168 Illinois State Laboratory of Natural History. 



evei", large quantities of detached cases L^'g- 2] were 

 found floating at the surface in the same vicinity— rough- 

 looking oblong or triquetral cases about an inch long, 

 formed by severing in a ragged way the connections of 

 the larval retreat at either end. In these were pupaa 

 and good-sized larvae, and it must be the usual habit 

 of this species to come to the surface in this manner 

 before pupation, and live in a detached case, like other 

 Hydrocampinse. In single instances, pieces of the leaves 

 of Nelumbo and Potamogeton entered into the construction 

 of these cases, and a side of one case was smoothly 

 built up of Lemna trisulca, which was abundant there at 

 that time. These cases were seen also in smaller numbers 

 in September and October, at the same place. The ima- 

 gos were quite generally distributed and abundant 

 along the lake and river shores in June, July, and the 

 first part of August — an earlier period than that of 

 Sydrocampa ohliteralis, which was still common in Sep- 

 tember, while the present species was not noticed after 

 August 24. In the breeding-cages they emerged July 18 

 and 26 and August 1. They have also been taken in Ur- 

 bana at electric light August 18 and 19. Young larvae, 

 doubtless of the new brood, were seen on the Vallisneria 

 July 23 in great abundance, and it is probable that 

 the species hibernates in the larval stage, a medium- 

 sized example having been taken at Station A De- 

 cember 17. 



