160 ELEMENTARY STUDIES IN INSECT LIFE 



with the structure and feeding habits of the insect. If 

 the injurious insect has mandibles and masticates its 

 food, it can then be reached by poisoned baits, or by 

 poisonous sprays thrown upon its food plants. If the 

 injurious form procures its food through a sucking- 

 tube, we then must use contact poisons, those which 

 destroy the insect by coining in contact with its body. 

 We should likewise become acquainted with our friends 

 in the insect tribe, in order that we may at all times 

 favor those which favor us. This whole subject is in- 

 cluded under the head of economic entomology a 

 phase of the study inviting to young students. 



In this study there should be at all times an attempt 

 to reach the proper point of view ; that is, the causes 

 and effects. For instance, the short-sighted fruit- 

 grower is sometimes prone to overestimate the evils at- 

 tending his vocation; some are wont to recall the "good 

 old times " when none of these pests existed. These 

 fruit-growers forget that in those times there were no 

 orchards, and that the apple industry was represented by 

 a few seedling trees growing about the pioneers' log 

 cabins. The farmer likewise sometimes becomes discon- 

 solate by reason of the unexpected attacks of an invading 

 insect horde. There is behind these attacks some cause. 

 The farmer has probably continued to raise throughout 

 a series of years, upon the same ground, the food plant 

 of the invading insect. Had there been frequent rota- 

 tion of crops this state of affairs would have been 

 avoided. In reulitv, then, the agriculturist himself 



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is at fault for the undue prevalence of the injuring 

 forms. If flies become exceedingly troublesome around 



