ENEMIES OF BROOK TROUT 



from the water by a screech-owl, the larvue being 

 pulled trom the case and devoured by the owl. 



Injurious Insects. 



The damage to fish-eggs and young fish caused by 

 insects and the larvjE which pass a portion of their ex- 

 istence in water, is less noticeable than the injury done 

 by the birds, but it is much greater than one would 

 suppose without investigation. 



The larvjfi of the dragon-flies, and the great water- 

 beetles and water-bugs are well-known enemies of fish. 



Several kinds of water-beetles, particularly the rapa- 

 cious dytiscus, devour fry in enormous numbers, and 

 the great water-bug, called helostoma by entomologists, 

 is also injurious in trout-waters. Both the beetles and 

 their larvae completely devour eggs and little fish 

 measuring several inches in length, while they often 

 eat holes into larger fish. This large water-beetle 

 often leaves the water, perhaps for a little exercise. 

 Whether they fly during daylight I cannot say, but I 

 have seen and secured them near an electric light lo- 

 cated within a short distance of a stream. 



We do not see and therefore do not know the full 

 extent of the depredations continually going on around 

 us, but when we stop to realize the fruits of our labor 

 and patient expectation, we are astonished by the 

 scarcity of fish and often inclined to place the blame 

 where it does not belong. Nature's checks upon over- 

 production are sometimes more effective than man's 



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