On destroying Insects injurious to Cultivation. 353 



tlcscends, as before described ; and this experiment has 

 daily been repeated and verified for some months past. 



I therefore at length venture, with all deference, to an- 

 nounce this plain and indispulai)le fact, and to submit it to 

 the consideraiion and comments of the scientific among 

 the nunjcrous readers of the Philosophical Magazine ; and 

 shall be grateful to those gentlemen who will take the trouble 

 to inform me, through the sanie medium, whether anything 

 similar has been produced ; and favour me with their obser- 

 vation upon, and candid opinion of, tbis presumed novelty, 

 tke possibility of which cannot bb admitted consistently uiitk 

 the present thmry ofr.iechanics. 



I shall probably have further important communications 



to make on this subject in the next Philosophical Magazine, 



B , "e. V. 



January 20, 1808. 



LI [I, On destroying Insects injurious to Cuhivation. 

 To Mr. TillocL 



DEAU SIR, 



Among all the casualties to which vegetable life is ex- 

 posed, nothing seems so destructive or difficult to' be ob- 

 viated, as the effects of predatory insects. There is pro- 

 bably an infinite variety of vermin, particularly in green- 

 houses, stoves, and similar contrivances to force vegetation, 

 which, in the shape of Hies, caterpillars, worms, or gvubs, 

 are constantly blasting the hopes of the cultivator. I be- 

 lieve, however, it has been clearly ascertained, that the 

 most prevailing and obnoxious of all these enemies is the 

 plant-iouse, the aph's of Linnasus; a genus perhaps the 

 Hjost numerous of the whole system, for every kind of ve- 

 getable has, it is said, a species of this insect, to whose 

 ravages it is peculiarly liable: and another circumstance 

 tends materially to confirm the njischicf, when it h^s once 

 btgiui, for, according to the general opinion of naturalists, 

 tht-e pernicious animals multiply with astonishing rapidity 

 and certainty, wherever they inlrud? ; and from their 

 Vul. 'Jy. No. IIG. Ja-T. laOS. Z atmcture. 



