IV PREFACE 



tion ; and so on. The sequence of the work will be de- 

 termined largely by the season of the year. Life his- 

 tories and ecology will naturally be confined to spring 

 and fall. During the winter months anatomical work 

 can be well conducted upon material previously pre- 

 served. 



The aim of the book has not been to familiarize the 

 student with a number of isolated facts. It has been 

 the endeavor to induce the student to become ac- 

 quainted, through personal observations in the field 

 and laboratory, with some of the important biological 

 problems as presented by insects. Insects exist in cer- 

 tain given shapes, and in great or few numbers. There 

 are reasons for such conditions, causes which, wher- 

 ever possible, the student should be led to see. Insects 

 affect one another ; they bear certain relations to physi- 

 cal conditions, and to other forms of life, both plant 

 and animal. They affect man himself. These inter- 

 relations are subjects to be kept in view. 



Insect life furnishes many practical subjects for 

 nature-study lessons. Things that live and move elicit 

 the interest and attention of pupils. Nature-study, to 

 have an educative or disciplinary value, must not stop 

 with superficial or passing observations. The educa- 

 tive value derived from nature study does not consist 

 in the number of facts imparted, but in the develop- 

 ment of the ability to acquire knowledge through care- 

 ful and independent personal observation. The pupil 

 at a glance will see that a caterpillar has come out of 

 the egg, the caterpillar has changed to a chrysalis, and 

 later that a butterfly has emerged from this chrysalis. 



