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 larve 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 things 
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 public waters. 
H. M. Smiru, 
Commissioner of Fisheries. 
