2 BULLETIN OF THE BUREAU OF FISHERIES. 



Chironomidae — Continued. Page. 



Group VI .' 33 



Group VI: Subgroup A. — Metriocnemus knabi Coquillett 33 



Head structures 33 



Feeding habits 34 



Group VI : Subgroup B. — Orthocladius sp.( ?) 35 



Larval characters 35 



Feeding habits 33 



Group VI : Subgroup C. — Prodiamesa sp 36 



Body structures 36 



Mouth parts 36 



Feeding habits 37 



Subfamily Tanypinse 37 



Mouth parts 39 



Feeding habits 4° 



Subfamily Ceratopogonins: 4 2 



Body structures 43 



Head structures 44 



Feeding habits   45 



Summary 4° 



Orphnephilid* 4^ 



Habitat 4§ 



Feeding habits 5° 



Explanation of figures 5 1 



Bibliography °° 



CHIRONOMIDAE. 

 INTRODUCTION. 



The insects belonging to the family Chironomidae, commonly known as midges, 

 constitute an obscure group of Diptera which, on account of their small size and inoffen- 

 sive habits, have very largely escaped notice except as they may have been mistaken for 

 mosquitoes, which they resemble only in general appearence. They are, however, very- 

 common in every community from the polar region to the Tropics. The adults are often 

 seen on moist evenings flying in dense swarms near the ground, over sidewalks, or 

 under trees by the roadside, and it is in this brief period of their existence, consisting 

 of from 5 to 10 days, that they are most familiar to the general public. 



Closely related to the Chironomidae are the Orphnephilidae, a family of semiaquatic 

 insects as scarce as the Chironomidae are common, the only known habitat in this country 

 being in the environment of Ithaca, N. Y. The larval stages of the Chironomidae, 

 which extend over a period varying from all winter to 25 or 30 days, according to food 

 and weather conditions, are only infrequently observed, chiefly because of the small 

 size and secluded habits of the larvae. They are aquatic, mainly fresh-water, insects 

 living in burrows which they construct by fastening together the debris found at the 

 bottom of ponds with silk secreted by their salivary glands. The great abundance of 

 these larvae and their relation to other aquatic organisms were the fundamental consid- 

 erations that gave impetus to this study. It was hoped that an investigation of 

 their feeding habits would give a clue to the chief adaptations which have given rise to 

 their numerical dominance and widespread distribution. 



