INSECTS AFFECTING 

 VEGETATION 



PART'I 



ENTOMOLOGY. 



INTRODUCTION. 



THERE is a constant and rapidly increasing demand from 

 farmers, horticulturists and others more or less directly in- 

 terested in insects, or more frequently in the ravages and 

 losses caused by them, for a book giving in a condensed form 

 such information as is required to fight our tiny foes in an intelli- 

 gent manner. Information of this kind in a printed form is of 

 more utility than any number of letters that mi^it be written, since 

 the illustrations necessary to describe clearly any insect can not 

 well be given in a letter. (Minn., E. S. B. 28.) 



When we consider the immense numbers of insects that exist 

 in all parts of the habitable globe the task, to give in a few printed 

 pages even an outline of their classification, seems to be a more than 

 futile effort. Moreover, any classification of this multitude of forms 

 (one million species of existing insects is not an exaggerated esti- 

 mate) must be a more or less artificial one. 



Geologists speak of the age of shells, of fishes, of reptiles, periods 

 all passed long ago, and they might well call the present geological 

 age the age of insects, because these animals outnumber all others 

 combined. In fact insects are found in every part of the globe that 

 man has ever been able to reach, with the exception of the oceans, 

 where they are replaced by closely allied animals, the crustaceans. 

 And yet, notwithstanding the abundance of insects and their almost 

 omnipresence, how few persons are really able to give a definition 

 of an insect? The term insect is derived from two latin words in 

 and seco eut into, because the body is insected or divided into 

 rings. At one time this term was applied to the entire group of 

 articulates or jointed animals, and consequently early writers spoke 

 of six-legged, eight-legged, many-legged insects. Articulates or 

 jointed animals, which by persons not familiar with zoology are fre- 

 quently called insects are : Wood-lice or Sow-bugs, Mites and Ticks, 

 Spiders, Harvest-men, Book-scorpions, True-scorpions, Centipedes, 

 Thousand-legs and others not found in Minnesota. None of these 

 animals possess the essential characters of true insects, 



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