DESTRUCTIVE INSECTS. 303 



pillars, is one method to destroy them. They may 

 also be driven away by fumigations of sulphur, or 

 other suffocating- effluvia. 



The foregoing 1 , and many other insects, are found 

 on cultivated plants, which are all more or less inju- 

 rious. To be acquainted with their names, economy, 

 and with the methods of killing or banishing them, 

 is of material consequence ; but as " prevention is 

 better than cure," the whole attention of the cultivator 

 should be directed to this point. It is often seen that 

 plants, subjected to the attack of insects, or of a 

 peculiar injury in one season, are particularly liable 

 to be again affected in the next. It is expedient, 

 therefore, that the application of remedies precede 

 the attack ; if peach and nectarine trees were period- 

 ically washed with a lixivium of soap in the course 

 of the autumn, winter, and spring, it is not probable 

 that mildew would appear on them in summer. And 

 where the visit of the aphides may be expected on 

 trees, the autumn is certainly the season when they 

 would be most effectually repulsed. It is in this 

 season that the eggs of insects are deposited on those 

 plants or substances which yield convenient suste- 

 nance for their young. With this view the careful 

 mothers seek the furrows of the bark, the indentations 

 round the buds and branches, as safe depots for their 

 ova. But did they find these recesses already occu- 

 pied by any quality offensive to them, they would 

 be disgusted, and seek a place elsewhere. The aphides 

 are viviparous in warm weather, and oviparous when 



