6 INTRODUCTION. 



nature's own books, which can be studied by teacher 

 and pupil together, both learners at the same source. 

 Some of the best results in the teaching of Natural 

 History have been ultimately attained by those who 

 have started in their work by encouraging their stu- 

 dents to collect, and many have gained considerable 

 knowledge and owe their success to this method. 



This Guide could not have been completed if Miss 

 J. M. Arms had not joined the undersigned in the 

 work, and if it had not been for the free gift of the 

 illustrations. These were paid for by the same ap- 

 preciative but unknown friend, who also gave the 

 drawings used in the Guide on Wortns and C^'usta- 

 cea. The number and value of the drawings con- 

 tributed in the present work very much exceed those 

 used in any previous Guide, because Insects form the 

 most favorable, and are apt to become the favorite, 

 means for the teaching of observation in the schools. 

 For the same reason, the text of this Guide has been 

 prepared with greater care than that of the preceding 

 Guides, and discussions of some questions of more 

 advanced scientific character have been brought for- 

 ward in its pages. Teachers are beginning to demand 

 explanations ; and while theoretical considerations are 

 largely out of place in the school-room, they are not 

 out of place in a treatise addressed, as this is, to 

 teachers themselves. 



We desire to return thanks to the entomologists 

 who have assisted us in various ways, — Dr. A. S. 

 Packard, Dr. Hermann A. Hagen, Professor C. H. 

 Fernald, Islx. Edward Burgess, Dr. C. V. Riley, and 

 especially Mr. Samuel Jienshaw, who has been con- 



