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AJV ECONOMIC ENTOMOLOGY. 



profitable, and are always to be preferred to decomposing vege- 

 table matter, from the insect stand-point. The details of the 

 applications to be made are found where the insects themselves 

 are treated. Where barn-yard manure must be used, it is always 

 a good plan to mix it wath air-slacked lime, land plaster, or kainit, 

 and this can be done as fast as it is made in the stable. It will 

 add to its value, wdll hold the ammonia, and will make the mixture 

 an undesirable one for insects to live in. 



Grass land may be kept tolerably free from undesirable pests 

 infesting the roots by using as fertilizer a mixture of one hun- 

 dred bushels of lime and one ton of kainit slaked together. This 

 may be applied in the spring, and will act as a stimulant as well 

 as destroy many of the insects inhabiting the soil. 



There are yet other ways in which we can head off* insects ; for 

 instance, in the selection of the time of planting. It happens 

 frequently that insects make their appearance at a very definite 

 time, and in the ordinary course of nature have only a few days 

 within which they must lay their eggs and provide for the con- 

 tinuance of their kind. If they do not find the cultivated food- 

 plant, they are compelled to make use of some substitute wild 

 plant, on which they do not thrive as well ; or they may not be 

 able to oviposit at all, and a large proportion will p^ish without 

 being able to reproduce their kind. 



When the life history of a seriously injurious insect is known, 

 it will often pay to adapt our farm practice so as to prevent injury. 

 For instance, experience has proved that the Hessian-fly appears, 

 ready to lay eggs for a late fall brood, during the early days of 

 September. By delaying planting until after the middle of that 

 month, or even later where the latitude makes this feasible, the 

 insects are compelled to lay their eggs in grasses other than 

 wheat, or in the volunteer grain that they find in fields or along 

 the roads. 



Cranberry growers take advantage of their knowledge of the 

 life history of the Teras infesting that crop by keeping the bogs 

 covered with water until after the middle of May, thus compelling 

 the moths to lay their eggs on other plants belonging to the same 

 natural family. 



In a similar way we can sometimes induce the insects to ovi- 

 posit in a trap crop planted especially to attract them and pro- 



