AQUATIC INSECTS IX NEW YORK STATE 



447 



Fig. 2i Pupa of Stalls infumata xZ 

 (After Needham) 



from water [fig. 22], MialTs observations of S. lutaria 



quite agree with this, and he further states that the adult 



emerges after two or three 



weeks. 



Adults. These have already 



been described above. They are 



verv awkward fliers and are 



easily caught even without a 



net. This quite agrees with the 



generalized form of the wing 



venation [fig. 23]. In fact, the 



adults when approached, will 



often run rather than attempt 



to fly. It is probable that 



the insect lives in the winged 



form only a few days. All 



specimens taken were found 



to die within three days. The 



dates on which the adults 



have been collected near Ithaca 



range from May 13 to June 



16, through a series of years. 



They are diurnal in their 



habits and seem to prefer bright sunshine. I have found them 



most abundantly in their egg-laying places at midday, though 



they also frequent the same places and are active till almost 



dark. 



The short life taken with the fact that the mouth parts of 



the adult are very poorly developed, would indicate that the 



adults do not take food. It 

 was reported to Dr Hagen and 

 to the national museum some 

 j-ears ago that the adults of 

 S. nevadensis were very 

 injurious to grapevine leaves. 

 This is the only case of injury 

 yet charged to any members 

 of the family, and may be a 

 false charge. On the other 

 hand, the adults, flying near 



the surface of water, serve as an abundant sui)ply of food for 

 fishes. • 



KEY TO SPECIES OF SIALIS 



a Body and wings black or blackish 



b Head black with flat, shining streaks and spots 

 yellowish 



!'t A 



Fig. 23 Fore wing ofSlalls infumata x4 



