

 the intestines. It is there alone that they find tlieir subsist- 

 ence, and their superabundance occasionally proves fatal to 

 these animals. Other oestri are lodged in the frontal sinuses 

 of sheep, where they grow and derive their nutriment from 

 the mucus of the nose. 



Even jnan himself is very far from being exempt from the 



