INSECTICIDES, PREVENTIVES, AND MACHINERY. 425 



can be easily kept in check by fall ploughing and burning the 

 butts and roots, and a good effect will also be produced as against 

 the corn-root-louse and similar pests. Instances might easily be 

 multiplied without adding to the force of the suggestion that the 

 ground should be kept as free as possible from all growth that 

 might afford lodgement or shelter for insects. 



Another important operation which can be made use of is 

 ploughing at the proper time, and, among other things, fall 

 ploughing, whenever possible, is to be recommended, especially 

 of sod land. Many different kinds of insects live in sod, among 

 them cut-worms and wire-worms, both well-known and important 

 pests. A great deal can be done in the direction of destroying 

 these creatures by ploughing the land late in fall. Under the 

 proper headings will be found the reasons why such an operation 

 proves beneficial in special cases ; but in general we can say that, 

 by disturbing the land after the insects have prepared for their 

 winter rest, they are exposed to their natural enemies when more 

 helpless than usual. A great many are then in the pupa state, 

 absolutely unable to help themselves, and breaking their cells at 

 that time means death to them. A very large percentage of 

 reduction in the number of injurious insects can be effected by 

 this practice alone. I am aware that fall ploughing is inadvisable 

 on some kinds of land, but it is directly beneficial on others. It 

 is a measure that must be used with judgment, and each farmer 

 should know enough about his own land to decide whether or not 

 fall ploughing is advisable. I distinctly recommend it wherever 

 it is possible. As a rule, where the ground is to remain bare, 

 the ploughing should be done as late in the season as possible, 

 that the insects may not be able to re-establish themselves ; for 

 instance, when the corn-root-louse is the object of the attack, 

 early ploughing allows the ants that shelter them to construct 

 new galleries and gather in their belongings to safe shelter, while 

 very late ploughing makes it impossible for the ants to work, so 

 that they and the lice both perish : the latter almost certainly. 

 The date of ploughing, other than in fall, is sometimes important ; 

 thus, against the root web-worms in fields after grass, if the sod 

 is turned very early, before the moths have appeared and laid 

 their eggs, the crop remains free. If delayed until the sod has 

 become stocked v\-ith eggs, the corn is almost certain to suffer. 



