Entomology of the Illinois Ri/oer. 243 



In July and Aug;ust oviposition was noticed, and egg 

 masses became frequent. Our last date for the imago 

 is August 15. On the 11th of August, a female was 

 observed ovipositing on the side of a wooden frame 

 standing over the water. The ^gg mass was placed in 

 a breeding-cage, and one week later, on the 18th, many 

 larvae hatched from it. Another ^^g mass of the same 

 form and appearance, placed on the dry bark of a stick 

 projecting from the water, was brought in July 27, from 

 which hatched on August 4 larvse apparently of this 

 species. The larvae were at this time more commonly 

 found in water among the vegetation, less commonly in 

 the sand of the shore, and young individuals became 

 frequent. 



During the winter, good-sized larvse sometimes oc- 

 curred in dip-net collections, and March 18 they were 

 again found to be common at Station C, in loose drift, 

 partly frozen, left b^'^ an early spring rise. The previous 

 year they were common in April far from the margin, 

 amongst sticks, logs, and other drift., marking the 

 higher stage reached by the water on March 19 of that 

 year. These situations remained moist for a long time, 

 harboring a large variety of aquatic forms, some of 

 which completed their transformations successfully while 

 others apparently failed, the river remaining low and 

 the weather dry. 



The iraagos in our general collections were taken at 

 frequent intervals and on twenty-two occasions between 

 June 30 and September 2, also on September 19 and 29» 

 and once in October, the counties represented being Rock 

 Island, Grundy, Tazewell, Mason, McLean, Champaign, 

 and Jackson, 



These dates, taken in connection with the observations 

 here recorded, go to show that the species is single- 

 brooded, hibernating in the larval stage and mostly 

 emerging in July after a brief pupal period, the eggs 

 being laid without delay and producing larvae a week 

 later. 



