NO. 2192. DRAGONFLIES, CALIFORNIA AND NEVADA— KENNEDY. 615 



The United States Reclamation Service has recently dammed the 

 outlet and raised the surface of the water several feet. This has 

 covered many of the beaches and may account for part of the scarcity 

 of aquatic insects. 



AL TAHOE. 



In the swamp at Al Tahoe at the southern end of the lake were 

 taken Lestes uncatus Kirby, Lestes congener Hagen, Lestes disjunctus 

 Seh's, Enallagma cyathigerum (Charpentier), Aeshna interrupta neva- 

 densis Walker, Llhellula quadrimaculata Linnaeus, Sympetrum ohtrusum 

 (Hagen), Sympetrum pallipes (Hagen), and Sympetrum corruptum 

 (Hagen). 



MCKINNEY LAKES, MCKINNEY LANDING, LAKE TAHOE, ELEVATION 7,000 FEET. 



Four small lakes lie on the divide between McKinney Creek, which 

 flows into Tahoe, and the Rubicon River, which flows into the 

 American River or Pacific drainage. All are glacial lakes filled by 

 sediment until very shallow, three of them being covered by Uly 

 pads and not over 4 feet deep. The open lake contains fish and so 

 has little insect life. The other three fairly swarm with Odonata, 

 in spite of their elevation and the crags carrying snow patches, which 

 rise on either side of them. The water of these is surprisingly warm, 

 in fact much too warm to drink with pleasure. This unusual warmth 

 in the lake water at this altitude is probably due to the fact that 

 the lakes are very shallow and have black, peaty bottoms which, with 

 the long, clear summer season, permit the sun to raise the tempera- 

 ture of the water. However, all the flourishing species are truly 

 Canadian, even the hardiest of the lower forms existing at tliis ele- 

 vation in scanty numbers. 



1. LESTES CONGENEK Hagen. 



Not common. Three pairs taken. 



2. LESTES UNCATUS Kirby. 



Occasional. 



3. ENALLAGMA CYATHIGERUM (Charpentier). 



Rarely taken. 



4. COENAGRION RESOLUTUM (Hagen). 



This is the common damsel fly about the lakes. 



5. CORDULIA SHURTLEFFI Scudder. 



Common about the lakes. 



6. SOMATOCHLORA SEMICIRCULARIS (Selys). 



Common. This species is found only over patches of sedges stand- 

 ing in shallow water. Apparently the females oviposit in such sedge 

 patches, and the males are there to find the females. 



7. AESHNA INTERRUPTA NEVADENSIS Walker. 



This is very abundant about two of these lakes. The exuviae 

 hang on the sedges in vast numbers. (See p. 581.) 



