98 THE LIFE OF DEVILS LAKE 



Philhydrus sp. This is the common hydrophilid of Devils Lake. 

 All stages were found. The species was also present in Lake A, 

 Lake P, Stump Lake and a fresh water pond. 



HYDRACARINA 



There are several species of mites in the Devils Lake complex, as 

 yet only partly identified. Dr. Karl Viets has determined Hy- 

 drachna schneideri and H. valida, both from Main Lake, the former 

 from Spring and C Lakes also. One specimen of Diplodontus despiciens 

 from Spring Lake has been identified by Prof. Ruth Marshall, while 

 Prof. R. H. Wolcott has found a third species of Hydrachna, as yet 

 undetermined, in Main Lake. Eylais sp. occurs rather commonly 

 in Main Lake and E. extendens has been taken in Lakes Spring and 

 P. A single specimen of Hydryphantes was found by Prof. Wolcott 

 in a collection from a shore pool close to the lake edge. The latter 

 was probably formed in part by rain and partly by wash from the 

 lake, from which the Hydryphantes undoubtedly came. 



Mites are fairly common in Main Lake but do not occur in 

 sufficient numbers in the plancton samples to give definite records 

 of their seasonal distribution. 



Other than Main Lake I have recorded mites from Spring Lake 

 and Lakes C and P only, but they doubtless occur elsewhere in the 

 complex. 



FISH 



At present there is but a single species of fish inhabiting Devils 

 Lake, the stickleback (Eucalia inconstans), altho previously it is re- 

 ported to have swarmed with pickerel (Esox lucius?), and Lord 

 (1884) reports the "shiner," and Pope (1908) the minnow (Pime- 

 phales phomelas) as occurring here. 



The reasons for the disappearance of fish from Devils Lake are 

 probably primarily the increase in concentration of the lake water, 

 and secondarily the loss of suitable breeding grounds for the pickerel, 

 thru the cutting off of the coulee which formerly flowed into Min- 

 newaukan Bay, but which in recent years has only done so excep- 

 tionally. The ruthless destruction of the pickerel by the fishermen 

 was probably a contributing cause, and there is some evidence (but 

 very uncertain), from the accounts of early observers, of an epidemic 

 among the fish. 



Since 1908 numerous experiments have been made in the intro- 

 duction of various species of fish (chiefly yellow perch — Perca 

 flavescens) into Devils Lake, but without any permanent success, 

 and on the tolerance of fish for several different salts in varying 

 concentrations.* 



In another part of this report** I am discussing briefly the 



•See Popp (1908), Brannon (1911, 1913) and Young (1923). 

 •♦See p. 106. 



