163 



BULLETIN OF THE BUREAU OF FISHERIES. 

 Contents of stomachs of 126 large brook (rout. 



Food elements. 



Fish remains... 



Araneida 



Hydracbnidse ( water mites i 



Ephemerida 



Orthoptera 



Hemiptera 



Neuroptera 



Trichoptera 



Lepidoptera (moths) 



Number 

 of speci- 

 mens 

 in which 

 found. 



Average 

 percent 



(if 

 element. 



92.5 

 12.4 

 4.4 

 31.0 

 47. 

 13.(1 

 10.0 

 22. 5 

 16.4 



Food elements. 



Number 

 of speci- 

 mens 

 in which 

 found. 



Diptera 



Chironomus (larvae and pupie) 

 Coleoptera 



Hymenoptera 



Insect fragments 



Crustacea (Entomostraca) — 



Vegetable debris 



Sand and gravel 



Average 



percent 



of 

 clement. 



14.0 



11.0 

 15. 7 

 32 8 

 41. N 

 4.5 

 64.0 

 15. 5 



The fish remains consisted of young suckers. All of the specimens that had 

 eaten Araneida and Hydrachnidae came from Lake Creek. About one-fourth of the 

 Hemiptera were Corixa, and about one-half the Hymenoptera were ants. 



One of the two specimens containing Entomostraca was taken in Upper Lake 

 and had eaten only Daphnia, while the other was caught in Lower Lake and had 

 eaten both Daphnia and Cyclops. 



Nearly all the vegetable material found was in the stomachs of specimens that 

 were caught with a seine in Lake Creek, just a short distance above Upper Lake. 

 It consisted, for the most part, of pieces of the small roots of the willows growing 

 along the creek, and was probably taken by accident. 



Needham (1901) states that Chironomus, Corethra, and Trichoptera were the 

 most important food elements found in the brook trout he examined. In this ease, 

 however, the four chief elements of animal food, named in the order of their impor- 

 tance, were Hymenoptera, Coleoptera, Orthoptera. and Chironomus. 



Fry. — Twenty-six specimens of fry were obtained from Lake Creek in August, 

 1902. They were too small to be positively identified, varying in length from \ to 

 \\ inches (2.2 to 3 centimeters). The stomachs of all except one contained food, but 

 it was found to be in such condition that very little of it could be recognized. 



Contents of stomach* of £6 fry. 



Pood elements. 



Ephemerida (nymphs) 



Orthoptera 



Lepidoptera (moths) .. 



Number ,..„„„„ 

 of speci-l A,e 



in which 

 found. 



per cent 



of 

 element. 



Food elements. 



50 Diptera 



60 Chironomus (larvae and pupse) 

 in Inject fragments 



A \ erage 



Numbei 



5 

 23 



72 

 22 

 80 



