ARTIFICIAL REMEDIES FOR DISEASE. 119 



REMEDIES AGAINST THE CAUSE. 



(465.) The absolute destruction of the Aphis by human 

 means is doubtless an impossibility, and the only means 

 which we could adopt would be to destroy the insect the 

 moment it appeared upon the potatoe plant. This simple 

 remedy is, however, exceedingly difficult to apply, even 

 when we wish to protect a single plant. I had an infested 

 plant in a pot at Finsbury Circus, and though I frequently 

 tried to eradicate the insect, yet there was continually 

 some one or other left ; for these little rascals crawl into 

 chinks and crannies, from which they come forth at their 

 convenience, and rapidly multiply. 



(466.) If the protection of a single plant be so difficult, 

 how much more so must be the protection of the potatoe 

 plants covering large tracts of land ? We must conduct 

 our campaign against the destroyer in this case by adopt- 

 ing a more wholesale remedy. On the small scale, the 

 infusion or vapor of tobacco would destroy them, but it 

 would be impossible for the agriculturist to employ that 

 remedy over large fields. 



(467.) Many kinds of Aphides are destroyed by water, 

 and I had to lament the loss of several pet colonies of the 

 Aphis rosce, which were destroyed by the rain of a thunder- 

 storm ; and it is said that the hop plantations of the whole 

 county of Kent may be cleared of their Aphides by a single 

 thunder-storm. The cultivators of rose-trees practically 

 syringe the infested trees, and so get rid of their pest. 



(468.) Neither water nor thunder-storms seem to have 

 much influence upon the vastator, further than that the 

 electricity seems to occasion a great migration of these 

 creatures. The vastator appears to cling very tightly to 



