FOREWORD. 



The accompanying paper by Prof. Charles Branch Wilson, concerning a group of 

 common insects in relation to fish culture, merits a special comment. The author has 

 not confined himself to a mere list of dragonflies and damselflies or to the recording of 

 observations regarding their distribution, abundance, habits, and life history. He has 

 supplied such necessary information, but, more important from the point of view of the 

 Bureau of Fisheries, he has treated these insects fully and judiciously in their relations 

 to fish, and thus in their relations to the food supply and welfare of man. 



We know that some insects, through destruction of crops and property or through 

 injurious effect upon public health, are to be classed as insidious enemies of humanity 

 and to be combated in every possible way; but there are others which we have learned 

 to class as allies in the struggle for existence, since they make it possible for us to have 

 useful articles of food and clothing, or are destructive to enemy insects. 



There are many insects of several orders, including the dragonflies and damselflies, 

 which, before they begin to fly, spend a long period of existence in the water where they 

 have direct or indirect relations to the useful fishes. The attitude assumed toward any 

 of these must depend on whether they are found to be useful or harmful to fishes and to 

 man. The relations of insects and fishes are complex. Voracious insect larvae may 

 destroy the fry of fishes or may consume food otherwise available to young fishes; they 

 may destroy other and more dangerous enemies of fishes; or they may feed upon tuings 

 that are not available to the desirable fishes and themselves become food for fishes. It 

 is necessary to accumulate exact information and wisely to balance the good against the 

 evil before we can determine whether the abundance of any particular aquatic insect 

 should be opposed or promoted in the interests of an increased food supply from fishes. 



After a thorough analysis of all that has been known regarding the dragonflies and 

 damselflies and all that has been learned in the course of this investigation, the author 

 concludes with evident justification that these insects are, on the whole, of great eco- 

 nomic importance, and he recommends them to the favor of the fish-culturist. 



Studies such as this, which can be applied not only to other insects but to various 

 kinds of aquatic animals and plants, will necessarily have the effect of enabling us to 

 apply more intelligence to the practices of fish culture and the production of food from 

 private and pubHc waters. 



H. M. Smith, 



Commissioner of Fisheries. 



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