Entomology of the Illinois Rvuer. 165 



CHARACTERS USED IX TABULATING AQUA I'lC LEPIDOPTEKA. 



The characters separating the Noctuidae and Pyralidae 

 in the following; kev are those developed by recent at- 

 tempts at a more natural classification of the Lepidop- 

 tera, and are of wide application in separatiuo^ hi<:^her and 

 lower forms. The distinctive features of Cataclysta are 

 taken from Guenee. A piliferous tubercle is tj'pieally a 

 darker and slightly elevated spot, bearing one or more 

 stiff hairs or bristles. In a typical noctuid larva the 

 first and uppermost of these, as seen on one of the 

 middle segments of the abdomen, is on the middle fold 

 of the segment, subdorsal in situation ; the second is 

 lower down, and on the posterior fold; the third is be- 

 neath the first but above the spiracle; the fourth is pos- 

 terior again; the fifth beneath the third and below the 

 spiracle. In the pyralids the arrangement of the fourth 

 and fifth is different, as shown in the key. 



KEYS TO AQUATIC LEPIDOPTERA. 



LarvcB. 

 Middle abdominal segments with the fourth and fifth 

 piliferous tubercles approximate or united. 

 (Pyralidae.) 

 Ocelli five. 



Body with long respiratory filaments. [Fig. 1.] 



Paraponyx, 

 Body without respiratory filaments. 



Elongate, moniliform. Oataclysta, 



Rather thick at middle, slightly flattened, ends 



tapering. [Fig. 10.] Hydrocampa. 



Ocelli six. Pyrausta nelumhialis. 



Middle segments of abdomen with the fourth and fifth 



piliferous tubercles distant from each other. (Noc- 



tuidsB.) Nonagria, Avzama. 



