NO. 2192. DRAaONFLIES, CALIFORNIA AND NEVADA— KENNEDY. 583 



(California), where, at an elevation of 7,000 feet, this species domi- 

 nated aU other dragonfly life. Here, in a momitain pass fairly level 

 for about two miles, lie four small, shallow lakes, two of which flow 

 east into McKinncy Creek and Lake Tahoe, and two flow west into 

 the Rubicon River and the Pacific drainage. On both sides rise 

 granite crags for a thousand feet above the level of the lakes, with 

 their lower slopes and the borders of the lakes covered by green firs, 

 and their higher naked slopes spotted white with small patches of 

 snow. Three of the lakes are covered with yellow pond lilies and 

 fringed with sedges, while numerous clumps of gray wOlows dot 

 their shores. These lakes swarm with insect life and are apparently 

 without fish, while the fourth lake is free of aquatic plants and is said 

 to contam fish. This lake has few dragonflies. The three lakes sup- 

 porting dragonflies were surprismgly warm. Expectmg cold lakes at 

 this altitude, I found the water too warm to drink with relish. This 

 unusual warmth appeared to be due to the shallowness, the depth 

 not exceeding three feet, and to the black peaty mud covering the 

 bottom, which combination with the constant clear weather in this 

 region during the summer months caused the lake water to heat 

 rapidly from the sim's rays. At this elevation the air was so cool 

 that Aeshna was easily taken on the wing and in two days' collect- 

 ing I succeeded in catching 60 males and 28 females. 



This species emerges from these lakes in immense numbers. I 

 have never seen Aeshna exuviae so numerous. At the lake about 

 which I did most of my collecting there was a zone of sedges 5 to 

 25 feet wide along the shore. The majority of the sedge stems were 

 riddled with eggs, and exuviae hung frequently two or three deep on 

 the promment ones. I picked nearly a quart from an area about 15 

 feet square. While adults swarm over these ponds, they are not 

 one-tenth as abundant as the exuviae, a fact explamed by the wander- 

 ing proclivities of both males and females. 



As far as is known, those species of Aeshna which have been ob- 

 served have emerged in the nighttime. I have reared both multi- 

 color and californica, which emerge about michiight, but this species 

 on these lakes, where the night temperature usually approaches 

 freezmg, emerges in the daytime. I found many tenerals and took 

 ten mdividuals in the act of emerging, which occurred at any time 

 from 10 in the morning to 4 in the afternoon. This change m the 

 time of emergence, perhaps, permits this species to live at this alti- 

 tude, a thousand feet higher than I took any other species of Aeshna; 

 and a true alpine habitat with nightly freezmg temperatures. 



At my earliest arrival on the lakes (10 in the morning) females 

 were ovipositing and males were circling the borders of the lakes 

 catchmg msects and watchmg for females, which were usually cap- 

 tured while ovipositmg. The males, while around the lakes, usually 

 flew at a height of from 1 to 4 feet above the sedge border, gradually 



