PREFACE. 



NATURAL science studies are essentially studies of 

 things, not books. The teacher in preparing a course 

 of instruction must he governed largely hy the ma- 

 terial procurable. Work in marine biology can never 

 be properly conducted away from the seashore, nor 

 tropical life thoroughly presented in the temperate 

 zone. In the study of animal life, insects present a 

 fertile field. They outnumber all other forms, and are 

 ever accessible. Under observation in their native 

 haunts, or, in many cases, surrounded by artificial con- 

 ditions, they conduct themselves naturally. The study 

 of insects has therefore come to form a prominent part 

 of zoological instruction. 



This book on insect life is divided into two parts. 

 Part I deals with the development of insects and their 

 relations to their surroundings. Part II is devoted to 

 Methods, Equipment, and Laboratory Exercises. The 

 laboratory exercises consist of elementary work in the 

 development, structure, function, and systematic ar- 

 rangement of insects. The two parts are intended to be 

 taken together. For example, in the laboratory exer- 

 cises on metamorphosis, the detailed account of the life 

 histories in Part I furnishes additional suggestions on 

 points to be observed; the discussion of the special 

 sense accompanies the anatomical work ; the chapter on 

 wealth of insect life amplifies the schemes of classifica- 



(iii) 



