46 



smoke, sufficient to fill the houre, may be pro- 

 cured in the space of ten or fifteen minutes ; 

 unless it happens to be very extensive ; in 

 which ease, it will require a proportional in- 

 crease of time, to do the business as it should 

 be. Note, that, if the insects are strong and 

 numerous, it will be necessary to repeat the 

 operation at least twice successively : the calm- 

 est weather should be chosen for this work, 

 and it is also necessary, to examine the house 

 with care, lest there should be any holes, or 

 cracks in the glass, or elsewhere, through which 

 the smoke might evaporate too freely ; other- 

 wise, it cannot be reasonably expected to have 

 the desired effect. 



For the third, fourth, and fifth species, I am 

 of opinion , that there is none of the several ex- 

 pensive methods mentioned in different authors 

 so effectual, as simply picking them off: this 

 may be said to be tedious, but then it has surety 

 to plead ; besides, that the plants are in no 

 manner disfigured by the operation ; but unless 

 regularity be observed in looking for them, ex- 

 amining plant by plant, and leaf by leaf, from 

 top to bottom, and also any incisions, or cracks 

 that may be in the bark of the stem, &a there 



