164 Illinois State Lahoratoi^ of Natural History. 



B. PupoB. 

 Prothoracic spiracles small and lateral, or wanting. 

 Appendages mostly free from each other. 

 Pupae formed on land ; without gills. 



Antennal joints fewer than twelve. Coleoptera. 

 Antennal joints numerous, more than twelve. 



Neui'optera. 

 Pupae formed in the water in a case; with filament- 

 ous gills. Trichoptera. 

 Appendages, head, and thorax all united. 



Lepidoptera. 



Prothoracic spiracles dorsal, prominently developed, 



often borne at the end of antenna-like 



appendages; or the pupa is concealed in the 



hardened last larval skin. Diptera, 



LEPIDOPTERA. 



Two groups of this order may be considered here; those 

 epecies which feed internally on aquatic plants and breathe 

 by spiracles, probably making no use of the air contained 

 in the water, although it seems that some can swim 

 from one plant to another when occasion requires; and 

 those which feed externally, being provided with means 

 for appropriating oxygen from the air in the water, at 

 least in the earlier stages, and therefoi-e completely aquat- 

 ic during a part of their life; living in cases or shelters 

 usually covered exteriorly with green plant tissue, and fill- 

 ing these cases with air during the pupal and sometimes 

 also during the later larval period. To the former group 

 belong certain Noctuidoe, such as Arzama and Nonagria, 

 and a pyralid (Pyrausta) herein treated ; to the latter 

 group belong the members of the remarkable and inter- 

 esting pyralid subfamily Hydrocampinae. 



