CHAPTER V. 



HOW TO OBSERVE INSECTS. 

 H. E. SUMMERS,. Ames, Iowa. 



Insects, in consequence of their abundance, their convenient 

 size, and the ease with which they may be kept alive in the school 

 room, furnish perhaps the best material with which to begin the 

 study of zoology with young pupils. They may be studied in 

 many different ways, each of which will lead to the discovery of 

 new facts concerning them and bring us nearer to a full know- 

 ledge of their relation to the entire living world. Their structure 

 as illustrated in various selected forms may be investigated, and 

 by a comparison of these forms the student will come to appreciate 

 the meaning of homology, and when the reason for this homology 

 is learned, to understand the principles in accordance with which 

 animals are classified. Again, observation of the habits, especially 

 of aquatic insects, furnish a never ending source of delight and in- 

 struction to children. Last to be here mentioned, their metamor- 

 phoses, or the transformations that they pass through before 

 reaching the adult state, bring the pupil in contact with facts so 

 wonderful that an interest is often aroused that lasts through life. 



This paper is devoted to some hints on what and how to observe 

 certain facts illustrating more particularly this last topic. And it 

 should be fully understood that these suggestions are for the use 

 of the teacher, not of the pupil. Most of what is here dogmati- 

 cally stated, the teacher should, by judicious questioning, lead the 

 pupils to discover for themselves. 



Throughout the entire summer there may be seen flitting about 

 in gardens, especially around the cabbage and other plants 

 belonging to the mustard family, medium sized, white butter- 

 flies, usually with a few black spots, and often slightly tinged 

 with yellow. There may be two different kinds of these; the one 

 usually most common is known as the cabbage butterfly, the other 

 as the checkered white. Figure 33. The former is the one here 

 considered, although most of what is said applies equally well to 

 the latter. 



