AQUATIC INSECTS IN NEW YORK STATE 241 



This is our largest species. It was not common at Saranac 

 Inn, though a few could be found at any time about the timbers 

 by the shores of the larger ponds. I bred it there. I had pre- 

 viously bred it at Ithaca, where it is yery common, and during 

 the summer of 1901 I bred from Fall creek many additional' 

 examples. The species is a common and characteristic one 

 about the shores of the great lakes. It belongs on wave-beaten 

 shores and in the larger and more rapid streams. In Fall creek 

 its nymphs are found under stones in even the swiftest water,, 

 clinging, as stone flies cling, to the rocks. It is the only dragon 

 flv to be found inhabiting such situations. 



Kellicott made some interesting observations on the species 

 at Lakeside on Lake Erie. The species .was ovipositing in pairs 

 on the dock timbers. The females would sometimes descend the 

 timbers into the water, carrying the males with them. The 

 females would remain submerged a long time (once almost an 

 hour) while ovipositing, but the males would disengage them- 

 selves and come up ont of the water after 5 to 20 minutes. The 

 descent is made by the backing downward of the female as she 

 reaches ever for new territory in which to distribute her eggs. 



Nymph. Length 17mm, gills 6mm additional, abdomen lOnim;, 

 width of head Imm. Antennae seven jointed, the second joint 

 one third longer than the first. The single raptorial seta of 

 the lateral lobe of the labium is very minute, difficult to see at 

 all. The median lobe of the labium is very prominent, about 

 half as long as it is wide. In the center of the mentum is an 

 elongate V-shaped chitinization, the V opening forward. The 

 abdomen is relatively long, the wing cases reaching scarcely to 

 the base of the fourth segment. The gills are more than twice 

 as long as wide, with parallel margins and obtuse apexes, black- 

 ish, with the apical fifth more or less covered with white. 



The head is more depressed, and the legs are more sprawling 

 than in other species, due perhaps to the habitat. The stone 

 flies and May flies living in rapids are modified in form along 

 the same lines. At transformation the nymphs depart farther 

 from the water than in the other species, often going several 

 yards up the banks. 



The seasonal range for imagos of this species is from May 

 cill October. 



