BULLETIN OF THE UNITED STATES FISH COMMISSION. 103 



CONNECTION OF ABUNDANCE OF IVIOSS AND OF BLACK FEIES WITH 



ABUNDANCE OF TKOCT. 



[From Scientific Farmer, May, 1878.] 



It requires but very little imagination to connect the presence of moss 

 growth with the pleasures and convenience of man, so close are the links 

 of facts which join one circumstance with another. In the unsettled 

 wooded regions we find the torment of black flies and mosquitoes, which 

 oppress the inhabitants and render it difficult in the newly-cleared land 

 of Maine to summer young stock. On the confines of the Arctic regions 

 they are mentioned by voyagers as plagues of existence ; and they are 

 a serious drawback to the comfort of the tourist who seeks in the Gulf 

 of Bothnia to see the midnight sun. Lsestadius says that he will not 

 affirm that they have ever devoured a living man, but that many young 

 cattle, such as lambs and calves, have been worried out of their lives 

 by them. All the people of Lapland declare that young birds are killed 

 by them, which is not improbable, says our author. Wherever in Maine 

 we find trout the most abundant, there we find the black fly, the gnat, 

 and the mosquito in overpowering abundance ; and as the country be- 

 comes settled these pests of man diminish and disappear ; and, as angler- 

 sportsmen note with grief, there is a diminution of the fish, which they 

 ascribe usually to poaching, and to the destruction brought about by 

 the rod, the spear, or the seine ; and in cases of late years have en- 

 deavored to check this disappearance through the hatching of ova and 

 the restocking of the waters. These gentlemen, however commendable 

 their intentions, have overlooked the fact that there is a relation be- 

 tween the fish and its food ; and with the destruction of the moss of 

 the forests the breeding ground of the food insects is taken away, and 

 the food supply thereby diminished. In the clearing of the land and 

 the thinning of the forests are causes at work, through the diminution 

 of the insects which furnish the food to the trout, by the destruction of 

 the mosses, whereby the moisture essential for the development of the 

 insect ova is retained, which acts more disastrously on the fish than the 

 rod or the spear. In proof of this we offer our own experience that in- 

 sects abound in greater abundance in mossy woods than in second 

 growth; that trout brooks which flow through mossy woods are usually 

 more prolific of trout than neighboring brooks whose flow is through 

 cleared land or second growth; that artificially-stocked ponds and 

 streams in settled regions are never equal to the support of as much 

 trout-life as like streams in the backwoods of Maine; that fishing can- 

 not exterminate trout in the region of the black fly. Let us illustrate 

 by an opposite fact recorded by Williams in his History of Vermont. 

 In a pond formed by damming a small stream, to obtain water-power 

 for a saw -mill, and covering one thousand acres of primitive forest, the 



