394 Inland Water Culture 



fish. In a most extensive examination of the contents 

 of fish stomachs Forbes ('88) found them "of remarkable 

 importance, making in fact nearly one- tenth of the 

 food of all the fishes studied/' Ferguson fed some red- 

 bellied minnows (Chrosomus erythrogaster) for 22 days 

 all the midge larvae (Chronomus viridicollis) they would 

 eat and nothing else. The grown minnows ate on an 

 average twenty-five blood-worms per day; the half- 

 grown ones, eleven. The senior author ('03) found that 

 25 brook trout taken at random from one of the best 

 natural ponds of the New York State Fish and Game 

 Commission at Saranac Inn, N. Y., had in their 

 stomachs more than 100 blood-worms each. 



Midge larvae are among the most ubiquitous of 

 freshwater organisms. They feed mainly upon dia- 

 toms, and other simple organisms found in water or 

 growing sessile on or round about their homes; the 

 larger ones eat also the disintegrating tissues of the 

 higher plants. They dwell among all sorts of aquatic 

 plants, spreading their thin filmy tubes in every crevice 

 or along the stems. Little is seen of them there on 

 casual observation. They are like the rodents of the 

 fields, hidden in their runways. But one cannot place 

 a handful of any water weed in a dish of water without 

 soon seeing some dislodged midge larvae swimming 

 about the edges with characteristic figure-of- 8 -shaped 

 loopings of the body. 



They dwell on the bottom (see fig. 134 on p. 226). 

 Indeed, as already noted, they may dwell far out on the 

 bottom under the deep water of great lakes. Here in 

 deep darkness and heavy pressure they dwell in enor- 

 mous numbers feeding upon the rich spoils of the plancton 

 rained down on them by gravity from above. They 

 often fill the soft bed with their silt-covered flocculent 

 tubes. 



