94 THE LIFE OF DEVILS LAKE 



They are seldom found in the open water, being restricted mostly 

 to the Ruppia zone near shore. 



Crustacea may occur in oxygen-free water, together with other 

 animals.* 



INSECTA 



The aquatic insects of Devils Lake and adjoining waters have 

 been studied by Mr. C. K. Sibley of the Department of Entomology 

 of Cornell University, assisted by Miss Helen Stegenga formerly of 

 the University of North Dakota. A few data have been supplied 

 by Professors C. J. Needham, E. Matheson, Mr. C. R. Plunkett and 

 C H. Kennedy. Many of the forms, however, are still awaiting 

 specific determination. 



With the exception of the corixids and occasional chironomids, 

 the insects of Devils Lake are found in the shore and Ruppia zones 

 and in the ooze. While they occasionally occur in the plancton 

 catches, they do so too infrequentlj- to warrant any conclusions re- 

 garding their seasonal distribution. Much remains to be done, not 

 only in their classification, but also in a study of their food, repro- 

 duction and reactions. The present report can be considered only 

 as a beginning. 



Most important, in respect both to variety and number, are the 

 chironomids. Their larvae are present at all times in the year in 

 the ooze, while in summer the most conspicuous insects about the 

 shores are members of this family, Avhich fill the air with their 

 swarms in the evening, and during the day lie hidden in the grass 

 and brush. 



Second in importance to the chironomids are the corixids, of 

 which at least two species inhabit the lakes, and which are common 

 everj'W'here, especially in the Ruppia zone. 



On the whole, however, the insect fauna of Devils Lake cannot 

 be said to be rich in species, tho plentiful in number of individuals. 



Its constituent species are characteristically those of fresh 

 water, tho a species of Ephydra, which is a salt and alkaline water 

 form, is common in Main and Mission Lakes. 



Several species of dragon and damsel flies naturally occur in the 

 Devils Lake region, but only one, so far as known, breeds in the 

 main lake. This is an undetermined (probably new) species of 

 Enallagma with a two-segmented gill, which according to Professor 

 Needham is "unlike anything in our eastern fauna." 



Damsel fly nymphs are very common in the shore and Ruppia 

 zones of Main and Stump Lakes, and have been taken in Lake 0. 



*See p. 107. 



