AQUATIC INSECTS IN THE ADIRONDACKS 395 



also, than specialists have always been willing to admit. It has a para- 

 mount economic value also, for it forms the basis of nearly all intelligent 

 economic procedure. We do not yet know how the teeming aquatic life 

 of our streams and lakes and ponds maybe manipulated as terrestrial life 

 is manipulated to serve human needs, but this we may learn in due 

 time, and, when we have learned it, the accurate knowledge of the 

 habits of aquatic species of insects will be as necessary then as such 

 knowledge of economic terrestrial species is now. 



The following pages contain new observations on the habits of many 

 species — occasionally on groups of species. These will be found under 

 the accounts of the groups and the species in part 3 of this report. 



Food relations of insects and fishes. It was planned from the 

 beginning that we should study fish food, if the opportunity offered for 

 making a real contribution to the present knowledge of that subject. 

 When, through the courtesy of the state fish commission, we were given 

 working quarters in the Adirondack, hatchery, we were the more desirous 

 of attacking some of the problems which scientific fish culture needs to 

 have solved; what problems, it was at first a little difficult to decide. 



In the culture of all animals there are two principal objects to be 

 sought: i) protection for the young, and 2) forage. Past triumphs of 

 fish culture have come from the mastery of the difficulties in securing the 

 first of these, the second has scarcely been seriously undertaken. 

 While extensive food studies have been made by Prof. Forbes and a 

 number of others, from which we have learned in general terms what 

 fishes eat, still there is hardly a fish of which we may say we know what 

 species it eats, at what age, at what season, in what situations, with 

 what choice* of food. And so little are the essential features of good 

 foraging ground understood that each planting of fry in a new place is 

 still largely an experiment. 



So it seemed to me that any new study of fish food should include the 

 study of the feeding grounds, feeding habits, choice of food offered, and 

 conditions that make for the continuance and possible increase of the 

 food supply. The two smaller propagating ponds at Saranac Inn, Bone 

 and Little Green seemed to offer an excellent opportunity for contrasting 

 conditions relative to these points. Bone pond has been well stocked 

 with brook trout for some years, while Little Green, after numerous 

 annual plantings, has. remained as barren of trout as ever. 



Through the earlier part of the season some random collections of food 

 were made from trout caught in gill nets set for suckers ; but not till 

 August was there opportunity to make the studies outhned above, and 



