THE POTATOE DISEASE. 121 



(472.) We might perhaps try the experiment of rearing 

 large quantities of ducks, and turning them loose in infect- 

 ed fields to eat the vermin, as by that means we should 

 convert the destroying insect into a source of profit to our- 

 selves. It would be perhaps especially advisable to enacit 

 laws to prohibit the destruction either of the soft-billed 

 birds or their eggs, as the number of insects they devour 

 is almost incredible. 



(473.) It would be impossible practically to breed lady- 

 birds and ichneumons on any other but a very small scale, 

 but we should be very careful to preserve these valuable 

 natural devourers of the Aphides. 



(474.) Should the wheat become seriously attacked, I 

 really know not what remedy can be applied to destroy 

 the creature ; but I am in hopes that such may not be the 

 case, or rather that the grain may be too forward when the 

 pest appears, to be extensively damaged by it. 



(475.) In considering the means to be adopted for the 

 prevention of the disease, we should bear in mind that the 

 creature has not come hitherto in great abundance till July 

 or August ; hence, if we could get the plants ripe before 

 that period, we should cheat the insect of his spoil. It is 

 impossible to tell how much earlier the insect may appear 

 another year ; but, as we can only act for the future by 

 the consideration of the past, it would be advisable to use 

 such plants as render their produce early. 



(476.) With respect to the pptatoe, the use of the early 

 kinds is most strongly to be commended ; and these should 

 be employed, during the prevalence of the disease, as much 

 as possible to the exclusion of the late varieties. 



(477.) Johnson strongly recommends autumn planting 

 as a means of preserving the potatoe plant against the 



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