CATALOGUE OF INSECTS. 17 



and consequent injury. All parts of a plant or tree may be attacked, 

 and either the tissue destroyed or the juices drained. The damage 

 done may be either by destroying the plant or lessening the value of 

 the product. The function of the economic entomologist is to indicate 

 to the agriculturist the method of checking or altogether preventing 

 this damage, or of reducing it as much as possible. In the following 

 list some idea is given of the number and character of the species, 

 injurious as well as beneficial, and of the other host that is of no 

 economic importance though filling its place in nature's plan of con- 

 stant change of matter from inorganic to organic and from vegetable 

 to animal ; only to return eventually to the inorganic compounds in 

 condition to start anew on the cycle of change. 



2 IN 



