56 FLIES. 



found to answer best thus to prepare the ground 

 beforehand. 



In this way we join many points that are wanted. 

 It is very difficult to say, in Insect prevention, use 

 this or that treatment ; but we should bear in mind 

 that there are certain points we want to bring about, 

 and the chief one of these is to keep the croj) safe. 

 For this many arrangements must go on together : 

 we need a fertile soil, but at the same time we need 

 that the fertility should be of a kind adapted, if pos- 

 sible, to feed the plant, rather than the insect ; and 

 therefore in many cases chemical dressings are the 

 most serviceable. 



