28 



PRIZE ESSAY 



and III.) before it reaches its perfect condition. From the egg- 

 to the larva ; from the larva to the pupa ; and from the pupa 



PUPA.— FIG. II. 



CATEEPILLAE.— FIG. I. 



MOTH.— FIG. III. 



or chrysalis to the imago or perfect insect. The larvae of insects 

 are commonly distinguished in popular phraseology in the fol- 

 lowing manner : 



Grubs are the larvse of the coleoptera or beetles ; maggots the 

 larvse of the diptera or two winged flies ; caterpillars the larvae 

 of butterflies, moths and sphinges. 



38. Most insects breathe through small openings called stigmata, 

 spiracles or air holes, placed on the side of each segment of the 

 body. These air holes can be distinctly seen without difficulty 

 in.naked caterpillars (fig. I.) The opening can be closed at will 

 by the insect. The air holes are connected with ramifying tubes 

 called air tubes or trachse. 



39. The following scheme of a systematic arrangement of in- 

 sects is based upon the peculiarities in the construction and 



