108 Annals Entomological Society of America [Vol. IV, 



the median slit in the nymphal skin and the complete freeing 

 of the sub-imago. After its first short flight the insect remained 

 on the shrub for about five minutes before disappearing higher 

 up in the air. This custom of resting upon near-by objects is 

 a habit varying with the species and apparently also with weather 

 conditions. For example, sub-imagoes of Chirotonetes albo- 

 manicatus which usually fly upward immediately on emerging 

 in clear weather walk about for a while on the shore, or take 

 very short first flights on dark days. The period of greatest 

 effort during emergence is that which precedes the splitting of 

 the nymphal skin. The splitting is doubtless urged on by the 

 distention of the alimentary canal which is caused by the air 

 or water which has been swallowed. 



Mating nights of Blasturus cupidus were observed over 

 Fall Creek in the late afternoon of April 31, the height of their 

 transformation season. About thirty individuals flying in 

 close ranks rose and fell at varying altitudes of ten to thirty 

 feet. When at their greatest height they were scarcely dis- 

 tinguishable against the sky, but when they were lowest the 

 forelegs and the setae might be discerned. The forelegs were 

 held stiffly, straight forward from the head, and the setae, 

 projected at a wide angle behind, appearing to vibrate as the 

 insects swung downward. After a few moments of ecstatic 

 rising and falling, one of the individuals flying high in the 

 swarm descended to one of the lowest, coupled with it and 

 veered obliquely downward and across the stream. When 

 about to alight on the opposite shore the two separated, one 

 disappeared and the other turned back and flew close to the 

 surface of the stream frequently brushing the water with the 

 abdomen. Such matings were three times observed. At- 

 tempts to capture a fertilized female failed. The eggs brushed 

 from the abdomen into the rapidly running water were, of 

 course, impossible to find. 



Leptophlebia. 



Occurrence, habitat. Nymphs of this genus were found in a 

 greater variety of situations than any other group. While 

 it is for the most part a genus which belongs to the small rills 

 it also takes advantage of the secluded places in the larger 

 streams. Two species were common in this locality. These 

 were Leptophlebia mollis, common after May 20, and L. prae- 

 pedita, collected frequently after May 29. 



