262 Illinois State Laboratory of Natural History. 



Paparium. — Closely resembling larva, more inflated^, 

 especially near middle; body bisinuate posteriorly, bein^ 

 bent upward at segment 7, thence arcuate and convex- 

 above to the last segment, which is flexed upward; 

 ventral stripes more or less obhterated. 



0. hinotata Loew. 

 Types collected in Illinois by Dr. Le Baron. 



0. megacephala Loew. 



This large and handsome species is not common ia 

 Illinois. Our specimens are mostly from the northern 

 portion,— from Carroll, Bureau, and McHenry counties,^ 

 although one is from the Illinois River bottoms in Taze- 

 well county. 



0. vertebrata Say. [Fig. 60.] 



From pupae as much alike as two prints from the 

 same cut were reared males of this species, and females 

 agreeing with the description of 0. willistoni Day. 

 There is no oth6r female known for vertehrata, nor any 

 male for willistoni, and no other unisexual species known- 

 to me can possibly belong to either. Their close rela- 

 tionship is evident from the foregoing key, in which both 

 forms are included under the name vertehrata, and I feel 

 justified in treating them as sexes of one species under 

 the older name. 



The females were seen ovipositing at the same times 

 and places and in the same manner as 0. cincta, but 

 not in such numbers, vertebrata being much the less com. 

 mon about Havana. Young were obtained July 27 from 

 the eggs of this species. 



A young larva was taken Apr. 14 under drift on shore 

 among the examples of 0. cincta, and the older larvae 

 were taken frequently throughout the season, usually in 

 floating vegetation with O. cincta, rarely on the springy 

 shore,the last date of their occurrence being Sept. 14. 

 Pupae were noted on the water in June, July, and August. 

 The hibernating larvae must be largely young, as these be« 



