2.32 INDIRECT iJExNEIlTii BEKIVKD TllOX INSECl*. 



renovation of our meadows and pastures. In the rich 

 fields near Rye in Sussex I particularly observed this 

 effect ; and I have since at home remarked, that at cer- 

 tain times of the year dead plants may be every where 

 observed, pulled up by the cattle as they feed, whose 

 place is supplied by new offsets. So that, when in mo- 

 derate numbers, these insects do no more harm to the 

 grass than would the sharp-toothed harrows vi'hich it has 

 been sometimes advised to apply to hide-bound pastures, 

 and the beneficial operation of which in loosening the 

 sub-soil these insect borers closely imitate. 



Nor would it be difficult to show that the ordinary 

 good effects of some of those insects, which torment our- 

 selves and our cattle, preponderate over their evil ones. 

 Mr. Clark is inclined to think that the gentle irritation 

 o^ CEstrus Equi is advantageous to the stomach of the 

 horse rather than the contrary. On the same principle 

 it is not improbable that the Tabani often act as useful 

 plebotomists to our full-fed animals ; and that the con- 

 stant motion in which they are kept in summer by the 

 attacks of the Stomoxys and other flies, may prevent 

 diseases that would be brought on by indolence and re- 

 pletion. And in the case of man himself, if I do not go 

 po far as with Linne to give the louse the credit of pre- 

 serving full-fed boys from coughs, epilepsy, fee, we may 

 safely regard as no small good, the stimulus which these, 

 and others of the insect assailants of the persons of the 

 dirty and the vicious, afford to personal cleanliness and 

 purity. 



I might enlarge greatly upon the foregoing view of 

 the subject : but this is unnecessary, as numerous facts 

 will occur in subsequent letters whicli you Avill readily 



