AQUATIC MIDGES AND SOME RELATED INSECTS. 3 



That they do subsist in great numbers has been called to the author's attention 

 not alone by his own observations, but by various published and unpublished works of 

 students who have recorded them as forming an important part of the food of trout, 

 suckers, and various other fish, and of salamanders, dragonflies, mayflies, and a variety 

 of other predacious aquatic organisms. Herein lies the chief interest of these obser- 

 vations from the fish-cultural point of view, that a careful study is made of a particular 

 group of animals which are engaged in converting vegetable detritus and other organic 

 materials existing in fishponds into a form suitable for consumption by fish. How 

 useful they are as a direct medium in transforming and conserving the food supply 

 furnished by the microorganisms found in small quantities in all habitats will be shown 

 in greater detail in the subsequent discussion. 



In beginning this work the larvae of many species were examined in order to deter- 

 mine their stomach contents. The organisms found were so similar, both in number 

 and variety, to those available in a given locality that there seemed to be little or no 

 sorting in their method of feeding. Consequently, attention was directed more to their 

 method of capturing food than to the substances eaten, and it was here that the funda- 

 mental adaptations were found which enable the different genera and species to live in 

 a similar environment with a minimum amount of competition. The small size of the 

 larvae and their great power of tiding over periods of food shortage, together with their 

 capacity to live in habitats containing a scanty supply of oxygen, readily enable them 

 to subsist where a larger animal would find the food supply insufficient or the environ- 

 ment unsuited to its manner of life. 



In this study of the feeding habits the author has endeavored to associate into 

 groups those larvae which obtain their food in an essentially similar manner. An attempt 

 has been made to cover the entire family. The subfamily Chironominae has been divided 

 into six groups, while the subfamilies Tanypinae and Ceratopogoninse each constitute 

 but a single group. The number of these divisions shows in a somewhat graphic way 

 the relative size and amount of specialization of the three subfamilies. It is to be hoped 

 that these groups will be found sufficient to accommodate all the various species of the 

 family, although the two consecutive seasons devoted to this work, in the absence of ' 

 any considerable literature on the feeding habits of the larvae, are all too short a time to 

 exhaust a study involving such small and relatively obscure organisms. 



This work was done in the entomological laboratory of Cornell University, under 

 the direction of Prof. J. G. Needham, to whom the author is greatly indebted for much 

 counsel, assistance, and encouragement in the prosecution of the work. The author 

 wishes to acknowledge his appreciation of the assistance rendered by Prof. O. A. Johann- 

 sen in the identification of specimens, general suggestions, and sympathetic interest and 

 encouragement in every phase of the work. He is also greatly indebted for many favors 

 from the various members of the Department, to whom he wishes to express his appre- 

 ciation for the thoughtfulness that prompted such generous cooperation. 



TECHNIQUE. 



In order to carry on the laboratory experiments with various chironomids it was 

 found desirable to keep a number of living larvae always on hand. For most larvae very 

 simple containers proved most satisfactory. Those that live in the manner described 

 under Group III were brought home, together with "a small mass of the debris in which 



